Hydrogeology

When a well is pumped or otherwise discharged, water‐levels in its neighborhood are lowered. Unless this lowering occurs instantaneously it represents a loss of storage, either by the un‐watering of a portion of the previously saturated sediments if the aquifer is nonartesian or by release of stored water by the compaction of the aquifer due to the lowered pressure if the aquifer is artesian. The mathematical theory of ground‐water hydraulics has been based, apparently entirely, on a postulate that equilibrium has been attained and therefore that water‐levels are no longer falling. In a great number of hydrologic problems, involving a well or pumping district near or in which water‐levels are falling, the current theory is therefore not strictly applicable. This paper investigates in part the nature and consequences of a mathematical theory that considers the motion of ground‐water before equilibrium is reached and, as a consequence, involves time as a variable.

@article{doi101029tr016i002p00519,
    author = "Theis, C.V.",
    title = "The relation between the lowering of the Piezometric surface and the rate and duration of discharge of a well using ground‐water storage",
    year = "1935",
    journal = "Transactions American Geophysical Union",
    abstract = "When a well is pumped or otherwise discharged, water‐levels in its neighborhood are lowered. Unless this lowering occurs instantaneously it represents a loss of storage, either by the un‐watering of a portion of the previously saturated sediments if the aquifer is nonartesian or by release of stored water by the compaction of the aquifer due to the lowered pressure if the aquifer is artesian. The mathematical theory of ground‐water hydraulics has been based, apparently entirely, on a postulate that equilibrium has been attained and therefore that water‐levels are no longer falling. In a great number of hydrologic problems, involving a well or pumping district near or in which water‐levels are falling, the current theory is therefore not strictly applicable. This paper investigates in part the nature and consequences of a mathematical theory that considers the motion of ground‐water before equilibrium is reached and, as a consequence, involves time as a variable.",
    url = "https://doi.org/10.1029/tr016i002p00519",
    doi = "10.1029/tr016i002p00519",
    openalex = "W2065463790"
}

Two examples of a previously unrecognized condition which may be confused with congenital heart disease are cited in this report. The condition may occur anywhere in rural areas where well water is used in infant feeding. REPORT OF CASES Case 1.— C. H., a white female baby, was born two weeks before the expected date by cesarean section because of toxemia of pregnancy, which had been severe for one month. The birth weight was 3,870 Gm. (8 pounds 8 ounces). There was no known neonatal distress. On the twelfth day after birth, when she left the hospital, she weighed 3,720 grams (8 pounds 3 ounces). The formula she was receiving at that time was evaporated milk 210 cc. and water 540 cc. with 30 Gm. of a dextrin-maltose preparation. She was admitted to a local hospital at 18 days of age because of vomiting, excessive crying and failure to gain

@article{doi101001jama194502860360014004,
    author = "Comly, Hunter H.",
    title = "CYANOSIS IN INFANTS CAUSED BY NITRATES IN WELL WATER",
    year = "1945",
    journal = "Journal of the American Medical Association",
    abstract = "Two examples of a previously unrecognized condition which may be confused with congenital heart disease are cited in this report. The condition may occur anywhere in rural areas where well water is used in infant feeding. REPORT OF CASES Case 1.— C. H., a white female baby, was born two weeks before the expected date by cesarean section because of toxemia of pregnancy, which had been severe for one month. The birth weight was 3,870 Gm. (8 pounds 8 ounces). There was no known neonatal distress. On the twelfth day after birth, when she left the hospital, she weighed 3,720 grams (8 pounds 3 ounces). The formula she was receiving at that time was evaporated milk 210 cc. and water 540 cc. with 30 Gm. of a dextrin-maltose preparation. She was admitted to a local hospital at 18 days of age because of vomiting, excessive crying and failure to gain",
    url = "https://doi.org/10.1001/jama.1945.02860360014004",
    doi = "10.1001/jama.1945.02860360014004",
    openalex = "W2077395072",
    references = "doi101001archpedi194002000030184020, doi101001jama193302740300020007, doi101016s0021925818449411, doi1010970000044119341200000003, doi101128jb2442732811932, doi101172jci100997, doi101172jci101033, doi101172jci101409, doi103181003797275614591"
}

@article{doi1010160016703753900519,
    author = "Epstein, Samuel and Mayeda, T. K.",
    title = "Variation of O18 content of waters from natural sources",
    year = "1953",
    journal = "Geochimica et Cosmochimica Acta",
    url = "https://doi.org/10.1016/0016-7037(53)90051-9",
    doi = "10.1016/0016-7037(53)90051-9",
    openalex = "W2039248536",
    references = "doi1010160016703753900660, doi1010160016703757900893, doi101021ja01305a026, doi101021ja01315a511, doi101021ja01862a010, doi101039jr9470000562, doi10106311745698, doi101126science1082810489, doi10113000167606195162399mopato20co2, doi10113000167606195162417cits20co2"
}

Introduction 3 Purpose and scope of report 4 Acknowledgments 5 Properties of water 5 Composition of the earth's crust 6 Water as a geochemical agent The role of water in erosion Chemistry of weathering processes Collection of quality-of-water data Collection of water samples Surface-water sampling Ground-water sampling Completeness of sample coverage Analyses of water samples Field testing of water Electric logs as indicators of ground-water quality Laboratory procedures Expression of water analyses Analyses reported in terms of hypothetical combinations Analyses expressed in terms of ions Determinations included in analyses Units used in reporting analyses Weight-per-weight units Weight-per-volume units Equivalent-weight units Composition of anhydrous residue Parts per million as calcium carbonate Comparison of units of expression Significance of properties and constituents reported in water analyses_ _ Specific electrical conductance Units for reporting conductance Physical basis of conductance Range of conductance values Accuracy and reproducibility of conductance values Hydrogen-ion concentration (pH) Hydrolysis Buffered solutions Interpretation of pH data Range of pH values Accuracy and reproducibility of pH values Color Sources and significance of color in water 49 Residue on evaporition 49 Theoretical basis of determination 50 Range of concentration 51 Accuracy and reproducibility of results 51 III Significance of properties and constituents reported in water analyses-Continued Acidity Sources of acidity of natural water Chemistry of acidity determination Range of concentration Reproducibility of acidity data Sulfate Sources of sulfate in natural water Chemistry of sulfate in natural water Range of concentration Accuracy and reproducibility of results Chloride Sources of chloride in water Chemistry of chloride in natural water Oceanic chloride Juvenile chloride Cyclic chloride Range of concentration Accuracy and reproducibility of results Fluoride Source of fluoride in water Chemistry of fluoride in natural water Range of concentration Accuracy and reproducibility of results Nitrate Source of nitrate in water Chemistry of nitrate in natural water 116 Range of concentration Accuracy and reproducibility of results Phosphate Sources of phosphate Chemistry of phosphate in natural water 119 Range of concentration 120 Accuracy and reproducibility of results 120 Boron 120 Sources of boron 120 Chemistry of boron in natural water Range of concentration 122 Accuracy and reproducibility of results 122 Trace or minor constituents-Cations 124 Heavy metals 124 Titanium 124 Chromium 124 Zinc 125 Nickel and cobalt 126 Copper 126 Tin 127 Lead 127 Cadmium 128 Mercury 128 Arsenic 129 Selenium 130 Significance of properties and constituents reported in water analyses-Continued Trace or minor constituents-Cations-Continued Alkaline-earth metals Beryllium Strontium Barium Alkali metals and ammonium Lithium Rubidium Cesium Ammonium Radioactive components Uranium Radium Radon Thorium Trace or minor constituents-Anions Bromide Iodide Sulfite and thiosulf ate Total dissolved solids-Computed Chemistry of dissolved solids determination Accuracy and reproducibility of results Dissolved gases Biochemical oxygen demand Hardness Utilization Range of concentration Accuracy and reproducibility of results Percent sodium Sodium-adsorption ratio Density Organization and study of water-analysis data Evaluation of water analyses Tabulation Study techniques Inspection and comparison Use of ratios Use of averages 156 Palmer's geochemical classification 162 Graphical representation 164 Scatter diagrams 165 Ionic-concentration diagrams 168 Percentage-composition diagrams Frequency diagrams Chemical analyses plotted against nonchemical variables 186 Hydrographs 186 Dissolved-solids rating curves 188 Water-quality profiles 192 Quality-of-water maps 192 Selection of study techniques 10. Effect of temperature on solubility of calcium carbonate (calcite) in water in the presence of CO2 VIII CONTENTS Page FIGURE 11. Solubility of magnesium carbonate in water at 25C in the presence of CO2 81 12. Relation of conductance to chloride, hardness, and sulfate concentrations, Gila River at Bylas, Ariz., Oct. 1, 1943 to Sept. 30, 1944 13. Sodium-chloride relationship, Gila River at Bylas, Ariz., Oct. 1, 1943, to Sept. 30, 1944 14. Analyses represented by vertical bar graphs of equivalents per million 15. Analyses represented by bar graphs of parts per million 16. Bar graph of equivalents per million which also shows hardness values in parts per million 17. Analyses in equivalents per million represented by vectors__ _ 18. Analyses represented by patterns based on equivalents per million 19. Analyses represented by linear plotting of cumulative percentage composition based on parts per million 20. Analyses represented by logarithmic plotting of concentrations in parts per million 21. Analyses represented by circular diagrams subdivided on the basis of percent of total equivalents per million 22. Analyses represented by bar-patterns based on percent of total equivalents per million 23. Analyses represented by patterns drawn on radial coordinates.. 24. Analyses represented by three points plotted in trilinear diagram (after A. M. Piper) 25. Number of samples having percent sodium within ranges indicated, San Simon artesian basin, Ariz 26. Cumulative frequency curve of specific conductance, Allegheny, Monongahela and Ohio River waters, Pittsburgh area, Pennsylvania, 1944-50 27. Specific conductance of daily samples and daily mean discharge, San Francisco River at Clifton, Ariz., Oct. 1, 1943 to Sept. 30, 1944 28. Bicarbonate, sulfate, hardness, and pH of samples collected in cross section of Susquehanna River at Harrisburg, Pa., July 8, 1947 29. Temperature and dissolved solids of water in Lake Mead in Virgin and Boulder Canyons, 1948 194 30. Total concentration and hardness of water from deeper wells in Prairie Creek Unit, Nebr 31. Ratio of alkalinity to sulfate in water from unconsolidated deposits in the Torrington area, Nebr 32. Map of portions of Apache and Navajo counties, Ariz., showing mineral content of ground water in the Coconino sandstone_ 198 33. Analyses of waters associated with igneous rocks 206 34. Analyses of waters associated with resistate sediments 209 35. Analyses of waters associated with hydrolyzate sediments_ _ _ 36. Weighted-average analyses for Rio Grande at San Acacia, N. Mex., for two periods in the 1945-46 water year 212 37. Analyses of waters associated with precipitate-type sediments.. 38. Analyses of waters associated with evaporate sediments 215 39. Analyses of waters associated with metamorphic rocks 217 40. Diagram for use in interpreting the analysis of irrigation water_ 251 2 CHEMICAL CHARACTERISTICS OF NATURAL WATER

@misc{doi103133wsp1473ed1,
    author = "Hem, John David",
    title = "Study and interpretation of the chemical characteristics of natural water",
    year = "1959",
    abstract = "Introduction 3 Purpose and scope of report 4 Acknowledgments 5 Properties of water 5 Composition of the earth's crust 6 Water as a geochemical agent The role of water in erosion Chemistry of weathering processes Collection of quality-of-water data Collection of water samples Surface-water sampling Ground-water sampling Completeness of sample coverage Analyses of water samples Field testing of water Electric logs as indicators of ground-water quality Laboratory procedures Expression of water analyses Analyses reported in terms of hypothetical combinations Analyses expressed in terms of ions Determinations included in analyses Units used in reporting analyses Weight-per-weight units Weight-per-volume units Equivalent-weight units Composition of anhydrous residue Parts per million as calcium carbonate Comparison of units of expression Significance of properties and constituents reported in water analyses\_ \_ Specific electrical conductance Units for reporting conductance Physical basis of conductance Range of conductance values Accuracy and reproducibility of conductance values Hydrogen-ion concentration (pH) Hydrolysis Buffered solutions Interpretation of pH data Range of pH values Accuracy and reproducibility of pH values Color Sources and significance of color in water 49 Residue on evaporition 49 Theoretical basis of determination 50 Range of concentration 51 Accuracy and reproducibility of results 51 III Significance of properties and constituents reported in water analyses-Continued Acidity Sources of acidity of natural water Chemistry of acidity determination Range of concentration Reproducibility of acidity data Sulfate Sources of sulfate in natural water Chemistry of sulfate in natural water Range of concentration Accuracy and reproducibility of results Chloride Sources of chloride in water Chemistry of chloride in natural water Oceanic chloride Juvenile chloride Cyclic chloride Range of concentration Accuracy and reproducibility of results Fluoride Source of fluoride in water Chemistry of fluoride in natural water Range of concentration Accuracy and reproducibility of results Nitrate Source of nitrate in water Chemistry of nitrate in natural water 116 Range of concentration Accuracy and reproducibility of results Phosphate Sources of phosphate Chemistry of phosphate in natural water 119 Range of concentration 120 Accuracy and reproducibility of results 120 Boron 120 Sources of boron 120 Chemistry of boron in natural water Range of concentration 122 Accuracy and reproducibility of results 122 Trace or minor constituents-Cations 124 Heavy metals 124 Titanium 124 Chromium 124 Zinc 125 Nickel and cobalt 126 Copper 126 Tin 127 Lead 127 Cadmium 128 Mercury 128 Arsenic 129 Selenium 130 Significance of properties and constituents reported in water analyses-Continued Trace or minor constituents-Cations-Continued Alkaline-earth metals Beryllium Strontium Barium Alkali metals and ammonium Lithium Rubidium Cesium Ammonium Radioactive components Uranium Radium Radon Thorium Trace or minor constituents-Anions Bromide Iodide Sulfite and thiosulf ate Total dissolved solids-Computed Chemistry of dissolved solids determination Accuracy and reproducibility of results Dissolved gases Biochemical oxygen demand Hardness Utilization Range of concentration Accuracy and reproducibility of results Percent sodium Sodium-adsorption ratio Density Organization and study of water-analysis data Evaluation of water analyses Tabulation Study techniques Inspection and comparison Use of ratios Use of averages 156 Palmer's geochemical classification 162 Graphical representation 164 Scatter diagrams 165 Ionic-concentration diagrams 168 Percentage-composition diagrams Frequency diagrams Chemical analyses plotted against nonchemical variables 186 Hydrographs 186 Dissolved-solids rating curves 188 Water-quality profiles 192 Quality-of-water maps 192 Selection of study techniques 10. Effect of temperature on solubility of calcium carbonate (calcite) in water in the presence of CO2 VIII CONTENTS Page FIGURE 11. Solubility of magnesium carbonate in water at 25C in the presence of CO2 81 12. Relation of conductance to chloride, hardness, and sulfate concentrations, Gila River at Bylas, Ariz., Oct. 1, 1943 to Sept. 30, 1944 13. Sodium-chloride relationship, Gila River at Bylas, Ariz., Oct. 1, 1943, to Sept. 30, 1944 14. Analyses represented by vertical bar graphs of equivalents per million 15. Analyses represented by bar graphs of parts per million 16. Bar graph of equivalents per million which also shows hardness values in parts per million 17. Analyses in equivalents per million represented by vectors\_\_ \_ 18. Analyses represented by patterns based on equivalents per million 19. Analyses represented by linear plotting of cumulative percentage composition based on parts per million 20. Analyses represented by logarithmic plotting of concentrations in parts per million 21. Analyses represented by circular diagrams subdivided on the basis of percent of total equivalents per million 22. Analyses represented by bar-patterns based on percent of total equivalents per million 23. Analyses represented by patterns drawn on radial coordinates.. 24. Analyses represented by three points plotted in trilinear diagram (after A. M. Piper) 25. Number of samples having percent sodium within ranges indicated, San Simon artesian basin, Ariz 26. Cumulative frequency curve of specific conductance, Allegheny, Monongahela and Ohio River waters, Pittsburgh area, Pennsylvania, 1944-50 27. Specific conductance of daily samples and daily mean discharge, San Francisco River at Clifton, Ariz., Oct. 1, 1943 to Sept. 30, 1944 28. Bicarbonate, sulfate, hardness, and pH of samples collected in cross section of Susquehanna River at Harrisburg, Pa., July 8, 1947 29. Temperature and dissolved solids of water in Lake Mead in Virgin and Boulder Canyons, 1948 194 30. Total concentration and hardness of water from deeper wells in Prairie Creek Unit, Nebr 31. Ratio of alkalinity to sulfate in water from unconsolidated deposits in the Torrington area, Nebr 32. Map of portions of Apache and Navajo counties, Ariz., showing mineral content of ground water in the Coconino sandstone\_ 198 33. Analyses of waters associated with igneous rocks 206 34. Analyses of waters associated with resistate sediments 209 35. Analyses of waters associated with hydrolyzate sediments\_ \_ \_ 36. Weighted-average analyses for Rio Grande at San Acacia, N. Mex., for two periods in the 1945-46 water year 212 37. Analyses of waters associated with precipitate-type sediments.. 38. Analyses of waters associated with evaporate sediments 215 39. Analyses of waters associated with metamorphic rocks 217 40. Diagram for use in interpreting the analysis of irrigation water\_ 251 2 CHEMICAL CHARACTERISTICS OF NATURAL WATER",
    url = "https://doi.org/10.3133/wsp1473\_ed1",
    doi = "10.3133/wsp1473\_ed1",
    openalex = "W2064299399",
    references = "doi101001jama194502860360014004, doi101002j155188331936tb13785x, doi101002j155188331942tb19682x, doi101029tr022i003p00593, doi101029tr025i006p00914, doi101093aibsbulletin4314a, doi101130001676061957681637twovo20co2, doi102118951376g, doi1023071438154, openalexw3121961717"
}

The relationship between deuterium and oxygen-18 concentrations in natural meteoric waters from many parts of the world has been determined with a mass spectrometer. The isotopic enrichments, relative to ocean water, display a linear correlation over the entire range for waters which have not undergone excessive evaporation.

@article{doi101126science13334651702,
    author = "Craig, Harmon",
    title = "Isotopic Variations in Meteoric Waters",
    year = "1961",
    journal = "Science",
    abstract = "The relationship between deuterium and oxygen-18 concentrations in natural meteoric waters from many parts of the world has been determined with a mass spectrometer. The isotopic enrichments, relative to ocean water, display a linear correlation over the entire range for waters which have not undergone excessive evaporation.",
    url = "https://doi.org/10.1126/science.133.3465.1702",
    doi = "10.1126/science.133.3465.1702",
    openalex = "W2072191315",
    references = "doi1010160016703753900519, doi1010160016703753900660, doi101126science13334671833, openalexw428795670"
}

A standard, based on the set of ocean water samples used by Epstein and Mayeda to obtain a reference standard for oxygen-18 data, but defined relative to the National Bureau of Standards isotopic reference water sample, is proposed for reporting both deuterium and oxygen-18 variations in natural waters relative to the same water. The range of absolute concentrations of both isotopes in meteoric-waters is discussed.

@article{doi101126science13334671833,
    author = "Craig, Harmon",
    title = "Standard for Reporting Concentrations of Deuterium and Oxygen-18 in Natural Waters",
    year = "1961",
    journal = "Science",
    abstract = "A standard, based on the set of ocean water samples used by Epstein and Mayeda to obtain a reference standard for oxygen-18 data, but defined relative to the National Bureau of Standards isotopic reference water sample, is proposed for reporting both deuterium and oxygen-18 variations in natural waters relative to the same water. The range of absolute concentrations of both isotopes in meteoric-waters is discussed.",
    url = "https://doi.org/10.1126/science.133.3467.1833",
    doi = "10.1126/science.133.3467.1833",
    openalex = "W2045469782",
    references = "doi1010160016703753900519, doi1010160016703757900248, doi101126science13334651702"
}

gallons per day), exclusive of water used to develop water power. This estimated use amounts to about 1,500 gpd {gal Ions per day) per capita. An additional 2,000,000 mgd were used to develop waterpower.

@article{doi103133cir456,
    author = "MacKichan, Kenneth Allen and Kammerer, J.C.",
    title = "Estimated use of water in the United States, 1960",
    year = "1961",
    journal = "U.S. Geological Survey circular/U.S. Geological Survey Circular",
    abstract = "gallons per day), exclusive of water used to develop water power. This estimated use amounts to about 1,500 gpd (gal Ions per day) per capita. An additional 2,000,000 mgd were used to develop waterpower.",
    url = "https://doi.org/10.3133/cir456",
    doi = "10.3133/cir456",
    openalex = "W2011796950"
}

@article{doi1010160016703762900273,
    author = "Morey, G. W. and Fournier, Robert O. and Rowe, J. J.",
    title = "The solubility of quartz in water in the temperature interval from 25° to 300° C",
    year = "1962",
    journal = "Geochimica et Cosmochimica Acta",
    url = "https://doi.org/10.1016/0016-7037(62)90027-3",
    doi = "10.1016/0016-7037(62)90027-3",
    openalex = "W2060027402"
}

@article{doi101111j215334901970tb00540x,
    author = "Hagemann, Robert and Nief, Guillaume and Roth, E.",
    title = "Absolute isotopic scale for deuterium analysis of natural waters. Absolute D/H ratio for SMOW",
    year = "1970",
    journal = "Tellus",
    url = "https://doi.org/10.1111/j.2153-3490.1970.tb00540.x",
    doi = "10.1111/j.2153-3490.1970.tb00540.x",
    openalex = "W4245811558"
}

The absolute isotopic ratios of the hydrogen content of two reference water standards called “SMOW”2 and “SLAP3 were measured to define an absolute isotopic scale. This isotopic scale can be used to normalize measurements of the natural isotopic variations in waters. The principle of the method used to define the zero of the scale is given. The absolute D/H ratios of SMOW and SLAP were measured by mass spectrometric comparison with calibration mixtures prepared in the laboratory. The following values are obtained: (DH)SMOW=155.76±0.05×10−6 (DH)SLAP=89.02±0.05×10−6 δSLAP/SMOV=428.50±0.10Samples of about 20 cc of the reference standards SMOW and SLAP are available from the International Atomic Energy Agency, on request.

@article{doi103402tellusav22i610278,
    author = "Hagemann, Robert and Nief, Guillaume and Roth, E.",
    title = "Absolute isotopic scale for deuterium analysis of natural waters. Absolute D/H ratio for SMOW 1",
    year = "1970",
    journal = "Tellus A Dynamic Meteorology and Oceanography",
    abstract = "The absolute isotopic ratios of the hydrogen content of two reference water standards called “SMOW”2 and “SLAP3 were measured to define an absolute isotopic scale. This isotopic scale can be used to normalize measurements of the natural isotopic variations in waters. The principle of the method used to define the zero of the scale is given. The absolute D/H ratios of SMOW and SLAP were measured by mass spectrometric comparison with calibration mixtures prepared in the laboratory. The following values are obtained: (DH)SMOW=155.76±0.05×10−6 (DH)SLAP=89.02±0.05×10−6 δSLAP/SMOV=428.50±0.10Samples of about 20 cc of the reference standards SMOW and SLAP are available from the International Atomic Energy Agency, on request.",
    url = "https://doi.org/10.3402/tellusa.v22i6.10278",
    doi = "10.3402/tellusa.v22i6.10278",
    openalex = "W1977727470"
}

@article{doi1010160022169471900631,
    title = "Definitions of selected ground-water terms: Revisions and conceptual refinements",
    year = "1971",
    journal = "Journal of Hydrology",
    url = "https://doi.org/10.1016/0022-1694(71)90063-1",
    doi = "10.1016/0022-1694(71)90063-1",
    openalex = "W4242045774"
}

Area (8); area of influence (145). l/VT/(K'/V) (95).

@article{doi103133pp708,
    author = "Lohman, Stanley William",
    title = "Ground-Water Hydraulics",
    year = "1972",
    journal = "USGS professional paper",
    abstract = "Area (8); area of influence (145). l/VT/(K'/V) (95).",
    url = "https://doi.org/10.3133/pp708",
    doi = "10.3133/pp708",
    openalex = "W2256178971"
}

@article{thrailkill1972carbonate5,
    author = "Thrailkill, J. V",
    title = "Carbonate chemistry of aquifer and stream water in Kentucky",
    year = "1972",
    journal = "Journal of Hydrology, v. 16, p. 93-104",
    note = "talkorigins\_source = {true}; raw\_reference = {Thrailkill, J. V., 1972, Carbonate chemistry of aquifer and stream water in Kentucky: Journal of Hydrology, v. 16, p. 93-104.}"
}

@article{doi101021j100551a008,
    author = "Rolston, J. H. and Hartog, J. Den and Butler, J. P.",
    title = "The deuterium isotope separation factor between hydrogen and liquid water",
    year = "1976",
    journal = "The Journal of Physical Chemistry",
    url = "https://doi.org/10.1021/j100551a008",
    doi = "10.1021/j100551a008",
    openalex = "W131875977"
}

Abstract: WATEQF is a FORTRAN IV computer program that models the thermodynamic speciation of inorganic ions and complex species in solution for a given water analysis. The original version (WATEQ) was written in 1973 by A. H. Truesdell and B. F. Jones in Programming Language/one (PL/1). With but a few exceptions, the thermochemical data, speciation, activity coefficients, and general calculation procedure of WATEQF is identical to the PL/1 version. This report notes the differences between WATEQF and WATEQ, demonstrates how to set up the input data to execute WATEQF, provides a test case for comparison, and makes available a listing of WATEQF.

@misc{doi103133wri7613,
    author = "Plummer, L. Niel and Jones, Blair F. and Truesdell, A.H.",
    title = "WATEQF; a FORTRAN IV version of WATEQ: a computer program for calculating chemical equilibrium of natural waters",
    year = "1976",
    abstract = "Abstract: WATEQF is a FORTRAN IV computer program that models the thermodynamic speciation of inorganic ions and complex species in solution for a given water analysis. The original version (WATEQ) was written in 1973 by A. H. Truesdell and B. F. Jones in Programming Language/one (PL/1). With but a few exceptions, the thermochemical data, speciation, activity coefficients, and general calculation procedure of WATEQF is identical to the PL/1 version. This report notes the differences between WATEQF and WATEQ, demonstrates how to set up the input data to execute WATEQF, provides a test case for comparison, and makes available a listing of WATEQF.",
    url = "https://doi.org/10.3133/wri7613",
    doi = "10.3133/wri7613",
    openalex = "W48205232"
}

@misc{guisti1978hydrogeology2,
    author = "Guisti, E. V",
    title = "Hydrogeology of the karst of Puerto Rico",
    year = "1978",
    howpublished = "United States Geological Survey, Professional Paper, v. 1012; 68 pp",
    note = "talkorigins\_source = {true}; raw\_reference = {Guisti, E. V., 1978, Hydrogeology of the karst of Puerto Rico: United States Geological Survey, Professional Paper, v. 1012; 68 pp.}"
}

@article{openalexw2746809854,
    author = "Konikow, Leonard F.",
    title = "Calibration of Ground-Water Models",
    year = "1978",
    openalex = "W2746809854"
}

@misc{ref1978hydrogeochemical1,
    author = "---",
    title = "Hydrogeochemical conditions of the oil and gas reserves of the Tunguska basin",
    year = "1978",
    howpublished = "Geology of Oil and Gas, v. 3, p. 30-36",
    note = "talkorigins\_source = {true}; raw\_reference = {---, 1978, Hydrogeochemical conditions of the oil and gas reserves of the Tunguska basin: Geology of Oil and Gas, v. 3, p. 30-36.}"
}

@article{doi1010160020708x80900174,
    author = "Unterweger, Michael P. and Coursey, Bert M. and Schima, F.J. and Mann, W.B.",
    title = "Preparation and calibration of the 1978 National Bureau of Standards tritiated-water standards",
    year = "1980",
    journal = "The International Journal of Applied Radiation and Isotopes",
    url = "https://doi.org/10.1016/0020-708x(80)90017-4",
    doi = "10.1016/0020-708x(80)90017-4",
    openalex = "W2004177332"
}

@article{doi101021ac50064a053,
    author = "Tse, R. S. and Wong, S. C. and Yuen, C. P.",
    title = "Determination of deuterium/hydrogen ratios in natural waters by Fourier transform nuclear magnetic resonance spectrometry",
    year = "1980",
    journal = "Analytical Chemistry",
    url = "https://doi.org/10.1021/ac50064a053",
    doi = "10.1021/ac50064a053",
    openalex = "W2071806691"
}

@misc{meler1981hydrologic4,
    author = "Meler, M. F. and Carpenter, P. J. and Janda, R. J",
    title = "Hydrologic effects of Mount St. Helens' 1980 eruption",
    year = "1981",
    howpublished = "Eos, v. 62, no. 33, p. 625-626",
    note = "talkorigins\_source = {true}; raw\_reference = {Meler, M. F., Carpenter, P. J., and Janda, R. J., 1981, Hydrologic effects of Mount St. Helens' 1980 eruption: Eos, v. 62, no. 33, p. 625-626.}"
}

@article{doi101021ac00243a035,
    author = "Coleman, Max and Shepherd, T. J. and Durham, John J. and Rouse, J. E. and Moore, Gillian R.",
    title = "Reduction of water with zinc for hydrogen isotope analysis",
    year = "1982",
    journal = "Analytical Chemistry",
    url = "https://doi.org/10.1021/ac00243a035",
    doi = "10.1021/ac00243a035",
    openalex = "W2092868748"
}

BALANCE is a Fortran computer program designed to define and quantify chemical reactions between ground water and minerals. Using (1) the chemical compositions of water samples from two points along a flow path and (2) a set of mineral phases hypothesized to be the reactive constituents in the system, the program calculates the mass transfer (amounts of the phases entering or leaving the aqueous phase) necessary to account for the observed changes in composition between the two water samples. Additional constraints can be included in the problem formulation to account for mixing of two end-member waters, redox reactions, and, in a simplified form, isotopic composition. The computer code and a description of the input necessary to run the program are presented. Three examples typical of groundwater systems are described.

@misc{doi103133wri8214,
    author = "Parkhurst, David L. and Plummer, L. Niel and Thorstenson, Donald C.",
    title = "BALANCE: A computer program for calculating mass transfer for geochemical reactions in ground water",
    year = "1982",
    abstract = "BALANCE is a Fortran computer program designed to define and quantify chemical reactions between ground water and minerals. Using (1) the chemical compositions of water samples from two points along a flow path and (2) a set of mineral phases hypothesized to be the reactive constituents in the system, the program calculates the mass transfer (amounts of the phases entering or leaving the aqueous phase) necessary to account for the observed changes in composition between the two water samples. Additional constraints can be included in the problem formulation to account for mixing of two end-member waters, redox reactions, and, in a simplified form, isotopic composition. The computer code and a description of the input necessary to run the program are presented. Three examples typical of groundwater systems are described.",
    url = "https://doi.org/10.3133/wri8214",
    doi = "10.3133/wri8214",
    openalex = "W135036310"
}

1. The Hydrologic Cycle. 2. Chemical Background. 3. Organic Compounds in Natural Waters. 4. The Carbonate System and pH Control. 5. Clay Minerals and Ion Exchange. 6. Stability Relationships and Silicate Equilibria. 7. Kinetics. 8. Weathering and Water Chemistry, I: Principles. 9. Weathering and Water Chemistry, II: Examples. 10. Acid Deposition and Surface Water Chemistry. 11. Evaporation and Saline Waters. 12. The Oceans. 13. Redox Equilibria. 14. Redox Conditions in Natural Waters. 15. Trace Elements. 16. Mathematical and Numerical Models. 17. Isotopes. Appendices.

@book{openalexw1591787667,
    author = "Drever, James I.",
    title = "Geochemistry of Natural Waters",
    year = "1982",
    abstract = "1. The Hydrologic Cycle. 2. Chemical Background. 3. Organic Compounds in Natural Waters. 4. The Carbonate System and pH Control. 5. Clay Minerals and Ion Exchange. 6. Stability Relationships and Silicate Equilibria. 7. Kinetics. 8. Weathering and Water Chemistry, I: Principles. 9. Weathering and Water Chemistry, II: Examples. 10. Acid Deposition and Surface Water Chemistry. 11. Evaporation and Saline Waters. 12. The Oceans. 13. Redox Equilibria. 14. Redox Conditions in Natural Waters. 15. Trace Elements. 16. Mathematical and Numerical Models. 17. Isotopes. Appendices.",
    openalex = "W1591787667"
}

@article{doi101021es00115a705,
    author = "Smeenk, Ir. J.G.M.M.",
    title = "Drinking water contaminants",
    year = "1983",
    journal = "Environmental Science \& Technology",
    url = "https://doi.org/10.1021/es00115a705",
    doi = "10.1021/es00115a705",
    openalex = "W2314464333"
}

@article{doi101021ac00284a058,
    author = "Kendall, Carol and Coplen, Tyler B.",
    title = "Multi-sample conversion of water to hydrogen by zinc for stable isotope determination",
    year = "1985",
    journal = "Analytical Chemistry",
    url = "https://doi.org/10.1021/ac00284a058",
    doi = "10.1021/ac00284a058",
    openalex = "W2043828653"
}

Central High Plains model calibration.

@article{doi103133pp1400d,
    author = "Luckey, Richard R. and Gutentag, Edwin D. and Heimes, F.J. and Weeks, John B.",
    title = "Digital simulation of ground-water flow in the High Plains Aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming",
    year = "1986",
    journal = "USGS professional paper",
    abstract = "Central High Plains model calibration.",
    url = "https://doi.org/10.3133/pp1400d",
    doi = "10.3133/pp1400d",
    openalex = "W1558055298"
}

Abstract To help make decisions on shifting of crop species in water management strategies, information is needed on comparative water use characteristics of the principal row crops. The objective of this study was to compare the water use characteristics of six row crops grown in a replicated and randomized field experiment. Crops were corn (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], pearl millet [Pennisetum amerlcanum (L.) Leeke], pinto bean (Phaseolus vulgaris L.), soybean [Glycine max (L.) Merr.], and sunflower (Helianthus annuus L.). Crops were grown near Manhattan, KS, on Muir silt loam (Cumulic Haplustoll) in 1981 and on Eudora silt loam (Fluventic Hapludoll) in 1982, and near Tribune, KS, on Ulysses silt loam (Aridic Haplustoll) in both 1981 and 1982. Soil water content was determined to the 3.1‐m soil profile depth by the neutron attenuation method. Measured evapotranspiration (ET) was calculated as the sum of soil water depletion, rainfall, and irrigation. Reference ET was calculated by using the original Jensen‐Haise equation. The maximum value of measured ET/reference ET was greater for sunflower (1.35) than for the other five crops (ranged from 1.05 to 1.15). The mean daily water use rate of sunflower (6.1 mm d− 1) was 22% greater than the mean of the other five crops (5.0 mm d− 1). The mean dry matter water use efficiency was 17.5 Mg ha− 1 m− 1 for the group of C 3 crops (pinto bean, soybean, and sunflower) and 33.3 Mg ha− 1 m− 1 for the group of C 4 crops (corn, grain sorghum, and pearl millet). Sunflower depleted significantly more water from deeper soil depths (0.99‐1.60 m) than the other five crops at Manhattan in 1981 and 1982. Our findings consistently showed that sunflower had a greater daily water use rate than the other five crops.

@article{doi102134agronj198800021962008000010019x,
    author = "Hattendorf, M. J. and Redelfs, M. S. and Amos, Brigid and Stone, L. R. and Gwin, Roy E.",
    title = "Comparative Water Use Characteristics of Six Row Crops",
    year = "1988",
    journal = "Agronomy Journal",
    abstract = "Abstract To help make decisions on shifting of crop species in water management strategies, information is needed on comparative water use characteristics of the principal row crops. The objective of this study was to compare the water use characteristics of six row crops grown in a replicated and randomized field experiment. Crops were corn (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], pearl millet [Pennisetum amerlcanum (L.) Leeke], pinto bean (Phaseolus vulgaris L.), soybean [Glycine max (L.) Merr.], and sunflower (Helianthus annuus L.). Crops were grown near Manhattan, KS, on Muir silt loam (Cumulic Haplustoll) in 1981 and on Eudora silt loam (Fluventic Hapludoll) in 1982, and near Tribune, KS, on Ulysses silt loam (Aridic Haplustoll) in both 1981 and 1982. Soil water content was determined to the 3.1‐m soil profile depth by the neutron attenuation method. Measured evapotranspiration (ET) was calculated as the sum of soil water depletion, rainfall, and irrigation. Reference ET was calculated by using the original Jensen‐Haise equation. The maximum value of measured ET/reference ET was greater for sunflower (1.35) than for the other five crops (ranged from 1.05 to 1.15). The mean daily water use rate of sunflower (6.1 mm d− 1) was 22\% greater than the mean of the other five crops (5.0 mm d− 1). The mean dry matter water use efficiency was 17.5 Mg ha− 1 m− 1 for the group of C 3 crops (pinto bean, soybean, and sunflower) and 33.3 Mg ha− 1 m− 1 for the group of C 4 crops (corn, grain sorghum, and pearl millet). Sunflower depleted significantly more water from deeper soil depths (0.99‐1.60 m) than the other five crops at Manhattan in 1981 and 1982. Our findings consistently showed that sunflower had a greater daily water use rate than the other five crops.",
    url = "https://doi.org/10.2134/agronj1988.00021962008000010019x",
    doi = "10.2134/agronj1988.00021962008000010019x",
    openalex = "W2055053987"
}

The Regional Aquifer-System Analysis (RASA) Program was started in 1978 following a congressional mandate to develop quantitative appraisals of the major ground-water systems of the United States. The RASA Program represents a systematic effort to study a number of the Nation's most important aquifer systems, which in aggregate underlie much of the country and which represent an important component of the Nation's total water supply. In general, the boundaries of these studies are identified by the hydrologic extent of each system and accordingly transcend the political subdivisions to which investigations have often arbitrarily been limited in the past. The broad objective for each study is to assemble geologic, hydrologic, and geochemical information, to analyze and develop an understanding of the system, and to develop predictive capabilities that will contribute to the effective management of the system. The use of computer simulation is an important element of the RASA studies, both to develop an understanding of the natural, undisturbed hydrologic system and the changes brought about in it by human activities, and to provide a means of predicting the regional effects of future pumping or other stresses.

@article{doi103133pp1403c,
    author = "Bush, Peter W. and Johnston, Richard H.",
    title = "Ground-water hydraulics, regional flow, and ground-water development of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama",
    year = "1988",
    journal = "USGS professional paper",
    abstract = "The Regional Aquifer-System Analysis (RASA) Program was started in 1978 following a congressional mandate to develop quantitative appraisals of the major ground-water systems of the United States. The RASA Program represents a systematic effort to study a number of the Nation's most important aquifer systems, which in aggregate underlie much of the country and which represent an important component of the Nation's total water supply. In general, the boundaries of these studies are identified by the hydrologic extent of each system and accordingly transcend the political subdivisions to which investigations have often arbitrarily been limited in the past. The broad objective for each study is to assemble geologic, hydrologic, and geochemical information, to analyze and develop an understanding of the system, and to develop predictive capabilities that will contribute to the effective management of the system. The use of computer simulation is an important element of the RASA studies, both to develop an understanding of the natural, undisturbed hydrologic system and the changes brought about in it by human activities, and to provide a means of predicting the regional effects of future pumping or other stresses.",
    url = "https://doi.org/10.3133/pp1403c",
    doi = "10.3133/pp1403c",
    openalex = "W1566268436"
}

This report presents a finite-difference model and its associated modular computer program. The model simulates flow in three dimensions. The report includes detailed explanations of physical and mathematical concepts on which the model is based and an explanation of how those concepts are incorporated in the modular structure of the computer program. The modular structure consists of a Main Program and a series of highly independent subroutines called 'modules.' The modules are grouped into 'packages.' Each package deals with a specific feature of the hydrologic system which is to be simulated, such as flow from rivers or flow into drains, or with a specific method of solving linear equations which describe the flow system, such as the Strongly Implicit Procedure or Slice-Successive Overrelaxation. The division of the program into modules permits the user to examine specific hydrologic features of the model independently. This also facilita development of additional capabilities because new packages can be added to the program without modifying the existing packages. The input and output systems of the computer program are also designed to permit maximum flexibility. Ground-water flow within the aquifer is simulated using a block-centered finite-difference approach. Layers can be simulated as confined, unconfined, or a combination of confined and unconfined. Flow associated with external stresses, such as wells, areal recharge, evapotranspiration, drains, and streams, can also be simulated. The finite-difference equations can be solved using either the Strongly Implicit Procedure or Slice-Successive Overrelaxation. The program is written in FORTRAN 77 and will run without modification on most computers that have a FORTRAN 77 compiler. For each program,module, this report includes a narrative description, a flow chart, a list of variables, and a module listing.

@misc{doi103133twri06a1chinese,
    author = "McDonald, Michael G. and Harbaugh, Arlen W. and Guo, Wei‐Xing and Lü, Guoping",
    title = "A modular three-dimensional finite-difference fround-water flow model",
    year = "1988",
    abstract = "This report presents a finite-difference model and its associated modular computer program. The model simulates flow in three dimensions. The report includes detailed explanations of physical and mathematical concepts on which the model is based and an explanation of how those concepts are incorporated in the modular structure of the computer program. The modular structure consists of a Main Program and a series of highly independent subroutines called 'modules.' The modules are grouped into 'packages.' Each package deals with a specific feature of the hydrologic system which is to be simulated, such as flow from rivers or flow into drains, or with a specific method of solving linear equations which describe the flow system, such as the Strongly Implicit Procedure or Slice-Successive Overrelaxation. The division of the program into modules permits the user to examine specific hydrologic features of the model independently. This also facilita development of additional capabilities because new packages can be added to the program without modifying the existing packages. The input and output systems of the computer program are also designed to permit maximum flexibility. Ground-water flow within the aquifer is simulated using a block-centered finite-difference approach. Layers can be simulated as confined, unconfined, or a combination of confined and unconfined. Flow associated with external stresses, such as wells, areal recharge, evapotranspiration, drains, and streams, can also be simulated. The finite-difference equations can be solved using either the Strongly Implicit Procedure or Slice-Successive Overrelaxation. The program is written in FORTRAN 77 and will run without modification on most computers that have a FORTRAN 77 compiler. For each program,module, this report includes a narrative description, a flow chart, a list of variables, and a module listing.",
    url = "https://doi.org/10.3133/twri06a1\_chinese",
    doi = "10.3133/twri06a1\_chinese",
    openalex = "W4249762064"
}

@article{doi1010160016703789902731,
    author = "Wehrli, Bernhard and Stumm, Werner",
    title = "Vanadyl in natural waters: Adsorption and hydrolysis promote oxygenation",
    year = "1989",
    journal = "Geochimica et Cosmochimica Acta",
    url = "https://doi.org/10.1016/0016-7037(89)90273-1",
    doi = "10.1016/0016-7037(89)90273-1",
    openalex = "W2046957942"
}

@article{doi1010160883288989901007,
    author = "Horita, Juske and Ueda, Akira and Mizukami, Kanae and Takatori, Isao",
    title = "Automatic δD and δ18O analyses of multi-water samples using H2- and CO2-water equilibration methods with a common equilibration set-up",
    year = "1989",
    journal = "International Journal of Radiation Applications and Instrumentation Part A Applied Radiation and Isotopes",
    url = "https://doi.org/10.1016/0883-2889(89)90100-7",
    doi = "10.1016/0883-2889(89)90100-7",
    openalex = "W2004706176"
}

This report presents a computer program for the simulation of streamaquifer relations. A formal release of this report will be available in the future as a chapter in Techniques of Water Resources Investigations of the U.S. Geological Survey. The program documented in this report is designed for incorporation into the modular finite-difference ground-water flow model developed by the U.S. Geological Survey. The performance of this computer program has been tested in models of both hypothetical and actual ground-water flow systems. Future applications, however, may reveal errors that were not detected in the test simulations. Prior to the formal release of this report, users are requested to notify the originating office of any errors found in the report or in the computer program.

@article{doi103133ofr88729,
    author = "Prudic, David E.",
    title = "Documentation of a computer program to simulate stream-aquifer relations using a modular, finite-difference, ground-water flow model",
    year = "1989",
    journal = "Antarctica A Keystone in a Changing World",
    abstract = "This report presents a computer program for the simulation of streamaquifer relations. A formal release of this report will be available in the future as a chapter in Techniques of Water Resources Investigations of the U.S. Geological Survey. The program documented in this report is designed for incorporation into the modular finite-difference ground-water flow model developed by the U.S. Geological Survey. The performance of this computer program has been tested in models of both hypothetical and actual ground-water flow systems. Future applications, however, may reveal errors that were not detected in the test simulations. Prior to the formal release of this report, users are requested to notify the originating office of any errors found in the report or in the computer program.",
    url = "https://doi.org/10.3133/ofr88729",
    doi = "10.3133/ofr88729",
    openalex = "W1482615773"
}

@article{doi103133ofr90140,
    author = "Ward, J.R. and Harr, C.A.",
    title = "Methods for collection and processing of surface-water and bed- material samples for physical and chemical analyses",
    year = "1990",
    journal = "Antarctica A Keystone in a Changing World",
    url = "https://doi.org/10.3133/ofr90140",
    doi = "10.3133/ofr90140",
    openalex = "W1504735445"
}

This report documents PCG2: a numerical code to be used with the U.S. Geological Survey modular three-dimensional, finite-difference, ground-water flow model. PCG2 uses the preconditioned conjugate-gradient method to solve the equations produced by the model for hydraulic head. Linear or nonlinear flow conditions may be simulated. PCG2 includes two reconditioning options: modified incomplete Cholesky preconditioning, which is efficient on scalar computers; and polynomial preconditioning, which requires less computer storage and, with modifications that depend on the computer used, is most efficient on vector computers. Convergence of the solver is determined using both head-change and residual criteria. Nonlinear problems are solved using Picard iterations. This documentation provides a description of the preconditioned conjugate gradient method and the two preconditioners, detailed instructions for linking PCG2 to the modular model, sample data inputs, a brief description of PCG2, and a FORTRAN listing.

@misc{doi103133wri904048,
    author = "Hill, Mary C.",
    title = "PRECONDITIONED CONJUGATE-GRADIENT 2 (PCG2), a computer program for solving ground-water flow equations",
    year = "1990",
    abstract = "This report documents PCG2: a numerical code to be used with the U.S. Geological Survey modular three-dimensional, finite-difference, ground-water flow model. PCG2 uses the preconditioned conjugate-gradient method to solve the equations produced by the model for hydraulic head. Linear or nonlinear flow conditions may be simulated. PCG2 includes two reconditioning options: modified incomplete Cholesky preconditioning, which is efficient on scalar computers; and polynomial preconditioning, which requires less computer storage and, with modifications that depend on the computer used, is most efficient on vector computers. Convergence of the solver is determined using both head-change and residual criteria. Nonlinear problems are solved using Picard iterations. This documentation provides a description of the preconditioned conjugate gradient method and the two preconditioners, detailed instructions for linking PCG2 to the modular model, sample data inputs, a brief description of PCG2, and a FORTRAN listing.",
    url = "https://doi.org/10.3133/wri904048",
    doi = "10.3133/wri904048",
    openalex = "W1946434600"
}

@book{issar1990water3,
    author = "Issar, A. S",
    title = "Water Shall Flow from the Rock (Hydrogeology and Climate in the Lands of the Bible)",
    year = "1990",
    publisher = "New York, Springer-Verlag, 213 p",
    note = "talkorigins\_source = {true}; raw\_reference = {Issar, A. S., 1990, Water Shall Flow from the Rock (Hydrogeology and Climate in the Lands of the Bible): New York, Springer-Verlag, 213 p.}"
}

The Origin of Porosity and Permeability. Ground-Water Movement. Main Equations of Flow, Boundary Conditions, and Flow Nets. Ground Water in the Basin Hydrologic Cycle. Hydraulic Testing: Models, Methods, and Applications. Ground Water as a Resource. Stress, Strain, and Pore Fluids. Heat Transport in Ground-Water Flow. Solute Transport. Principles of Aqueous Geochemistry. Chemical Reactions. Colloids and Microorganisms. The Equations of Mass Transport. Mass Transport in Natural Ground-Water Systems. Mass Transport in Ground-Water Flow: Geologic Systems. Introduction to Contaminant Hydrogeology. Modeling the Transport of Dissolved Contaminants. Multiphase Fluid Systems. Remediation: Overview and Removal Options. In Situ Destruction and Risk Assessment. Answers to Problems. Appendices. References. Index.

@book{openalexw1604940817,
    author = "Domenico, P. A. and Schwartz, Franklin W.",
    title = "Physical and chemical hydrogeology",
    year = "1990",
    abstract = "The Origin of Porosity and Permeability. Ground-Water Movement. Main Equations of Flow, Boundary Conditions, and Flow Nets. Ground Water in the Basin Hydrologic Cycle. Hydraulic Testing: Models, Methods, and Applications. Ground Water as a Resource. Stress, Strain, and Pore Fluids. Heat Transport in Ground-Water Flow. Solute Transport. Principles of Aqueous Geochemistry. Chemical Reactions. Colloids and Microorganisms. The Equations of Mass Transport. Mass Transport in Natural Ground-Water Systems. Mass Transport in Ground-Water Flow: Geologic Systems. Introduction to Contaminant Hydrogeology. Modeling the Transport of Dissolved Contaminants. Multiphase Fluid Systems. Remediation: Overview and Removal Options. In Situ Destruction and Risk Assessment. Answers to Problems. Appendices. References. Index.",
    url = "https://openalex.org/W1604940817",
    openalex = "W1604940817"
}

@article{doi101021ac00009a014,
    author = "Coplen, Tyler B. and Wildman, Joe D. and Chen, Julie.",
    title = "Improvements in the gaseous hydrogen-water equilibration technique for hydrogen isotope-ratio analysis",
    year = "1991",
    journal = "Analytical Chemistry",
    url = "https://doi.org/10.1021/ac00009a014",
    doi = "10.1021/ac00009a014",
    openalex = "W2075978033",
    references = "doi1010160006291x7490285x, doi1010160168117685830366, doi1010160168962288900425, doi1010160883288989901007, doi101016s0092640x7080016x, doi101021ac00284a058, doi101021ac60068a025, doi101021j100551a008, doi101038271534a0, doi1011161574781"
}

@book{doi101016s0166111608x70359,
    author = "Helsel, Dennis R. and Hirsch, Robert M.",
    title = "Statistical Methods in Water Resources",
    year = "1992",
    booktitle = "Studies in environmental science",
    url = "https://doi.org/10.1016/s0166-1116(08)x7035-9",
    doi = "10.1016/s0166-1116(08)x7035-9",
    openalex = "W1582248076"
}

statistics 16 Major-element chemistry 16 Trace-element chemistry Oxidation-reduction

@article{doi103133ofr92642,
    author = "Parkhurst, David L. and Christenson, Scott C. and Breit, George N.",
    title = "Ground-water-quality assessment of the Central Oklahoma Aquifer, Oklahoma: Geochemical and geohydrologic investigations",
    year = "1993",
    journal = "Antarctica A Keystone in a Changing World",
    abstract = "statistics 16 Major-element chemistry 16 Trace-element chemistry Oxidation-reduction",
    url = "https://doi.org/10.3133/ofr92642",
    doi = "10.3133/ofr92642",
    openalex = "W1536595865"
}

Water quality in the Upper Floridan aquifer in the Valdosta, Georgia area is adversely affected by direct recharge from the Withlacoochee River. Water enters the aquifer along a short reach of the river where sinkholes have formed in the stream bed. The water receives little filtration as it recharges the Upper Floridan aquifer through these sinkholes. Naturally occurring organic material in the river provides a readily available source of energy for the growth of microbiota in the aquifer. Microbiological processes and chemical reactions in the aquifer produce methane and hydrogen sulfide as the water from the river mixes with ground water and moves downgradient in the aquifer. Humic substances associated with the organic material in the ground water in this area can form trihalomethanes when the water is chlorinated for public supply. To assess areas most suitable for ground-water supply development, areal distributions of total organic carbon, total sulfide, and methane in the Upper Floridan aquifer were mapped and used to evaluate areas affected by recharge from the Withlacoochee River. Areas where concentrations of total organic carbon, total sulfide, and methane were less than or equal to 2.0 milligrams per liter, 0.5 milligrams per liter, and 100 micrograms per liter, respectively, were considered to be relatively unaffected by recharge from the river and to have the greatest potential for water- resources development.

@misc{doi103133wri934044,
    author = "McConnell, James B. and Hacke, C.M.",
    title = "Hydrogeology, water quality, and water-resources development potential of the upper Floridan Aquifer in the Valdosta area, south-central Georgia",
    year = "1993",
    abstract = "Water quality in the Upper Floridan aquifer in the Valdosta, Georgia area is adversely affected by direct recharge from the Withlacoochee River. Water enters the aquifer along a short reach of the river where sinkholes have formed in the stream bed. The water receives little filtration as it recharges the Upper Floridan aquifer through these sinkholes. Naturally occurring organic material in the river provides a readily available source of energy for the growth of microbiota in the aquifer. Microbiological processes and chemical reactions in the aquifer produce methane and hydrogen sulfide as the water from the river mixes with ground water and moves downgradient in the aquifer. Humic substances associated with the organic material in the ground water in this area can form trihalomethanes when the water is chlorinated for public supply. To assess areas most suitable for ground-water supply development, areal distributions of total organic carbon, total sulfide, and methane in the Upper Floridan aquifer were mapped and used to evaluate areas affected by recharge from the Withlacoochee River. Areas where concentrations of total organic carbon, total sulfide, and methane were less than or equal to 2.0 milligrams per liter, 0.5 milligrams per liter, and 100 micrograms per liter, respectively, were considered to be relatively unaffected by recharge from the river and to have the greatest potential for water- resources development.",
    url = "https://doi.org/10.3133/wri934044",
    doi = "10.3133/wri934044",
    openalex = "W70251890",
    references = "doi1013065d25b7cf16c111d78645000102c1865d, doi103133ofr90140, doi103133pp1403b, doi103133pp1403c, doi103133pp1403d, doi103133pp708, doi103133wri78117, doi103133wri894072, doi103133wsp1473ed1"
}

The Coordination Chemistry of the Hydrous Oxide--Water Interface. Surface Charge and the Electric Double Layer. Adsorption. The Kinetics of Surface Controlled Dissolution of Oxide Minerals: An Introduction to Weathering. Precipitation and Nucleation. Particle--Particle Interaction. Carbonates and Their Reactivities. Redox Processes Mediated by Surfaces. Heterogeneous Photochemistry. Regulation of Trace Elements by the Solid--Water Interface in Surface Waters. References. Index.

@article{doi105860choice303839,
    title = "Chemistry of the solid-water interface: processes at the mineral-water and particle-water interface in natural systems",
    year = "1993",
    journal = "Choice Reviews Online",
    abstract = "The Coordination Chemistry of the Hydrous Oxide--Water Interface. Surface Charge and the Electric Double Layer. Adsorption. The Kinetics of Surface Controlled Dissolution of Oxide Minerals: An Introduction to Weathering. Precipitation and Nucleation. Particle--Particle Interaction. Carbonates and Their Reactivities. Redox Processes Mediated by Surfaces. Heterogeneous Photochemistry. Regulation of Trace Elements by the Solid--Water Interface in Surface Waters. References. Index.",
    url = "https://doi.org/10.5860/choice.30-3839",
    doi = "10.5860/choice.30-3839",
    openalex = "W2016378899"
}

1. An Introduction to Global Fresh Water Issues 2. World Fresh Water Resources 3. Water Quality and Health 4. Water and Ecosystems 5. Water and Agriculture 6. Water and Energy 7. Water and Economic Development 8. Water, Politics, and International Law 9. Water in the 21st Century

@book{openalexw1973523254,
    author = "Gleick, Peter H.",
    title = "Water in crisis: a guide to the world's fresh water resources",
    year = "1993",
    abstract = "1. An Introduction to Global Fresh Water Issues 2. World Fresh Water Resources 3. Water Quality and Health 4. Water and Ecosystems 5. Water and Agriculture 6. Water and Energy 7. Water and Economic Development 8. Water, Politics, and International Law 9. Water in the 21st Century",
    openalex = "W1973523254"
}

@article{openalexw2779842343,
    author = "Rutledge, A.T.",
    title = "Computer programs for describing the recession of ground-water discharge and for estimating mean ground-water recharge and discharge from streamflow records",
    year = "1993",
    openalex = "W2779842343"
}

@article{doi1023072623756,
    author = "Thomas, Caroline",
    title = "Water in crisis: a guide to the world’s fresh water resources",
    year = "1994",
    journal = "International Affairs",
    url = "https://doi.org/10.2307/2623756",
    doi = "10.2307/2623756",
    openalex = "W2606175721"
}

The mission of the U.S. Geological Survey (USGS) is to assess the quantity and quality of the earth resources of the Nation and to provide information that will assist resource managers and policymakers at Federal, State, and local levels in making sound decisions. Assessment of water-quality conditions and trends is an important part of this overall mission.

@article{doi103133cir1136,
    author = "Mueller, David K. and Helsel, Dennis R.",
    title = "Nutrients in the Nation's Waters--Too Much of a Good Thing?",
    year = "1996",
    journal = "U.S. Geological Survey circular/U.S. Geological Survey Circular",
    abstract = "The mission of the U.S. Geological Survey (USGS) is to assess the quantity and quality of the earth resources of the Nation and to provide information that will assist resource managers and policymakers at Federal, State, and local levels in making sound decisions. Assessment of water-quality conditions and trends is an important part of this overall mission.",
    url = "https://doi.org/10.3133/cir1136",
    doi = "10.3133/cir1136",
    openalex = "W1597836107"
}

A number of changes have been made to the U.S. Geological Survey modular finite-difference ground-water flow model, which is commonly known as MODFLOW. Existing MODFLOW input files will work with the revised model. Also, the basic structure and computational methods of the model have been maintained. Those familiar with the original model should have no difficulty adapting to the revised model. Some of the most significant changes are:

@article{doi103133ofr96485,
    author = "Harbaugh, Arlen W. and McDonald, Michael G.",
    title = "User's documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-difference ground-water flow model",
    year = "1996",
    journal = "Antarctica A Keystone in a Changing World",
    abstract = "A number of changes have been made to the U.S. Geological Survey modular finite-difference ground-water flow model, which is commonly known as MODFLOW. Existing MODFLOW input files will work with the revised model. Also, the basic structure and computational methods of the model have been maintained. Those familiar with the original model should have no difficulty adapting to the revised model. Some of the most significant changes are:",
    url = "https://doi.org/10.3133/ofr96485",
    doi = "10.3133/ofr96485",
    openalex = "W1608329731"
}

The Usquepaug-Queen River Basin study describes the hydrogeology, water quality, and simulation of pumping from wells for selected ground-water-development alternatives in the ground-water reservoir under average (1975-90) and drought (1963-66) conditions. In general, ground-water quality is suitable for most purposes. The study provides an evaluation of the effects of simulated pumping of 4 to 11 million gallons per day of ground water on the stream-wetland-aquifer system.Three principal geologic units underlie the Usquepaug-Queen River Basin glacial stratified deposits (stratified drift), glacial till, and crystalline bedrock. Thick and extensive deposits of saturated coarse-grained stratified deposits form the major and most productive aquifer in the Usquepaug-Queen River Basin. The 36.1-square mile Usquepaug-Queen River Basin is in the Pawcatuck River Basin in southern Rhode Island. Stratified deposits cover about 42 percent of the basin and reach a maximum known thickness of 122 feet. The stratified deposits are subdivided into coarse-grained units (dominantly fine to very coarse sand and gravel) and fine-grained units (dominantly very fine sand, silt, and clay). Transmissivity is highest in coarse-grained stratified materials, which have the capability of yielding relatively high volumes of water to wells. Transmissivity is lowest in fine-grained stratified materials, which consist predominantly of lakebottom deposits. Transmissivity of the stratified drift aquifer ranges from 1,900 to 27,800 feet squared per day, and horizontal hydraulic conductivity ranges from 25 to 470 feet per day. The stratified-drift aquifer is the only aquifer in the Usquepaug-Queen River Basin capable of producing yields of 0.5 million gallons per day or more from individual wells. Pumping from ground-water and surface-water sources in the Usquepaug-Queen River Basin averaged 0.28 million gallons per day during 1989 and 0.48 million gallons per day during 1990.Ground water and surface water (which is primarily ground-water runoff) in the UsquepaugQueen River Basin are suitable for most purposes on the basis of a comparison of physical properties and chemical constituents to drinking-water standards. Ground water in the basin is somewhat corrosive because of its low hydrogen-ion concentration. Specific conductance and concentrations of dissolved chloride and dissolved sodium are high in ground water in parts of the Usquepaug-Queen River Basin, which indicates the effects of highway de-icing salts on groundwater quality. Nitrogen (nitrite plus nitrate) concentrations in some localized areas exceed the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter for drinking water.The effects of selected ground-waterdevelopment alternatives on ground-water levels, wetland-water levels, and streamflow in the Usquepaug-Queen ground-water reservoir were evaluated by means of a three-layer ground-waterflow model. Development alternatives were simulated for average annual (1975-90) and drought (1963-66) conditions. In general, higher simulated pumping rates produced greater drawdowns than lower pumping rates. Drawdowns generally can be reduced by distributing the total pumping over many wells; however, drawdowns were minimal (less than 1.3 feet) in well SNW 906, which was near a major stream (recharge boundary); and drawdowns were substantial (at least 12 feet) in well EXW 33, which was near the edge of the model aquifer boundary (barrier boundary). Total gains in flow from ground-water discharge for all streams in the model area were not affected by the location of wells; however, the amount of ground-water pumpage derived from induced infiltration of streamflow varies significantly. Water levels in the wetlands tend to be constant even during simulated pumping. In general, pumping during simulated drought conditions increased drawdowns fractionally and greatly reduced overall streamflow gains.Pumping from the Usquepaug-Queen stratified-drift aquifer causes infiltration of streamflow along stream segments simulated in the ground-water-flow model. Results of simulations for average conditions show that from 56 to 75 percent of the total water pumped is derived from intercepted ground-water runoff and that the amount of well water derived from induced recharge of streamflow ranged from 20 to 39 percent. The areal extent of contributing areas for selected simulated pumping wells suggest that large areas of stratified drift may need to be protected from land-use practices that are incompatible with the development of potable ground water in the Usquepaug-Queen ground-water reservoir.

@misc{doi103133wri974126,
    author = "Dickerman, David C. and Kliever, John D. and Stone, Janet Radway",
    title = "Hydrogeology, water quality, and simulation of ground-water-development alternatives in the Usquepaug-Queen ground-water reservoir, southern Rhode Island",
    year = "1997",
    abstract = "The Usquepaug-Queen River Basin study describes the hydrogeology, water quality, and simulation of pumping from wells for selected ground-water-development alternatives in the ground-water reservoir under average (1975-90) and drought (1963-66) conditions. In general, ground-water quality is suitable for most purposes. The study provides an evaluation of the effects of simulated pumping of 4 to 11 million gallons per day of ground water on the stream-wetland-aquifer system.Three principal geologic units underlie the Usquepaug-Queen River Basin glacial stratified deposits (stratified drift), glacial till, and crystalline bedrock. Thick and extensive deposits of saturated coarse-grained stratified deposits form the major and most productive aquifer in the Usquepaug-Queen River Basin. The 36.1-square mile Usquepaug-Queen River Basin is in the Pawcatuck River Basin in southern Rhode Island. Stratified deposits cover about 42 percent of the basin and reach a maximum known thickness of 122 feet. The stratified deposits are subdivided into coarse-grained units (dominantly fine to very coarse sand and gravel) and fine-grained units (dominantly very fine sand, silt, and clay). Transmissivity is highest in coarse-grained stratified materials, which have the capability of yielding relatively high volumes of water to wells. Transmissivity is lowest in fine-grained stratified materials, which consist predominantly of lakebottom deposits. Transmissivity of the stratified drift aquifer ranges from 1,900 to 27,800 feet squared per day, and horizontal hydraulic conductivity ranges from 25 to 470 feet per day. The stratified-drift aquifer is the only aquifer in the Usquepaug-Queen River Basin capable of producing yields of 0.5 million gallons per day or more from individual wells. Pumping from ground-water and surface-water sources in the Usquepaug-Queen River Basin averaged 0.28 million gallons per day during 1989 and 0.48 million gallons per day during 1990.Ground water and surface water (which is primarily ground-water runoff) in the UsquepaugQueen River Basin are suitable for most purposes on the basis of a comparison of physical properties and chemical constituents to drinking-water standards. Ground water in the basin is somewhat corrosive because of its low hydrogen-ion concentration. Specific conductance and concentrations of dissolved chloride and dissolved sodium are high in ground water in parts of the Usquepaug-Queen River Basin, which indicates the effects of highway de-icing salts on groundwater quality. Nitrogen (nitrite plus nitrate) concentrations in some localized areas exceed the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter for drinking water.The effects of selected ground-waterdevelopment alternatives on ground-water levels, wetland-water levels, and streamflow in the Usquepaug-Queen ground-water reservoir were evaluated by means of a three-layer ground-waterflow model. Development alternatives were simulated for average annual (1975-90) and drought (1963-66) conditions. In general, higher simulated pumping rates produced greater drawdowns than lower pumping rates. Drawdowns generally can be reduced by distributing the total pumping over many wells; however, drawdowns were minimal (less than 1.3 feet) in well SNW 906, which was near a major stream (recharge boundary); and drawdowns were substantial (at least 12 feet) in well EXW 33, which was near the edge of the model aquifer boundary (barrier boundary). Total gains in flow from ground-water discharge for all streams in the model area were not affected by the location of wells; however, the amount of ground-water pumpage derived from induced infiltration of streamflow varies significantly. Water levels in the wetlands tend to be constant even during simulated pumping. In general, pumping during simulated drought conditions increased drawdowns fractionally and greatly reduced overall streamflow gains.Pumping from the Usquepaug-Queen stratified-drift aquifer causes infiltration of streamflow along stream segments simulated in the ground-water-flow model. Results of simulations for average conditions show that from 56 to 75 percent of the total water pumped is derived from intercepted ground-water runoff and that the amount of well water derived from induced recharge of streamflow ranged from 20 to 39 percent. The areal extent of contributing areas for selected simulated pumping wells suggest that large areas of stratified drift may need to be protected from land-use practices that are incompatible with the development of potable ground water in the Usquepaug-Queen ground-water reservoir.",
    url = "https://doi.org/10.3133/wri974126",
    doi = "10.3133/wri974126",
    openalex = "W80885304",
    references = "doi101086622910, doi1023071788077, doi103133cir456, doi103133ofr88729, doi103133twri04b1, doi103133twri06a1chinese, doi103133wri904048, doi103133wsp1473ed1, openalexw2746809854, openalexw2779842343"
}

1. The Hydrologic Cycle. 2. Chemical Background. 3. The Carbonate System and pH Control 4. Clay Minerals and Cation Exchange. 5. Adsorption. 6. Organic Compounds in Natural Waters. 7. Redox Equilibria. 8. Redox Conditions in Natural Waters. 9. Heavy Metals and Metalloids. 10. Stability Relationships and Silicate Equilibria. 11. Kinetics. 12. Weathering and Water Chemistry. 13. Acid Water. 14. Isotopes. 15. Evaporation and Saline Waters. 16. Transport and Reaction Modeling References. Glossary of Geologic Terms. Appendix I: Piper and Stiff Diagrams. Appendix II: Standard-State Thermodynamic Data for Some Common Species. Appendix III: Equilibrium Constants at 25 C and Enthalpies of Reaction for Selected Reactions. Answers to Problems. Author Index. Subject Index.

@book{openalexw1566391996,
    author = "Drever, James I.",
    title = "The Geochemistry of Natural Waters: Surface and Groundwater Environments",
    year = "1997",
    journal = "Medical Entomology and Zoology",
    abstract = "1. The Hydrologic Cycle. 2. Chemical Background. 3. The Carbonate System and pH Control 4. Clay Minerals and Cation Exchange. 5. Adsorption. 6. Organic Compounds in Natural Waters. 7. Redox Equilibria. 8. Redox Conditions in Natural Waters. 9. Heavy Metals and Metalloids. 10. Stability Relationships and Silicate Equilibria. 11. Kinetics. 12. Weathering and Water Chemistry. 13. Acid Water. 14. Isotopes. 15. Evaporation and Saline Waters. 16. Transport and Reaction Modeling References. Glossary of Geologic Terms. Appendix I: Piper and Stiff Diagrams. Appendix II: Standard-State Thermodynamic Data for Some Common Species. Appendix III: Equilibrium Constants at 25 C and Enthalpies of Reaction for Selected Reactions. Answers to Problems. Author Index. Subject Index.",
    openalex = "W1566391996"
}

@article{doi101016s0022169498002364,
    author = "Katz, Brian G. and Catches, John S. and Bullen, Thomas D. and Michel, Robert L.",
    title = "Changes in the isotopic and chemical composition of ground water resulting from a recharge pulse from a sinking stream",
    year = "1998",
    journal = "Journal of Hydrology",
    url = "https://doi.org/10.1016/s0022-1694(98)00236-4",
    doi = "10.1016/s0022-1694(98)00236-4",
    openalex = "W2062233814",
    references = "doi103133wri934044"
}

The quality of water in the Upper Floridan aquifer near Valdosta, Georgia is affected locally by discharge of Withlacoochee River water through sinkholes in the river bed. Data on transient tracers and other dissolved substances, including Cl−, 3H, tritiogenic helium-3 (3He), chlorofluorocarbons (CFC-11, CFC-12, CFC-113), organic C (DOC), O2 (DO), H2S, CH4, δ18O, δD, and 14C were investigated as tracers of Withlacoochee River water in the Upper Floridan aquifer. The concentrations of all tracers were affected by dilution and mixing. Dissolved Cl−, δ18O, δD, CFC-12, and the quantity (3H+3He) are stable in water from the Upper Floridan aquifer, whereas DOC, DO, H2S, CH4, 14C, CFC-11, and CFC-113 are affected by microbial degradation and other geochemical processes occurring within the aquifer. Groundwater mixing fractions were determined by using dissolved Cl− and δ18O data, recognizing 3 end-member water types in the groundwater mixtures: (1) Withlacoochee River water (δ18O=−2.5±0.3‰, Cl−=12.2±2 mg/l), (2) regional infiltration water (δ18O=−4.2±0.1‰, Cl−=2.3±0.1 mg/l), and (3) regional paleowater resident in the Upper Floridan aquifer (δ18O=−3.4±0.1‰, Cl−=2.6±0.1 mg/l) (uncertainties are ±1σ). Error simulation procedures were used to define uncertainties in mixing fractions. Fractions of river water in groundwater range from 0 to 72% and average 10%. The influence of river-water discharge on the quality of water in the Upper Floridan aquifer was traced from the sinkhole area on the Withlacoochee River 25 km SE in the direction of regional groundwater flow. Infiltration of water is most significant to the N and NW of Valdosta, but becomes negligible to the S and SE in the direction of general thickening of post-Eocene confining beds overlying the Upper Floridan aquifer.

@article{doi101016s0883292798000316,
    author = "Plummer, L. Niel and Busenberg, Eurybiades and McConnell, James B. and Drenkard, S. and Schlösser, Peter and Michel, Robert L.",
    title = "Flow of river water into a Karstic limestone aquifer. 1. Tracing the young fraction in groundwater mixtures in the Upper Floridan Aquifer near Valdosta, Georgia",
    year = "1998",
    journal = "Applied Geochemistry",
    abstract = "The quality of water in the Upper Floridan aquifer near Valdosta, Georgia is affected locally by discharge of Withlacoochee River water through sinkholes in the river bed. Data on transient tracers and other dissolved substances, including Cl−, 3H, tritiogenic helium-3 (3He), chlorofluorocarbons (CFC-11, CFC-12, CFC-113), organic C (DOC), O2 (DO), H2S, CH4, δ18O, δD, and 14C were investigated as tracers of Withlacoochee River water in the Upper Floridan aquifer. The concentrations of all tracers were affected by dilution and mixing. Dissolved Cl−, δ18O, δD, CFC-12, and the quantity (3H+3He) are stable in water from the Upper Floridan aquifer, whereas DOC, DO, H2S, CH4, 14C, CFC-11, and CFC-113 are affected by microbial degradation and other geochemical processes occurring within the aquifer. Groundwater mixing fractions were determined by using dissolved Cl− and δ18O data, recognizing 3 end-member water types in the groundwater mixtures: (1) Withlacoochee River water (δ18O=−2.5±0.3‰, Cl−=12.2±2 mg/l), (2) regional infiltration water (δ18O=−4.2±0.1‰, Cl−=2.3±0.1 mg/l), and (3) regional paleowater resident in the Upper Floridan aquifer (δ18O=−3.4±0.1‰, Cl−=2.6±0.1 mg/l) (uncertainties are ±1σ). Error simulation procedures were used to define uncertainties in mixing fractions. Fractions of river water in groundwater range from 0 to 72\% and average 10\%. The influence of river-water discharge on the quality of water in the Upper Floridan aquifer was traced from the sinkhole area on the Withlacoochee River 25 km SE in the direction of regional groundwater flow. Infiltration of water is most significant to the N and NW of Valdosta, but becomes negligible to the S and SE in the direction of general thickening of post-Eocene confining beds overlying the Upper Floridan aquifer.",
    url = "https://doi.org/10.1016/s0883-2927(98)00031-6",
    doi = "10.1016/s0883-2927(98)00031-6",
    openalex = "W2151121490",
    references = "doi103133wri934044"
}

Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier‐induced floods, and the prediction of runoff from glacierized drainage basins. To this end we have synthesized a conceptual model of water movement through a temperate glacier from the surface to the outlet stream. Processes that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology. Where a glacier is covered by a layer of porous, permeable firn (the accumulation zone), the flux of water to the glacier interior varies slowly because the firn temporarily stores water and thereby smooths out variations in the supply rate. In the firn‐free ablation zone, in contrast, the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time. Water moves from the surface to the bed through an upward branching arborescent network consisting of both steeply inclined conduits, formed by the enlargement of intergranular veins, and gently inclined conduits, spawned by water flow along the bottoms of near‐surface fractures (crevasses). Englacial drainage conduits deliver water to the glacier bed at a limited number of points, probably a long distance downglacier of where water enters the glacier. Englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn. Their size adjusts so that they are usually full of water and flow is pressurized. In contrast, water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms; flow is otherwise in an open‐channel configuration. The subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically. An upglacier branching, arborescent network of channels incised into the basal ice conveys water rapidly. Much of the water flux to the bed probably enters directly into the arborescent channel network, which covers only a small fraction of the glacier bed. More extensive spatially is a nonarborescent network, which commonly includes cavities (gaps between the glacier sole and bed), channels incised into the bed, and a layer of permeable sediment. The nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system. The arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network. The volume of water stored by a glacier varies diurnally and seasonally. Small, temperate alpine glaciers seem to attain a maximum seasonal water storage of ∼200 mm of water averaged over the area of the glacier bed, with daily fluctuations of as much as 20–30 mm. The likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes, so most water storage may actually occur englacially. Stored water may also be released abruptly and catastrophically in the form of outburst floods.

@article{doi10102997rg03579,
    author = "Fountain, Andrew G. and Walder, Joseph S.",
    title = "Water flow through temperate glaciers",
    year = "1998",
    journal = "Reviews of Geophysics",
    abstract = "Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier‐induced floods, and the prediction of runoff from glacierized drainage basins. To this end we have synthesized a conceptual model of water movement through a temperate glacier from the surface to the outlet stream. Processes that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology. Where a glacier is covered by a layer of porous, permeable firn (the accumulation zone), the flux of water to the glacier interior varies slowly because the firn temporarily stores water and thereby smooths out variations in the supply rate. In the firn‐free ablation zone, in contrast, the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time. Water moves from the surface to the bed through an upward branching arborescent network consisting of both steeply inclined conduits, formed by the enlargement of intergranular veins, and gently inclined conduits, spawned by water flow along the bottoms of near‐surface fractures (crevasses). Englacial drainage conduits deliver water to the glacier bed at a limited number of points, probably a long distance downglacier of where water enters the glacier. Englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn. Their size adjusts so that they are usually full of water and flow is pressurized. In contrast, water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms; flow is otherwise in an open‐channel configuration. The subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically. An upglacier branching, arborescent network of channels incised into the basal ice conveys water rapidly. Much of the water flux to the bed probably enters directly into the arborescent channel network, which covers only a small fraction of the glacier bed. More extensive spatially is a nonarborescent network, which commonly includes cavities (gaps between the glacier sole and bed), channels incised into the bed, and a layer of permeable sediment. The nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system. The arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network. The volume of water stored by a glacier varies diurnally and seasonally. Small, temperate alpine glaciers seem to attain a maximum seasonal water storage of ∼200 mm of water averaged over the area of the glacier bed, with daily fluctuations of as much as 20–30 mm. The likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes, so most water storage may actually occur englacially. Stored water may also be released abruptly and catastrophically in the form of outburst floods.",
    url = "https://doi.org/10.1029/97rg03579",
    doi = "10.1029/97rg03579",
    openalex = "W2170329098",
    references = "doi101002esp3290070108, doi101017s0022143000014623, doi101029jb092ib09p09059, openalexw1604940817"
}

Abstract In natural ground water systems, both chlorine and bromine occur primarily as monovalent anions, chloride and bromide. Although dissolution or precipitation of halite, biological activity in the root zone, anion sorption, and exchange can affect chloride/bromide ratios in some settings, movement of the ions in potable ground water is most often conservative. Atmospheric precipitation will generally have mass ratios between 50 and 150; shallow ground water, between 100 and 200; domestic sewage, between 300 and 600; water affected by dissolution of halite, between 1000 and 10,000; and summer runoff from urban streets, between 10 and 100. These, and other distinctive elemental ratios, are useful in the reconstruction of the origin and movement of ground water, as illustrated by case studies investigating sources of salinity in ground water from Alberta, Kansas, and Arizona, and infiltration rates and pathways at Yucca Mountain, Nevada.

@article{doi101111j174565841998tb01099x,
    author = "Davis, Stanley N. and Whittemore, Donald O. and Fabryka-Martin, J.",
    title = "Uses of Chloride/Bromide Ratios in Studies of Potable Water",
    year = "1998",
    journal = "Ground Water",
    abstract = "Abstract In natural ground water systems, both chlorine and bromine occur primarily as monovalent anions, chloride and bromide. Although dissolution or precipitation of halite, biological activity in the root zone, anion sorption, and exchange can affect chloride/bromide ratios in some settings, movement of the ions in potable ground water is most often conservative. Atmospheric precipitation will generally have mass ratios between 50 and 150; shallow ground water, between 100 and 200; domestic sewage, between 300 and 600; water affected by dissolution of halite, between 1000 and 10,000; and summer runoff from urban streets, between 10 and 100. These, and other distinctive elemental ratios, are useful in the reconstruction of the origin and movement of ground water, as illustrated by case studies investigating sources of salinity in ground water from Alberta, Kansas, and Arizona, and infiltration rates and pathways at Yucca Mountain, Nevada.",
    url = "https://doi.org/10.1111/j.1745-6584.1998.tb01099.x",
    doi = "10.1111/j.1745-6584.1998.tb01099.x",
    openalex = "W1985547002",
    references = "doi1010160022169487901855, doi101021es60108a007, doi101029jb095ib08p12895, doi101029wr015i006p01479, doi101146annurevea18050190001133, doi1011751520046919580150417tcocsp20co2, doi101306212f8cab2b2411d78648000102c1865d, doi1021187504ms, doi103133wsp1473ed1, openalexw1546084400, openalexw2087194314"
}

Abstract This study explores the use of multiple isotopic tracers to evaluate the processes involved in nitrate attenuation in ground water. δ 15 N and δ 18 O are used to provide information about the role of denitrification on nitrate attenuation, and δ 34 S, δ 18 O, and δ 13 C are used to evaluate the role of reduced sulfur and carbon as electron donors for nitrate reduction. The focus of this study is a zone of significant NO 3 −1 attenuation occurring in a sand aquifer impacted by septic system contamination. The NO 3 −1 pattern, the ground water flow system, and changes in other chemical parameters suggest that the NO 3 −1 depletion is caused by denitrification. This is supported by the nitrate δ 15 N and δ 18 O data which both show significant isotopic enrichment as NO 3 −1 depletion proceeds along the flow path. The increase of sulfate and dissolved inorganic carbon observed in the zone of nitrate attenuation suggests that reduced sulfur in addition to carbon is also involved in denitrification. This is supported by a trend toward depleted sulfate δ 34 S and δ 18 O values in the zone of sulfate increase, which reflects the input of sulfate formed by the oxidation of biogenic pyrite present in the aquifer sediments. The trend toward depleted δ 13 values in the zone of increasing dissolved inorganic carbon reflects the input of organic carbon into this carbon pool. Chemical mass balance indicates that carbon is the dominant electron donor; however, this study demonstrates the effectiveness of using multiple isotopic tracers for providing insight into the processes affecting nitrate attenuation in ground water.

@article{doi101111j174565841998tb02104x,
    author = "Aravena, Ramón and Robertson, W. D.",
    title = "Use of Multiple Isotope Tracers to Evaluate Denitrification in Ground Water: Study of Nitrate from a Large‐Flux Septic System Plume",
    year = "1998",
    journal = "Ground Water",
    abstract = "Abstract This study explores the use of multiple isotopic tracers to evaluate the processes involved in nitrate attenuation in ground water. δ 15 N and δ 18 O are used to provide information about the role of denitrification on nitrate attenuation, and δ 34 S, δ 18 O, and δ 13 C are used to evaluate the role of reduced sulfur and carbon as electron donors for nitrate reduction. The focus of this study is a zone of significant NO 3 −1 attenuation occurring in a sand aquifer impacted by septic system contamination. The NO 3 −1 pattern, the ground water flow system, and changes in other chemical parameters suggest that the NO 3 −1 depletion is caused by denitrification. This is supported by the nitrate δ 15 N and δ 18 O data which both show significant isotopic enrichment as NO 3 −1 depletion proceeds along the flow path. The increase of sulfate and dissolved inorganic carbon observed in the zone of nitrate attenuation suggests that reduced sulfur in addition to carbon is also involved in denitrification. This is supported by a trend toward depleted sulfate δ 34 S and δ 18 O values in the zone of sulfate increase, which reflects the input of sulfate formed by the oxidation of biogenic pyrite present in the aquifer sediments. The trend toward depleted δ 13 values in the zone of increasing dissolved inorganic carbon reflects the input of organic carbon into this carbon pool. Chemical mass balance indicates that carbon is the dominant electron donor; however, this study demonstrates the effectiveness of using multiple isotopic tracers for providing insight into the processes affecting nitrate attenuation in ground water.",
    url = "https://doi.org/10.1111/j.1745-6584.1998.tb02104.x",
    doi = "10.1111/j.1745-6584.1998.tb02104.x",
    openalex = "W1969799349"
}

The purpose of this report is to present consistent and current water-use estimates by state and water-resources region for the United States, Puerto Rico, the U.S. Virgin Islands, and the District of Columbia. Estimates of water withdrawn from surface- and ground-water sources, estimates of consumptive use, and estimates of instream use and wastewater releases during 1995 are presented in this report. This report discusses eight categories of offstream water use--public supply, domestic, commercial, irrigation, livestock, industrial, mining, and thermoelectric power--and one category of instream use: hydroelectric power.

@article{doi103133cir1200,
    author = "Solley, Wayne B. and Pierce, Robert R. and Perlman, Howard A.",
    title = "Estimated use of water in the United States in 1995",
    year = "1998",
    journal = "U.S. Geological Survey circular/U.S. Geological Survey Circular",
    abstract = "The purpose of this report is to present consistent and current water-use estimates by state and water-resources region for the United States, Puerto Rico, the U.S. Virgin Islands, and the District of Columbia. Estimates of water withdrawn from surface- and ground-water sources, estimates of consumptive use, and estimates of instream use and wastewater releases during 1995 are presented in this report. This report discusses eight categories of offstream water use--public supply, domestic, commercial, irrigation, livestock, industrial, mining, and thermoelectric power--and one category of instream use: hydroelectric power.",
    url = "https://doi.org/10.3133/cir1200",
    doi = "10.3133/cir1200",
    openalex = "W1964385596"
}

The Rush Springs aquifer, in western Oklahoma, is equivalent to the Permian-age Rush Springs Formation. It is composed of very fine-grained to fine-grained sandstone that is massive to highly cross-bedded and is underlain by less-permeable Marlow Formation. Reported irrigation well yields exceed 1,000 gallons per minute; yields reported on 89 drillers' logs ranged from 11 to 850 gallons per minute. Transmissivities range from 670 to 1,870 feet squared per day. Specific yields for core samples range from 0.13 to 0.34. Estimates of hydraulic conductivities at one site ranged from 1.05 to 5.62 feet per day. The Rush Springs aquifer is recharged by infiltration of precipitation, ranging from 0.2 to more than 2 inches per year. Discharge is primarily to streams and rivers where the Rush Springs aquifer crops. Estimated total withdrawal was 54.7 million gallons per day in 1990. Over 42 million gallons per day, or 77.8 percent of water withdrawn, was used for irrigation of crops. Thirty-five of the 64 wells sampled produced nitrate concentration that equaled or exceeded drinking water standards. Sulfate concentration also exceeds the drinking water standards in some areas. Two major water types occur in the aquifer, a calcium-magnesium bicarbonate type and a calcium sulfate type. Dissolved solids concentrations in water samples from the aquifer ranged from 52 to 1,840 milligrams per liter. The chemical composition of ground water in the Rush Springs aquifer is the result of chemical reactions between the recharge waters and minerals in the overlying soils and rocks in the Rush Springs and Marlow Formations. Saturation indices of minerals were calculated for 64 water-quality analyses using the geochemical computer model WATEQF. Mass transfer rates were calculated using the mass-balance model NETPATH.

@misc{doi103133wri984081,
    author = "Becker, Mark F. and Runkle, Donna L.",
    title = "Hydrogeology, water quality, and geochemistry of the Rush Springs aquifer, western Oklahoma",
    year = "1998",
    abstract = "The Rush Springs aquifer, in western Oklahoma, is equivalent to the Permian-age Rush Springs Formation. It is composed of very fine-grained to fine-grained sandstone that is massive to highly cross-bedded and is underlain by less-permeable Marlow Formation. Reported irrigation well yields exceed 1,000 gallons per minute; yields reported on 89 drillers' logs ranged from 11 to 850 gallons per minute. Transmissivities range from 670 to 1,870 feet squared per day. Specific yields for core samples range from 0.13 to 0.34. Estimates of hydraulic conductivities at one site ranged from 1.05 to 5.62 feet per day. The Rush Springs aquifer is recharged by infiltration of precipitation, ranging from 0.2 to more than 2 inches per year. Discharge is primarily to streams and rivers where the Rush Springs aquifer crops. Estimated total withdrawal was 54.7 million gallons per day in 1990. Over 42 million gallons per day, or 77.8 percent of water withdrawn, was used for irrigation of crops. Thirty-five of the 64 wells sampled produced nitrate concentration that equaled or exceeded drinking water standards. Sulfate concentration also exceeds the drinking water standards in some areas. Two major water types occur in the aquifer, a calcium-magnesium bicarbonate type and a calcium sulfate type. Dissolved solids concentrations in water samples from the aquifer ranged from 52 to 1,840 milligrams per liter. The chemical composition of ground water in the Rush Springs aquifer is the result of chemical reactions between the recharge waters and minerals in the overlying soils and rocks in the Rush Springs and Marlow Formations. Saturation indices of minerals were calculated for 64 water-quality analyses using the geochemical computer model WATEQF. Mass transfer rates were calculated using the mass-balance model NETPATH.",
    url = "https://doi.org/10.3133/wri984081",
    doi = "10.3133/wri984081",
    openalex = "W135885694",
    references = "doi1010160022169471900631, doi101029wr026i009p01981, doi101126science902343493, doi101130001676061983941415parodm20co2, doi1011639789004281554004, doi103133cir1136, doi103133ofr92642, doi103133wri7613, doi103133wri8214, doi103133wri914078"
}

@article{doi101007s100400050218,
    author = "Crandall, Christy A. and Katz, Brian G. and Hirten, Joshua J.",
    title = "Hydrochemical evidence for mixing of river water and groundwater during high-flow conditions, lower Suwannee River basin, Florida, USA",
    year = "1999",
    journal = "Hydrogeology Journal",
    url = "https://doi.org/10.1007/s100400050218",
    doi = "10.1007/s100400050218",
    openalex = "W2112614209",
    references = "doi103133wri934044"
}

@article{doi103133wri994104,
    author = "Luckey, Richard L. and Becker, M.",
    title = "Hydrogeology, water use, and simulation of flow in the High Plains aquifer in northwestern Oklahoma, southeastern Colorado, southwestern Kansas, northeastern New Mexico, and northwestern Texas",
    year = "1999",
    journal = "Water-Resources Investigations Report",
    url = "https://www.semanticscholar.org/paper/6c748a13c772bba6c071b7fc315c686422b5faea",
    doi = "10.3133/WRI994104",
    is_oa = "true",
    semanticscholar_citation_count = "61",
    semanticscholar_id = "6c748a13c772bba6c071b7fc315c686422b5faea"
}

Abstract Management of near‐channel ground water and surface water to maintain stream health and flood plain ecological function requires hydrogeologists to refocus their conceptual models of water exchange between the aquifer and stream. The high hydraulic conductivity fluvial plain directs ground water flow down‐plain where it exchanges with the stream channel creating gaining, losing, flow‐through, and parallel‐flow reaches. The resulting complex flow system requires consideration when profiles representing ground water flowpaths are constructed. In addition to interaction at the scale of the fluvial plain, exchange of ground water and surface water within and immediately adjacent to the stream channel creates hyporheic zones. The physical and bio‐geochemical extent of these zones depends on the head distribution and ground water flow directions, stream hydraulics, and channel bed conditions, and magnitudes and distributions of hydrogeologic parameters. Simulated conceptualizations of flow dynamics caused by slight increases in hydraulic potentials at the surface water‐stream bed interface indicate stream‐ground water mixing could occur to a depth of 1.7 m below the channel. Rescaling of traditional hydrogeologic approaches to include the fluvial plain and channel scale will result in opportunities to expand hydrogeologic research and participate in interdisciplinary research teams attempting to decipher and manage fluvial systems.

@article{doi101111j174565842000tb00228x,
    author = "Woessner, William",
    title = "Stream and Fluvial Plain Ground Water Interactions: Rescaling Hydrogeologic Thought",
    year = "2000",
    journal = "Ground Water",
    abstract = "Abstract Management of near‐channel ground water and surface water to maintain stream health and flood plain ecological function requires hydrogeologists to refocus their conceptual models of water exchange between the aquifer and stream. The high hydraulic conductivity fluvial plain directs ground water flow down‐plain where it exchanges with the stream channel creating gaining, losing, flow‐through, and parallel‐flow reaches. The resulting complex flow system requires consideration when profiles representing ground water flowpaths are constructed. In addition to interaction at the scale of the fluvial plain, exchange of ground water and surface water within and immediately adjacent to the stream channel creates hyporheic zones. The physical and bio‐geochemical extent of these zones depends on the head distribution and ground water flow directions, stream hydraulics, and channel bed conditions, and magnitudes and distributions of hydrogeologic parameters. Simulated conceptualizations of flow dynamics caused by slight increases in hydraulic potentials at the surface water‐stream bed interface indicate stream‐ground water mixing could occur to a depth of 1.7 m below the channel. Rescaling of traditional hydrogeologic approaches to include the fluvial plain and channel scale will result in opportunities to expand hydrogeologic research and participate in interdisciplinary research teams attempting to decipher and manage fluvial systems.",
    url = "https://doi.org/10.1111/j.1745-6584.2000.tb00228.x",
    doi = "10.1111/j.1745-6584.2000.tb00228.x",
    openalex = "W1988618327",
    references = "crossref1996the, doi103133wri974126, doi105860choice342173"
}

Abstract Concentrations of naturally occurring arsenic in ground water vary regionally due to a combination of climate and geology. Although slightly less than half of 30,000 arsenic analyses of ground water in the United States were 1 μg/L, about 10% exceeded 10 μg/L. At a broad regional scale, arsenic concentrations exceeding 10 μg/L appear to be more frequently observed in the western United States than in the eastern half. Arsenic concentrations in ground water of the Appalachian Highlands and the Atlantic Plain generally are very low (1 μg/L). Concentrations are somewhat greater in the Interior Plains and the Rocky Mountain System. Investigations of ground water in New England, Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin within the last decade suggest that arsenic concentrations exceeding 10 μg/L are more widespread and common than previously recognized. Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 μg/L in ground water. This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i.e., petroleum products) organic carbon. Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the western United States. Sulfide minerals are both a source and sink for arsenic. Geothermal water and high evaporation rates also are associated with arsenic concentrations 10g/L in ground and surface water, particularly in the west.

@article{doi101111j174565842000tb00251x,
    author = "Welch, Alan H. and Westjohn, David B. and Helsel, Dennis R. and Wanty, Richard B.",
    title = "Arsenic in Ground Water of the United States: Occurrence and Geochemistry",
    year = "2000",
    journal = "Ground Water",
    abstract = "Abstract Concentrations of naturally occurring arsenic in ground water vary regionally due to a combination of climate and geology. Although slightly less than half of 30,000 arsenic analyses of ground water in the United States were 1 μg/L, about 10\% exceeded 10 μg/L. At a broad regional scale, arsenic concentrations exceeding 10 μg/L appear to be more frequently observed in the western United States than in the eastern half. Arsenic concentrations in ground water of the Appalachian Highlands and the Atlantic Plain generally are very low (1 μg/L). Concentrations are somewhat greater in the Interior Plains and the Rocky Mountain System. Investigations of ground water in New England, Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin within the last decade suggest that arsenic concentrations exceeding 10 μg/L are more widespread and common than previously recognized. Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 μg/L in ground water. This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i.e., petroleum products) organic carbon. Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the western United States. Sulfide minerals are both a source and sink for arsenic. Geothermal water and high evaporation rates also are associated with arsenic concentrations 10g/L in ground and surface water, particularly in the west.",
    url = "https://doi.org/10.1111/j.1745-6584.2000.tb00251.x",
    doi = "10.1111/j.1745-6584.2000.tb00251.x",
    openalex = "W1985879113"
}

ABSTRACT: Pond‐cypress, a deciduous conifer, is a dominant canopy species in depressional wetlands of the southeastern Coastal Plain (SCP). Extensive premature decline and death of pond‐cypress trees in central Florida have been attributed to hydroperiod alterations due to excessive withdrawals of ground water from the Floridan aquifer. One factor identified in the decline process is basal decay, which may be related to the presence of Botryosphaeria rhodina and Fusarium species (nonaggressive, facultative fungal pathogens). These fungi have been cultured from sapwood tissue of declining pond‐cypress associated with ground water mining, but not from pond‐cypress away from ground water mimng areas. In this experiment, differences in soluble (nonstructural) carbohydrate composition of branch tips were evaluated for one‐and two‐year old, nursery‐grown (unsheltered) pond‐cypress, following a year of growth under treatment conditions (control, fungal inoculation, water stress, and fungal inoculation plus water stress) in a growth chamber. Results from two methods of wet chemical analysis were compared (trimethylsilyl methylglycoside‐Method A, and alditol acetate ‐ Method B). Three pentoses (arabinose, rhamnose, and xylose) and three hexoses (galactose, glucose, and mannose) were identified in branch tips from both age classes. A fourth hexose (fucose) also was identified in samples from the younger trees. The acidic sugar, galacturonic acid, was identified in both age classes using Method A. Results suggest that prolonged water stress is correlated with greater relative concentrations of the neutral soluble sugars rhamnose (P = 0.02), xylose (P = 0.02), and galactose (P = 0.02), in addition to the acidic sugar galacturonic acid (P = 0.01), for Method A, and arabinose (P = 0.02) for Method B. These results also suggest that in the absence of water stress, the fungal pathogen B. rhodina does not penetrate to the sapwood of the trees, and that inoculation with this fungal pathogen is not correlated with differences in relative concentrations of nonstructural, soluble carbohydrates, based on Method A analysis. Empirical evidence suggests that pond‐cypress trees in depressional wetlands respond similarly to anthropogenic perturbations of ground water, but not to natural periods of drought in the absence of such perturbations. Therefore, pond‐cypress appear to be integrators of groundwater perturbations. Greater concentrations of the soluble sugars identified in this study in pond‐cypress branch tips may be hydroecological indicators of such anthropogenic perturbations as unsustainable yield from the regional aquifer and adverse impacts from aquifer storage and recovery (ASR) activities in the SCP.

@article{doi101111j175216882000tb04248x,
    author = "Bacchus, Sydney T. and Hamazaki, Toshihide and Britton, Kerry O. and Haines, Bruce L.",
    title = "SOLUBLE SUGAR COMPOSITION OF POND‐CYPRESS: A POTENTIAL HYDROECOLOGICAL INDICATOR OF GROUND WATER PERTURBATIONS 1",
    year = "2000",
    journal = "JAWRA Journal of the American Water Resources Association",
    abstract = "ABSTRACT: Pond‐cypress, a deciduous conifer, is a dominant canopy species in depressional wetlands of the southeastern Coastal Plain (SCP). Extensive premature decline and death of pond‐cypress trees in central Florida have been attributed to hydroperiod alterations due to excessive withdrawals of ground water from the Floridan aquifer. One factor identified in the decline process is basal decay, which may be related to the presence of Botryosphaeria rhodina and Fusarium species (nonaggressive, facultative fungal pathogens). These fungi have been cultured from sapwood tissue of declining pond‐cypress associated with ground water mining, but not from pond‐cypress away from ground water mimng areas. In this experiment, differences in soluble (nonstructural) carbohydrate composition of branch tips were evaluated for one‐and two‐year old, nursery‐grown (unsheltered) pond‐cypress, following a year of growth under treatment conditions (control, fungal inoculation, water stress, and fungal inoculation plus water stress) in a growth chamber. Results from two methods of wet chemical analysis were compared (trimethylsilyl methylglycoside‐Method A, and alditol acetate ‐ Method B). Three pentoses (arabinose, rhamnose, and xylose) and three hexoses (galactose, glucose, and mannose) were identified in branch tips from both age classes. A fourth hexose (fucose) also was identified in samples from the younger trees. The acidic sugar, galacturonic acid, was identified in both age classes using Method A. Results suggest that prolonged water stress is correlated with greater relative concentrations of the neutral soluble sugars rhamnose (P = 0.02), xylose (P = 0.02), and galactose (P = 0.02), in addition to the acidic sugar galacturonic acid (P = 0.01), for Method A, and arabinose (P = 0.02) for Method B. These results also suggest that in the absence of water stress, the fungal pathogen B. rhodina does not penetrate to the sapwood of the trees, and that inoculation with this fungal pathogen is not correlated with differences in relative concentrations of nonstructural, soluble carbohydrates, based on Method A analysis. Empirical evidence suggests that pond‐cypress trees in depressional wetlands respond similarly to anthropogenic perturbations of ground water, but not to natural periods of drought in the absence of such perturbations. Therefore, pond‐cypress appear to be integrators of groundwater perturbations. Greater concentrations of the soluble sugars identified in this study in pond‐cypress branch tips may be hydroecological indicators of such anthropogenic perturbations as unsustainable yield from the regional aquifer and adverse impacts from aquifer storage and recovery (ASR) activities in the SCP.",
    url = "https://doi.org/10.1111/j.1752-1688.2000.tb04248.x",
    doi = "10.1111/j.1752-1688.2000.tb04248.x",
    openalex = "W2004128730",
    references = "doi103133wri934044"
}

The hydrogeology and ground-water quality of Seminole County in east-central Florida was evaluated. A ground-water flow model was developed to simulate the effects of both present day (September 1996 through August 1997) and projected 2020 ground-water withdrawals on the water levels in the surficial aquifer system and the potentiometric surface of the Upper and Lower Floridan aquifers in Seminole County and vicinity. The Floridan aquifer system is the major source of ground water in the study area. In 1965, ground-water withdrawals from the Floridan aquifer system in Seminole County were about 11 million gallons per day. In 1995, withdrawals totaled about 69 million gallons per day. Of the total ground water used in 1995, 74 percent was for public supply, 12 percent for domestic self-supplied, 10 percent for agriculture self-supplied, and 4 percent for recreational irrigation. The principal water-bearing units in Seminole County are the surficial aquifer system and the Floridan aquifer system. The two aquifer systems are separated by the intermediate confining unit, which contains beds of lower permeability sediments that confine the water in the Floridan aquifer system. The Floridan aquifer system has two major water-bearing zones (the Upper Floridan aquifer and the Lower Floridan aquifer), which are separated by a less-permeable semiconfining unit. Upper Floridan aquifer water levels and spring flows have been affected by ground-water development. Long-term hydrographs of four wells tapping the Upper Floridan aquifer show a general downward trend from the early 1950's until 1990. The declines in water levels are caused predominantly by increased pumpage and below average annual rainfall. From 1991 to 1998, water levels rose slightly, a trend that can be explained by an increase in average annual rainfall. Long-term declines in the potentiometric surface varied throughout the area, ranging from about 3 to 12 feet. Decreases in spring discharge also have been observed in a few springs with long-term record. Chloride concentrations in water from the Upper Floridan aquifer in Seminole County range areally from 6.2 to 5,300 milligrams per liter. Chloride concentrations are lowest in the recharge areas of the Floridan aquifer system in the western part of Seminole County and near Geneva. The most highly mineralized water occurs adjacent to the Wekiva River in northwestern Seminole County, around the eastern part of Lake Jesup, and along the St. Johns River in eastern Seminole County. Analysis of limited long-term water-quality data indicates that the chloride concentrations in water for most wells in the Floridan aquifer system in Seminole County have not changed significantly in the 20-year period from 1976 to 1996, and probably not since the mid 1950's. Analysis of water samples collected from some Upper Floridan aquifer springs, however, indicates that the water has become more mineralized during recent years. Increases in specific conductance and concentrations of major cations and anions were observed at several of the springs within the study area where long-term water-quality data were available. Associated with these increases in the mineralization of spring water has been an increase in total nitrate-plus- nitrite as nitrogen concentration. A three-dimensional model was developed to simulate ground-water flow in the surficial and Floridan aquifer systems. The steady-state ground-water flow model was calibrated to water-level data that was averaged over a 1-year period from September 1996 through August 1997. The calibrated flow model generally produced simulated water levels in reasonably close agreement with measured water levels. As a result, the calibrated model was used to simulate the effects of expected increases in ground-water withdrawals on the water levels in the surficial aquifer system and on the potentiometric surface of the Upper and Lower Floridan aquifers in Seminole County. The ca

@misc{doi103133wri014182,
    author = "Spechler, Rick M. and Halford, Keith J.",
    title = "Hydrogeology, water quality, and simulated effects of ground-water withdrawals from the Floridan aquifer system, Seminole County and vicinity, Florida",
    year = "2001",
    abstract = "The hydrogeology and ground-water quality of Seminole County in east-central Florida was evaluated. A ground-water flow model was developed to simulate the effects of both present day (September 1996 through August 1997) and projected 2020 ground-water withdrawals on the water levels in the surficial aquifer system and the potentiometric surface of the Upper and Lower Floridan aquifers in Seminole County and vicinity. The Floridan aquifer system is the major source of ground water in the study area. In 1965, ground-water withdrawals from the Floridan aquifer system in Seminole County were about 11 million gallons per day. In 1995, withdrawals totaled about 69 million gallons per day. Of the total ground water used in 1995, 74 percent was for public supply, 12 percent for domestic self-supplied, 10 percent for agriculture self-supplied, and 4 percent for recreational irrigation. The principal water-bearing units in Seminole County are the surficial aquifer system and the Floridan aquifer system. The two aquifer systems are separated by the intermediate confining unit, which contains beds of lower permeability sediments that confine the water in the Floridan aquifer system. The Floridan aquifer system has two major water-bearing zones (the Upper Floridan aquifer and the Lower Floridan aquifer), which are separated by a less-permeable semiconfining unit. Upper Floridan aquifer water levels and spring flows have been affected by ground-water development. Long-term hydrographs of four wells tapping the Upper Floridan aquifer show a general downward trend from the early 1950's until 1990. The declines in water levels are caused predominantly by increased pumpage and below average annual rainfall. From 1991 to 1998, water levels rose slightly, a trend that can be explained by an increase in average annual rainfall. Long-term declines in the potentiometric surface varied throughout the area, ranging from about 3 to 12 feet. Decreases in spring discharge also have been observed in a few springs with long-term record. Chloride concentrations in water from the Upper Floridan aquifer in Seminole County range areally from 6.2 to 5,300 milligrams per liter. Chloride concentrations are lowest in the recharge areas of the Floridan aquifer system in the western part of Seminole County and near Geneva. The most highly mineralized water occurs adjacent to the Wekiva River in northwestern Seminole County, around the eastern part of Lake Jesup, and along the St. Johns River in eastern Seminole County. Analysis of limited long-term water-quality data indicates that the chloride concentrations in water for most wells in the Floridan aquifer system in Seminole County have not changed significantly in the 20-year period from 1976 to 1996, and probably not since the mid 1950's. Analysis of water samples collected from some Upper Floridan aquifer springs, however, indicates that the water has become more mineralized during recent years. Increases in specific conductance and concentrations of major cations and anions were observed at several of the springs within the study area where long-term water-quality data were available. Associated with these increases in the mineralization of spring water has been an increase in total nitrate-plus- nitrite as nitrogen concentration. A three-dimensional model was developed to simulate ground-water flow in the surficial and Floridan aquifer systems. The steady-state ground-water flow model was calibrated to water-level data that was averaged over a 1-year period from September 1996 through August 1997. The calibrated flow model generally produced simulated water levels in reasonably close agreement with measured water levels. As a result, the calibrated model was used to simulate the effects of expected increases in ground-water withdrawals on the water levels in the surficial aquifer system and on the potentiometric surface of the Upper and Lower Floridan aquifers in Seminole County. The ca",
    url = "https://doi.org/10.3133/wri014182",
    doi = "10.3133/wri014182",
    openalex = "W144625416"
}

@article{doi101007s1004000101824,
    author = "Bouwer, Herman",
    title = "Artificial recharge of groundwater: hydrogeology and engineering",
    year = "2002",
    journal = "Hydrogeology Journal",
    url = "https://doi.org/10.1007/s10040-001-0182-4",
    doi = "10.1007/s10040-001-0182-4",
    openalex = "W2100667239"
}

@article{doi101016s0883292702000185,
    author = "Smedley, Pauline and Kinniburgh, D.G.",
    title = "A review of the source, behaviour and distribution of arsenic in natural waters",
    year = "2002",
    journal = "Applied Geochemistry",
    url = "https://doi.org/10.1016/s0883-2927(02)00018-5",
    doi = "10.1016/s0883-2927(02)00018-5",
    openalex = "W2149602337",
    references = "doi1010079783642730931, doi1010160016703755900429, doi1010160375674273900034, doi101038333134a0, doi1012019781439833544, stewart1963marine"
}

In contrast to most other fields of noble gas geochemistry that mostly regard atmospheric noble gases as 'contamination,' air-derived noble gases make up the far largest and hence most important contribution to the noble gas abundance in meteoric waters, such as lakes and ground waters. Atmospheric noble gases enter the meteoric water cycle by gas partitioning during air / water exchange with the atmosphere. In lakes and oceans noble gases are exchanged with the free atmosphere at the surface of the open water body. In ground waters gases partition between the water phase and the soil air of the quasi-saturated zone, the transition between the unsaturated and the saturated zone. Extensive measurements have shown that noble gas concentrations of open waters agree well with the noble gas solubility equilibrium according to (free) air /(free) water partitioning, whereby the aquatic concentration is directly proportional to the respective atmospheric noble gas abundance (Henry law, Aeschbach-Hertig et al. 1999b). In applications in lakes and ground waters the gas specific Henry coefficient can simplifying be assumed to depend only on temperature and salinity of the water. Hence the equilibrium concentrations of noble gases implicitly convey information on the physical properties of the water during gas exchange at the air / water interface, i.e., air pressure, temperature and salinity of the exchanging water mass. The ubiquitous presence of atmospheric noble gases in the meteoric water cycle defines a natural baseline, which masks other noble gas components until their abundance is sufficiently large that these components can be separated against the natural atmospheric background. For most classical geochemical aspects this typical feature of natural waters may look at first sight as a disadvantage. In fact it turns out to be advantageous because in most cases the noble gas abundance in water can be understood as a binary mixture of two distinct noble gas components - a well- constrained atmospheric component and a residual component of non-atmospheric origin. Only very few processes are able to fractionate atmospheric noble gases. All these processes are controlled by well-understood physical mechanisms, which in consequence constrain air-derived noble gases and any other component completely. In addition to atmospheric noble gases basically two non-atmospheric noble gas components are present in most natural waters: radiogenic noble gases and terrigenic noble gases from different geochemical compartments of the Earth.

@article{doi102138rmg20024714,
    author = "Kipfer, Rolf and Aeschbach, Werner and Peeters, Frank and Stute, M.",
    title = "Noble Gases in Lakes and Ground Waters",
    year = "2002",
    journal = "Reviews in Mineralogy and Geochemistry",
    abstract = "In contrast to most other fields of noble gas geochemistry that mostly regard atmospheric noble gases as 'contamination,' air-derived noble gases make up the far largest and hence most important contribution to the noble gas abundance in meteoric waters, such as lakes and ground waters. Atmospheric noble gases enter the meteoric water cycle by gas partitioning during air / water exchange with the atmosphere. In lakes and oceans noble gases are exchanged with the free atmosphere at the surface of the open water body. In ground waters gases partition between the water phase and the soil air of the quasi-saturated zone, the transition between the unsaturated and the saturated zone. Extensive measurements have shown that noble gas concentrations of open waters agree well with the noble gas solubility equilibrium according to (free) air /(free) water partitioning, whereby the aquatic concentration is directly proportional to the respective atmospheric noble gas abundance (Henry law, Aeschbach-Hertig et al. 1999b). In applications in lakes and ground waters the gas specific Henry coefficient can simplifying be assumed to depend only on temperature and salinity of the water. Hence the equilibrium concentrations of noble gases implicitly convey information on the physical properties of the water during gas exchange at the air / water interface, i.e., air pressure, temperature and salinity of the exchanging water mass. The ubiquitous presence of atmospheric noble gases in the meteoric water cycle defines a natural baseline, which masks other noble gas components until their abundance is sufficiently large that these components can be separated against the natural atmospheric background. For most classical geochemical aspects this typical feature of natural waters may look at first sight as a disadvantage. In fact it turns out to be advantageous because in most cases the noble gas abundance in water can be understood as a binary mixture of two distinct noble gas components - a well- constrained atmospheric component and a residual component of non-atmospheric origin. Only very few processes are able to fractionate atmospheric noble gases. All these processes are controlled by well-understood physical mechanisms, which in consequence constrain air-derived noble gases and any other component completely. In addition to atmospheric noble gases basically two non-atmospheric noble gas components are present in most natural waters: radiogenic noble gases and terrigenic noble gases from different geochemical compartments of the Earth.",
    url = "https://doi.org/10.2138/rmg.2002.47.14",
    doi = "10.2138/rmg.2002.47.14",
    openalex = "W1973157140",
    references = "doi1010160022169482901470, doi106028jres105043"
}

The Rhode Island Water Resources Board is considering expanded use of ground-water resources from the Big River area because increasing water demands in Rhode Island may exceed the capacity of current sources. This report describes the hydrology of the area and numerical simulation models that were used to examine effects of ground-water withdrawals during 1964?98 and to describe potential effects of different withdrawal scenarios in the area. The Big River study area covers 35.7 square miles (mi2) and includes three primary surface-water drainage basins?the Mishnock River Basin above Route 3, the Big River Basin, and the Carr River Basin, which is a tributary to the Big River. The principal aquifer (referred to as the surficial aquifer) in the study area, which is defined as the area of stratified deposits with a saturated thickness estimated to be 10 feet or greater, covers an area of 10.9 mi2. On average, an estimated 75 cubic feet per second (ft3/s) of water flows through the study area and about 70 ft3/s flows out of the area as streamflow in either the Big River (about 63 ft3/s) or the Mishnock River (about 7 ft3/s). Numerical simulation models are used to describe the hydrology of the area under simulated predevelopment conditions, conditions during 1964?98, and conditions that might occur in 14 hypothetical ground-water withdrawal scenarios with total ground-water withdrawal rates in the area that range from 2 to 11 million gallons per day. Streamflow depletion caused by these hypothetical ground-water withdrawals is calculated by comparison with simulated flows for the predevelopment conditions, which are identical to simulated conditions during the 1964?98 period but without withdrawals at public-supply wells and wastewater recharge. Interpretation of numerical simulation results indicates that the three basins in the study area are in fact a single ground-water resource. For example, the Carr River Basin above Capwell Mill Pond is naturally losing water to the Mishnock River Basin. Withdrawals in the Carr River Basin can deplete streamflows in the Mishnock River Basin. Withdrawals in the Mishnock River Basin deplete streamflows in the Big River Basin and can intercept water flowing to the Flat River Reservoir North of Hill Farm Road in Coventry, Rhode Island. Withdrawals in the Big River Basin can deplete streamflows in the western unnamed tributary to the Carr River, but do not deplete streamflows in the Mishnock River Basin or in the Carr River upstream of Capwell Mill Pond. Because withdrawals deplete streamflows in the study area, the total amount of ground water that may be withdrawn for public supply depends on the minimum allowable streamflow criterion that is applied for each basin.

@misc{doi103133wri034222,
    author = "Granato, Gregory E. and Barlow, Paul M. and Dickerman, David C.",
    title = "Hydrogeology and Simulated Effects of Ground-Water Withdrawals in the Big River Area, Rhode Island",
    year = "2003",
    abstract = "The Rhode Island Water Resources Board is considering expanded use of ground-water resources from the Big River area because increasing water demands in Rhode Island may exceed the capacity of current sources. This report describes the hydrology of the area and numerical simulation models that were used to examine effects of ground-water withdrawals during 1964?98 and to describe potential effects of different withdrawal scenarios in the area. The Big River study area covers 35.7 square miles (mi2) and includes three primary surface-water drainage basins?the Mishnock River Basin above Route 3, the Big River Basin, and the Carr River Basin, which is a tributary to the Big River. The principal aquifer (referred to as the surficial aquifer) in the study area, which is defined as the area of stratified deposits with a saturated thickness estimated to be 10 feet or greater, covers an area of 10.9 mi2. On average, an estimated 75 cubic feet per second (ft3/s) of water flows through the study area and about 70 ft3/s flows out of the area as streamflow in either the Big River (about 63 ft3/s) or the Mishnock River (about 7 ft3/s). Numerical simulation models are used to describe the hydrology of the area under simulated predevelopment conditions, conditions during 1964?98, and conditions that might occur in 14 hypothetical ground-water withdrawal scenarios with total ground-water withdrawal rates in the area that range from 2 to 11 million gallons per day. Streamflow depletion caused by these hypothetical ground-water withdrawals is calculated by comparison with simulated flows for the predevelopment conditions, which are identical to simulated conditions during the 1964?98 period but without withdrawals at public-supply wells and wastewater recharge. Interpretation of numerical simulation results indicates that the three basins in the study area are in fact a single ground-water resource. For example, the Carr River Basin above Capwell Mill Pond is naturally losing water to the Mishnock River Basin. Withdrawals in the Carr River Basin can deplete streamflows in the Mishnock River Basin. Withdrawals in the Mishnock River Basin deplete streamflows in the Big River Basin and can intercept water flowing to the Flat River Reservoir North of Hill Farm Road in Coventry, Rhode Island. Withdrawals in the Big River Basin can deplete streamflows in the western unnamed tributary to the Carr River, but do not deplete streamflows in the Mishnock River Basin or in the Carr River upstream of Capwell Mill Pond. Because withdrawals deplete streamflows in the study area, the total amount of ground water that may be withdrawn for public supply depends on the minimum allowable streamflow criterion that is applied for each basin.",
    url = "https://doi.org/10.3133/wri034222",
    doi = "10.3133/wri034222",
    openalex = "W1532304071",
    references = "doi103133wri974126"
}

On behalf of the World Health Organization (WHO), I have undertaken a series of literature-based investigations examining the global burden of disease related to a number of environmental risk factors associated with drinking water. In this article I outline the investigation of drinking-water nitrate concentration and methemoglobinemia. The exposure assessment was based on levels of nitrate in drinking water greater than the WHO guideline value of 50 mg/L. No exposure-response relationship, however, could be identified that related drinking-water nitrate level to methemoglobinemia. Indeed, although it has previously been accepted that consumption of drinking water high in nitrates causes methemoglobinemia in infants, it appears now that nitrate may be one of a number of co-factors that play a sometimes complex role in causing the disease. I conclude that, given the apparently low incidence of possible water-related methemoglobinemia, the complex nature of the role of nitrates, and that of individual behavior, it is currently inappropriate to attempt to link illness rates with drinking-water nitrate levels.

@article{doi101289ehp7216,
    author = "Fewtrell, Lorna",
    title = "Drinking-Water Nitrate, Methemoglobinemia, and Global Burden of Disease: A Discussion",
    year = "2004",
    journal = "Environmental Health Perspectives",
    abstract = "On behalf of the World Health Organization (WHO), I have undertaken a series of literature-based investigations examining the global burden of disease related to a number of environmental risk factors associated with drinking water. In this article I outline the investigation of drinking-water nitrate concentration and methemoglobinemia. The exposure assessment was based on levels of nitrate in drinking water greater than the WHO guideline value of 50 mg/L. No exposure-response relationship, however, could be identified that related drinking-water nitrate level to methemoglobinemia. Indeed, although it has previously been accepted that consumption of drinking water high in nitrates causes methemoglobinemia in infants, it appears now that nitrate may be one of a number of co-factors that play a sometimes complex role in causing the disease. I conclude that, given the apparently low incidence of possible water-related methemoglobinemia, the complex nature of the role of nitrates, and that of individual behavior, it is currently inappropriate to attempt to link illness rates with drinking-water nitrate levels.",
    url = "https://doi.org/10.1289/ehp.7216",
    doi = "10.1289/ehp.7216",
    openalex = "W2045507079",
    references = "doi101001jama194502860360014004"
}

To meet water-supply needs in central Florida for 2020, the St. Johns River is being considered as a source of water supply to augment ground water from the Floridan aquifer system. Current (2004) information on streamflow and water-quality characteristics of the St. Johns River in east-central Florida is needed by water resources planners to assess the feasibility of using the river as an alternate source of water supply and to design water treatment facilities. To address this need, streamflow and water quality of the 90-mile-long middle reach of the St. Johns River, Florida, from downstream of Lake Poinsett to near DeLand, were characterized by using retrospective (1991-99) and recently collected data (2000-02). Streamflow characteristics were determined by using data from water years 1933-2000. Water-quality characteristics were described using data from 1991-99 at 15 sites on the St. Johns River and 1 site each near the mouths of the Econlockhatchee and Wekiva Rivers. Data were augmented with biweekly water-quality data and continuous physical properties data at four St. Johns River sites and quarterly data from sites on the Wekiva River, Blackwater Creek, and downstream of Blue Springs from 2000-02. Water-quality constituents described were limited to information on physical properties, major ions and other inorganic constituents, nutrients, organic carbon, suspended solids, and phytoplankton chlorophyll-a. The occurrence of antibiotics, human prescription and nonprescription drugs, pesticides, and a suite of organic constituents, which may indicate domestic or industrial waste, were described at two St. Johns River sites using limited data collected in water years 2002-03. The occurrence of these same constituents in water from a pilot water treatment facility on Lake Monroe also was described using data from one sampling event conducted in March 2003. Dissolved oxygen concentration and water pH values in the St. Johns River were significantly lower during high-flow conditions than during low-flow conditions. Low dissolved oxygen concentrations may have resulted from the input of water from marsh areas or the subsequent decomposition of organic matter transported to the river during high-flow events. Low water pH values during high-flow conditions likely resulted from the increased dissolved organic carbon concentrations in the river. Concentrations of total dissolved solids and other inorganic constituents in the St. Johns River were inversely related with streamflow. Most major ion concentrations, total dissolved solids concentrations, and specific conductance values varied substantially at the Christmas, Sanford, and DeLand sites during low-flow periods in 2000-01 probably reflecting wind and tidal effects. Sulfide concentrations as high as 6 milligrams per liter (mg/L) were measured in the St. Johns River during high-flow periods. Increased sulfide concentrations likely resulted from the decomposition of organic matter or the reduction of sulfate. Bromide concentrations as high as 17 mg/L were measured at the most upstream site on the St. Johns River during 2000-02. Temporal variations in bromide were characterized by sharp peaks in concentration during low-flow periods. Peaks in bromide concentrations tended to coincide with peaks in chloride concentrations because the likely source of both constituents is ground water affected by relict seawater. Median dissolved organic carbon concentrations ranged from 15 to 26 mg/L during 2000-02, and concentrations as high as 42 mg/L were measured. Water color values and dissolved organic carbon concentrations generally were significantly greater during high-flow conditions than during low-flow conditions. Specific ultraviolet light absorbance data indicated the organic carbon during high-flow events was more aromatic in composition and likely originated from terrestrially derived sources compared to organic carbon in the river during other times of the year. D

@article{doi103133sir20045177,
    author = "Kroening, Sharon E.",
    title = "Streamflow and water-quality characteristics at selected sites of the St. Johns River in central Florida, 1933 to 2002",
    year = "2004",
    journal = "Scientific investigations report",
    abstract = "To meet water-supply needs in central Florida for 2020, the St. Johns River is being considered as a source of water supply to augment ground water from the Floridan aquifer system. Current (2004) information on streamflow and water-quality characteristics of the St. Johns River in east-central Florida is needed by water resources planners to assess the feasibility of using the river as an alternate source of water supply and to design water treatment facilities. To address this need, streamflow and water quality of the 90-mile-long middle reach of the St. Johns River, Florida, from downstream of Lake Poinsett to near DeLand, were characterized by using retrospective (1991-99) and recently collected data (2000-02). Streamflow characteristics were determined by using data from water years 1933-2000. Water-quality characteristics were described using data from 1991-99 at 15 sites on the St. Johns River and 1 site each near the mouths of the Econlockhatchee and Wekiva Rivers. Data were augmented with biweekly water-quality data and continuous physical properties data at four St. Johns River sites and quarterly data from sites on the Wekiva River, Blackwater Creek, and downstream of Blue Springs from 2000-02. Water-quality constituents described were limited to information on physical properties, major ions and other inorganic constituents, nutrients, organic carbon, suspended solids, and phytoplankton chlorophyll-a. The occurrence of antibiotics, human prescription and nonprescription drugs, pesticides, and a suite of organic constituents, which may indicate domestic or industrial waste, were described at two St. Johns River sites using limited data collected in water years 2002-03. The occurrence of these same constituents in water from a pilot water treatment facility on Lake Monroe also was described using data from one sampling event conducted in March 2003. Dissolved oxygen concentration and water pH values in the St. Johns River were significantly lower during high-flow conditions than during low-flow conditions. Low dissolved oxygen concentrations may have resulted from the input of water from marsh areas or the subsequent decomposition of organic matter transported to the river during high-flow events. Low water pH values during high-flow conditions likely resulted from the increased dissolved organic carbon concentrations in the river. Concentrations of total dissolved solids and other inorganic constituents in the St. Johns River were inversely related with streamflow. Most major ion concentrations, total dissolved solids concentrations, and specific conductance values varied substantially at the Christmas, Sanford, and DeLand sites during low-flow periods in 2000-01 probably reflecting wind and tidal effects. Sulfide concentrations as high as 6 milligrams per liter (mg/L) were measured in the St. Johns River during high-flow periods. Increased sulfide concentrations likely resulted from the decomposition of organic matter or the reduction of sulfate. Bromide concentrations as high as 17 mg/L were measured at the most upstream site on the St. Johns River during 2000-02. Temporal variations in bromide were characterized by sharp peaks in concentration during low-flow periods. Peaks in bromide concentrations tended to coincide with peaks in chloride concentrations because the likely source of both constituents is ground water affected by relict seawater. Median dissolved organic carbon concentrations ranged from 15 to 26 mg/L during 2000-02, and concentrations as high as 42 mg/L were measured. Water color values and dissolved organic carbon concentrations generally were significantly greater during high-flow conditions than during low-flow conditions. Specific ultraviolet light absorbance data indicated the organic carbon during high-flow events was more aromatic in composition and likely originated from terrestrially derived sources compared to organic carbon in the river during other times of the year. D",
    url = "https://doi.org/10.3133/sir20045177",
    doi = "10.3133/sir20045177",
    openalex = "W1502164649",
    references = "doi103133wri014182"
}

@article{openalexw1607015536,
    author = "Kwong, Y. T. John",
    title = "Mine Water Hydrogeology and Geochemistry",
    year = "2004",
    journal = "Geoscience Canada",
    url = "https://openalex.org/W1607015536",
    openalex = "W1607015536"
}

The age, or residence time, of water is a fundamental descriptor of catchment hydrology, revealing information about the storage, flow pathways, and source of water in a single integrated measure. While there has been tremendous recent interest in residence time estimation to characterize watersheds, there are relatively few studies that have quantified residence time at the watershed scale, and fewer still that have extended those results beyond single catchments to larger landscape scales. We examined topographic controls on residence time for seven catchments (0.085–62.4 km 2) that represent diverse geologic and geomorphic conditions in the western Cascade Mountains of Oregon. Our primary objective was to determine the dominant physical controls on catchment‐scale water residence time and specifically test the hypothesis that residence time is related to the size of the basin. Residence times were estimated by simple convolution models that described the transfer of precipitation isotopic composition to the stream network. We found that base flow mean residence times for exponential distributions ranged from 0.8 to 3.3 years. Mean residence time showed no correlation to basin area (r 2 < 0.01) but instead was correlated (r 2 = 0.91) to catchment terrain indices representing the flow path distance and flow path gradient to the stream network. These results illustrate that landscape organization (i.e., topography) rather than basin area controls catchment‐scale transport. Results from this study may provide a framework for describing scale‐invariant transport across climatic and geologic conditions, whereby the internal form and structure of the basin defines the first‐order control on base flow residence time.

@article{doi1010292004wr003657,
    author = "McGuire, K. J. and McDonnell, Jeffrey J. and Weiler, Markus and Kendall, Carol and McGlynn, B. L. and Welker, J. M. and Seibert, Jan",
    title = "The role of topography on catchment‐scale water residence time",
    year = "2005",
    journal = "Water Resources Research",
    abstract = "The age, or residence time, of water is a fundamental descriptor of catchment hydrology, revealing information about the storage, flow pathways, and source of water in a single integrated measure. While there has been tremendous recent interest in residence time estimation to characterize watersheds, there are relatively few studies that have quantified residence time at the watershed scale, and fewer still that have extended those results beyond single catchments to larger landscape scales. We examined topographic controls on residence time for seven catchments (0.085–62.4 km 2) that represent diverse geologic and geomorphic conditions in the western Cascade Mountains of Oregon. Our primary objective was to determine the dominant physical controls on catchment‐scale water residence time and specifically test the hypothesis that residence time is related to the size of the basin. Residence times were estimated by simple convolution models that described the transfer of precipitation isotopic composition to the stream network. We found that base flow mean residence times for exponential distributions ranged from 0.8 to 3.3 years. Mean residence time showed no correlation to basin area (r 2 < 0.01) but instead was correlated (r 2 = 0.91) to catchment terrain indices representing the flow path distance and flow path gradient to the stream network. These results illustrate that landscape organization (i.e., topography) rather than basin area controls catchment‐scale transport. Results from this study may provide a framework for describing scale‐invariant transport across climatic and geologic conditions, whereby the internal form and structure of the basin defines the first‐order control on base flow residence time.",
    url = "https://doi.org/10.1029/2004wr003657",
    doi = "10.1029/2004wr003657",
    openalex = "W2135843060",
    references = "doi1010160022169482901470, doi1012019781482242911"
}

Heat carried by ground water serves as a tracer to identify surface water infiltration, flow through fractures, and flow patterns in ground water basins. Temperature measurements can be analyzed for recharge and discharge rates, the effects of surface warming, interchange with surface water, hydraulic conductivity of streambed sediments, and basin-scale permeability. Temperature data are also used in formal solutions of the inverse problem to estimate ground water flow and hydraulic conductivity. The fundamentals of using heat as a ground water tracer were published in the 1960s, but recent work has significantly expanded the application to a variety of hydrogeological settings. In recent work, temperature is used to delineate flows in the hyporheic zone, estimate submarine ground water discharge and depth to the salt-water interface, and in parameter estimation with coupled ground water and heat-flow models. While short reviews of selected work on heat as a ground water tracer can be found in a number of research papers, there is no critical synthesis of the larger body of work found in the hydrogeological literature. The purpose of this review paper is to fill that void and to show that ground water temperature data and associated analytical tools are currently underused and have not yet realized their full potential.

@article{doi101111j17456584200500052x,
    author = "Anderson, Mary P.",
    title = "Heat as a Ground Water Tracer",
    year = "2005",
    journal = "Ground Water",
    abstract = "Heat carried by ground water serves as a tracer to identify surface water infiltration, flow through fractures, and flow patterns in ground water basins. Temperature measurements can be analyzed for recharge and discharge rates, the effects of surface warming, interchange with surface water, hydraulic conductivity of streambed sediments, and basin-scale permeability. Temperature data are also used in formal solutions of the inverse problem to estimate ground water flow and hydraulic conductivity. The fundamentals of using heat as a ground water tracer were published in the 1960s, but recent work has significantly expanded the application to a variety of hydrogeological settings. In recent work, temperature is used to delineate flows in the hyporheic zone, estimate submarine ground water discharge and depth to the salt-water interface, and in parameter estimation with coupled ground water and heat-flow models. While short reviews of selected work on heat as a ground water tracer can be found in a number of research papers, there is no critical synthesis of the larger body of work found in the hydrogeological literature. The purpose of this review paper is to fill that void and to show that ground water temperature data and associated analytical tools are currently underused and have not yet realized their full potential.",
    url = "https://doi.org/10.1111/j.1745-6584.2005.00052.x",
    doi = "10.1111/j.1745-6584.2005.00052.x",
    openalex = "W2146904562",
    references = "doi10102993jb01427, doi101126science2344777689, openalexw1604940817"
}

Elevated concentrations of sodium (Na+) and chloride (Cl-) in surface and ground water are common in the United States and other countries, and can serve as indicators of, or may constitute, a water quality problem. We have characterized the most prevalent natural and anthropogenic sources of Na+ and Cl- in ground water, primarily in Illinois, and explored techniques that could be used to identify their source. We considered seven potential sources that included agricultural chemicals, septic effluent, animal waste, municipal landfill leachate, sea water, basin brines, and road deicers. The halides Cl-, bromide (Br), and iodide (I) were useful indicators of the sources of Na+-Cl- contamination. Iodide enrichment (relative to Cl-) was greatest in precipitation, followed by uncontaminated soil water and ground water, and landfill leachate. The mass ratios of the halides among themselves, with total nitrogen (N), and with Na+ provided diagnostic methods for graphically distinguishing among sources of Na+ and Cl- in contaminated water. Cl/Br ratios relative to Cl- revealed a clear, although overlapping, separation of sample groups. Samples of landfill leachate and ground water known to be contaminated by leachate were enriched in I and Br; this provided an excellent fingerprint for identifying leachate contamination. In addition, total N, when plotted against Cl/Br ratios, successfully separated water contaminated by road salt from water contaminated by other sources.

@article{doi101111j17456584200500127x,
    author = "Panno, Samuel V. and Hackley, Keith C. and Hwang, H.H. and Greenberg, Sallie and Krapac, Ivan G. and Landsberger, S. and O’Kelly, D. J.",
    title = "Characterization and Identification of Na‐Cl Sources in Ground Water",
    year = "2005",
    journal = "Ground Water",
    abstract = "Elevated concentrations of sodium (Na+) and chloride (Cl-) in surface and ground water are common in the United States and other countries, and can serve as indicators of, or may constitute, a water quality problem. We have characterized the most prevalent natural and anthropogenic sources of Na+ and Cl- in ground water, primarily in Illinois, and explored techniques that could be used to identify their source. We considered seven potential sources that included agricultural chemicals, septic effluent, animal waste, municipal landfill leachate, sea water, basin brines, and road deicers. The halides Cl-, bromide (Br), and iodide (I) were useful indicators of the sources of Na+-Cl- contamination. Iodide enrichment (relative to Cl-) was greatest in precipitation, followed by uncontaminated soil water and ground water, and landfill leachate. The mass ratios of the halides among themselves, with total nitrogen (N), and with Na+ provided diagnostic methods for graphically distinguishing among sources of Na+ and Cl- in contaminated water. Cl/Br ratios relative to Cl- revealed a clear, although overlapping, separation of sample groups. Samples of landfill leachate and ground water known to be contaminated by leachate were enriched in I and Br; this provided an excellent fingerprint for identifying leachate contamination. In addition, total N, when plotted against Cl/Br ratios, successfully separated water contaminated by road salt from water contaminated by other sources.",
    url = "https://doi.org/10.1111/j.1745-6584.2005.00127.x",
    doi = "10.1111/j.1745-6584.2005.00127.x",
    openalex = "W2127777553",
    references = "doi1010160016703753900519, doi101016b9780444408266500078, doi101021ac00243a035, doi101111j174565841998tb01099x, doi1012019781439833544, doi1012019781482242911, doi1023072623756, openalexw1566391996, openalexw1973523254"
}

Human alteration of the nitrogen cycle has resulted in steadily accumulating nitrate in our water resources. The U.S. maximum contaminant level and World Health Organization guidelines for nitrate in drinking water were promulgated to protect infants from developing methemoglobinemia, an acute condition. Some scientists have recently suggested that the regulatory limit for nitrate is overly conservative; however, they have not thoroughly considered chronic health outcomes. In August 2004, a symposium on drinking-water nitrate and health was held at the International Society for Environmental Epidemiology meeting to evaluate nitrate exposures and associated health effects in relation to the current regulatory limit. The contribution of drinking-water nitrate toward endogenous formation of N-nitroso compounds was evaluated with a focus toward identifying subpopulations with increased rates of nitrosation. Adverse health effects may be the result of a complex interaction of the amount of nitrate ingested, the concomitant ingestion of nitrosation cofactors and precursors, and specific medical conditions that increase nitrosation. Workshop participants concluded that more experimental studies are needed and that a particularly fruitful approach may be to conduct epidemiologic studies among susceptible subgroups with increased endogenous nitrosation. The few epidemiologic studies that have evaluated intake of nitrosation precursors and/or nitrosation inhibitors have observed elevated risks for colon cancer and neural tube defects associated with drinking-water nitrate concentrations below the regulatory limit. The role of drinking-water nitrate exposure as a risk factor for specific cancers, reproductive outcomes, and other chronic health effects must be studied more thoroughly before changes to the regulatory level for nitrate in drinking water can be considered.

@article{doi101289ehp8043,
    author = "Ward, Mary H. and deKok, Theo M. and Levallois, Patrick and Brender, Jean D. and Guliš, Gabriel and Nolan, Bernard T. and VanDerslice, James",
    title = "Workgroup Report: Drinking-Water Nitrate and Health—Recent Findings and Research Needs",
    year = "2005",
    journal = "Environmental Health Perspectives",
    abstract = "Human alteration of the nitrogen cycle has resulted in steadily accumulating nitrate in our water resources. The U.S. maximum contaminant level and World Health Organization guidelines for nitrate in drinking water were promulgated to protect infants from developing methemoglobinemia, an acute condition. Some scientists have recently suggested that the regulatory limit for nitrate is overly conservative; however, they have not thoroughly considered chronic health outcomes. In August 2004, a symposium on drinking-water nitrate and health was held at the International Society for Environmental Epidemiology meeting to evaluate nitrate exposures and associated health effects in relation to the current regulatory limit. The contribution of drinking-water nitrate toward endogenous formation of N-nitroso compounds was evaluated with a focus toward identifying subpopulations with increased rates of nitrosation. Adverse health effects may be the result of a complex interaction of the amount of nitrate ingested, the concomitant ingestion of nitrosation cofactors and precursors, and specific medical conditions that increase nitrosation. Workshop participants concluded that more experimental studies are needed and that a particularly fruitful approach may be to conduct epidemiologic studies among susceptible subgroups with increased endogenous nitrosation. The few epidemiologic studies that have evaluated intake of nitrosation precursors and/or nitrosation inhibitors have observed elevated risks for colon cancer and neural tube defects associated with drinking-water nitrate concentrations below the regulatory limit. The role of drinking-water nitrate exposure as a risk factor for specific cancers, reproductive outcomes, and other chronic health effects must be studied more thoroughly before changes to the regulatory level for nitrate in drinking water can be considered.",
    url = "https://doi.org/10.1289/ehp.8043",
    doi = "10.1289/ehp.8043",
    openalex = "W2052871899",
    references = "doi101001jama194502860360014004"
}

Nitrate pollution of the karstic groundwater is an increasingly serious problem with the development of Guiyang, the capital city of Guizhou Province, southwest China. The higher content of NO3- in groundwater compared to surface water during both summer and winter seasons indicates that the karstic groundwater system cannot easily recover once contaminated with nitrate. In order to assess the sources and conversion of nitrate in the groundwater of Guiyang, we analyzed the major ions, delta(15)N-NH4+, delta(15)N-NO3-, and delta(18)O-NO3- in surface and groundwater samples collected during both summer and winter seasons. The results show that nitrate is the major dominant species of nitrogen in most water samples and there is a big variation of nitrate sources in groundwater between winter and summer season, due to fast response of groundwater to rain or surface water in the karst area. Combined with information on NO3- /Cl-, the variations of the isotope values of nitrate in the groundwater show a mixing process of multiple sources of nitrate, especially in the summer season. Chemical fertilizer and nitrification of nitrogen-containing organic materials contribute nitrate to suburban groundwater, while the sewage effluents and denitrification mainly control the nitrate distribution in urban groundwater.

@article{doi101021es0610129,
    author = "Liu, Cong‐Qiang and Li, Si‐Liang and Lang, Yunchao and Xiao, Huayun",
    title = "Using δ 15 N- and δ 18 O-Values To Identify Nitrate Sources in Karst Ground Water, Guiyang, Southwest China",
    year = "2006",
    journal = "Environmental Science \& Technology",
    abstract = "Nitrate pollution of the karstic groundwater is an increasingly serious problem with the development of Guiyang, the capital city of Guizhou Province, southwest China. The higher content of NO3- in groundwater compared to surface water during both summer and winter seasons indicates that the karstic groundwater system cannot easily recover once contaminated with nitrate. In order to assess the sources and conversion of nitrate in the groundwater of Guiyang, we analyzed the major ions, delta(15)N-NH4+, delta(15)N-NO3-, and delta(18)O-NO3- in surface and groundwater samples collected during both summer and winter seasons. The results show that nitrate is the major dominant species of nitrogen in most water samples and there is a big variation of nitrate sources in groundwater between winter and summer season, due to fast response of groundwater to rain or surface water in the karst area. Combined with information on NO3- /Cl-, the variations of the isotope values of nitrate in the groundwater show a mixing process of multiple sources of nitrate, especially in the summer season. Chemical fertilizer and nitrification of nitrogen-containing organic materials contribute nitrate to suburban groundwater, while the sewage effluents and denitrification mainly control the nitrate distribution in urban groundwater.",
    url = "https://doi.org/10.1021/es0610129",
    doi = "10.1021/es0610129",
    openalex = "W1983340920",
    references = "doi101001jama194502860360014004"
}

Abstract. Interactions between groundwater and surface water play a fundamental role in the functioning of riparian ecosystems. In the context of sustainable river basin management it is crucial to understand and quantify exchange processes between groundwater and surface water. Numerous well-known methods exist for parameter estimation and process identification in aquifers and surface waters. Only in recent years has the transition zone become a subject of major research interest; thus, the need has evolved for appropriate methods applicable in this zone. This article provides an overview of the methods that are currently applied and described in the literature for estimating fluxes at the groundwater – surface water interface. Considerations for choosing appropriate methods are given including spatial and temporal scales, uncertainties, and limitations in application. It is concluded that a multi-scale approach combining multiple measuring methods may considerably constrain estimates of fluxes between groundwater and surface water.

@article{doi105194hess108732006,
    author = "Kalbus, E. and Reinstorf, Frido and Schirmer, Mario",
    title = "Measuring methods for groundwater – surface water interactions: a review",
    year = "2006",
    journal = "Hydrology and earth system sciences",
    abstract = "Abstract. Interactions between groundwater and surface water play a fundamental role in the functioning of riparian ecosystems. In the context of sustainable river basin management it is crucial to understand and quantify exchange processes between groundwater and surface water. Numerous well-known methods exist for parameter estimation and process identification in aquifers and surface waters. Only in recent years has the transition zone become a subject of major research interest; thus, the need has evolved for appropriate methods applicable in this zone. This article provides an overview of the methods that are currently applied and described in the literature for estimating fluxes at the groundwater – surface water interface. Considerations for choosing appropriate methods are given including spatial and temporal scales, uncertainties, and limitations in application. It is concluded that a multi-scale approach combining multiple measuring methods may considerably constrain estimates of fluxes between groundwater and surface water.",
    url = "https://doi.org/10.5194/hess-10-873-2006",
    doi = "10.5194/hess-10-873-2006",
    openalex = "W2125790452",
    references = "doi1012019781482242911, openalexw1598440325, openalexw1604940817"
}

Reduction/oxidation (redox) conditions in 15 principal aquifer (PA) systems of the United States, and their impact on several water quality issues, were assessed from a large data base collected by the National Water-Quality Assessment Program of the USGS. The logic of these assessments was based on the observed ecological succession of electron acceptors such as dissolved oxygen, nitrate, and sulfate and threshold concentrations of these substrates needed to support active microbial metabolism. Similarly, the utilization of solid-phase electron acceptors such as Mn(IV) and Fe(III) is indicated by the production of dissolved manganese and iron. An internally consistent set of threshold concentration criteria was developed and applied to a large data set of 1692 water samples from the PAs to assess ambient redox conditions. The indicated redox conditions then were related to the occurrence of selected natural (arsenic) and anthropogenic (nitrate and volatile organic compounds) contaminants in ground water. For the natural and anthropogenic contaminants assessed in this study, considering redox conditions as defined by this framework of redox indicator species and threshold concentrations explained many water quality trends observed at a regional scale. An important finding of this study was that samples indicating mixed redox processes provide information on redox heterogeneity that is useful for assessing common water quality issues. Given the interpretive power of the redox framework and given that it is relatively inexpensive and easy to measure the chemical parameters included in the framework, those parameters should be included in routine water quality monitoring programs whenever possible.

@article{doi101111j17456584200700385x,
    author = "McMahon, Peter B. and Chapelle, Francis H.",
    title = "Redox Processes and Water Quality of Selected Principal Aquifer Systems",
    year = "2007",
    journal = "Ground Water",
    abstract = "Reduction/oxidation (redox) conditions in 15 principal aquifer (PA) systems of the United States, and their impact on several water quality issues, were assessed from a large data base collected by the National Water-Quality Assessment Program of the USGS. The logic of these assessments was based on the observed ecological succession of electron acceptors such as dissolved oxygen, nitrate, and sulfate and threshold concentrations of these substrates needed to support active microbial metabolism. Similarly, the utilization of solid-phase electron acceptors such as Mn(IV) and Fe(III) is indicated by the production of dissolved manganese and iron. An internally consistent set of threshold concentration criteria was developed and applied to a large data set of 1692 water samples from the PAs to assess ambient redox conditions. The indicated redox conditions then were related to the occurrence of selected natural (arsenic) and anthropogenic (nitrate and volatile organic compounds) contaminants in ground water. For the natural and anthropogenic contaminants assessed in this study, considering redox conditions as defined by this framework of redox indicator species and threshold concentrations explained many water quality trends observed at a regional scale. An important finding of this study was that samples indicating mixed redox processes provide information on redox heterogeneity that is useful for assessing common water quality issues. Given the interpretive power of the redox framework and given that it is relatively inexpensive and easy to measure the chemical parameters included in the framework, those parameters should be included in routine water quality monitoring programs whenever possible.",
    url = "https://doi.org/10.1111/j.1745-6584.2007.00385.x",
    doi = "10.1111/j.1745-6584.2007.00385.x",
    openalex = "W2124631354"
}

The Salt Pond region of southern Rhode Island extends from Westerly to Narragansett Bay and forms the natural boundary between the Atlantic Ocean and the shallow, highly permeable freshwater aquifer of the South Coastal Basin. Large inputs of fresh ground water coupled with the low flushing rates to the open ocean make the salt ponds particularly susceptible to eutrophication and bacterial contamination. Ground-water discharge to the salt ponds is an important though poorly quantified source of contaminants, such as dissolved nutrients. A ground-water-flow model was developed and used to delineate the watersheds to the salt ponds, including the areas that contribute ground water directly to the ponds and the areas that contribute ground water to streams that flow into ponds. The model also was used to calculate ground-water fluxes to these coastal areas for long-term average conditions. As part of the modeling analysis, adjustments were made to model input parameters to assess potential uncertainties in model-calculated watershed delineations and in ground-water discharge to the salt ponds. The results of the simulations indicate that flow to the salt ponds is affected primarily by the ease with which water is transmitted through a glacial moraine deposit near the regional ground-water divide, and by the specified recharge rate used in the model simulations. The distribution of the total freshwater flow between direct ground-water discharge and ground-water-derived surface-water (streamflow) discharge to the salt ponds is affected primarily by simulated stream characteristics, including the streambed-aquifer connection and the stream stage. The simulated position of the ground-water divide and, therefore, the model-calculated watershed delineations for the salt ponds, were affected only by changes in the transmissivity of the glacial moraine. Selected changes in other simulated hydraulic parameters had substantial effects on total freshwater discharge and the distribution of direct ground-water discharge and ground-water-derived surface-water (streamflow) discharge to the salt ponds, but still provided a reasonable match to the hydrologic data available for model calibration. To reduce the uncertainty in predictions of watershed areas and ground-water discharge to the salt ponds, additional hydrogeologic data would be required to constrain the model input parameters that have the greatest effect on the simulation results.

@article{doi103133sir20065271,
    author = "Masterson, John P. and Sorenson, Jason R. and Stone, Janet Radway and Moran, S. Bradley and Hougham, Andrea",
    title = "Hydrogeology and Simulated Ground-Water Flow in the Salt Pond Region of Southern Rhode Island",
    year = "2007",
    journal = "Scientific investigations report",
    abstract = "The Salt Pond region of southern Rhode Island extends from Westerly to Narragansett Bay and forms the natural boundary between the Atlantic Ocean and the shallow, highly permeable freshwater aquifer of the South Coastal Basin. Large inputs of fresh ground water coupled with the low flushing rates to the open ocean make the salt ponds particularly susceptible to eutrophication and bacterial contamination. Ground-water discharge to the salt ponds is an important though poorly quantified source of contaminants, such as dissolved nutrients. A ground-water-flow model was developed and used to delineate the watersheds to the salt ponds, including the areas that contribute ground water directly to the ponds and the areas that contribute ground water to streams that flow into ponds. The model also was used to calculate ground-water fluxes to these coastal areas for long-term average conditions. As part of the modeling analysis, adjustments were made to model input parameters to assess potential uncertainties in model-calculated watershed delineations and in ground-water discharge to the salt ponds. The results of the simulations indicate that flow to the salt ponds is affected primarily by the ease with which water is transmitted through a glacial moraine deposit near the regional ground-water divide, and by the specified recharge rate used in the model simulations. The distribution of the total freshwater flow between direct ground-water discharge and ground-water-derived surface-water (streamflow) discharge to the salt ponds is affected primarily by simulated stream characteristics, including the streambed-aquifer connection and the stream stage. The simulated position of the ground-water divide and, therefore, the model-calculated watershed delineations for the salt ponds, were affected only by changes in the transmissivity of the glacial moraine. Selected changes in other simulated hydraulic parameters had substantial effects on total freshwater discharge and the distribution of direct ground-water discharge and ground-water-derived surface-water (streamflow) discharge to the salt ponds, but still provided a reasonable match to the hydrologic data available for model calibration. To reduce the uncertainty in predictions of watershed areas and ground-water discharge to the salt ponds, additional hydrogeologic data would be required to constrain the model input parameters that have the greatest effect on the simulation results.",
    url = "https://doi.org/10.3133/sir20065271",
    doi = "10.3133/sir20065271",
    openalex = "W47306613",
    references = "doi103133wri974126"
}

@article{doi101016japgeochem200811019,
    author = "Nordstrom, D. Kirk and McCleskey, R. Blaine and Ball, James W.",
    title = "Sulfur geochemistry of hydrothermal waters in Yellowstone National Park: IV Acid–sulfate waters",
    year = "2008",
    journal = "Applied Geochemistry",
    url = "https://doi.org/10.1016/j.apgeochem.2008.11.019",
    doi = "10.1016/j.apgeochem.2008.11.019",
    openalex = "W1965411955",
    references = "doi101021ac00009a014"
}

Abstract: Ground‐water flow paths constrain the extent of nitrogen (N) sinks in deep, stratified soils of riparian wetlands. We examined ground‐water flow paths at four forested riparian wetlands in deep, low gradient, stratified deposits subjected to Southern New England’s temperate, humid climate. Mid‐day piezometric heads were recorded during the high water table period in April/May and again in late November at one site. Coupling field data with a two‐dimensional steady‐state ground‐water flow model, flow paths and fluxes were derived to 3 m depths. April/May evapotranspiration (ET) dominated total outflux (44‐100%) while flux to the stream was <10% of total outflux. ET exerted upward ground‐water flux through shallow carbon‐rich soils, increasing opportunities for N transformations and diverting flow from the stream. Dormant season results showed a marked increase in flux to the stream (27% of the total flux). Riparian sites with deep water tables (naturally or because of increased urbanization or other hydrologic modifications) or shallow root zones may not generate ground‐water upwelling to meet evaporative demand, thereby increasing the risk of N movement to streams. As water managers balance issues of water quality with water quantity, they will be faced with decisions regarding riparian management. Further work towards refining our understanding of ET mediation of N and water flux at the catchment scale will serve to inform these decisions.

@article{doi101111j17521688200800218x,
    author = "Kellogg, D. Q. and Gold, Arthur J. and Groffman, Peter M. and Stolt, Mark H. and Addy, Kelly",
    title = "Riparian Ground‐Water Flow Patterns Using Flownet Analysis: Evapotranspiration‐Induced Upwelling and Implications for N Removal 1",
    year = "2008",
    journal = "JAWRA Journal of the American Water Resources Association",
    abstract = "Abstract: Ground‐water flow paths constrain the extent of nitrogen (N) sinks in deep, stratified soils of riparian wetlands. We examined ground‐water flow paths at four forested riparian wetlands in deep, low gradient, stratified deposits subjected to Southern New England’s temperate, humid climate. Mid‐day piezometric heads were recorded during the high water table period in April/May and again in late November at one site. Coupling field data with a two‐dimensional steady‐state ground‐water flow model, flow paths and fluxes were derived to 3 m depths. April/May evapotranspiration (ET) dominated total outflux (44‐100\%) while flux to the stream was <10\% of total outflux. ET exerted upward ground‐water flux through shallow carbon‐rich soils, increasing opportunities for N transformations and diverting flow from the stream. Dormant season results showed a marked increase in flux to the stream (27\% of the total flux). Riparian sites with deep water tables (naturally or because of increased urbanization or other hydrologic modifications) or shallow root zones may not generate ground‐water upwelling to meet evaporative demand, thereby increasing the risk of N movement to streams. As water managers balance issues of water quality with water quantity, they will be faced with decisions regarding riparian management. Further work towards refining our understanding of ET mediation of N and water flux at the catchment scale will serve to inform these decisions.",
    url = "https://doi.org/10.1111/j.1752-1688.2008.00218.x",
    doi = "10.1111/j.1752-1688.2008.00218.x",
    openalex = "W2001157842",
    references = "doi103133wri974126"
}

@article{doi103133sir20085156,
    author = "Jurgens, B. and Burow, K. R. and Dalgish, B. A. and Shelton, Jennifer L.",
    title = "Hydrogeology, Water Chemistry, and Factors Affecting the Transport of Contaminants in the Zone of Contribution of a Public-Supply Well in Modesto, Eastern San Joaquin Valley, California",
    year = "2008",
    journal = "Scientific Investigations Report",
    booktitle = "Scientific Investigations Report",
    url = "https://www.semanticscholar.org/paper/42611e779e9c37a3e069303f4b2f08ab05f4ebc7",
    doi = "10.3133/SIR20085156",
    is_oa = "true",
    semanticscholar_citation_count = "53",
    semanticscholar_id = "42611e779e9c37a3e069303f4b2f08ab05f4ebc7"
}

@article{doi101002rcm4083,
    author = "Brand, Willi A. and Geilmann, Heike and Crosson, E. and Rella, Chris W.",
    title = "Cavity ring‐down spectroscopy versus high‐temperature conversion isotope ratio mass spectrometry; a case study on δ 2 H and δ 18 O of pure water samples and alcohol/water mixtures",
    year = "2009",
    journal = "Rapid Communications in Mass Spectrometry",
    url = "https://doi.org/10.1002/rcm.4083",
    doi = "10.1002/rcm.4083",
    openalex = "W2128415685",
    references = "doi101021ac00009a014"
}

@article{doi101038ngeo722,
    author = "Brooks, J. Renée and Barnard, Holly and Coulombe, R. and McDonnell, Jeffrey J.",
    title = "Ecohydrologic separation of water between trees and streams in a Mediterranean climate",
    year = "2009",
    journal = "Nature Geoscience",
    url = "https://doi.org/10.1038/ngeo722",
    doi = "10.1038/ngeo722",
    openalex = "W2166897237",
    references = "doi1012019781482242911"
}

We describe the mass spectrometric facility for measuring helium isotopes, neon, and tritium that has been operative at this institute since 1989, and also the sampling and sample preparation steps that precede the mass spectrometric analysis. For water samples in a near-equilibrium with atmospheric air, the facility achieves precision for (3)He/(4)He ratios of+/-0.4% or better, and+/-0.8 % or better for helium and neon concentrations. Tritium precision is typically+/-3 % and the detection limit 10 mTU (approximately 1.2.10(-3) Bq/kg of pure water). Sample throughputs can reach some thousands per year. These achievements are enabled, among other features, by automation of the measurement procedure and by elaborate calibration, assisted by continual development in detail. To date, we have measured more than 15,000 samples for tritium and 23,000 for helium isotopes and neon, mostly in the context of oceanographic and hydrologic work. Some results of such work are outlined. Even when atmospheric tritium concentrations have become rather uniform, tritium provides water ages if (3)He data are taken concurrently. The technique can resolve tritium concentrations in waters of the pre-nuclear era.

@article{doi10108010256010902871929,
    author = "Sültenfuß, Jürgen and Roether, Wolfgang and Rhein, Monika",
    title = "The Bremen mass spectrometric facility for the measurement of helium isotopes, neon, and tritium in water",
    year = "2009",
    journal = "Isotopes in Environmental and Health Studies",
    abstract = "We describe the mass spectrometric facility for measuring helium isotopes, neon, and tritium that has been operative at this institute since 1989, and also the sampling and sample preparation steps that precede the mass spectrometric analysis. For water samples in a near-equilibrium with atmospheric air, the facility achieves precision for (3)He/(4)He ratios of+/-0.4\% or better, and+/-0.8 \% or better for helium and neon concentrations. Tritium precision is typically+/-3 \% and the detection limit 10 mTU (approximately 1.2.10(-3) Bq/kg of pure water). Sample throughputs can reach some thousands per year. These achievements are enabled, among other features, by automation of the measurement procedure and by elaborate calibration, assisted by continual development in detail. To date, we have measured more than 15,000 samples for tritium and 23,000 for helium isotopes and neon, mostly in the context of oceanographic and hydrologic work. Some results of such work are outlined. Even when atmospheric tritium concentrations have become rather uniform, tritium provides water ages if (3)He data are taken concurrently. The technique can resolve tritium concentrations in waters of the pre-nuclear era.",
    url = "https://doi.org/10.1080/10256010902871929",
    doi = "10.1080/10256010902871929",
    openalex = "W2048821380",
    references = "doi106028jres105043"
}

Abstract. We present a detailed assessment of a commercially available water vapor isotope analyzer (WVIA, Los Gatos Research, Inc.) for simultaneous in-situ measurements of δ2H and δ18O in water vapor. This method, based on off-axis integrated cavity output spectroscopy, is an alternative to the conventional water trap/isotope ratio mass spectrometry (IRMS) techniques. We evaluate the analyzer in terms of precision, memory effects, concentration dependence, temperature sensitivity and long-term stability. A calibration system based on a droplet generator is used to characterize the performance and to calibrate the analyzer. Our results show that the precision at an averaging time of 15 s is 0.16‰ for δ2H and 0.08‰ for δ18O. The isotope ratios are strongly dependent on the water mixing ratio of the air. Taking into account this concentration dependence as well as the temperature sensitivity of the instrument we obtained a long-term stability of the water isotope measurements of 0.38‰ for δ2H and 0.25‰ for δ18O. The accuracy of the WVIA was further assessed by comparative measurements using IRMS and a dew point generator indicating a linear response in isotopic composition and H2O concentrations. The WVIA combined with a calibration system provides accurate high resolution water vapor isotope measurements and opens new possibilities for hydrological and ecological applications.

@article{doi105194amt3672010,
    author = "Sturm, Patrick and Knohl, Alexander",
    title = "Water vapor δ 2 H and δ 18 O measurements using off-axis integrated cavity output spectroscopy",
    year = "2010",
    journal = "Atmospheric measurement techniques",
    abstract = "Abstract. We present a detailed assessment of a commercially available water vapor isotope analyzer (WVIA, Los Gatos Research, Inc.) for simultaneous in-situ measurements of δ2H and δ18O in water vapor. This method, based on off-axis integrated cavity output spectroscopy, is an alternative to the conventional water trap/isotope ratio mass spectrometry (IRMS) techniques. We evaluate the analyzer in terms of precision, memory effects, concentration dependence, temperature sensitivity and long-term stability. A calibration system based on a droplet generator is used to characterize the performance and to calibrate the analyzer. Our results show that the precision at an averaging time of 15 s is 0.16‰ for δ2H and 0.08‰ for δ18O. The isotope ratios are strongly dependent on the water mixing ratio of the air. Taking into account this concentration dependence as well as the temperature sensitivity of the instrument we obtained a long-term stability of the water isotope measurements of 0.38‰ for δ2H and 0.25‰ for δ18O. The accuracy of the WVIA was further assessed by comparative measurements using IRMS and a dew point generator indicating a linear response in isotopic composition and H2O concentrations. The WVIA combined with a calibration system provides accurate high resolution water vapor isotope measurements and opens new possibilities for hydrological and ecological applications.",
    url = "https://doi.org/10.5194/amt-3-67-2010",
    doi = "10.5194/amt-3-67-2010",
    openalex = "W2140492483",
    references = "doi101021ac00009a014"
}

The effects of human-induced alteration of groundwater flow patterns on concentrations of naturally-occurring trace elements were examined in five hydrologically distinct aquifer systems in the USA. Although naturally occurring, these trace elements can exceed concentrations that are considered harmful to human health. The results show that pumping-induced hydraulic gradient changes and artificial connection of aquifers by well screens can mix chemically distinct groundwater. Chemical reactions between these mixed groundwaters and solid aquifer materials can result in the mobilization of trace elements such as U, As and Ra, with subsequent transport to water-supply wells. For example, in the High Plains aquifer near York, Nebraska, mixing of shallow, oxygenated, lower-pH water from an unconfined aquifer with deeper, confined, anoxic, higher-pH water is facilitated by wells screened across both aquifers. The resulting higher-O2, lower-pH mixed groundwater facilitated the mobilization of U from solid aquifer materials, and dissolved U concentrations were observed to increase significantly in nearby supply wells. Similar instances of trace element mobilization due to human-induced mixing of groundwaters were documented in: (1) the Floridan aquifer system near Tampa, Florida (As and U), (2) Paleozoic sedimentary aquifers in eastern Wisconsin (As), (3) the basin-fill aquifer underlying the California Central Valley near Modesto (U), and (4) Coastal Plain aquifers of New Jersey (Ra). Adverse water-quality impacts attributed to human activities are commonly assumed to be related solely to the release of the various anthropogenic contaminants to the environment. The results show that human activities including various land uses, well drilling, and pumping rates and volumes can adversely impact the quality of water in supply wells, when associated with naturally-occurring trace elements in aquifer materials. This occurs by causing subtle but significant changes in geochemistry and associated trace element mobilization as well as enhancing advective transport processes.

@article{doi101016japgeochem201101033,
    author = "Ayotte, Joseph D. and Szabó, Zoltán and Focazio, Michael J. and Eberts, Sandra M.",
    title = "Effects of human-induced alteration of groundwater flow on concentrations of naturally-occurring trace elements at water-supply wells",
    year = "2011",
    journal = "Applied Geochemistry",
    abstract = "The effects of human-induced alteration of groundwater flow patterns on concentrations of naturally-occurring trace elements were examined in five hydrologically distinct aquifer systems in the USA. Although naturally occurring, these trace elements can exceed concentrations that are considered harmful to human health. The results show that pumping-induced hydraulic gradient changes and artificial connection of aquifers by well screens can mix chemically distinct groundwater. Chemical reactions between these mixed groundwaters and solid aquifer materials can result in the mobilization of trace elements such as U, As and Ra, with subsequent transport to water-supply wells. For example, in the High Plains aquifer near York, Nebraska, mixing of shallow, oxygenated, lower-pH water from an unconfined aquifer with deeper, confined, anoxic, higher-pH water is facilitated by wells screened across both aquifers. The resulting higher-O2, lower-pH mixed groundwater facilitated the mobilization of U from solid aquifer materials, and dissolved U concentrations were observed to increase significantly in nearby supply wells. Similar instances of trace element mobilization due to human-induced mixing of groundwaters were documented in: (1) the Floridan aquifer system near Tampa, Florida (As and U), (2) Paleozoic sedimentary aquifers in eastern Wisconsin (As), (3) the basin-fill aquifer underlying the California Central Valley near Modesto (U), and (4) Coastal Plain aquifers of New Jersey (Ra). Adverse water-quality impacts attributed to human activities are commonly assumed to be related solely to the release of the various anthropogenic contaminants to the environment. The results show that human activities including various land uses, well drilling, and pumping rates and volumes can adversely impact the quality of water in supply wells, when associated with naturally-occurring trace elements in aquifer materials. This occurs by causing subtle but significant changes in geochemistry and associated trace element mobilization as well as enhancing advective transport processes.",
    url = "https://doi.org/10.1016/j.apgeochem.2011.01.033",
    doi = "10.1016/j.apgeochem.2011.01.033",
    openalex = "W2156488673",
    references = "doi101007s1004000101833, doi1010160016703778900017, doi1010160048969789901897, doi101016jtim200412002, doi101016s0166111608x70359, doi101016s0883292702000185, doi101111j174565842000tb00251x, doi101111j17456584200700385x, doi101111j17456584200900635x, doi103133sir20085156, openalexw1591787667, openalexw590308574"
}

A total of 1270 raw-water samples (before treatment) were collected from 15 principal and other major aquifer systems (PAs) used for drinking water in 45 states in all major physiographic provinces of the USA and analyzed for concentrations of the Ra isotopes 224Ra, 226Ra and 228Ra establishing the framework for evaluating Ra occurrence. The US Environmental Protection Agency Maximum Contaminant Level (MCL) of 0.185 Bq/L (5 pCi/L) for combined Ra (226Ra plus 228Ra) for drinking water was exceeded in 4.02% (39 of 971) of samples for which both 226Ra and 228Ra were determined, or in 3.15% (40 of 1266) of the samples in which at least one isotope concentration (226Ra or 228Ra) was determined. The maximum concentration of combined Ra was 0.755 Bq/L (20.4 pCi/L) in water from the North Atlantic Coastal Plain quartzose sand aquifer system. All the exceedences of the MCL for combined Ra occurred in water samples from the following 7 PAs (in order of decreasing relative frequency of occurrence): the Midcontinent and Ozark Plateau Cambro-Ordovician dolomites and sandstones, the North Atlantic Coastal Plain, the Floridan, the crystalline rocks (granitic, metamorphic) of New England, the Mesozoic basins of the Appalachian Piedmont, the Gulf Coastal Plain, and the glacial sands and gravels (highest concentrations in New England). The concentration of Ra was consistently controlled by geochemical properties of the aquifer systems, with the highest concentrations most likely to be present where, as a consequence of the geochemical environment, adsorption of the Ra was slightly decreased. The result is a slight relative increase in Ra mobility, especially notable in aquifers with poor sorptive capacity (Fe-oxide-poor quartzose sands and carbonates), even if Ra is not abundant in the aquifer solids. The most common occurrence of elevated Ra throughout the USA occurred in anoxic water (low dissolved-O2) with high concentrations of Fe or Mn, and in places, high concentrations of the competing ions Ca, Mg, Ba and Sr, and occasionally of dissolved solids, K, SO4 and HCO3. The other water type to frequently contain elevated concentrations of the Ra radioisotopes was acidic (low pH), and had in places, high concentrations of NO3 and other acid anions, and on occasion, of the competing divalent cations, Mn and Al. One or the other of these broad water types was commonly present in each of the PAs in which elevated concentrations of combined Ra occurred. Concentrations of 226Ra or 228Ra or combined Ra correlated significantly with those of the above listed water-quality constituents (on the basis of the non-parametric Spearman correlation technique) and loaded on principal components describing the above water types from the entire data set and for samples from the PAs with the highest combined Ra concentrations. Concentrations of 224Ra and 226Ra were significantly correlated to those of 228Ra (Spearman’s rank correlation coefficient, +0.236 and +0.326, respectively). Activity ratios of 224Ra/228Ra in the water samples were mostly near 1 when concentrations of both isotopes were greater than or equal to 0.037 Bq/L (1 pCi/L), the level above which analytical results were most reliable. Co-occurrence among these highest concentrations of the Ra radionuclides was most likely in those PAs where chemical conditions are most conducive to Ra mobility (e.g. acidic North Atlantic Coastal Plain). The concentrations of 224Ra were occasionally greater than 0.037 Bq/L and the ratios of 224Ra/228Ra were generally highest in the PAs composed of alluvial sands and Cretaceous/Tertiary sandstones from the western USA, likely because concentrations of 224Ra are enhanced in solution relative to those of 228Ra by alpha recoil from the aquifer matrix. Rapid adsorption of the two Ra isotopes (controlled by the alkaline and oxic aquifer geochemistry) combined with preferential faster recoil of 224Ra generates a 224Ra/228Ra ratio much greater than 1. The 228Ra/226Ra activity ratio was locally variable, and was generally lower than 1 (226Ra rich) in samples from PAs with carbonate bedrock, but was typically greater than 1 (228Ra rich) in PAs composed of unconsolidated sand.

@article{doi101016japgeochem201111002,
    author = "Szabó, Zoltán and dePaul, Vincent T. and Fischer, Jeffrey M. and Kraemer, Thomas F. and Jacobsen, Eric",
    title = "Occurrence and geochemistry of radium in water from principal drinking-water aquifer systems of the United States",
    year = "2011",
    journal = "Applied Geochemistry",
    abstract = "A total of 1270 raw-water samples (before treatment) were collected from 15 principal and other major aquifer systems (PAs) used for drinking water in 45 states in all major physiographic provinces of the USA and analyzed for concentrations of the Ra isotopes 224Ra, 226Ra and 228Ra establishing the framework for evaluating Ra occurrence. The US Environmental Protection Agency Maximum Contaminant Level (MCL) of 0.185 Bq/L (5 pCi/L) for combined Ra (226Ra plus 228Ra) for drinking water was exceeded in 4.02\% (39 of 971) of samples for which both 226Ra and 228Ra were determined, or in 3.15\% (40 of 1266) of the samples in which at least one isotope concentration (226Ra or 228Ra) was determined. The maximum concentration of combined Ra was 0.755 Bq/L (20.4 pCi/L) in water from the North Atlantic Coastal Plain quartzose sand aquifer system. All the exceedences of the MCL for combined Ra occurred in water samples from the following 7 PAs (in order of decreasing relative frequency of occurrence): the Midcontinent and Ozark Plateau Cambro-Ordovician dolomites and sandstones, the North Atlantic Coastal Plain, the Floridan, the crystalline rocks (granitic, metamorphic) of New England, the Mesozoic basins of the Appalachian Piedmont, the Gulf Coastal Plain, and the glacial sands and gravels (highest concentrations in New England). The concentration of Ra was consistently controlled by geochemical properties of the aquifer systems, with the highest concentrations most likely to be present where, as a consequence of the geochemical environment, adsorption of the Ra was slightly decreased. The result is a slight relative increase in Ra mobility, especially notable in aquifers with poor sorptive capacity (Fe-oxide-poor quartzose sands and carbonates), even if Ra is not abundant in the aquifer solids. The most common occurrence of elevated Ra throughout the USA occurred in anoxic water (low dissolved-O2) with high concentrations of Fe or Mn, and in places, high concentrations of the competing ions Ca, Mg, Ba and Sr, and occasionally of dissolved solids, K, SO4 and HCO3. The other water type to frequently contain elevated concentrations of the Ra radioisotopes was acidic (low pH), and had in places, high concentrations of NO3 and other acid anions, and on occasion, of the competing divalent cations, Mn and Al. One or the other of these broad water types was commonly present in each of the PAs in which elevated concentrations of combined Ra occurred. Concentrations of 226Ra or 228Ra or combined Ra correlated significantly with those of the above listed water-quality constituents (on the basis of the non-parametric Spearman correlation technique) and loaded on principal components describing the above water types from the entire data set and for samples from the PAs with the highest combined Ra concentrations. Concentrations of 224Ra and 226Ra were significantly correlated to those of 228Ra (Spearman’s rank correlation coefficient, +0.236 and +0.326, respectively). Activity ratios of 224Ra/228Ra in the water samples were mostly near 1 when concentrations of both isotopes were greater than or equal to 0.037 Bq/L (1 pCi/L), the level above which analytical results were most reliable. Co-occurrence among these highest concentrations of the Ra radionuclides was most likely in those PAs where chemical conditions are most conducive to Ra mobility (e.g. acidic North Atlantic Coastal Plain). The concentrations of 224Ra were occasionally greater than 0.037 Bq/L and the ratios of 224Ra/228Ra were generally highest in the PAs composed of alluvial sands and Cretaceous/Tertiary sandstones from the western USA, likely because concentrations of 224Ra are enhanced in solution relative to those of 228Ra by alpha recoil from the aquifer matrix. Rapid adsorption of the two Ra isotopes (controlled by the alkaline and oxic aquifer geochemistry) combined with preferential faster recoil of 224Ra generates a 224Ra/228Ra ratio much greater than 1. The 228Ra/226Ra activity ratio was locally variable, and was generally lower than 1 (226Ra rich) in samples from PAs with carbonate bedrock, but was typically greater than 1 (228Ra rich) in PAs composed of unconsolidated sand.",
    url = "https://doi.org/10.1016/j.apgeochem.2011.11.002",
    doi = "10.1016/j.apgeochem.2011.11.002",
    openalex = "W2108558109",
    references = "doi101111j17456584200900635x"
}

@article{doi101016jjhazmat201111073,
    author = "Crane, Richard A. and Scott, Thomas B.",
    title = "Nanoscale zero-valent iron: Future prospects for an emerging water treatment technology",
    year = "2011",
    journal = "Journal of Hazardous Materials",
    url = "https://doi.org/10.1016/j.jhazmat.2011.11.073",
    doi = "10.1016/j.jhazmat.2011.11.073",
    openalex = "W2059582758",
    references = "openalexw659357407"
}

@article{doi101016jsedgeo201104015,
    author = "Kele, Sándor and Özkul, Mehmet and Fórizs, István and Gökgöz, Ali and Baykara, Mehmet Oruç and Alçiçek, Mehmet Cihat and Németh, Tibor",
    title = "Stable isotope geochemical study of Pamukkale travertines: New evidences of low-temperature non-equilibrium calcite-water fractionation",
    year = "2011",
    journal = "Sedimentary Geology",
    url = "https://doi.org/10.1016/j.sedgeo.2011.04.015",
    doi = "10.1016/j.sedgeo.2011.04.015",
    openalex = "W2047821851",
    references = "doi101021ac00009a014"
}

Across West Bengal and Bangladesh, concentrations of Cl in much groundwater exceed the natural, upper limit of 10 mg/L. The Cl/Br mass ratios in groundwaters range up to 2500 and scatter along mixing lines between waste-water and dilute groundwater, with many falling near the mean end-member value for waste-water of 1561 at 126 mg/L Cl. Values of Cl/Br exceed the seawater ratio of 288 in uncommon NO(3)-bearing groundwaters, and in those containing measurable amounts of salt-corrected SO(4) (SO(4) corrected for marine salt). The data show that shallow groundwater tapped by tube-wells in the Bengal Basin has been widely contaminated by waste-water derived from pit latrines, septic tanks, and other methods of sanitary disposal, although reducing conditions in the aquifers have removed most evidence of NO(3) additions from these sources, and much evidence of their additions of SO(4). In groundwaters from wells in palaeo-channel settings, end-member modelling shows that >25% of wells yield water that comprises ≥10% of waste-water. In palaeo-interfluvial settings, only wells at the margins of the palaeo-interfluvial sequence contain detectable waste water. Settings are identifiable by well-colour survey, owner information, water composition, and drilling. Values of Cl/Br and faecal coliform counts are both inversely related to concentrations of pollutant As in groundwater, suggesting that waste-water contributions to groundwater in the near-field of septic-tanks and pit-latrines (within 30 m) suppress the mechanism of As-pollution and lessen the prevalence and severity of As pollution. In the far-field of such sources, organic matter in waste-water may increase groundwater pollution by As.

@article{doi101016jscitotenv201207068,
    author = "McArthur, J.M. and Sikdar, Pradip K. and Hoque, M. A. and Ghosal, Utsab",
    title = "Waste-water impacts on groundwater: Cl/Br ratios and implications for arsenic pollution of groundwater in the Bengal Basin and Red River Basin, Vietnam",
    year = "2012",
    journal = "The Science of The Total Environment",
    abstract = "Across West Bengal and Bangladesh, concentrations of Cl in much groundwater exceed the natural, upper limit of 10 mg/L. The Cl/Br mass ratios in groundwaters range up to 2500 and scatter along mixing lines between waste-water and dilute groundwater, with many falling near the mean end-member value for waste-water of 1561 at 126 mg/L Cl. Values of Cl/Br exceed the seawater ratio of 288 in uncommon NO(3)-bearing groundwaters, and in those containing measurable amounts of salt-corrected SO(4) (SO(4) corrected for marine salt). The data show that shallow groundwater tapped by tube-wells in the Bengal Basin has been widely contaminated by waste-water derived from pit latrines, septic tanks, and other methods of sanitary disposal, although reducing conditions in the aquifers have removed most evidence of NO(3) additions from these sources, and much evidence of their additions of SO(4). In groundwaters from wells in palaeo-channel settings, end-member modelling shows that >25\% of wells yield water that comprises ≥10\% of waste-water. In palaeo-interfluvial settings, only wells at the margins of the palaeo-interfluvial sequence contain detectable waste water. Settings are identifiable by well-colour survey, owner information, water composition, and drilling. Values of Cl/Br and faecal coliform counts are both inversely related to concentrations of pollutant As in groundwater, suggesting that waste-water contributions to groundwater in the near-field of septic-tanks and pit-latrines (within 30 m) suppress the mechanism of As-pollution and lessen the prevalence and severity of As pollution. In the far-field of such sources, organic matter in waste-water may increase groundwater pollution by As.",
    url = "https://doi.org/10.1016/j.scitotenv.2012.07.068",
    doi = "10.1016/j.scitotenv.2012.07.068",
    openalex = "W2067369295",
    references = "doi101016jjhydrol201011017, doi101111j17456584200500127x"
}

Despite broad recognition of the value of the goods and services provided by nature, existing tools for assessing and valuing ecosystem services often fall short of the needs and expectations of decision makers. Here we address one of the most important missing components in the current ecosystem services toolbox: a comprehensive and generalizable framework for describing and valuing water quality-related services. Water quality is often misrepresented as a final ecosystem service. We argue that it is actually an important contributor to many different services, from recreation to human health. We present a valuation approach for water quality-related services that is sensitive to different actions that affect water quality, identifies aquatic endpoints where the consequences of changing water quality on human well-being are realized, and recognizes the unique groups of beneficiaries affected by those changes. We describe the multiple biophysical and economic pathways that link actions to changes in water quality-related ecosystem goods and services and provide guidance to researchers interested in valuing these changes. Finally, we present a valuation template that integrates biophysical and economic models, links actions to changes in service provision and value estimates, and considers multiple sources of water quality-related ecosystem service values without double counting.

@article{doi101073pnas1215991109,
    author = "Keeler, Bonnie and Polasky, Stephen and Brauman, Kate A. and Johnson, Kris and Finlay, Jacques C. and O’Neill, Ann Marie and Kovacs, Kent and Dalzell, B. J.",
    title = "Linking water quality and well-being for improved assessment and valuation of ecosystem services",
    year = "2012",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Despite broad recognition of the value of the goods and services provided by nature, existing tools for assessing and valuing ecosystem services often fall short of the needs and expectations of decision makers. Here we address one of the most important missing components in the current ecosystem services toolbox: a comprehensive and generalizable framework for describing and valuing water quality-related services. Water quality is often misrepresented as a final ecosystem service. We argue that it is actually an important contributor to many different services, from recreation to human health. We present a valuation approach for water quality-related services that is sensitive to different actions that affect water quality, identifies aquatic endpoints where the consequences of changing water quality on human well-being are realized, and recognizes the unique groups of beneficiaries affected by those changes. We describe the multiple biophysical and economic pathways that link actions to changes in water quality-related ecosystem goods and services and provide guidance to researchers interested in valuing these changes. Finally, we present a valuation template that integrates biophysical and economic models, links actions to changes in service provision and value estimates, and considers multiple sources of water quality-related ecosystem service values without double counting.",
    url = "https://doi.org/10.1073/pnas.1215991109",
    doi = "10.1073/pnas.1215991109",
    openalex = "W1997333234",
    references = "doi101001jama194502860360014004"
}

The National Water-Quality Assessment Program (NAWQA) of the U.S. Geological Survey began a series of groundwater studies in 2001 in representative aquifers across the Nation in order to increase understanding of the factors that affect transport of anthropogenic and natural contaminants (TANC) to public-supply wells. One of 10 regional-scale TANC studies was conducted in the Middle Rio Grande Basin (MRGB) in New Mexico, where a more detailed local-scale study subsequently investigated the hydrogeology, water chemistry, and factors affecting the transport of contaminants in the zone of contribution of one 363-meter (m) deep public-supply well in Albuquerque. During 2007 through 2009, samples were collected for the local-scale study from 22 monitoring wells and 3 public-supply (supply) wells for analysis of major and trace elements, arsenic speciation, nutrients, dissolved organic carbon, volatile organic compounds (VOCs), dissolved gases, stable isotopes, and tracers of young and old water. To study groundwater chemistry and ages at various depths within the aquifer, the monitoring wells were divided into three categories: (1) each shallow well was screened across the water table or had a screen midpoint within 18.3 m of the water level in the well; (2) each intermediate well had a screen midpoint between about 27.1 and 79.6 m below the water level in the well; and (3) each deep well had a screen midpoint about 185 m or more below the water level in the well. The 24-square-kilometer study area surrounding the "studied supply well" (SSW), one of the three supply wells, consists of primarily urban land within the MRGB, a deep alluvial basin with an aquifer composed of unconsolidated to moderately consolidated deposits of sand, gravel, silt, and clay. Conditions generally are unconfined, but are semiconfined at depth. Groundwater withdrawals for public supply have substantially changed the primary direction of flow from northeast to southwest under predevelopment conditions, to west to east under modern conditions. Analysis of age tracers indicates that groundwater from most sampled wells is dominated by old (pre-1950) water, ranging in mean age from about 4,000 years to more than 22,000 years, but includes a fraction of young (post-1950) recharge. Patterns in chemical and isotopic data are consistent with the conclusions that shallow groundwater in the area typically includes a fraction that evaporated prior to recharge and (or) flushed accumulated solutes out of the unsaturated zone during recharge, and that shallow groundwater has mixed to deeper parts of the aquifer, which receives recharge mainly by seepage from the Rio Grande. Among shallow and intermediate wells that produced water with a fraction of young recharge, that fraction ranged between 1.5 and 46 percent. Samples from the two deep wells had groundwater ages exceeding 18,000 years, with no fraction of young recharge. Two supply wells (including the SSW) had a fraction of young recharge, which ranged between about 3 and 11 percent, despite mean groundwater ages exceeding 10,000 years. The fraction of young recharge to the SSW varied seasonally, probably because seasonal pumping patterns affected local hydraulic gradients and (or) because of flow through the well bore when the SSW is not pumping. Well-bore flow data collected during winter (low-pumping season) indicated that about 61 percent of the water pumped from the SSW entered the well from the intermediate part of the aquifer, and that the remaining 39 percent entered from the deep part of the aquifer. Volatile organic compounds (VOCs) were detected in samples from most shallow and intermediate monitoring wells and from two of three supply wells, including the SSW. Detected VOCs were primarily chlorinated solvents or their degradation products. Many of the wells in which most of these VOCs were detected are located near known sites of solvent contamination that were targeted for sampling because trichloroethylene (TCE) and cis-1,2-dichloroethylene had been detected in the SSW, and several of these wells may have become contaminated at least partly because of enhanced vertical migration associated with the pumping of and (or) direct migration down deep well bores. Except for TCE in the sample from a shallow monitoring well, all detections of VOCs were at concentrations below Maximum Contaminant Levels (MCLs) set by the U.S. Environmental Protection Agency. Concentrations of all VOCs detected in the supply wells were less than one-tenth of the corresponding MCLs. However, the presence of VOCs in all but deep groundwater, including the detection of chloroform (a chlorination byproduct) in several shallow wells, indicates that groundwater in the study area commonly is affected by human activities, even to substantial depths. The only natural contaminant detected at concentrations near or above its MCL was arsenic, which has been detected at elevated concentrations across broad areas of the MRGB. Concentrations of arsenic, present primarily as arsenate, exceeded the MCL of 10 micrograms per liter (μg/L) in water from the two deep wells (one of which had the highest concentration, 35 μg/L), from one intermediate well, and from two supply wells, including the SSW. Water-quality and solid-phase data from this study are consistent with elevated arsenic concentrations in groundwater being related to pH-dependent desorption of arsenic from ferric oxyhydroxides in sediments in deep parts of the aquifer. Concentrations of nitrate ranged between 1.3 and 5.4 milligrams per liter (mg/L) in water from shallow wells screened across the water table, but were less than 0.9 mg/L in water from all but one deeper well. Nitrogen isotopes and chloride/bromide ratios for shallow wells were consistent with natural soil nitrogen. Nitrate concentrations and nitrogen isotopes indicated that denitrification is occurring at intermediate aquifer depths, and that the progress of the denitrification reaction typically is greatest for wells that include a fraction of groundwater associated with particular recharge sources or with known sites of contamination contributing organic compounds that can provide a carbon source for microbial respiration. Overall, hydrologic and chemical data from the study area indicate that young recharge is reaching the aquifer across broad areas and is migrating from shallow to intermediate depths of the aquifer as a result of mixing that is associated with human development of groundwater. Consequently, groundwater that human activities in the urban study area have affected is present at depths that are within the screened intervals of public-supply wells, resulting in detections of VOCs and implying greater vulnerability to anthropogenic contamination than might be assumed based on the dominantly old age of the regional groundwater. However, the fractions of old groundwater that public-supply wells produce substantially dilute the anthropogenic contaminants, while contributing natural contaminants (primarily arsenic) to the wells. Based on data from the SSW, vulnerability of public-supply wells to natural and anthropogenic contaminants in the area changes through time, including with seasonal changes in pumping stresses that alter the fractions of young and old water being contributed to wells.

@article{doi103133sir20115182,
    author = "Bexfield, Laura M. and Jurgens, Bryant C. and Crilley, Dianna M. and Christenson, Scott C.",
    title = "Hydrogeology, water chemistry, and transport processes in the zone of contribution of a public-supply well in Albuquerque, New Mexico, 2007-9",
    year = "2012",
    journal = "Scientific investigations report",
    abstract = {The National Water-Quality Assessment Program (NAWQA) of the U.S. Geological Survey began a series of groundwater studies in 2001 in representative aquifers across the Nation in order to increase understanding of the factors that affect transport of anthropogenic and natural contaminants (TANC) to public-supply wells. One of 10 regional-scale TANC studies was conducted in the Middle Rio Grande Basin (MRGB) in New Mexico, where a more detailed local-scale study subsequently investigated the hydrogeology, water chemistry, and factors affecting the transport of contaminants in the zone of contribution of one 363-meter (m) deep public-supply well in Albuquerque. During 2007 through 2009, samples were collected for the local-scale study from 22 monitoring wells and 3 public-supply (supply) wells for analysis of major and trace elements, arsenic speciation, nutrients, dissolved organic carbon, volatile organic compounds (VOCs), dissolved gases, stable isotopes, and tracers of young and old water. To study groundwater chemistry and ages at various depths within the aquifer, the monitoring wells were divided into three categories: (1) each shallow well was screened across the water table or had a screen midpoint within 18.3 m of the water level in the well; (2) each intermediate well had a screen midpoint between about 27.1 and 79.6 m below the water level in the well; and (3) each deep well had a screen midpoint about 185 m or more below the water level in the well. The 24-square-kilometer study area surrounding the "studied supply well" (SSW), one of the three supply wells, consists of primarily urban land within the MRGB, a deep alluvial basin with an aquifer composed of unconsolidated to moderately consolidated deposits of sand, gravel, silt, and clay. Conditions generally are unconfined, but are semiconfined at depth. Groundwater withdrawals for public supply have substantially changed the primary direction of flow from northeast to southwest under predevelopment conditions, to west to east under modern conditions. Analysis of age tracers indicates that groundwater from most sampled wells is dominated by old (pre-1950) water, ranging in mean age from about 4,000 years to more than 22,000 years, but includes a fraction of young (post-1950) recharge. Patterns in chemical and isotopic data are consistent with the conclusions that shallow groundwater in the area typically includes a fraction that evaporated prior to recharge and (or) flushed accumulated solutes out of the unsaturated zone during recharge, and that shallow groundwater has mixed to deeper parts of the aquifer, which receives recharge mainly by seepage from the Rio Grande. Among shallow and intermediate wells that produced water with a fraction of young recharge, that fraction ranged between 1.5 and 46 percent. Samples from the two deep wells had groundwater ages exceeding 18,000 years, with no fraction of young recharge. Two supply wells (including the SSW) had a fraction of young recharge, which ranged between about 3 and 11 percent, despite mean groundwater ages exceeding 10,000 years. The fraction of young recharge to the SSW varied seasonally, probably because seasonal pumping patterns affected local hydraulic gradients and (or) because of flow through the well bore when the SSW is not pumping. Well-bore flow data collected during winter (low-pumping season) indicated that about 61 percent of the water pumped from the SSW entered the well from the intermediate part of the aquifer, and that the remaining 39 percent entered from the deep part of the aquifer. Volatile organic compounds (VOCs) were detected in samples from most shallow and intermediate monitoring wells and from two of three supply wells, including the SSW. Detected VOCs were primarily chlorinated solvents or their degradation products. Many of the wells in which most of these VOCs were detected are located near known sites of solvent contamination that were targeted for sampling because trichloroethylene (TCE) and cis-1,2-dichloroethylene had been detected in the SSW, and several of these wells may have become contaminated at least partly because of enhanced vertical migration associated with the pumping of and (or) direct migration down deep well bores. Except for TCE in the sample from a shallow monitoring well, all detections of VOCs were at concentrations below Maximum Contaminant Levels (MCLs) set by the U.S. Environmental Protection Agency. Concentrations of all VOCs detected in the supply wells were less than one-tenth of the corresponding MCLs. However, the presence of VOCs in all but deep groundwater, including the detection of chloroform (a chlorination byproduct) in several shallow wells, indicates that groundwater in the study area commonly is affected by human activities, even to substantial depths. The only natural contaminant detected at concentrations near or above its MCL was arsenic, which has been detected at elevated concentrations across broad areas of the MRGB. Concentrations of arsenic, present primarily as arsenate, exceeded the MCL of 10 micrograms per liter (μg/L) in water from the two deep wells (one of which had the highest concentration, 35 μg/L), from one intermediate well, and from two supply wells, including the SSW. Water-quality and solid-phase data from this study are consistent with elevated arsenic concentrations in groundwater being related to pH-dependent desorption of arsenic from ferric oxyhydroxides in sediments in deep parts of the aquifer. Concentrations of nitrate ranged between 1.3 and 5.4 milligrams per liter (mg/L) in water from shallow wells screened across the water table, but were less than 0.9 mg/L in water from all but one deeper well. Nitrogen isotopes and chloride/bromide ratios for shallow wells were consistent with natural soil nitrogen. Nitrate concentrations and nitrogen isotopes indicated that denitrification is occurring at intermediate aquifer depths, and that the progress of the denitrification reaction typically is greatest for wells that include a fraction of groundwater associated with particular recharge sources or with known sites of contamination contributing organic compounds that can provide a carbon source for microbial respiration. Overall, hydrologic and chemical data from the study area indicate that young recharge is reaching the aquifer across broad areas and is migrating from shallow to intermediate depths of the aquifer as a result of mixing that is associated with human development of groundwater. Consequently, groundwater that human activities in the urban study area have affected is present at depths that are within the screened intervals of public-supply wells, resulting in detections of VOCs and implying greater vulnerability to anthropogenic contamination than might be assumed based on the dominantly old age of the regional groundwater. However, the fractions of old groundwater that public-supply wells produce substantially dilute the anthropogenic contaminants, while contributing natural contaminants (primarily arsenic) to the wells. Based on data from the SSW, vulnerability of public-supply wells to natural and anthropogenic contaminants in the area changes through time, including with seasonal changes in pumping stresses that alter the fractions of young and old water being contributed to wells.},
    url = "https://doi.org/10.3133/sir20115182",
    doi = "10.3133/sir20115182",
    openalex = "W16671934"
}

Groundwater age is a key aspect of production well vulnerability. Public drinking water supply wells typically have long screens and are expected to produce a mixture of groundwater ages. The groundwater age distributions of seven production wells of the Holten well field (Netherlands) were estimated from tritium‐helium (3 H/ 3 He), krypton‐85 (85 Kr), and argon‐39 (39 Ar), using a new application of a discrete age distribution model and existing mathematical models, by minimizing the uncertainty‐weighted squared differences of modeled and measured tracer concentrations. The observed tracer concentrations fitted well to a 4‐bin discrete age distribution model or a dispersion model with a fraction of old groundwater. Our results show that more than 75% of the water pumped by four shallow production wells has a groundwater age of less than 20 years and these wells are very vulnerable to recent surface contamination. More than 50% of the water pumped by three deep production wells is older than 60 years. 3 H/ 3 He samples from short screened monitoring wells surrounding the well field constrained the age stratification in the aquifer. The discrepancy between the age stratification with depth and the groundwater age distribution of the production wells showed that the well field preferentially pumps from the shallow part of the aquifer. The discrete groundwater age distribution model appears to be a suitable approach in settings where the shape of the age distribution cannot be assumed to follow a simple mathematical model, such as a production well field where wells compete for capture area.

@article{doi1010022013wr014012,
    author = "Visser, Ate and Broers, Hans Peter and Purtschert, Roland and Sültenfuß, Jürgen and de Jonge, Martin D.",
    title = "Groundwater age distributions at a public drinking water supply well field derived from multiple age tracers (85 Kr, 3 H/ 3 He, and 39 Ar)",
    year = "2013",
    journal = "Water Resources Research",
    abstract = "Groundwater age is a key aspect of production well vulnerability. Public drinking water supply wells typically have long screens and are expected to produce a mixture of groundwater ages. The groundwater age distributions of seven production wells of the Holten well field (Netherlands) were estimated from tritium‐helium (3 H/ 3 He), krypton‐85 (85 Kr), and argon‐39 (39 Ar), using a new application of a discrete age distribution model and existing mathematical models, by minimizing the uncertainty‐weighted squared differences of modeled and measured tracer concentrations. The observed tracer concentrations fitted well to a 4‐bin discrete age distribution model or a dispersion model with a fraction of old groundwater. Our results show that more than 75\% of the water pumped by four shallow production wells has a groundwater age of less than 20 years and these wells are very vulnerable to recent surface contamination. More than 50\% of the water pumped by three deep production wells is older than 60 years. 3 H/ 3 He samples from short screened monitoring wells surrounding the well field constrained the age stratification in the aquifer. The discrepancy between the age stratification with depth and the groundwater age distribution of the production wells showed that the well field preferentially pumps from the shallow part of the aquifer. The discrete groundwater age distribution model appears to be a suitable approach in settings where the shape of the age distribution cannot be assumed to follow a simple mathematical model, such as a production well field where wells compete for capture area.",
    url = "https://doi.org/10.1002/2013wr014012",
    doi = "10.1002/2013wr014012",
    openalex = "W2117177395",
    references = "doi101007s1004001108106"
}

The Environmental Isotopes Environmental Isotopes in Hydrogeology Stable Isotopes: Standards and Measurement Isotope Ratio Mass Spectrometry Radioisotopes Isotope Fractionation Isotope Fractionation (a), Enrichment (e), and Separation (D) Tracing the Hydrological Cycle Craig's Meteoric Relationship in Global Fresh Waters Partitioning of Isotopes Through the Hydrological Cycle Condensation, Precipitation, and the Meteoric Water Line A Closer Look at Rayleigh Distillation Effects of Extreme Evaporation Precipitation The T - d18O Correlation in Precipitation Local Effects on T - d18O Ice Cores and Paleotemperature Groundwater Recharge in Temperate Climates Recharge in Arid Regions Recharge from River-Connected Aquifers Hydrograph Separation in Catchment Studies Groundwater Mixing Tracing the Carbon Cycle Evolution of Carbon in Groundwaters Carbonate Geochemistry Carbon-13 in the Carbonate System Dissolved Organic Carbon Methane in Groundwaters Isotopic Composition of Carbonates Chapter 6. Groundwater Quality Sulphate, Sulphide and the Sulphur Cycle Nitrogen Cycles in Rural Watersheds The Fuhrberger Feld Study Source of Chloride Salinity Landfill Leachates Degredation of Chloro-organics and Hydrocarbon Sensitivity of Groundwater to Contamination Summary of Isotopes in Contaminant Hydrology Identifying and Dating Modern Groundwaters The of Groundwater Stable Isotopes Tritium in Precipitation Dating Groundwaters with Tritium Groundwater Dating with 3H -3He Chlorofluorocarbons (CFCs) Thermonuclear 36Cl Detecting Modern Groundwaters with 85Kr Submodern Groundwater Age Dating Old Groundwaters Stable Isotopes and Paleogroundwaters Groundwater Dating with Radiocarbon Correction for Carbonate Dissolution Some Additional Complications to 14C Dating 14C Dating with Dissolved Organic Carbon (DOC) Case Studies for 14C dating with DOC and DIC Chlorine-36 and Very Old Groundwater The Uranium Decay Series Water-Rock Interaction Mechanisms of Isotope Exchange High Temperature Systems Low Temperature Water-Rock Interaction Strontium Isotopes in Water and Rock Isotope Exchange in Gas-Water Reactions High pH Groundwaters-The Effect of Cement Reactions Field Methods for Sampling Groundwater Water in the Unsaturated Zone Precipitation Gases Geochemistry References Index Each chapter has Problems sections.

@book{doi1012019781482242911,
    author = "Clark, Ian and Fritz, P.",
    title = "Environmental Isotopes in Hydrogeology",
    year = "2013",
    abstract = "The Environmental Isotopes Environmental Isotopes in Hydrogeology Stable Isotopes: Standards and Measurement Isotope Ratio Mass Spectrometry Radioisotopes Isotope Fractionation Isotope Fractionation (a), Enrichment (e), and Separation (D) Tracing the Hydrological Cycle Craig's Meteoric Relationship in Global Fresh Waters Partitioning of Isotopes Through the Hydrological Cycle Condensation, Precipitation, and the Meteoric Water Line A Closer Look at Rayleigh Distillation Effects of Extreme Evaporation Precipitation The T - d18O Correlation in Precipitation Local Effects on T - d18O Ice Cores and Paleotemperature Groundwater Recharge in Temperate Climates Recharge in Arid Regions Recharge from River-Connected Aquifers Hydrograph Separation in Catchment Studies Groundwater Mixing Tracing the Carbon Cycle Evolution of Carbon in Groundwaters Carbonate Geochemistry Carbon-13 in the Carbonate System Dissolved Organic Carbon Methane in Groundwaters Isotopic Composition of Carbonates Chapter 6. Groundwater Quality Sulphate, Sulphide and the Sulphur Cycle Nitrogen Cycles in Rural Watersheds The Fuhrberger Feld Study Source of Chloride Salinity Landfill Leachates Degredation of Chloro-organics and Hydrocarbon Sensitivity of Groundwater to Contamination Summary of Isotopes in Contaminant Hydrology Identifying and Dating Modern Groundwaters The of Groundwater Stable Isotopes Tritium in Precipitation Dating Groundwaters with Tritium Groundwater Dating with 3H -3He Chlorofluorocarbons (CFCs) Thermonuclear 36Cl Detecting Modern Groundwaters with 85Kr Submodern Groundwater Age Dating Old Groundwaters Stable Isotopes and Paleogroundwaters Groundwater Dating with Radiocarbon Correction for Carbonate Dissolution Some Additional Complications to 14C Dating 14C Dating with Dissolved Organic Carbon (DOC) Case Studies for 14C dating with DOC and DIC Chlorine-36 and Very Old Groundwater The Uranium Decay Series Water-Rock Interaction Mechanisms of Isotope Exchange High Temperature Systems Low Temperature Water-Rock Interaction Strontium Isotopes in Water and Rock Isotope Exchange in Gas-Water Reactions High pH Groundwaters-The Effect of Cement Reactions Field Methods for Sampling Groundwater Water in the Unsaturated Zone Precipitation Gases Geochemistry References Index Each chapter has Problems sections.",
    url = "https://doi.org/10.1201/9781482242911",
    doi = "10.1201/9781482242911",
    openalex = "W1580961126"
}

Aquatic ecosystems are being degraded by anthropogenic pollution on a global scale. Septic tank systems (STS), which are widely distributed in rural and peri‐urban areas, are one potential source of water pollution. Although generally regarded as the most efficient method for onsite treatment of domestic wastewater, we question whether current regulation and management of these systems is sufficient to guarantee that they function effectively. Here, we present watershed‐specific examples that illustrate some of the problems that arise when many years of inadequate regulation and management result in a legacy of failing STS that can become long‐term, chronic sources of nutrient pollution. Our data suggest that more accurate accounting of the location, performance, and degree of failure of STS, and more research into their impacts on water quality, would improve source attribution of pollutants within rural watersheds. This would ensure that education of homeowners, mitigation, interdisciplinary research, and technological innovation could be targeted in a cost‐effective way.

@article{doi101890130131,
    author = "Withers, Paul J. A. and Jordan, Phil and May, Linda and Jarvie, Helen P. and Deal, Nancy",
    title = "Do septic tank systems pose a hidden threat to water quality?",
    year = "2013",
    journal = "Frontiers in Ecology and the Environment",
    abstract = "Aquatic ecosystems are being degraded by anthropogenic pollution on a global scale. Septic tank systems (STS), which are widely distributed in rural and peri‐urban areas, are one potential source of water pollution. Although generally regarded as the most efficient method for onsite treatment of domestic wastewater, we question whether current regulation and management of these systems is sufficient to guarantee that they function effectively. Here, we present watershed‐specific examples that illustrate some of the problems that arise when many years of inadequate regulation and management result in a legacy of failing STS that can become long‐term, chronic sources of nutrient pollution. Our data suggest that more accurate accounting of the location, performance, and degree of failure of STS, and more research into their impacts on water quality, would improve source attribution of pollutants within rural watersheds. This would ensure that education of homeowners, mitigation, interdisciplinary research, and technological innovation could be targeted in a cost‐effective way.",
    url = "https://doi.org/10.1890/130131",
    doi = "10.1890/130131",
    openalex = "W2098416107",
    references = "doi101016jjhydrol201011017"
}

diagram of a hypothetical aquifer showing groundwater

@article{doi103133sir20125077,
    author = "Masterson, John P. and Granato, Gregory E.",
    title = "Numerical simulation of groundwater and surface-water interactions in the Big River Management Area, central Rhode Island",
    year = "2013",
    journal = "Scientific investigations report",
    abstract = "diagram of a hypothetical aquifer showing groundwater",
    url = "https://doi.org/10.3133/sir20125077",
    doi = "10.3133/sir20125077",
    openalex = "W67481004",
    references = "doi103133wri974126"
}

@article{doi101007s1004001411683,
    author = "Missimer, T. and Hoppe-Jones, C. and Jadoon, K. and Li, Dong and Al-Mashharawi, S.",
    title = "Hydrogeology, water quality, and microbial assessment of a coastal alluvial aquifer in western Saudi Arabia: potential use of coastal wadi aquifers for desalination water supplies",
    year = "2014",
    journal = "Hydrogeology Journal",
    url = "https://www.semanticscholar.org/paper/13341d789cc2851d9b13217342b7f61bea636559",
    doi = "10.1007/s10040-014-1168-3",
    is_oa = "true",
    number = "8",
    pages = "1921-1934",
    semanticscholar_citation_count = "14",
    semanticscholar_id = "13341d789cc2851d9b13217342b7f61bea636559",
    volume = "22"
}

@article{doi101016jjhydrol201403041,
    author = "Ruffell, A.",
    title = "Lacustrine flow (divers, side scan sonar, hydrogeology, water penetrating radar) used to understand the location of a drowned person",
    year = "2014",
    journal = "Journal of Hydrology",
    url = "https://pureadmin.qub.ac.uk/ws/files/15791797/Lake\_hydrogeology\_and\_search.docx",
    doi = "10.1016/J.JHYDROL.2014.03.041",
    is_oa = "true",
    pages = "164-168",
    semanticscholar_citation_count = "10",
    semanticscholar_id = "87f58d4fd1400e6d3d25ebf0cd8fb7ed57311240",
    volume = "513"
}

@article{doi101016jscitotenv201402057,
    author = "Ayotte, Joseph D. and Belaval, Marcel and Olson, Scott A. and Burow, Karen R. and Flanagan, Sarah M. and Hinkle, Stephen R. and Lindsey, Bruce D.",
    title = "Factors affecting temporal variability of arsenic in groundwater used for drinking water supply in the United States",
    year = "2014",
    journal = "The Science of The Total Environment",
    url = "https://doi.org/10.1016/j.scitotenv.2014.02.057",
    doi = "10.1016/j.scitotenv.2014.02.057",
    openalex = "W2031033587",
    references = "doi101016japgeochem201101033, doi101111j17456584200900635x"
}

Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin.

@article{doi101111gwat12174,
    author = "Bexfield, Laura M. and Jurgens, Bryant C.",
    title = "Effects of Seasonal Operation on the Quality of Water Produced by Public‐Supply Wells",
    year = "2014",
    journal = "Ground Water",
    abstract = "Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin.",
    url = "https://doi.org/10.1111/gwat.12174",
    doi = "10.1111/gwat.12174",
    openalex = "W2048198477",
    references = "doi101007s1004000403246, doi101007s1004000905312, doi101007s1004001108106, doi101016japgeochem201101033, doi101021es00115a705, doi1010292007wr006252, doi101111j174565841998tb02841x, doi101111j1745658420050028x, doi101111j17456584200900635x, doi102134jeq20070061, doi103133sir20115182"
}

Streamflows, springs, and wetlands are important natural and cultural resources to the Caddo Nation. Consequently, the Caddo Nation is concerned about the vulnerability of the Rush Springs aquifer to overdrafting and whether the aquifer will continue to be a viable source of water to tribal members and other local residents in the future. Interest in the long-term viability of local water resources has resulted in ongoing development of a comprehensive water plan by the Caddo Nation. As part of a multiyear project with the Caddo Nation to provide information and tools to better manage and protect water resources, the U.S. Geological Survey studied the hydraulic connection between the Rush Springs aquifer and springs and streams overlying the aquifer. The Caddo Nation Tribal Jurisdictional Area is located in southwestern Oklahoma, primarily in Caddo County. Underlying the Caddo Nation Tribal Jurisdictional Area is the Permian-age Rush Springs aquifer. Water from the Rush Springs aquifer is used for irrigation, public, livestock and aquaculture, and other supply purposes. Groundwater from the Rush Springs aquifer also is withdrawn by domestic (self-supplied) wells, although domestic use was not included in the water-use summary in this report. Perennial streamflow in many streams and creeks overlying the Rush Springs aquifer, such as Cobb Creek, Lake Creek, and Willow Creek, originates from springs and seeps discharging from the aquifer. This report provides information on the evaluation of groundwater and surface-water resources in the Caddo Nation Jurisdictional Area, and in particular, information that describes the hydraulic connection between the Rush Springs aquifer and springs and streams overlying the aquifer. This report also includes data and analyses of base flow, evidence for groundwater and surface-water interactions, locations of springs and wetland areas, groundwater flows interpreted from potentiometric-surface maps, and hydrographs of water levels monitored in the Caddo Nation Tribal Jurisdictional Area from 2010 to 2013. Flow in streams overlying the Rush Springs aquifer, on average, were composed of 50 percent base flow in most years. Monthly mean base flow appeared to maintain streamflows throughout each year, but periods of zero flow were documented in daily hydrographs at each measured site, typically in the summer months. A pneumatic slug-test technique was used at 15 sites to determine the horizontal hydraulic conductivity of streambed sediments in streams overlying the Rush Springs aquifer. Converting horizontal hydraulic conductivities (Kh) from the slug-test analyses to vertical hydraulic conductivities (Kv) by using a ratio of Kv/Kh = 0.1 resulted in estimates of vertical streambed hydraulic conductivity ranging from 0.1 to 8.6 feet per day. Data obtained from a hydraulic potentiomanometer in streambed sediments and streams in August 2012 indicate that water flow was from the streambed sediments to the stream (gaining) at 6 of 15 sites, and that water flow was from the stream to the streambed sediments (losing) at 9 of 15 sites. The groundwater and surface-water interaction data collected at the Cobb Creek near Eakly, Okla., streamflow gaging station (07325800), indicate that the bedrock groundwater, alluvial groundwater, and surface-water resources are closely connected. Because of this hydrologic connection, large perennial streams in the study area may change from gaining to losing streams in the summer. The timing and severity of this change from a gaining to a losing condition probably is affected by the local or regional withdrawal of groundwater for irrigation in the summer growing season. Wells placed closer to streams have a greater and more immediate effect on alluvial groundwater levels and stream stages than wells placed farther from streams. Large-capacity irrigation wells, even those completed hundreds of feet below land surface in the bedrock aquifer, can induce surface-water flow from nearby streams by lowering alluvial groundwater levels below the stream altitude. Twenty-five new springs visible from public roads and paths were documented during a survey of springs in 2011. Most of the springs are in upland draws on the flanks of topographic ridges. Wetlands primarily were identified by using a combination of data sources including the National Wetlands Inventory, Soil Survey Geographic database frequently flooded soils maps, and aerial photographs. Regional flow directions were determined by analysis of water levels measured in 29 wells completed in the Rush 2 Springs aquifer in Caddo County and the Caddo Nation Tribal Jurisdictional Area. Water levels were monitored every 30 minutes in five wells by using a vented pressure transducer and a data-collection platform with real-time transmitting equipment in each well. Those five wells ranged in depth from 210 to 350 feet. Water levels in these five wells indicate that there was a decrease in water storage in the Rush Springs aquifer from October 2010 to June 2013.

@article{doi103133sir20145082,
    author = "Mashburn, Shana L. and Smith, S. Jerrod",
    title = "Evaluation of groundwater and surface-water interactions in the Caddo Nation Tribal Jurisdictional Area, Caddo County, Oklahoma, 2010-13",
    year = "2014",
    journal = "Scientific investigations report",
    abstract = "Streamflows, springs, and wetlands are important natural and cultural resources to the Caddo Nation. Consequently, the Caddo Nation is concerned about the vulnerability of the Rush Springs aquifer to overdrafting and whether the aquifer will continue to be a viable source of water to tribal members and other local residents in the future. Interest in the long-term viability of local water resources has resulted in ongoing development of a comprehensive water plan by the Caddo Nation. As part of a multiyear project with the Caddo Nation to provide information and tools to better manage and protect water resources, the U.S. Geological Survey studied the hydraulic connection between the Rush Springs aquifer and springs and streams overlying the aquifer. The Caddo Nation Tribal Jurisdictional Area is located in southwestern Oklahoma, primarily in Caddo County. Underlying the Caddo Nation Tribal Jurisdictional Area is the Permian-age Rush Springs aquifer. Water from the Rush Springs aquifer is used for irrigation, public, livestock and aquaculture, and other supply purposes. Groundwater from the Rush Springs aquifer also is withdrawn by domestic (self-supplied) wells, although domestic use was not included in the water-use summary in this report. Perennial streamflow in many streams and creeks overlying the Rush Springs aquifer, such as Cobb Creek, Lake Creek, and Willow Creek, originates from springs and seeps discharging from the aquifer. This report provides information on the evaluation of groundwater and surface-water resources in the Caddo Nation Jurisdictional Area, and in particular, information that describes the hydraulic connection between the Rush Springs aquifer and springs and streams overlying the aquifer. This report also includes data and analyses of base flow, evidence for groundwater and surface-water interactions, locations of springs and wetland areas, groundwater flows interpreted from potentiometric-surface maps, and hydrographs of water levels monitored in the Caddo Nation Tribal Jurisdictional Area from 2010 to 2013. Flow in streams overlying the Rush Springs aquifer, on average, were composed of 50 percent base flow in most years. Monthly mean base flow appeared to maintain streamflows throughout each year, but periods of zero flow were documented in daily hydrographs at each measured site, typically in the summer months. A pneumatic slug-test technique was used at 15 sites to determine the horizontal hydraulic conductivity of streambed sediments in streams overlying the Rush Springs aquifer. Converting horizontal hydraulic conductivities (Kh) from the slug-test analyses to vertical hydraulic conductivities (Kv) by using a ratio of Kv/Kh = 0.1 resulted in estimates of vertical streambed hydraulic conductivity ranging from 0.1 to 8.6 feet per day. Data obtained from a hydraulic potentiomanometer in streambed sediments and streams in August 2012 indicate that water flow was from the streambed sediments to the stream (gaining) at 6 of 15 sites, and that water flow was from the stream to the streambed sediments (losing) at 9 of 15 sites. The groundwater and surface-water interaction data collected at the Cobb Creek near Eakly, Okla., streamflow gaging station (07325800), indicate that the bedrock groundwater, alluvial groundwater, and surface-water resources are closely connected. Because of this hydrologic connection, large perennial streams in the study area may change from gaining to losing streams in the summer. The timing and severity of this change from a gaining to a losing condition probably is affected by the local or regional withdrawal of groundwater for irrigation in the summer growing season. Wells placed closer to streams have a greater and more immediate effect on alluvial groundwater levels and stream stages than wells placed farther from streams. Large-capacity irrigation wells, even those completed hundreds of feet below land surface in the bedrock aquifer, can induce surface-water flow from nearby streams by lowering alluvial groundwater levels below the stream altitude. Twenty-five new springs visible from public roads and paths were documented during a survey of springs in 2011. Most of the springs are in upland draws on the flanks of topographic ridges. Wetlands primarily were identified by using a combination of data sources including the National Wetlands Inventory, Soil Survey Geographic database frequently flooded soils maps, and aerial photographs. Regional flow directions were determined by analysis of water levels measured in 29 wells completed in the Rush 2 Springs aquifer in Caddo County and the Caddo Nation Tribal Jurisdictional Area. Water levels were monitored every 30 minutes in five wells by using a vented pressure transducer and a data-collection platform with real-time transmitting equipment in each well. Those five wells ranged in depth from 210 to 350 feet. Water levels in these five wells indicate that there was a decrease in water storage in the Rush Springs aquifer from October 2010 to June 2013.",
    url = "https://doi.org/10.3133/sir20145082",
    doi = "10.3133/sir20145082",
    openalex = "W117559269",
    references = "doi103133wri984081"
}

@article{doi103133sir20145153,
    author = "Darr, Michael J. and McCoy, K. and Rattray, G. and Durall, Roger A.",
    title = "Hydrogeology, water resources, and water budget of the upper Rio Hondo Basin, Lincoln County, New Mexico, 2010",
    year = "2014",
    journal = "Scientific Investigations Report",
    booktitle = "Scientific Investigations Report",
    url = "https://pubs.usgs.gov/sir/2014/5153/pdf/sir2014-5153.pdf",
    doi = "10.3133/SIR20145153",
    is_oa = "true",
    semanticscholar_citation_count = "2",
    semanticscholar_id = "f79a463c819ff0c6a24eb4fd52e7c5b13d488f48"
}

@article{doi101002hyp10775,
    author = "Koeniger, Paul and Gaj, Marcel and Beyer, Matthias and Himmelsbach, Thomas",
    title = "Review on soil water isotope-based groundwater recharge estimations",
    year = "2015",
    journal = "Hydrological Processes",
    url = "https://doi.org/10.1002/hyp.10775",
    doi = "10.1002/hyp.10775",
    openalex = "W2291169292",
    references = "doi101007s1004001107225"
}

Hexavalent chromium, Cr(VI), in 918 wells sampled throughout California between 2004 and 2012 by the Groundwater Ambient Monitoring and Assessment-Priority Basin Project (GAMA-PBP) ranged from less than the study reporting limit of 1 microgram per liter (μg/L) to 32 μg/L. Statewide, Cr(VI) was reported in 31 percent of wells and equaled or exceeded the recently established (2014) California Maximum Contaminant Level (MCL) for Cr(VI) of 10 μg/L in 4 percent of wells. Cr(VI) data collected for regulatory purposes overestimated Cr(VI) occurrence compared to spatially-distributed GAMA-PBP data. Ninety percent of chromium was present as Cr(VI), which was detected more frequently and at higher concentrations in alkaline (pH ≥ 8), oxic water; and more frequently in agricultural and urban land uses compared to native land uses. Chemical, isotopic (tritium and carbon-14), and noble-gas data show high Cr(VI) in water from wells in alluvial aquifers in the southern California deserts result from long groundwater-residence times and geochemical reactions such as silicate weathering that increase pH, while oxic conditions persist. High Cr(VI) in water from wells in alluvial aquifers along the west-side of the Central Valley results from high-chromium in source rock eroded to form those aquifers, and areal recharge processes (including irrigation return) that can mobilize chromium from the unsaturated zone. Cr(VI) co-occurred with oxyanions having similar chemistry, including vanadium, selenium, and uranium. Cr(VI) was positively correlated with nitrate, consistent with increased concentrations in areas of agricultural land use and mobilization of chromium from the unsaturated zone by irrigation return.

@article{doi101016japgeochem201508007,
    author = "Izbicki, John A. and Wright, Michael T. and Seymour, Whitney A. and McCleskey, R. Blaine and Fram, Miranda S. and Belitz, Kenneth and Esser, B. K.",
    title = "Cr(VI) occurrence and geochemistry in water from public-supply wells in California",
    year = "2015",
    journal = "Applied Geochemistry",
    abstract = "Hexavalent chromium, Cr(VI), in 918 wells sampled throughout California between 2004 and 2012 by the Groundwater Ambient Monitoring and Assessment-Priority Basin Project (GAMA-PBP) ranged from less than the study reporting limit of 1 microgram per liter (μg/L) to 32 μg/L. Statewide, Cr(VI) was reported in 31 percent of wells and equaled or exceeded the recently established (2014) California Maximum Contaminant Level (MCL) for Cr(VI) of 10 μg/L in 4 percent of wells. Cr(VI) data collected for regulatory purposes overestimated Cr(VI) occurrence compared to spatially-distributed GAMA-PBP data. Ninety percent of chromium was present as Cr(VI), which was detected more frequently and at higher concentrations in alkaline (pH ≥ 8), oxic water; and more frequently in agricultural and urban land uses compared to native land uses. Chemical, isotopic (tritium and carbon-14), and noble-gas data show high Cr(VI) in water from wells in alluvial aquifers in the southern California deserts result from long groundwater-residence times and geochemical reactions such as silicate weathering that increase pH, while oxic conditions persist. High Cr(VI) in water from wells in alluvial aquifers along the west-side of the Central Valley results from high-chromium in source rock eroded to form those aquifers, and areal recharge processes (including irrigation return) that can mobilize chromium from the unsaturated zone. Cr(VI) co-occurred with oxyanions having similar chemistry, including vanadium, selenium, and uranium. Cr(VI) was positively correlated with nitrate, consistent with increased concentrations in areas of agricultural land use and mobilization of chromium from the unsaturated zone by irrigation return.",
    url = "https://doi.org/10.1016/j.apgeochem.2015.08.007",
    doi = "10.1016/j.apgeochem.2015.08.007",
    openalex = "W1132777302",
    references = "doi101016japgeochem201406025"
}

In the present investigations, Laser Fluorimetry technique has been used for the microanalysis of uranium content in drinking water samples collected from different sources like the hand pumps, tube wells of various depths from wide range of locations in the four districts of SW-Punjab, India. The purpose of this study was to investigate the uranium concentration levels of ground water being used for drinking purposes and to determine its health effects, if any, to the local population of this region. Corresponding radiological and chemical risks have also been calculated for the uranium concentrations in ground water samples. Some other heavy elements have also been analysed using the Atomic Absorption Spectrometry. In this region, uranium concentration in 498 drinking water samples has been found to vary between 0.5–579 μgl−1with an average of 73.5 μgl−1. Data analysis revealed that 338 of 498 samples had uranium concentration higher than recommended safe limit of 30 μgl−1 (WHO, 2011) while 216 samples exceeded the threshold of 60 μgl−1 recommended by AERB, DAE, India, 2004.

@article{doi101016jjrras201501002,
    author = "Bajwa, B.S. and Kumar, Sanjeev and Singh, Surinder and Sahoo, Sunil Kumar and Tripathi, R.",
    title = "Uranium and other heavy toxic elements distribution in the drinking water samples of SW-Punjab, India",
    year = "2015",
    journal = "Journal of Radiation Research and Applied Sciences",
    abstract = "In the present investigations, Laser Fluorimetry technique has been used for the microanalysis of uranium content in drinking water samples collected from different sources like the hand pumps, tube wells of various depths from wide range of locations in the four districts of SW-Punjab, India. The purpose of this study was to investigate the uranium concentration levels of ground water being used for drinking purposes and to determine its health effects, if any, to the local population of this region. Corresponding radiological and chemical risks have also been calculated for the uranium concentrations in ground water samples. Some other heavy elements have also been analysed using the Atomic Absorption Spectrometry. In this region, uranium concentration in 498 drinking water samples has been found to vary between 0.5–579 μgl−1with an average of 73.5 μgl−1. Data analysis revealed that 338 of 498 samples had uranium concentration higher than recommended safe limit of 30 μgl−1 (WHO, 2011) while 216 samples exceeded the threshold of 60 μgl−1 recommended by AERB, DAE, India, 2004.",
    url = "https://doi.org/10.1016/j.jrras.2015.01.002",
    doi = "10.1016/j.jrras.2015.01.002",
    openalex = "W2078262068",
    references = "doi101111j17456584200900635x"
}

A large imbalance between recharge and water withdrawal has caused vital regions of the High Plains Aquifer (HPA) to experience significant declines in storage. A new predevelopment map coupled with a synthesis of annual water levels demonstrates that aquifer storage has declined by approximately 410 km(3) since the 1930s, a 15% larger decline than previous estimates. If current rates of decline continue, much of the Southern High Plains and parts of the Central High Plains will have insufficient water for irrigation within the next 20 to 30 years, whereas most of the Northern High Plains will experience little change in storage. In the western parts of the Central and northern part of the Southern High Plains, saturated thickness has locally declined by more than 50%, and is currently declining at rates of 10% to 20% of initial thickness per decade. The most agriculturally productive portions of the High Plains will not support irrigated production within a matter of decades without significant changes in management.

@article{doi101111gwat12350,
    author = "Haacker, Erin and Kendall, A. D. and Hyndman, D. W.",
    title = "Water Level Declines in the High Plains Aquifer: Predevelopment to Resource Senescence",
    year = "2015",
    journal = "Ground Water",
    abstract = "A large imbalance between recharge and water withdrawal has caused vital regions of the High Plains Aquifer (HPA) to experience significant declines in storage. A new predevelopment map coupled with a synthesis of annual water levels demonstrates that aquifer storage has declined by approximately 410 km(3) since the 1930s, a 15\% larger decline than previous estimates. If current rates of decline continue, much of the Southern High Plains and parts of the Central High Plains will have insufficient water for irrigation within the next 20 to 30 years, whereas most of the Northern High Plains will experience little change in storage. In the western parts of the Central and northern part of the Southern High Plains, saturated thickness has locally declined by more than 50\%, and is currently declining at rates of 10\% to 20\% of initial thickness per decade. The most agriculturally productive portions of the High Plains will not support irrigated production within a matter of decades without significant changes in management.",
    url = "https://doi.org/10.1111/gwat.12350",
    doi = "10.1111/gwat.12350",
    openalex = "W1534609677",
    references = "doi103133wri994104"
}

In spite of trying to understand processes in the same spatial domain, the catchment hydrology and water quality scientific communities are relatively disconnected and so are their respective models. This is emphasized by an inadequate representation of transport processes, in both catchment‐scale hydrological and water quality models. While many hydrological models at the catchment scale only account for pressure propagation and not for mass transfer, catchment scale water quality models are typically limited by overly simplistic representations of flow processes. With the objective of raising awareness for this issue and outlining potential ways forward we provide a nontechnical overview of (1) the importance of hydrology‐controlled transport through catchment systems as the link between hydrology and water quality; (2) the limitations of current generation catchment‐scale hydrological and water quality models; (3) the concept of transit times as tools to quantify transport; and (4) the benefits of transit time based formulations of solute transport for catchment‐scale hydrological and water quality models. There is emerging evidence that an explicit formulation of transport processes, based on the concept of transit times has the potential to improve the understanding of the integrated system dynamics of catchments and to provide a stronger link between catchment‐scale hydrological and water quality models. WIREs Water 2016, 3:629–657. doi: 10.1002/wat2.1155 This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water Quality

@article{doi101002wat21155,
    author = "Hrachowitz, Markus and Benettin, Paolo and van Breukelen, Boris M. and Fovet, Ophélie and Howden, Nicholas and Ruiz, Laurent and van der Velde, Ype and Wade, Andrew J.",
    title = "Transit times—the link between hydrology and water quality at the catchment scale",
    year = "2016",
    journal = "Wiley Interdisciplinary Reviews Water",
    abstract = "In spite of trying to understand processes in the same spatial domain, the catchment hydrology and water quality scientific communities are relatively disconnected and so are their respective models. This is emphasized by an inadequate representation of transport processes, in both catchment‐scale hydrological and water quality models. While many hydrological models at the catchment scale only account for pressure propagation and not for mass transfer, catchment scale water quality models are typically limited by overly simplistic representations of flow processes. With the objective of raising awareness for this issue and outlining potential ways forward we provide a nontechnical overview of (1) the importance of hydrology‐controlled transport through catchment systems as the link between hydrology and water quality; (2) the limitations of current generation catchment‐scale hydrological and water quality models; (3) the concept of transit times as tools to quantify transport; and (4) the benefits of transit time based formulations of solute transport for catchment‐scale hydrological and water quality models. There is emerging evidence that an explicit formulation of transport processes, based on the concept of transit times has the potential to improve the understanding of the integrated system dynamics of catchments and to provide a stronger link between catchment‐scale hydrological and water quality models. WIREs Water 2016, 3:629–657. doi: 10.1002/wat2.1155 This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water Quality",
    url = "https://doi.org/10.1002/wat2.1155",
    doi = "10.1002/wat2.1155",
    openalex = "W2398190531",
    references = "doi1010160022169482901470"
}

@article{doi101016jscitotenv201710241,
    author = "Yang, Yuanyuan and Zhao, Jian‐Liang and Liu, You-Sheng and Liu, Wang-Rong and Zhang, Qian-Qian and Yao, Li and Hu, Li-Xin and Zhang, Jin-Na and Jiang, Yu-Xia and Ying, Guang‐Guo",
    title = "Pharmaceuticals and personal care products (PPCPs) and artificial sweeteners (ASs) in surface and ground waters and their application as indication of wastewater contamination",
    year = "2017",
    journal = "The Science of The Total Environment",
    url = "https://doi.org/10.1016/j.scitotenv.2017.10.241",
    doi = "10.1016/j.scitotenv.2017.10.241",
    openalex = "W2766728918",
    references = "doi101016jjhydrol201011017"
}

@article{doi101016jscitotenv201712115,
    author = "Hagedorn, Benjamin and Clarke, Natalie and Ruane, M. and Faulkner, Kirsten E.",
    title = "Assessing aquifer vulnerability from lumped parameter modeling of modern water proportions in groundwater mixtures: Application to California's South Coast Range",
    year = "2017",
    journal = "The Science of The Total Environment",
    url = "https://doi.org/10.1016/j.scitotenv.2017.12.115",
    doi = "10.1016/j.scitotenv.2017.12.115",
    openalex = "W2780915063",
    references = "doi103133sir20115182"
}

First posted February 13, 2017 Revised March 27, 2017 For additional information, contact: Director, Oklahoma Water Science CenterU.S. Geological Survey 202 NW 66th, Bldg 7Oklahoma City, OK 73116http://ok.water.usgs.gov/ This report describes a study of the hydrogeology and simulation of groundwater flow for the Canadian River alluvial aquifer in western and central Oklahoma conducted by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board. The report (1) quantifies the groundwater resources of the Canadian River alluvial aquifer by developing a conceptual model, (2) summarizes the general water quality of the Canadian River alluvial aquifer groundwater by using data collected during August and September 2013, (3) evaluates the effects of estimated equal proportionate share (EPS) on aquifer storage and streamflow for time periods of 20, 40, and 50 years into the future by using numerical groundwater-flow models, and (4) evaluates the effects of present-day groundwater pumping over a 50-year period and sustained hypothetical drought conditions over a 10-year period on stream base flow and groundwater in storage by using numerical flow models. The Canadian River alluvial aquifer is a Quaternary-age alluvial and terrace unit consisting of beds of clay, silt, sand, and fine gravel sediments unconformably overlying Tertiary-, Permian-, and Pennsylvanian-age sedimentary rocks. For groundwater-flow modeling purposes, the Canadian River was divided into Reach I, extending from the Texas border to the Canadian River at the Bridgeport, Okla., streamgage (07228500), and Reach II, extending downstream from the Canadian River at the Bridgeport, Okla., streamgage (07228500), to the confluence of the river with Eufaula Lake. The Canadian River alluvial aquifer spans multiple climate divisions, ranging from semiarid in the west to humid subtropical in the east. The average annual precipitation in the study area from 1896 to 2014 was 34.4 inches per year (in/yr).A hydrogeologic framework of the Canadian River alluvial aquifer was developed that includes the areal and vertical extent of the aquifer and the distribution, texture variability, and hydraulic properties of aquifer materials. The aquifer areal extent ranged from less than 0.2 to 8.5 miles wide. The maximum aquifer thickness was 120 feet (ft), and the average aquifer thickness was 50 ft. Average horizontal hydraulic conductivity for the Canadian River alluvial aquifer was calculated to be 39 feet per day, and the maximum horizontal hydraulic conductivity was calculated to be 100 feet per day.Recharge rates to the Canadian River alluvial aquifer were estimated by using a soil-water-balance code to estimate the spatial distribution of groundwater recharge and a water-table fluctuation method to estimate localized recharge rates. By using daily precipitation and temperature data from 39 climate stations, recharge was estimated to average 3.4 in/yr, which corresponds to 8.7 percent of precipitation as recharge for the Canadian River alluvial aquifer from 1981 to 2013. The water-table fluctuation method was used at one site where continuous water-level observation data were available to estimate the percentage of precipitation that becomes groundwater recharge. Estimated annual recharge at that site was 9.7 in/yr during 2014.Groundwater flow in the Canadian River alluvial aquifer was identified and quantified by a conceptual flow model for the period 1981–2013. Inflows to the Canadian River alluvial aquifer include recharge to the water table from precipitation, lateral flow from the surrounding bedrock, and flow from the Canadian River, whereas outflows include flow to the Canadian River (base-flow gain), evapotranspiration, and groundwater use. Total annual recharge inflows estimated by the soil-water-balance code were multiplied by the area of each reach and then averaged over the simulated period to produce an annual average of 28,919 acre-feet per year (acre-ft/yr) for Reach I and 82,006 acre-ft/yr for Reach II. Stream base flow to the Canadian River was estimated to be the largest outflow of groundwater from the aquifer, measured at four streamgages, along with evapotranspiration and groundwater use, which were relatively minor discharge components.Objectives for the numerical groundwater-flow models included simulating groundwater flow in the Canadian River alluvial aquifer from 1981 to 2013 to address groundwater use and drought scenarios, including calculation of the EPS pumping rates. The EPS for the alluvial and terrace aquifers is defined by the Oklahoma Water Resources Board as the amount of fresh water that each landowner is allowed per year per acre of owned land to maintain a saturated thickness of at least 5 ft in at least 50 percent of the overlying land of the groundwater basin for a minimum of 20 years.The groundwater-flow models were calibrated to water-table altitude observations, streamgage base flows, and base-flow gain to the Canadian River. The Reach I water-table altitude observation root-mean-square error was 6.1 ft, and 75 percent of residuals were within ±6.7 ft of observed measurements. The average simulated stream base-flow residual at the Bridgeport streamgage (07228500) was 8.8 cubic feet per second (ft3/s), and 75 percent of residuals were within ±30 ft3/s of observed measurements. Simulated base-flow gain in Reach I was 8.8 ft3/s lower than estimated base-flow gain. The Reach II water-table altitude observation root-mean-square error was 4 ft, and 75 percent of residuals were within ±4.3 ft of the observations. The average simulated stream base-flow residual in Reach II was between 35 and 132 ft3/s. The average simulated base-flow gain residual in Reach II was between 11.3 and 61.1 ft3/s.Several future predictive scenarios were run, including estimating the EPS pumping rate for 20-, 40-, and 50-year life of basin scenarios, determining the effects of current groundwater use over a 50-year period into the future, and evaluating the effects of a sustained drought on water availability for both reaches. The EPS pumping rate was determined to be 1.35 acre-feet per acre per year ([acre-ft/acre]/yr) in Reach I and 3.08 (acre-ft/acre)/yr in Reach II for a 20-year period. For the 40- and 50-year periods, the EPS rate was determined to be 1.34 (acre-ft/acre)/yr in Reach I and 3.08 (acre-ft/acre)/yr in Reach II. Storage changes decreased in tandem with simulated groundwater pumping and were minimal after the first 15 simulated years for Reach I and the first 8 simulated years for Reach II.Groundwater pumping at year 2013 rates for a period of 50 years resulted in a 0.2-percent decrease in groundwater-storage volumes in Reach I and a 0.6-percent decrease in the groundwater-storage volumes in Reach II. The small changes in storage are due to groundwater use by pumping, which composes a small percentage of the total groundwater-flow model budgets for Reaches I and II.A sustained drought scenario was used to evaluate the effects of a hypothetical 10-year drought on water availability. A 10-year period was chosen where the effects of drought conditions would be simulated by decreasing recharge by 75 percent. In Reach I, average simulated stream base flow at the Bridgeport streamgage (07228500) decreased by 58 percent during the hypothetical 10-year drought compared to average simulated stream base flow during the nondrought period. In Reach II, average simulated stream base flows at the Purcell streamgage (07229200) and Calvin streamgage (07231500) decreased by 64 percent and 54 percent, respectively. In Reach I, the groundwater-storage drought scenario resulted in a storage decline of 30 thousand acre-feet, or an average decline in the water table of 1.2 ft. In Reach II, the groundwater-storage drought scenario resulted in a storage decline of 71 thousand acre-feet, or an average decline in the water table of 2.0 ft.

@article{doi103133sir20165180,
    author = "Ellis, John and Mashburn, Shana L. and Graves, Grant M. and Peterson, Steven M. and Smith, S. Jerrod and Fuhrig, Leland T. and Wagner, Derrick L. and Sanford, Jon E.",
    title = "Hydrogeology and simulation of groundwater flow and analysis of projected water use for the Canadian River alluvial aquifer, western and central Oklahoma",
    year = "2017",
    journal = "Scientific investigations report",
    abstract = "First posted February 13, 2017 Revised March 27, 2017 For additional information, contact: Director, Oklahoma Water Science CenterU.S. Geological Survey 202 NW 66th, Bldg 7Oklahoma City, OK 73116http://ok.water.usgs.gov/ This report describes a study of the hydrogeology and simulation of groundwater flow for the Canadian River alluvial aquifer in western and central Oklahoma conducted by the U.S. Geological Survey in cooperation with the Oklahoma Water Resources Board. The report (1) quantifies the groundwater resources of the Canadian River alluvial aquifer by developing a conceptual model, (2) summarizes the general water quality of the Canadian River alluvial aquifer groundwater by using data collected during August and September 2013, (3) evaluates the effects of estimated equal proportionate share (EPS) on aquifer storage and streamflow for time periods of 20, 40, and 50 years into the future by using numerical groundwater-flow models, and (4) evaluates the effects of present-day groundwater pumping over a 50-year period and sustained hypothetical drought conditions over a 10-year period on stream base flow and groundwater in storage by using numerical flow models. The Canadian River alluvial aquifer is a Quaternary-age alluvial and terrace unit consisting of beds of clay, silt, sand, and fine gravel sediments unconformably overlying Tertiary-, Permian-, and Pennsylvanian-age sedimentary rocks. For groundwater-flow modeling purposes, the Canadian River was divided into Reach I, extending from the Texas border to the Canadian River at the Bridgeport, Okla., streamgage (07228500), and Reach II, extending downstream from the Canadian River at the Bridgeport, Okla., streamgage (07228500), to the confluence of the river with Eufaula Lake. The Canadian River alluvial aquifer spans multiple climate divisions, ranging from semiarid in the west to humid subtropical in the east. The average annual precipitation in the study area from 1896 to 2014 was 34.4 inches per year (in/yr).A hydrogeologic framework of the Canadian River alluvial aquifer was developed that includes the areal and vertical extent of the aquifer and the distribution, texture variability, and hydraulic properties of aquifer materials. The aquifer areal extent ranged from less than 0.2 to 8.5 miles wide. The maximum aquifer thickness was 120 feet (ft), and the average aquifer thickness was 50 ft. Average horizontal hydraulic conductivity for the Canadian River alluvial aquifer was calculated to be 39 feet per day, and the maximum horizontal hydraulic conductivity was calculated to be 100 feet per day.Recharge rates to the Canadian River alluvial aquifer were estimated by using a soil-water-balance code to estimate the spatial distribution of groundwater recharge and a water-table fluctuation method to estimate localized recharge rates. By using daily precipitation and temperature data from 39 climate stations, recharge was estimated to average 3.4 in/yr, which corresponds to 8.7 percent of precipitation as recharge for the Canadian River alluvial aquifer from 1981 to 2013. The water-table fluctuation method was used at one site where continuous water-level observation data were available to estimate the percentage of precipitation that becomes groundwater recharge. Estimated annual recharge at that site was 9.7 in/yr during 2014.Groundwater flow in the Canadian River alluvial aquifer was identified and quantified by a conceptual flow model for the period 1981–2013. Inflows to the Canadian River alluvial aquifer include recharge to the water table from precipitation, lateral flow from the surrounding bedrock, and flow from the Canadian River, whereas outflows include flow to the Canadian River (base-flow gain), evapotranspiration, and groundwater use. Total annual recharge inflows estimated by the soil-water-balance code were multiplied by the area of each reach and then averaged over the simulated period to produce an annual average of 28,919 acre-feet per year (acre-ft/yr) for Reach I and 82,006 acre-ft/yr for Reach II. Stream base flow to the Canadian River was estimated to be the largest outflow of groundwater from the aquifer, measured at four streamgages, along with evapotranspiration and groundwater use, which were relatively minor discharge components.Objectives for the numerical groundwater-flow models included simulating groundwater flow in the Canadian River alluvial aquifer from 1981 to 2013 to address groundwater use and drought scenarios, including calculation of the EPS pumping rates. The EPS for the alluvial and terrace aquifers is defined by the Oklahoma Water Resources Board as the amount of fresh water that each landowner is allowed per year per acre of owned land to maintain a saturated thickness of at least 5 ft in at least 50 percent of the overlying land of the groundwater basin for a minimum of 20 years.The groundwater-flow models were calibrated to water-table altitude observations, streamgage base flows, and base-flow gain to the Canadian River. The Reach I water-table altitude observation root-mean-square error was 6.1 ft, and 75 percent of residuals were within ±6.7 ft of observed measurements. The average simulated stream base-flow residual at the Bridgeport streamgage (07228500) was 8.8 cubic feet per second (ft3/s), and 75 percent of residuals were within ±30 ft3/s of observed measurements. Simulated base-flow gain in Reach I was 8.8 ft3/s lower than estimated base-flow gain. The Reach II water-table altitude observation root-mean-square error was 4 ft, and 75 percent of residuals were within ±4.3 ft of the observations. The average simulated stream base-flow residual in Reach II was between 35 and 132 ft3/s. The average simulated base-flow gain residual in Reach II was between 11.3 and 61.1 ft3/s.Several future predictive scenarios were run, including estimating the EPS pumping rate for 20-, 40-, and 50-year life of basin scenarios, determining the effects of current groundwater use over a 50-year period into the future, and evaluating the effects of a sustained drought on water availability for both reaches. The EPS pumping rate was determined to be 1.35 acre-feet per acre per year ([acre-ft/acre]/yr) in Reach I and 3.08 (acre-ft/acre)/yr in Reach II for a 20-year period. For the 40- and 50-year periods, the EPS rate was determined to be 1.34 (acre-ft/acre)/yr in Reach I and 3.08 (acre-ft/acre)/yr in Reach II. Storage changes decreased in tandem with simulated groundwater pumping and were minimal after the first 15 simulated years for Reach I and the first 8 simulated years for Reach II.Groundwater pumping at year 2013 rates for a period of 50 years resulted in a 0.2-percent decrease in groundwater-storage volumes in Reach I and a 0.6-percent decrease in the groundwater-storage volumes in Reach II. The small changes in storage are due to groundwater use by pumping, which composes a small percentage of the total groundwater-flow model budgets for Reaches I and II.A sustained drought scenario was used to evaluate the effects of a hypothetical 10-year drought on water availability. A 10-year period was chosen where the effects of drought conditions would be simulated by decreasing recharge by 75 percent. In Reach I, average simulated stream base flow at the Bridgeport streamgage (07228500) decreased by 58 percent during the hypothetical 10-year drought compared to average simulated stream base flow during the nondrought period. In Reach II, average simulated stream base flows at the Purcell streamgage (07229200) and Calvin streamgage (07231500) decreased by 64 percent and 54 percent, respectively. In Reach I, the groundwater-storage drought scenario resulted in a storage decline of 30 thousand acre-feet, or an average decline in the water table of 1.2 ft. In Reach II, the groundwater-storage drought scenario resulted in a storage decline of 71 thousand acre-feet, or an average decline in the water table of 2.0 ft.",
    url = "https://doi.org/10.3133/sir20165180",
    doi = "10.3133/sir20165180",
    openalex = "W2601066798",
    references = "doi103133wri984081"
}

Abstract. Water isotopes in ice cores are used as a climate proxy for local temperature and regional atmospheric circulation as well as evaporative conditions in moisture source regions. Traditional measurements of water isotopes have been achieved using magnetic sector isotope ratio mass spectrometry (IRMS). However, a number of recent studies have shown that laser absorption spectrometry (LAS) performs as well or better than IRMS. The new LAS technology has been combined with continuous-flow analysis (CFA) to improve data density and sample throughput in numerous prior ice coring projects. Here, we present a comparable semi-automated LAS-CFA system for measuring high-resolution water isotopes of ice cores. We outline new methods for partitioning both system precision and mixing length into liquid and vapor components – useful measures for defining and improving the overall performance of the system. Critically, these methods take into account the uncertainty of depth registration that is not present in IRMS nor fully accounted for in other CFA studies. These analyses are achieved using samples from a South Pole firn core, a Greenland ice core, and the West Antarctic Ice Sheet (WAIS) Divide ice core. The measurement system utilizes a 16-position carousel contained in a freezer to consecutively deliver ∼ 1 m × 1.3 cm2 ice sticks to a temperature-controlled melt head, where the ice is converted to a continuous liquid stream and eventually vaporized using a concentric nebulizer for isotopic analysis. An integrated delivery system for water isotope standards is used for calibration to the Vienna Standard Mean Ocean Water (VSMOW) scale, and depth registration is achieved using a precise overhead laser distance device with an uncertainty of ±0.2 mm. As an added check on the system, we perform inter-lab LAS comparisons using WAIS Divide ice samples, a corroboratory step not taken in prior CFA studies. The overall results are important for substantiating data obtained from LAS-CFA systems, including optimizing liquid and vapor mixing lengths, determining melt rates for ice cores with different accumulation and thinning histories, and removing system-wide mixing effects that are convolved with the natural diffusional signal that results primarily from water molecule diffusion in the firn column.

@article{doi105194amt106172017,
    author = "Jones, Tyler R. and White, James W. C. and Steig, Eric J. and Vaughn, Bruce H. and Morris, Valerie and Gkinis, Vasileios and Markle, Bradley and Schoenemann, Spruce W.",
    title = "Improved methodologies for continuous-flow analysis of stable water isotopes in ice cores",
    year = "2017",
    journal = "Atmospheric measurement techniques",
    abstract = "Abstract. Water isotopes in ice cores are used as a climate proxy for local temperature and regional atmospheric circulation as well as evaporative conditions in moisture source regions. Traditional measurements of water isotopes have been achieved using magnetic sector isotope ratio mass spectrometry (IRMS). However, a number of recent studies have shown that laser absorption spectrometry (LAS) performs as well or better than IRMS. The new LAS technology has been combined with continuous-flow analysis (CFA) to improve data density and sample throughput in numerous prior ice coring projects. Here, we present a comparable semi-automated LAS-CFA system for measuring high-resolution water isotopes of ice cores. We outline new methods for partitioning both system precision and mixing length into liquid and vapor components – useful measures for defining and improving the overall performance of the system. Critically, these methods take into account the uncertainty of depth registration that is not present in IRMS nor fully accounted for in other CFA studies. These analyses are achieved using samples from a South Pole firn core, a Greenland ice core, and the West Antarctic Ice Sheet (WAIS) Divide ice core. The measurement system utilizes a 16-position carousel contained in a freezer to consecutively deliver ∼ 1 m × 1.3 cm2 ice sticks to a temperature-controlled melt head, where the ice is converted to a continuous liquid stream and eventually vaporized using a concentric nebulizer for isotopic analysis. An integrated delivery system for water isotope standards is used for calibration to the Vienna Standard Mean Ocean Water (VSMOW) scale, and depth registration is achieved using a precise overhead laser distance device with an uncertainty of ±0.2 mm. As an added check on the system, we perform inter-lab LAS comparisons using WAIS Divide ice samples, a corroboratory step not taken in prior CFA studies. The overall results are important for substantiating data obtained from LAS-CFA systems, including optimizing liquid and vapor mixing lengths, determining melt rates for ice cores with different accumulation and thinning histories, and removing system-wide mixing effects that are convolved with the natural diffusional signal that results primarily from water molecule diffusion in the firn column.",
    url = "https://doi.org/10.5194/amt-10-617-2017",
    doi = "10.5194/amt-10-617-2017",
    openalex = "W2481716356",
    references = "doi101021ac00009a014"
}

@article{doi103133sir20155164,
    author = "Izuka, S. and Engott, John A. and Rotzoll, K. and Bassiouni, M. and Johnson, Adam G. and Miller, L. and Mair, A.",
    title = "Volcanic aquifers of Hawai‘i—Hydrogeology, water budgets, and conceptual models",
    year = "2018",
    journal = "Scientific Investigations Report",
    booktitle = "Scientific Investigations Report",
    url = "https://pubs.usgs.gov/sir/2015/5164/sir20155164v2.pdf",
    doi = "10.3133/SIR20155164",
    is_oa = "true",
    semanticscholar_citation_count = "24",
    semanticscholar_id = "d168f7aad2231076da194cb1a62c20786b1dcd12"
}

@article{doi101016jmarpolbul2019110668,
    author = "Amato, Daniel W. and Whittier, Robert and Dulai, Henrietta and Smith, Celia M.",
    title = "Algal bioassays detect modeled loading of wastewater-derived nitrogen in coastal waters of OʻAHU, HAWAIʻI",
    year = "2019",
    journal = "Marine Pollution Bulletin",
    url = "https://doi.org/10.1016/j.marpolbul.2019.110668",
    doi = "10.1016/j.marpolbul.2019.110668",
    openalex = "W2992565365",
    references = "doi103133sir20155164"
}

The capture, treatment, and recharge of urban runoff can augment water supplies for water-scarce cities. This article describes trends in urban stormwater capture for potable water supply using examples from the U.S. and Australia. In water-limited climates, water supply potential exists for large scale stormwater harvesting and recharge, such as neighborhood-scale and larger projects. The beneficial use of urban stormwater to meet nonpotable water demands has been successfully demonstrated in the U.S. and internationally. However, in terms of potable water use in the U.S., the lack of a regulatory framework and uncertainty in treatment and water quality targets are barriers to wide-scale adoption of urban stormwater for recharge, which is not so evident in Australia. More data on urban stormwater quality, particularly with respect to pathogens and polar organic contaminants, are needed to better inform treatment requirements. New technologies hold promise for improved operation and treatment, but must be demonstrated in field trials. Stormwater treatment systems may be needed for large-scale recharge in highly urbanized areas where source control is challenging. The co-benefits of water supply, urban amenities, and pollution reduction are important for financing, public acceptance and implementation-but are rarely quantified.

@article{doi101021acsest8b05913,
    author = "Luthy, Richard G. and Sharvelle, Sybil and Dillon, Peter",
    title = "Urban Stormwater to Enhance Water Supply",
    year = "2019",
    journal = "Environmental Science \& Technology",
    abstract = "The capture, treatment, and recharge of urban runoff can augment water supplies for water-scarce cities. This article describes trends in urban stormwater capture for potable water supply using examples from the U.S. and Australia. In water-limited climates, water supply potential exists for large scale stormwater harvesting and recharge, such as neighborhood-scale and larger projects. The beneficial use of urban stormwater to meet nonpotable water demands has been successfully demonstrated in the U.S. and internationally. However, in terms of potable water use in the U.S., the lack of a regulatory framework and uncertainty in treatment and water quality targets are barriers to wide-scale adoption of urban stormwater for recharge, which is not so evident in Australia. More data on urban stormwater quality, particularly with respect to pathogens and polar organic contaminants, are needed to better inform treatment requirements. New technologies hold promise for improved operation and treatment, but must be demonstrated in field trials. Stormwater treatment systems may be needed for large-scale recharge in highly urbanized areas where source control is challenging. The co-benefits of water supply, urban amenities, and pollution reduction are important for financing, public acceptance and implementation-but are rarely quantified.",
    url = "https://doi.org/10.1021/acs.est.8b05913",
    doi = "10.1021/acs.est.8b05913",
    openalex = "W2916587026",
    references = "doi101007s0026700891191, doi101007s1004000404136, doi101016jjhydrol201605059, doi101016jwatres201901040, doi101021acsest5b00376, doi101021acsest5b05870, doi101021es202904x, doi10108010643389509388476, doi101089ees20120312, doi102166wst2007751, doi103133sir20085156, doi1041359781483388007n5"
}

Abstract Groundwater 18 O/ 16 O, 2 H/ 1 H, 13 C/ 12 C, 3 H, and 14 C data can help quantify molecular movements and chemical reactions governing groundwater recharge, quality, storage, flow, and discharge. Here, commonly applied approaches to isotopic data analysis are reviewed, involving groundwater recharge seasonality, recharge elevations, groundwater ages, paleoclimate conditions, and groundwater discharge. Reviewed works confirm and quantify long held tenets: (i) that recharge derives disproportionately from wet season and winter precipitation; (ii) that modern groundwaters comprise little global groundwater; (iii) that “fossil” (>12,000‐year‐old) groundwaters dominate global aquifer storage; (iv) that fossil groundwaters capture late‐Pleistocene climate conditions; (v) that surface‐borne contaminants are more common in younger groundwaters; and (vi) that groundwater discharges generate substantial streamflow. Groundwater isotope data are disproportionately common to midlatitudes and sedimentary basins equipped for irrigated agriculture, but less plentiful across high latitudes, hyperarid deserts, and equatorial rainforests. Some of these underexplored aquifer systems may be suitable targets for future field testing.

@article{doi1010292018rg000627,
    author = "Jasechko, Scott",
    title = "Global Isotope Hydrogeology―Review",
    year = "2019",
    journal = "Reviews of Geophysics",
    abstract = "Abstract Groundwater 18 O/ 16 O, 2 H/ 1 H, 13 C/ 12 C, 3 H, and 14 C data can help quantify molecular movements and chemical reactions governing groundwater recharge, quality, storage, flow, and discharge. Here, commonly applied approaches to isotopic data analysis are reviewed, involving groundwater recharge seasonality, recharge elevations, groundwater ages, paleoclimate conditions, and groundwater discharge. Reviewed works confirm and quantify long held tenets: (i) that recharge derives disproportionately from wet season and winter precipitation; (ii) that modern groundwaters comprise little global groundwater; (iii) that “fossil” (>12,000‐year‐old) groundwaters dominate global aquifer storage; (iv) that fossil groundwaters capture late‐Pleistocene climate conditions; (v) that surface‐borne contaminants are more common in younger groundwaters; and (vi) that groundwater discharges generate substantial streamflow. Groundwater isotope data are disproportionately common to midlatitudes and sedimentary basins equipped for irrigated agriculture, but less plentiful across high latitudes, hyperarid deserts, and equatorial rainforests. Some of these underexplored aquifer systems may be suitable targets for future field testing.",
    url = "https://doi.org/10.1029/2018rg000627",
    doi = "10.1029/2018rg000627",
    openalex = "W2943598625",
    references = "doi1010022013rg000443, doi1010022015wr017037, doi101007s1004001107225, doi1010160022169482901470, doi1010292004pa001071, doi101029tr016i002p00519, doi101038nature08238, doi101111j215334901964tb00181x, doi101126science1244693, doi101126science13334651702, doi101146annurevearth241225, doi101146annurevpp40060189002443, doi102458azujsrc5516947, doi103133sir20085156, doi105194bg1271292015, doi106028jres105043"
}

Abstract The time that water takes to travel through the terrestrial hydrological cycle and the critical zone is of great interest in Earth system sciences with broad implications for water quality and quantity. Most water age studies to date have focused on individual compartments (or subdisciplines) of the hydrological cycle such as the unsaturated or saturated zone, vegetation, atmosphere, or rivers. However, recent studies have shown that processes at the interfaces between the hydrological compartments (e.g., soil‐atmosphere or soil‐groundwater) govern the age distribution of the water fluxes between these compartments and thus can greatly affect water travel times. The broad variation from complete to nearly absent mixing of water at these interfaces affects the water ages in the compartments. This is especially the case for the highly heterogeneous critical zone between the top of the vegetation and the bottom of the groundwater storage. Here, we review a wide variety of studies about water ages in the critical zone and provide (1) an overview of new prospects and challenges in the use of hydrological tracers to study water ages, (2) a discussion of the limiting assumptions linked to our lack of process understanding and methodological transfer of water age estimations to individual disciplines or compartments, and (3) a vision for how to improve future interdisciplinary efforts to better understand the feedbacks between the atmosphere, vegetation, soil, groundwater, and surface water that control water ages in the critical zone.

@article{doi1010292018rg000633,
    author = "Sprenger, Matthias and Stumpp, Christine and Weiler, Markus and Aeschbach, Werner and Allen, Scott T. and Benettin, Paolo and Dubbert, Maren and Hartmann, Andreas and Hrachowitz, Markus and Kirchner, James W. and McDonnell, Jeffrey J. and Orlowski, Natalie and Penna, Daniele and Pfahl, Stephan and Rinderer, Michael and Rodriguez, Nicolas and Schmidt, Maximilian and Werner, Christiane",
    title = "The Demographics of Water: A Review of Water Ages in the Critical Zone",
    year = "2019",
    journal = "Reviews of Geophysics",
    abstract = "Abstract The time that water takes to travel through the terrestrial hydrological cycle and the critical zone is of great interest in Earth system sciences with broad implications for water quality and quantity. Most water age studies to date have focused on individual compartments (or subdisciplines) of the hydrological cycle such as the unsaturated or saturated zone, vegetation, atmosphere, or rivers. However, recent studies have shown that processes at the interfaces between the hydrological compartments (e.g., soil‐atmosphere or soil‐groundwater) govern the age distribution of the water fluxes between these compartments and thus can greatly affect water travel times. The broad variation from complete to nearly absent mixing of water at these interfaces affects the water ages in the compartments. This is especially the case for the highly heterogeneous critical zone between the top of the vegetation and the bottom of the groundwater storage. Here, we review a wide variety of studies about water ages in the critical zone and provide (1) an overview of new prospects and challenges in the use of hydrological tracers to study water ages, (2) a discussion of the limiting assumptions linked to our lack of process understanding and methodological transfer of water age estimations to individual disciplines or compartments, and (3) a vision for how to improve future interdisciplinary efforts to better understand the feedbacks between the atmosphere, vegetation, soil, groundwater, and surface water that control water ages in the critical zone.",
    url = "https://doi.org/10.1029/2018rg000633",
    doi = "10.1029/2018rg000633",
    openalex = "W2946531320",
    references = "doi101002hyp1145, doi101007s1004001108106, doi1010160022169482901470, doi1010292018rg000627"
}

Abstract Safe and secure water is a cornerstone of modern life in the global North. This article critically examines a set of prevalent myths about household water in high‐income countries, with a focus on Canada and the United States. Taking a relational approach, we argue that household water insecurity is a product of institutionalized structures and power, manifests unevenly through space and time, and is reproduced in places we tend to assume are the most water‐secure in the world. We first briefly introduce “modern water” and the modern infrastructural ideal, a highly influential set of ideas that have shaped household water provision and infrastructure development over the past two centuries. Against this backdrop, we consolidate evidence to disrupt a set of narratives about water in high‐income countries: the notion that water access is universal, clean, affordable, trustworthy, and uniformly or equitably governed. We identify five thematic areas of future research to delineate an agenda for advancing scholarship and action—including challenges of legal and regulatory regimes, the housing‐water nexus, water affordability, and water quality and contamination. Data gaps underpin the experiences of household water insecurity. Taken together, our review of water security for households in high‐income countries provides a conceptual map to direct critical research in this area for the coming years. This article is categorized under: Human Water > Human Water

@article{doi101002wat21486,
    author = "Meehan, Katie and Jepson, Wendy and Harris, Leila M. and Wutich, Amber and Beresford, Melissa and Fencl, Amanda and London, Jonathan and Pierce, Gregory and Radonic, Lucero and Wells, E. Christian and Wilson, Nicole J. and Adams, Ellis Adjei and Arsenault, Rachel and Brewis, Alexandra and Harrington, Victoria and Lambrinidou, Yanna and McGregor, Deborah and Patrick, Robert and Pauli, Benjamin J. and Pearson, Amber L. and Shah, Sameer H. and Splichalova, Dacotah and Workman, Cassandra L. and Young, Sera L.",
    title = "Exposing the myths of household water insecurity in the global north: A critical review",
    year = "2020",
    journal = "Wiley Interdisciplinary Reviews Water",
    abstract = "Abstract Safe and secure water is a cornerstone of modern life in the global North. This article critically examines a set of prevalent myths about household water in high‐income countries, with a focus on Canada and the United States. Taking a relational approach, we argue that household water insecurity is a product of institutionalized structures and power, manifests unevenly through space and time, and is reproduced in places we tend to assume are the most water‐secure in the world. We first briefly introduce “modern water” and the modern infrastructural ideal, a highly influential set of ideas that have shaped household water provision and infrastructure development over the past two centuries. Against this backdrop, we consolidate evidence to disrupt a set of narratives about water in high‐income countries: the notion that water access is universal, clean, affordable, trustworthy, and uniformly or equitably governed. We identify five thematic areas of future research to delineate an agenda for advancing scholarship and action—including challenges of legal and regulatory regimes, the housing‐water nexus, water affordability, and water quality and contamination. Data gaps underpin the experiences of household water insecurity. Taken together, our review of water security for households in high‐income countries provides a conceptual map to direct critical research in this area for the coming years. This article is categorized under: Human Water > Human Water",
    url = "https://doi.org/10.1002/wat2.1486",
    doi = "10.1002/wat2.1486",
    openalex = "W3092024657",
    references = "doi10108817489326ab6f10"
}

The use of groundwater, a major source of potable water, in developing countries has proven to be an invaluable resource for local populations. The ability to safely use this water for drinking, however, depends on its chemical quality, a factor primarily controlled by various aquifer attributes such as geology and geochemistry. On a global scale, groundwater is primarily sourced from either sedimentary or basement aquifers. In this study, we compared the groundwater constituents and trace elements found in these two types of aquifer system in the context of medical hydrogeology, i.e. the status of groundwater mineral nutrients and pollutants, and their complex interaction in relation to human health. The evaluation work used a collated geochemical dataset developed for Bangladesh sedimentary aquifer data ( n  = 474), basement aquifer data from Northern Ghana ( n  = 184) and Central Tanzania ( n  = 73). An assessment of the mineral concentration in regards to dietary needs showed that the sedimentary aquifers found in Bangladesh have almost double the concentration of salubrious minerals such as calcium, magnesium and iron relative to the basement aquifers (Ghana and Tanzania). It should be noted, however, that the groundwater was also found to contain excessive levels of arsenic in the sedimentary aquifers and high levels of fluoride in those countries sourcing water from within basement rock; levels at which both elements pose a serious public health threat. Excessive sodium in drinking water is also an issue as this, combined with the normal dietary sodium level intake, may lead to hypertension and cardio-metabolic diseases. Unfortunately, health-based guideline values for drinking water containing sodium are non-existent or poorly defined, a fact which warrants further consideration at both a national and international level. The use of groundwater for drinking may assist in increasing the level of mineral nutrient uptake in the local population, however, it must also be augmented by a nutritious food supply in order to satisfy normal human dietary requirements.

@article{doi101007s4174802000151z,
    author = "Nwankwo, Chihurumnanya Belema and Hoque, M. A. and Islam, Md. Atikul and Dewan, A.",
    title = "Groundwater Constituents and Trace Elements in the Basement Aquifers of Africa and Sedimentary Aquifers of Asia: Medical Hydrogeology of Drinking Water Minerals and Toxicants",
    year = "2020",
    journal = "Earth Systems and Environment",
    abstract = "The use of groundwater, a major source of potable water, in developing countries has proven to be an invaluable resource for local populations. The ability to safely use this water for drinking, however, depends on its chemical quality, a factor primarily controlled by various aquifer attributes such as geology and geochemistry. On a global scale, groundwater is primarily sourced from either sedimentary or basement aquifers. In this study, we compared the groundwater constituents and trace elements found in these two types of aquifer system in the context of medical hydrogeology, i.e. the status of groundwater mineral nutrients and pollutants, and their complex interaction in relation to human health. The evaluation work used a collated geochemical dataset developed for Bangladesh sedimentary aquifer data ( n = 474), basement aquifer data from Northern Ghana ( n = 184) and Central Tanzania ( n = 73). An assessment of the mineral concentration in regards to dietary needs showed that the sedimentary aquifers found in Bangladesh have almost double the concentration of salubrious minerals such as calcium, magnesium and iron relative to the basement aquifers (Ghana and Tanzania). It should be noted, however, that the groundwater was also found to contain excessive levels of arsenic in the sedimentary aquifers and high levels of fluoride in those countries sourcing water from within basement rock; levels at which both elements pose a serious public health threat. Excessive sodium in drinking water is also an issue as this, combined with the normal dietary sodium level intake, may lead to hypertension and cardio-metabolic diseases. Unfortunately, health-based guideline values for drinking water containing sodium are non-existent or poorly defined, a fact which warrants further consideration at both a national and international level. The use of groundwater for drinking may assist in increasing the level of mineral nutrient uptake in the local population, however, it must also be augmented by a nutritious food supply in order to satisfy normal human dietary requirements.",
    url = "https://link.springer.com/content/pdf/10.1007/s41748-020-00151-z.pdf",
    doi = "10.1007/s41748-020-00151-z",
    is_oa = "true",
    number = "2",
    pages = "369-384",
    semanticscholar_citation_count = "46",
    semanticscholar_id = "35c55953d7cb513f66115e13d732e5c773e7602a",
    volume = "4"
}

@article{doi101016jchemgeo2020120026,
    author = "Aron, Phoebe and Levin, Naomi E. and Beverly, Emily J. and Huth, Tyler E. and Passey, Benjamin H. and Pelletier, Elise M. and Poulsen, Christopher J. and Winkelstern, Ian Z. and Yarian, Drake",
    title = "Triple oxygen isotopes in the water cycle",
    year = "2020",
    journal = "Chemical Geology",
    url = "https://doi.org/10.1016/j.chemgeo.2020.120026",
    doi = "10.1016/j.chemgeo.2020.120026",
    openalex = "W3116930859",
    references = "doi1010292018rg000627"
}

Abstract The surface water and groundwater interaction in the Imphal River Basin in Northeast India using hydrogeology, hydrochemical and isotopic constituents has examined to elucidate hydrochemical evolution, surface water and groundwater mixing and recharge condition. Groundwater is characterized by Ca2+–Cl-–HCO3-facies while surface water exhibits Ca2+–Cl- type. Surface water prevailed the intermediate stage of chemical evolution while groundwater characterizes the late stage of chemical evolution. Analysis of flow net combined with hydrogeologic sections revealed significant relationship of surface water and groundwater in the basin. The upper and lower reaches are characterized by contour heads showing an upstream pointing curvature due to depression induced by groundwater discharge where contour lines cross a gaining stream. The middle reach is marked by contour curvature pointing downstream owing to mounding induced by groundwater recharge where it crosses a losing stream. Groundwater shows markedly depleted isotopic composition than surface water. Both surface water and groundwater fall below Global Meteoric Water Line and Local Meteoric Water Line indicating the source of water through infiltration of modern precipitation. The slope of the evaporation line and the original composition of water are identified as 4.92 and −6.58‰ and −42.17‰, respectively. Isotopic d-excess values revealed isotopic composition of semi-arid climate.

@article{doi101016jgsd2020100391,
    author = "Kshetrimayum, K. and Laishram, P.",
    title = "Assessment of surface water and groundwater interaction using hydrogeology, hydrochemical and isotopic constituents in the Imphal river basin, Northeast India",
    year = "2020",
    journal = "Groundwater for Sustainable Development",
    abstract = "Abstract The surface water and groundwater interaction in the Imphal River Basin in Northeast India using hydrogeology, hydrochemical and isotopic constituents has examined to elucidate hydrochemical evolution, surface water and groundwater mixing and recharge condition. Groundwater is characterized by Ca2+–Cl-–HCO3-facies while surface water exhibits Ca2+–Cl- type. Surface water prevailed the intermediate stage of chemical evolution while groundwater characterizes the late stage of chemical evolution. Analysis of flow net combined with hydrogeologic sections revealed significant relationship of surface water and groundwater in the basin. The upper and lower reaches are characterized by contour heads showing an upstream pointing curvature due to depression induced by groundwater discharge where contour lines cross a gaining stream. The middle reach is marked by contour curvature pointing downstream owing to mounding induced by groundwater recharge where it crosses a losing stream. Groundwater shows markedly depleted isotopic composition than surface water. Both surface water and groundwater fall below Global Meteoric Water Line and Local Meteoric Water Line indicating the source of water through infiltration of modern precipitation. The slope of the evaporation line and the original composition of water are identified as 4.92 and −6.58‰ and −42.17‰, respectively. Isotopic d-excess values revealed isotopic composition of semi-arid climate.",
    url = "https://www.semanticscholar.org/paper/72daf4ce8eee2d49fefdae464f3212fba8465824",
    doi = "10.1016/j.gsd.2020.100391",
    is_oa = "true",
    pages = "100391",
    semanticscholar_citation_count = "21",
    semanticscholar_id = "72daf4ce8eee2d49fefdae464f3212fba8465824",
    volume = "11"
}

@article{doi101016jjhydrol2020125619,
    author = "Wu, Huawu and Huang, Qi and Fu, Congsheng and Song, Fan and Liu, Jinzhao and Li, Jing",
    title = "Stable isotope signatures of river and lake water from Poyang Lake, China: Implications for river–lake interactions",
    year = "2020",
    journal = "Journal of Hydrology",
    url = "https://doi.org/10.1016/j.jhydrol.2020.125619",
    doi = "10.1016/j.jhydrol.2020.125619",
    openalex = "W3092445207",
    references = "doi1010292018rg000627"
}

Abstract Spatially explicit knowledge of the origins of water resources for ecosystems and rivers is challenging when using tracer data alone. We use simulations from a spatially distributed model calibrated by extensive ecohydrological data sets in a small, energy‐limited catchment, where hillslope‐riparian dynamics are broadly representative of humid boreal headwater catchments that are experiencing rapid environmental transition. We hypothesize that in addition to wetness status, landscape heterogeneity modulates the water pathways that sustain ecosystem function and streamflows. Simulations show that catchment storage inversely controls stream water ages year‐round, but only during the drier seasons for transpiration and soil evaporation. The ages of these evaporative outputs depend much less on wetness status in the oft‐saturated riparian soils than on the freely draining hillslopes that subsidize them. This work highlights the need to consider local dynamics and time‐changing lateral heterogeneities when interpreting the ages, and thus the vulnerability, of water resources feeding streams and ecosystems in landscapes.

@article{doi1010292020gl088897,
    author = "Kuppel, Sylvain and Tetzlaff, Doerthe and Maneta, Marco and Soulsby, Chris",
    title = "Critical Zone Storage Controls on the Water Ages of Ecohydrological Outputs",
    year = "2020",
    journal = "Geophysical Research Letters",
    abstract = "Abstract Spatially explicit knowledge of the origins of water resources for ecosystems and rivers is challenging when using tracer data alone. We use simulations from a spatially distributed model calibrated by extensive ecohydrological data sets in a small, energy‐limited catchment, where hillslope‐riparian dynamics are broadly representative of humid boreal headwater catchments that are experiencing rapid environmental transition. We hypothesize that in addition to wetness status, landscape heterogeneity modulates the water pathways that sustain ecosystem function and streamflows. Simulations show that catchment storage inversely controls stream water ages year‐round, but only during the drier seasons for transpiration and soil evaporation. The ages of these evaporative outputs depend much less on wetness status in the oft‐saturated riparian soils than on the freely draining hillslopes that subsidize them. This work highlights the need to consider local dynamics and time‐changing lateral heterogeneities when interpreting the ages, and thus the vulnerability, of water resources feeding streams and ecosystems in landscapes.",
    url = "https://doi.org/10.1029/2020gl088897",
    doi = "10.1029/2020gl088897",
    openalex = "W3043526692",
    references = "doi1010292018rg000627"
}

Stormwater biofilters are being implemented widely in urban environments to provide green space, alleviate flooding, and improve stormwater quality.

@article{doi101039d0ew00027b,
    author = "Boehm, Alexandria B. and Bell, Colin D. and Fitzgerald, Nicole J. M. and Gallo, Elizabeth and Higgins, Christopher P. and Hogue, T. S. and Luthy, Richard G. and Portmann, Andrea and Ulrich, Bridget A. and Wolfand, Jordyn M.",
    title = "Biochar-augmented biofilters to improve pollutant removal from stormwater – can they improve receiving water quality?",
    year = "2020",
    journal = "Environmental Science Water Research \& Technology",
    abstract = "Stormwater biofilters are being implemented widely in urban environments to provide green space, alleviate flooding, and improve stormwater quality.",
    url = "https://doi.org/10.1039/d0ew00027b",
    doi = "10.1039/d0ew00027b",
    openalex = "W3015553018",
    references = "doi101021acsest8b05913"
}

California has consistently altered natural water resources to provide water for its growing population and to support the fifth largest economy in the world. However, the old ways of coping with the California’s urban water needs—overdraft of groundwater, stream depletion, and greater imports—will no longer meet the demands of the 21st century. We examine California’s water history and present several promising solutions to the challenge of urban water security: a combination of conservation and efficiency, desalination, stormwater capture, water reuse, and water banking. These options for urban water, including direct potable reuse, will help dry cities in California and elsewhere achieve more sustainable and diversified water supply portfolios. Pilot and demonstration-scale projects, along with innovations in systems management and new regulations, point the way toward more resilient water supplies for dry cities. Movement toward regional collaboration, implementation of new technologies, and new regulatory regimes are helping to realize a one-water vision. Different cities will develop their own water supply portfolio options appropriate for their geography, values, and urban form on a path toward meeting the urban water challenges of this century.

@article{doi101061asceee194378700001715,
    author = "Luthy, Richard G. and Wolfand, Jordyn M. and Bradshaw, Jonathan L.",
    title = "Urban Water Revolution: Sustainable Water Futures for California Cities",
    year = "2020",
    journal = "Journal of Environmental Engineering",
    abstract = "California has consistently altered natural water resources to provide water for its growing population and to support the fifth largest economy in the world. However, the old ways of coping with the California’s urban water needs—overdraft of groundwater, stream depletion, and greater imports—will no longer meet the demands of the 21st century. We examine California’s water history and present several promising solutions to the challenge of urban water security: a combination of conservation and efficiency, desalination, stormwater capture, water reuse, and water banking. These options for urban water, including direct potable reuse, will help dry cities in California and elsewhere achieve more sustainable and diversified water supply portfolios. Pilot and demonstration-scale projects, along with innovations in systems management and new regulations, point the way toward more resilient water supplies for dry cities. Movement toward regional collaboration, implementation of new technologies, and new regulatory regimes are helping to realize a one-water vision. Different cities will develop their own water supply portfolio options appropriate for their geography, values, and urban form on a path toward meeting the urban water challenges of this century.",
    url = "https://doi.org/10.1061/(asce)ee.1943-7870.0001715",
    doi = "10.1061/(asce)ee.1943-7870.0001715",
    openalex = "W3022047303",
    references = "doi101021acsest8b05913"
}

Drought is a critical stressor that contributes to water insecurity. In the United States, an important pathway by which drought affects households' access to clean, reliable drinking water for basic needs is through the organization and activities of community water systems. Research on the local political economy of drinking water provision reveals the constraints on community water systems that affect their performance when confronting drought hazards. Fragmentation in responsibility for drinking water contributes to disparities in drought vulnerability, preparation, and response across households and across communities. The nature and extent of these disparities require further investigation to identify strategies for expanding water security in the face of drought and other water hazards.

@article{doi101126scienceaba7353,
    author = "Mullin, Megan",
    title = "The effects of drinking water service fragmentation on drought-related water security",
    year = "2020",
    journal = "Science",
    abstract = "Drought is a critical stressor that contributes to water insecurity. In the United States, an important pathway by which drought affects households' access to clean, reliable drinking water for basic needs is through the organization and activities of community water systems. Research on the local political economy of drinking water provision reveals the constraints on community water systems that affect their performance when confronting drought hazards. Fragmentation in responsibility for drinking water contributes to disparities in drought vulnerability, preparation, and response across households and across communities. The nature and extent of these disparities require further investigation to identify strategies for expanding water security in the face of drought and other water hazards.",
    url = "https://doi.org/10.1126/science.aba7353",
    doi = "10.1126/science.aba7353",
    openalex = "W3017198210",
    references = "doi10108817489326ab6f10"
}

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).

@article{doi103133ofr20201036,
    author = "Flickinger, Allison K. and Mitchell, Aurelia C.",
    title = "Water-table elevation maps for 2008 and 2016 and water-table elevation changes in the aquifer system underlying eastern Albuquerque, New Mexico",
    year = "2020",
    journal = "Antarctica A Keystone in a Changing World",
    abstract = "Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).",
    url = "https://doi.org/10.3133/ofr20201036",
    doi = "10.3133/ofr20201036",
    openalex = "W3025183606",
    references = "doi103133sir20115182"
}

First posted December 30, 2020 For additional information, contact: Director, Oklahoma-Texas Water Science CenterU.S. Geological Survey1505 Ferguson Lane Austin, Texas 78754–4501 The Washita River alluvial aquifer is a valley-fill and terrace alluvial aquifer along the valley of the Washita River in western Oklahoma that provides a productive source of groundwater for agricultural irrigation and water supply. The Oklahoma Water Resources Board (OWRB) has designated the westernmost section of the aquifer in Roger Mills and Custer Counties, Okla., as reach 1 of the Washita River alluvial aquifer; reach 1 is the focus of this report. The OWRB issued an order on November 13, 1990, that established the maximum annual yield (MAY; 120,320 acre-feet per year [acre-ft/yr]) and equal-proportionate-share (EPS) pumping rate (2.0 acre-feet per acre per year [(acre-ft/acre)/yr]) for reach 1 of the Washita River alluvial aquifer. The MAY and EPS were based on hydrologic investigations that evaluated the effects of potential groundwater withdrawals on groundwater availability in the Washita River alluvial aquifer. Every 20 years, the OWRB is statutorily required to update the hydrologic investigation on which the MAY and EPS were based. Because 30 years have elapsed since the last order was issued, the U.S. Geological Survey, in cooperation with the OWRB, conducted a new hydrologic investigation and evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the Washita River alluvial aquifer.The Washita River is the primary source of inflow to Foss Reservoir, a Bureau of Reclamation reservoir constructed in 1961 for flood control, water supply, and recreation. Foss Reservoir provides water for Bessie, Clinton, New Cordell, and Hobart, Okla. Nearly 98 percent of the total groundwater use from the Washita River alluvial aquifer during 1967 to 2015 was for irrigation; other uses of groundwater in the study area include public supply, mining, and agriculture.A hydrogeologic framework was developed for the Washita River alluvial aquifer and included the physical characteristics of the aquifer, the geologic setting, the hydraulic properties of hydrogeologic units, the potentiometric surface (water table), and groundwater-flow directions at a scale that captures the regional controls on groundwater flow. The Washita River alluvial aquifer consists of alluvium and terrace deposits that were transported primarily by water and range from clay to gravel in size. The terrace includes windblown deposits of silt size and, in some cases, contains gravel laid down at several levels along former courses of present-day rivers.A conceptual flow model is a simplified description of the aquifer system that includes hydrologic boundaries, major inflow and outflow sources of the groundwater-flow system, and a conceptual water budget with the estimated mean flows between those hydrologic boundaries. During the study period 1980–2015, mean annual groundwater withdrawals, predominantly used for agricultural irrigation, totaled 5,502 acre-ft/yr, or 14 percent of aquifer outflows. When applied across the 132-square-mile aquifer area used for modeling purposes (84,366 acres), mean annual recharge of 3.15 inches per year corresponds to a mean annual recharge volume of 22,169 acre-ft/yr, or 56 percent of aquifer inflows. The annual saturated-zone evapotranspiration outflow was 11,828 acre-ft/yr for the Washita River alluvial aquifer, or about 30 percent of aquifer outflows. For the Washita River alluvial aquifer, lateral flow was 17,157 acre-ft/yr, or 44 percent of the aquifer inflows. The conceptual flow model and hydrogeologic framework were used to conceptualize, design, and build the numerical groundwater-flow model.A numerical groundwater-flow model of the Washita River alluvial aquifer was constructed by using MODFLOW-2005. The Washita River alluvial aquifer groundwater-model grid was spatially discretized into 350-foot (ft) cells and two layers. Layer 1 represented the undifferentiated alluvium and terrace deposits of Quaternary age, and layer 2 represented the bedrock of Permian age, which was given a uniform nominal thickness of 100 ft. The groundwater-simulation period was temporally discretized into 433 monthly transient stress periods, representing January 1980 to December 2015. An initial 365-day steady-state stress period was configured to represent mean annual inflows and outflows from the Washita River alluvial aquifer for the study period. The groundwater-flow model was calibrated manually and by automated adjustment of model inputs by using PEST++. Calibration targets for the Washita River alluvial aquifer model included groundwater-level observations and reservoir-stage observations, as well as base-flow and stream-seepage estimates.Three groundwater-availability scenarios were used in the calibrated groundwater model to (1) estimate the EPS pumping rate that retains the saturated thickness that meets the minimum 20-year life of the aquifer, (2) quantify the effects of projected pumping rates on groundwater storage over a 50-year period, and (3) evaluate how projected pumping rates extended 50 years into the future and sustained hypothetical drought conditions over a 10-year period affect base flow and groundwater in storage. The results of the groundwater-availability scenarios could be used by the OWRB to reevaluate the established MAY of groundwater from the Washita River alluvial aquifer.EPS scenarios for the Washita River alluvial aquifer were run for periods of 20, 40, and 50 years. The 20-, 40-, and 50-year EPS pumping rates under normal recharge conditions were 1.7, 1.6, and 1.6 (acre-ft/acre)/yr, respectively. Given the aquifer area used for modeling purposes (84,366 acres), these rates correspond to annual yields of 142,579, 134,986, and 134,986 acre-ft/yr, respectively. Groundwater storage at the end of the 20-year EPS scenario was about 281,000 acre-feet (acre-ft), or about 306,000 acre-ft (52 percent) less than the starting storage. Considering the land-surface area of the Washita River alluvial aquifer and using a specific yield of 0.12, this decrease in storage was equivalent to a mean groundwater-level decline of about 30 ft. The Washita River downstream from Foss Reservoir and most of the streams in the study area were dry at the end of the 20-year EPS scenario. Foss Reservoir stage was below the dead-pool stage of 1,597 ft after about 7 years of pumping in the 20-year EPS scenario.Four projected 50-year groundwater-use scenarios were used to simulate the effects of selected well withdrawal rates on groundwater storage in the Washita River alluvial aquifer. These four scenarios used (1) no groundwater use, (2) groundwater use at the 2015 pumping rate, (3) mean groundwater use for the simulation period, and (4) increasing groundwater use. Groundwater storage after 50 years with no groundwater use was 545,249 acre-ft, or 693 acre-ft (0.1 percent) greater than the initial groundwater storage; this groundwater storage increase is equivalent to a mean groundwater-level increase of 0.1 ft. Groundwater storage at the end of the 50-year period with 2015 pumping rates was 543,831 acre-ft, or 723 acre-ft (0.1 percent) less than the initial storage; this groundwater storage decrease is equivalent to a mean groundwater-level decrease of 0.1 ft. Groundwater storage after 50 years with the mean pumping rate for the study period was 543,202 acre-ft, or 1,349 acre-ft (0.2 percent) less than the initial groundwater storage; this groundwater storage decrease is equivalent to a mean groundwater-level decrease of 0.1 ft. Groundwater storage at the end of the 50-year period with an increasing demand groundwater-pumping rate, which was 38 percent greater than the 2015 groundwater-pumping rate, was 542,584 acre-ft, or 1,967 acre-ft (0.4 percent) less than the initial storage; this groundwater storage decrease is equivalent to a mean groundwater-level decrease of 0.2 ft.A hypothetical 10-year-drought scenario was used to simulate the effects of a prolonged period of reduced recharge on groundwater storage in the Washita River alluvial aquifer and Foss Reservoir stage and storage. To simulate the hypothetical drought, recharge in the calibrated model was reduced by 50 percent during the simulated drought period (1983–1992). Groundwater storage at the end of the drought period in December 1992 was 562,000 acre-ft, or 36,000 acre-ft (6 percent) less than the groundwater storage of the calibrated groundwater model (598,000 acre-ft). At the end of the hypothetical drought, the largest changes in saturated thickness (as great as 43.5 ft) were in the area upgradient from Foss Reservoir, particularly in the terrace at the model boundary. Substantial decreases in the Foss Reservoir stage began during the fall of 1985 in conjunction with base-flow decreases of up to 100 percent at U.S. Geological Survey streamgage 07324200 Washita River near Hammon, Okla. These lake-stage declines outpaced groundwater-level declines in the surrounding aquifer. The minimum Foss Reservoir storage simulated during the drought period was 77,954 acre-ft, which was a decrease of 46 percent from the nondrought storage.

@article{doi103133sir20205118,
    author = "Ellis, John and Ryter, Derek W. and Fuhrig, Leland T. and Spears, Kyle Wayne and Mashburn, Shana L. and Rogers, Ian M.J.",
    title = "Hydrogeology, numerical simulation of groundwater flow, and effects of future water use and drought for reach 1 of the Washita River alluvial aquifer, Roger Mills and Custer Counties, western Oklahoma, 1980–2015",
    year = "2020",
    journal = "Scientific investigations report",
    abstract = "First posted December 30, 2020 For additional information, contact: Director, Oklahoma-Texas Water Science CenterU.S. Geological Survey1505 Ferguson Lane Austin, Texas 78754–4501 The Washita River alluvial aquifer is a valley-fill and terrace alluvial aquifer along the valley of the Washita River in western Oklahoma that provides a productive source of groundwater for agricultural irrigation and water supply. The Oklahoma Water Resources Board (OWRB) has designated the westernmost section of the aquifer in Roger Mills and Custer Counties, Okla., as reach 1 of the Washita River alluvial aquifer; reach 1 is the focus of this report. The OWRB issued an order on November 13, 1990, that established the maximum annual yield (MAY; 120,320 acre-feet per year [acre-ft/yr]) and equal-proportionate-share (EPS) pumping rate (2.0 acre-feet per acre per year [(acre-ft/acre)/yr]) for reach 1 of the Washita River alluvial aquifer. The MAY and EPS were based on hydrologic investigations that evaluated the effects of potential groundwater withdrawals on groundwater availability in the Washita River alluvial aquifer. Every 20 years, the OWRB is statutorily required to update the hydrologic investigation on which the MAY and EPS were based. Because 30 years have elapsed since the last order was issued, the U.S. Geological Survey, in cooperation with the OWRB, conducted a new hydrologic investigation and evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the Washita River alluvial aquifer.The Washita River is the primary source of inflow to Foss Reservoir, a Bureau of Reclamation reservoir constructed in 1961 for flood control, water supply, and recreation. Foss Reservoir provides water for Bessie, Clinton, New Cordell, and Hobart, Okla. Nearly 98 percent of the total groundwater use from the Washita River alluvial aquifer during 1967 to 2015 was for irrigation; other uses of groundwater in the study area include public supply, mining, and agriculture.A hydrogeologic framework was developed for the Washita River alluvial aquifer and included the physical characteristics of the aquifer, the geologic setting, the hydraulic properties of hydrogeologic units, the potentiometric surface (water table), and groundwater-flow directions at a scale that captures the regional controls on groundwater flow. The Washita River alluvial aquifer consists of alluvium and terrace deposits that were transported primarily by water and range from clay to gravel in size. The terrace includes windblown deposits of silt size and, in some cases, contains gravel laid down at several levels along former courses of present-day rivers.A conceptual flow model is a simplified description of the aquifer system that includes hydrologic boundaries, major inflow and outflow sources of the groundwater-flow system, and a conceptual water budget with the estimated mean flows between those hydrologic boundaries. During the study period 1980–2015, mean annual groundwater withdrawals, predominantly used for agricultural irrigation, totaled 5,502 acre-ft/yr, or 14 percent of aquifer outflows. When applied across the 132-square-mile aquifer area used for modeling purposes (84,366 acres), mean annual recharge of 3.15 inches per year corresponds to a mean annual recharge volume of 22,169 acre-ft/yr, or 56 percent of aquifer inflows. The annual saturated-zone evapotranspiration outflow was 11,828 acre-ft/yr for the Washita River alluvial aquifer, or about 30 percent of aquifer outflows. For the Washita River alluvial aquifer, lateral flow was 17,157 acre-ft/yr, or 44 percent of the aquifer inflows. The conceptual flow model and hydrogeologic framework were used to conceptualize, design, and build the numerical groundwater-flow model.A numerical groundwater-flow model of the Washita River alluvial aquifer was constructed by using MODFLOW-2005. The Washita River alluvial aquifer groundwater-model grid was spatially discretized into 350-foot (ft) cells and two layers. Layer 1 represented the undifferentiated alluvium and terrace deposits of Quaternary age, and layer 2 represented the bedrock of Permian age, which was given a uniform nominal thickness of 100 ft. The groundwater-simulation period was temporally discretized into 433 monthly transient stress periods, representing January 1980 to December 2015. An initial 365-day steady-state stress period was configured to represent mean annual inflows and outflows from the Washita River alluvial aquifer for the study period. The groundwater-flow model was calibrated manually and by automated adjustment of model inputs by using PEST++. Calibration targets for the Washita River alluvial aquifer model included groundwater-level observations and reservoir-stage observations, as well as base-flow and stream-seepage estimates.Three groundwater-availability scenarios were used in the calibrated groundwater model to (1) estimate the EPS pumping rate that retains the saturated thickness that meets the minimum 20-year life of the aquifer, (2) quantify the effects of projected pumping rates on groundwater storage over a 50-year period, and (3) evaluate how projected pumping rates extended 50 years into the future and sustained hypothetical drought conditions over a 10-year period affect base flow and groundwater in storage. The results of the groundwater-availability scenarios could be used by the OWRB to reevaluate the established MAY of groundwater from the Washita River alluvial aquifer.EPS scenarios for the Washita River alluvial aquifer were run for periods of 20, 40, and 50 years. The 20-, 40-, and 50-year EPS pumping rates under normal recharge conditions were 1.7, 1.6, and 1.6 (acre-ft/acre)/yr, respectively. Given the aquifer area used for modeling purposes (84,366 acres), these rates correspond to annual yields of 142,579, 134,986, and 134,986 acre-ft/yr, respectively. Groundwater storage at the end of the 20-year EPS scenario was about 281,000 acre-feet (acre-ft), or about 306,000 acre-ft (52 percent) less than the starting storage. Considering the land-surface area of the Washita River alluvial aquifer and using a specific yield of 0.12, this decrease in storage was equivalent to a mean groundwater-level decline of about 30 ft. The Washita River downstream from Foss Reservoir and most of the streams in the study area were dry at the end of the 20-year EPS scenario. Foss Reservoir stage was below the dead-pool stage of 1,597 ft after about 7 years of pumping in the 20-year EPS scenario.Four projected 50-year groundwater-use scenarios were used to simulate the effects of selected well withdrawal rates on groundwater storage in the Washita River alluvial aquifer. These four scenarios used (1) no groundwater use, (2) groundwater use at the 2015 pumping rate, (3) mean groundwater use for the simulation period, and (4) increasing groundwater use. Groundwater storage after 50 years with no groundwater use was 545,249 acre-ft, or 693 acre-ft (0.1 percent) greater than the initial groundwater storage; this groundwater storage increase is equivalent to a mean groundwater-level increase of 0.1 ft. Groundwater storage at the end of the 50-year period with 2015 pumping rates was 543,831 acre-ft, or 723 acre-ft (0.1 percent) less than the initial storage; this groundwater storage decrease is equivalent to a mean groundwater-level decrease of 0.1 ft. Groundwater storage after 50 years with the mean pumping rate for the study period was 543,202 acre-ft, or 1,349 acre-ft (0.2 percent) less than the initial groundwater storage; this groundwater storage decrease is equivalent to a mean groundwater-level decrease of 0.1 ft. Groundwater storage at the end of the 50-year period with an increasing demand groundwater-pumping rate, which was 38 percent greater than the 2015 groundwater-pumping rate, was 542,584 acre-ft, or 1,967 acre-ft (0.4 percent) less than the initial storage; this groundwater storage decrease is equivalent to a mean groundwater-level decrease of 0.2 ft.A hypothetical 10-year-drought scenario was used to simulate the effects of a prolonged period of reduced recharge on groundwater storage in the Washita River alluvial aquifer and Foss Reservoir stage and storage. To simulate the hypothetical drought, recharge in the calibrated model was reduced by 50 percent during the simulated drought period (1983–1992). Groundwater storage at the end of the drought period in December 1992 was 562,000 acre-ft, or 36,000 acre-ft (6 percent) less than the groundwater storage of the calibrated groundwater model (598,000 acre-ft). At the end of the hypothetical drought, the largest changes in saturated thickness (as great as 43.5 ft) were in the area upgradient from Foss Reservoir, particularly in the terrace at the model boundary. Substantial decreases in the Foss Reservoir stage began during the fall of 1985 in conjunction with base-flow decreases of up to 100 percent at U.S. Geological Survey streamgage 07324200 Washita River near Hammon, Okla. These lake-stage declines outpaced groundwater-level declines in the surrounding aquifer. The minimum Foss Reservoir storage simulated during the drought period was 77,954 acre-ft, which was a decrease of 46 percent from the nondrought storage.",
    url = "https://doi.org/10.3133/sir20205118",
    doi = "10.3133/sir20205118",
    openalex = "W3115746685",
    references = "doi103133wri984081"
}

In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used as drinking water source, according to their quality and seasonal variation. The physico-chemical parameters of waters were compared with the guideline values for drinking water established by the World Health Organization and the Directive 98/83/EC. The nitrate and Cr concentrations exceeded the guideline value in the springs from Southern Dobrogea, but met the quality criteria in those from Northern Dobrogea, thus, to be used as drinking water, the karstic springs located in Southern Dobrogea require treatment for nitrates removal. Heavy metals pollution indices showed low to medium cumulative heavy metal pollution in all springs, while the human health risk assessment by oral exposure indicated possible noncarcinogenic risks of nitrates, both for adults and children in springs from South Dobrogea. A rigorous monitoring of the water quality before human consumption is recommended for all four studied water sources.

@article{doi103390w12123510,
    author = "Moldovan, Ana and Hoaghia, Maria-Alexandra and Kovács, Enikő and Mirea, Ionuț Cornel and Kenesz, Marius and Arghir, Răzvan Adrian and Petculescu, Alexandru and Levei, Erika Andrea and Moldovan, Oana Teodora",
    title = "Quality and Health Risk Assessment Associated with Water Consumption—A Case Study on Karstic Springs",
    year = "2020",
    journal = "Water",
    abstract = "In rural areas without centralized water supply systems, inhabitants often use groundwater of unknown quality as drinking water, without understanding the possible negative consequences on their health. Karstic spring waters from Dobrogea region in Romania were assessed for their potential to be used as drinking water source, according to their quality and seasonal variation. The physico-chemical parameters of waters were compared with the guideline values for drinking water established by the World Health Organization and the Directive 98/83/EC. The nitrate and Cr concentrations exceeded the guideline value in the springs from Southern Dobrogea, but met the quality criteria in those from Northern Dobrogea, thus, to be used as drinking water, the karstic springs located in Southern Dobrogea require treatment for nitrates removal. Heavy metals pollution indices showed low to medium cumulative heavy metal pollution in all springs, while the human health risk assessment by oral exposure indicated possible noncarcinogenic risks of nitrates, both for adults and children in springs from South Dobrogea. A rigorous monitoring of the water quality before human consumption is recommended for all four studied water sources.",
    url = "https://doi.org/10.3390/w12123510",
    doi = "10.3390/w12123510",
    openalex = "W3111245433",
    references = "doi101016japgeochem201101033, doi101016jgsd201810004"
}

Abstract Nitrate pollution of ground and surface water bodies all over the world is generally linked with continually increasing global fertilizer nitrogen (N) use. But after 1990, with more fertilizer N consumption in developing countries especially in East and South Asia than in the industrialized nations in North America and Europe, nitrate pollution of freshwaters is now increasingly becoming a pervasive global problem. In this review it has been attempted to review the research information generated during the last two decades from all over the world on different aspects of nitrate pollution of natural water bodies. It is now evident that not more than 50% of the fertilizer N is directly used by the crops to which it is applied. While a small portion may directly leach down and may reach ground and surface water bodies, a large proportion ends up in the soil organic N pool from where N is mineralized and is taken up by plants and/or lost via leaching during several decades. Present trends of nitrate pollution of freshwaters, therefore, reflect legacies of current and past applications of fertilizers and manures. Tools such as simulation models and the natural variation in the stable isotopes of N and oxygen are now being extensively used to study the contribution of fertilizers and other sources to nitrate enrichment of freshwaters. Impacts of agricultural stewardship measures are being assessed and nitrate enrichment of water bodies is being managed using modern digital models and frameworks. Improved water and fertilizer management in agroecosystems can reduce the contribution of fertilizers to nitrate pollution of water bodies but a host of factors determine the magnitude. Future research needs are also considered.

@article{doi101007s42452021045218,
    author = "Sıngh, Bijay and Craswell, E. T.",
    title = "Fertilizers and nitrate pollution of surface and ground water: an increasingly pervasive global problem",
    year = "2021",
    journal = "SN Applied Sciences",
    abstract = "Abstract Nitrate pollution of ground and surface water bodies all over the world is generally linked with continually increasing global fertilizer nitrogen (N) use. But after 1990, with more fertilizer N consumption in developing countries especially in East and South Asia than in the industrialized nations in North America and Europe, nitrate pollution of freshwaters is now increasingly becoming a pervasive global problem. In this review it has been attempted to review the research information generated during the last two decades from all over the world on different aspects of nitrate pollution of natural water bodies. It is now evident that not more than 50\% of the fertilizer N is directly used by the crops to which it is applied. While a small portion may directly leach down and may reach ground and surface water bodies, a large proportion ends up in the soil organic N pool from where N is mineralized and is taken up by plants and/or lost via leaching during several decades. Present trends of nitrate pollution of freshwaters, therefore, reflect legacies of current and past applications of fertilizers and manures. Tools such as simulation models and the natural variation in the stable isotopes of N and oxygen are now being extensively used to study the contribution of fertilizers and other sources to nitrate enrichment of freshwaters. Impacts of agricultural stewardship measures are being assessed and nitrate enrichment of water bodies is being managed using modern digital models and frameworks. Improved water and fertilizer management in agroecosystems can reduce the contribution of fertilizers to nitrate pollution of water bodies but a host of factors determine the magnitude. Future research needs are also considered.",
    url = "https://doi.org/10.1007/s42452-021-04521-8",
    doi = "10.1007/s42452-021-04521-8",
    openalex = "W3145334583",
    references = "doi101016b9780444815460500239, doi101038nature15743"
}

@article{doi101016jwatres2021116814,
    author = "Kim, Seok Hee and Kim, Ho-Rim and Yu, Soonyoung and Kang, Hyun-Ji and Hyun, Ik-Hyun and Song, Y and Kim, Hyun-Koo and Yun, Seong‐Taek",
    title = "Shift of nitrate sources in groundwater due to intensive livestock farming on Jeju Island, South Korea: With emphasis on legacy effects on water management",
    year = "2021",
    journal = "Water Research",
    url = "https://doi.org/10.1016/j.watres.2021.116814",
    doi = "10.1016/j.watres.2021.116814",
    openalex = "W3120868311",
    references = "doi101016japgeochem201406025"
}

Globally, over 200 million people are chronically exposed to arsenic (As) and/or manganese (Mn) from drinking water. We used machine-learning (ML) boosted regression tree (BRT) models to predict high As (>10 μg/L) and Mn (>300 μg/L) in groundwater from the glacial aquifer system (GLAC), which spans 25 states in the northern United States and provides drinking water to 30 million people. Our BRT models' predictor variables (PVs) included recently developed three-dimensional estimates of a suite of groundwater age metrics, redox condition, and pH. We also demonstrated a successful approach to significantly improve ML prediction sensitivity for imbalanced data sets (small percentage of high values). We present predictions of the probability of high As and high Mn concentrations in groundwater, and uncertainty, at two nonuniform depth surfaces that represent moving median depths of GLAC domestic and public supply wells within the three-dimensional model domain. Predicted high likelihood of anoxic condition (high iron or low dissolved oxygen), predicted pH, relative well depth, several modeled groundwater age metrics, and hydrologic position were all PVs retained in both models; however, PV importance and influence differed between the models. High-As and high-Mn groundwater was predicted with high likelihood over large portions of the central part of the GLAC.

@article{doi101021acsest0c06740,
    author = "Erickson, Melinda L. and Elliott, Sarah and Brown, Craig J. and Stackelberg, Paul E. and Ransom, Katherine M. and Reddy, James E. and Cravotta, Charles A.",
    title = "Machine-Learning Predictions of High Arsenic and High Manganese at Drinking Water Depths of the Glacial Aquifer System, Northern Continental United States",
    year = "2021",
    journal = "Environmental Science \& Technology",
    abstract = "Globally, over 200 million people are chronically exposed to arsenic (As) and/or manganese (Mn) from drinking water. We used machine-learning (ML) boosted regression tree (BRT) models to predict high As (>10 μg/L) and Mn (>300 μg/L) in groundwater from the glacial aquifer system (GLAC), which spans 25 states in the northern United States and provides drinking water to 30 million people. Our BRT models' predictor variables (PVs) included recently developed three-dimensional estimates of a suite of groundwater age metrics, redox condition, and pH. We also demonstrated a successful approach to significantly improve ML prediction sensitivity for imbalanced data sets (small percentage of high values). We present predictions of the probability of high As and high Mn concentrations in groundwater, and uncertainty, at two nonuniform depth surfaces that represent moving median depths of GLAC domestic and public supply wells within the three-dimensional model domain. Predicted high likelihood of anoxic condition (high iron or low dissolved oxygen), predicted pH, relative well depth, several modeled groundwater age metrics, and hydrologic position were all PVs retained in both models; however, PV importance and influence differed between the models. High-As and high-Mn groundwater was predicted with high likelihood over large portions of the central part of the GLAC.",
    url = "https://doi.org/10.1021/acs.est.0c06740",
    doi = "10.1021/acs.est.0c06740",
    openalex = "W3144233634",
    references = "doi101016japgeochem201101033"
}

@article{doi101038s41893021006938,
    author = "McKuin, Brandi and Zumkehr, Andrew and Ta, Jenny and Bales, Roger C. and Viers, Joshua H. and Pathak, Tapan B. and Campbell, J. Elliott",
    title = "Energy and water co-benefits from covering canals with solar panels",
    year = "2021",
    journal = "Nature Sustainability",
    url = "https://doi.org/10.1038/s41893-021-00693-8",
    doi = "10.1038/s41893-021-00693-8",
    openalex = "W3139514973",
    references = "doi10108817489326ab6f10"
}

@article{doi101038s43017021001819,
    author = "Gimeno, Luís and Eiras‐Barca, Jorge and Durán‐Quesada, Ana María and Domínguez, Francina and van der Ent, Ruud and Sodemann, Harald and Sánchez‐Murillo, Ricardo and Nieto, Raquel and Kirchner, James W.",
    title = "The residence time of water vapour in the atmosphere",
    year = "2021",
    journal = "Nature Reviews Earth \& Environment",
    url = "https://doi.org/10.1038/s43017-021-00181-9",
    doi = "10.1038/s43017-021-00181-9",
    openalex = "W3177726038",
    references = "doi1010292018rg000627"
}

@article{doi101038s4301702100219y,
    author = "Siirila‐Woodburn, Erica R. and Rhoades, Alan M. and Hatchett, Benjamin J. and Huning, Laurie S. and Szinai, Julia and Tague, C. and Nico, Peter and Feldman, Daniel and Jones, Andrew D. and Collins, William D. and Kaatz, L.",
    title = "A low-to-no snow future and its impacts on water resources in the western United States",
    year = "2021",
    journal = "Nature Reviews Earth \& Environment",
    url = "https://doi.org/10.1038/s43017-021-00219-y",
    doi = "10.1038/s43017-021-00219-y",
    openalex = "W3211042890",
    references = "doi1010022015rg000481, doi101021acsest8b05913, doi101038s4301702000305, doi101126scienceaay9187, doi101175amsmonographsd1800181"
}

Water has been known since antiquity as the catalyst and survival of mankind. Therefore, hydraulic structures have been constructed to resolve various hydraulic problems which are exposed such as: pollution, eutrophication, accelerated siltation, intense evaporation and water leakage. In Algeria, the problem of water leaks has appeared in many dams, among them the Hammam Grouz dam in the north-east of the country. Indeed, the hydro-technical work is considered as the most threatened in the country by this thorny problem. During the period between 1984-1987, there is a lack of suitable site for dam construction in this area led the services concerned to build this infrastructure in a cluse composed of limestone (Cenomanian) moderately karstic which are characterized by dissolutions concentrated along the joints. This site was consolidated and sealed during the construction of the dyke dam that allows its exploitation before a real test. However, it should be noted that the water level rose above the normal reservoir level for the first time (January 26, 2003) showed that this site can no longer withstand the strong pressure forces caused by the coastline water. In fact, significant water leaks have appeared at the lower gallery and downstream foot of the right bank. The following variation of water leaks over time, it can be observed that a convergence of stability of the level of the water level in the bowl to levels not exceeding 718 m which is the equivalent of less than 1/3 of the original storage capacity of the dam. The appearance of significant water leaks at the Hammam Grouz dam as soon as the spill was first discharged indicated that the sealing works carried out during the construction of the dyke had either lost their effectiveness or they were not perfect. The settlement works carried out today at the level of the basin and the banks of this hydraulic infrastructure. Despite having minimized the flow of the resurgences that appeared downstream of the dike, they did not solve the problem definitively. This may result in the appearance of a place of water leaks. Indeed, during the hydrological year 2007/2008, the appearance of a vortex in November 2007 within the lake rendering the dam of Hammam Grouz useless because it was empty during the first three months of the year 2008, in addition to the water loss that threaten them. This phenomenon floods the lower gallery of the dyke with each rise of the level of water beyond a limit threshold. Hence, it is impossible to perform some monitoring related to stability control. The harmful effects of the problem of water leakage, the stability of the dike and the quantity of water stored, especially with water scarcity in this semi-arid region, require treatment of this phenomenon. The most adapted techniques are the use of sealing materials. Having the same characteristics as the places to be waterproofed and which adapt sufficiently to their geological formations, the allocation of sealing works to a highly qualified co-contractor, are of great importance in order to provide satisfactory sealing results to make it watertight in order to operate it properly. Doi: 10.28991/HEF-2021-02-03-08 Full Text: PDF

@article{doi1028991hef2021020308,
    author = "Toumi, A. and Remini, B.",
    title = "Evaluation of Geology and Hydrogeology of the Water Leakage in Hammam-Grouz Dam, Algeria",
    year = "2021",
    journal = "Journal of Human, Earth, and Future",
    abstract = "Water has been known since antiquity as the catalyst and survival of mankind. Therefore, hydraulic structures have been constructed to resolve various hydraulic problems which are exposed such as: pollution, eutrophication, accelerated siltation, intense evaporation and water leakage. In Algeria, the problem of water leaks has appeared in many dams, among them the Hammam Grouz dam in the north-east of the country. Indeed, the hydro-technical work is considered as the most threatened in the country by this thorny problem. During the period between 1984-1987, there is a lack of suitable site for dam construction in this area led the services concerned to build this infrastructure in a cluse composed of limestone (Cenomanian) moderately karstic which are characterized by dissolutions concentrated along the joints. This site was consolidated and sealed during the construction of the dyke dam that allows its exploitation before a real test. However, it should be noted that the water level rose above the normal reservoir level for the first time (January 26, 2003) showed that this site can no longer withstand the strong pressure forces caused by the coastline water. In fact, significant water leaks have appeared at the lower gallery and downstream foot of the right bank. The following variation of water leaks over time, it can be observed that a convergence of stability of the level of the water level in the bowl to levels not exceeding 718 m which is the equivalent of less than 1/3 of the original storage capacity of the dam. The appearance of significant water leaks at the Hammam Grouz dam as soon as the spill was first discharged indicated that the sealing works carried out during the construction of the dyke had either lost their effectiveness or they were not perfect. The settlement works carried out today at the level of the basin and the banks of this hydraulic infrastructure. Despite having minimized the flow of the resurgences that appeared downstream of the dike, they did not solve the problem definitively. This may result in the appearance of a place of water leaks. Indeed, during the hydrological year 2007/2008, the appearance of a vortex in November 2007 within the lake rendering the dam of Hammam Grouz useless because it was empty during the first three months of the year 2008, in addition to the water loss that threaten them. This phenomenon floods the lower gallery of the dyke with each rise of the level of water beyond a limit threshold. Hence, it is impossible to perform some monitoring related to stability control. The harmful effects of the problem of water leakage, the stability of the dike and the quantity of water stored, especially with water scarcity in this semi-arid region, require treatment of this phenomenon. The most adapted techniques are the use of sealing materials. Having the same characteristics as the places to be waterproofed and which adapt sufficiently to their geological formations, the allocation of sealing works to a highly qualified co-contractor, are of great importance in order to provide satisfactory sealing results to make it watertight in order to operate it properly. Doi: 10.28991/HEF-2021-02-03-08 Full Text: PDF",
    url = "https://www.hefjournal.org/index.php/HEF/article/download/74/pdf",
    doi = "10.28991/hef-2021-02-03-08",
    is_oa = "true",
    number = "3",
    pages = "269-295",
    semanticscholar_citation_count = "13",
    semanticscholar_id = "c21b2027309aa204068cf674b744ae2806979884",
    volume = "2"
}

First posted October 4, 2021 For additional information, contact: Director, New Mexico Water Science Center U.S. Geological Survey 6700 Edith Blvd. NE Albuquerque, NM 87113 In 1999, a jet-fuels release was discovered at the Bulk Fuels Facility on Kirtland Air Force Base, Albuquerque, New Mexico. Contaminants had reached the water table and migrated north-northeast toward water-supply wells. Monitoring wells were installed downgradient from the facility to determine the primary zones of groundwater production for water-supply wells and assess contaminant presence. The monitoring wells are screened within the Santa Fe Group aquifer system, which includes clay units, at depths as great as 445 meters below land surface, and were categorized as water table, shallow, middle, deep, and aquifer-test pumping wells. Water-supply wells are screened across multiple water-bearing units within the aquifer system. All wells were sampled for major ions, trace elements, nutrients, stable isotopes, dissolved gases, tritium, carbon isotopes, and chlorofluorocarbons. The deeper and water-supply wells have evidence of longer groundwater residence times, as much as thousands of years, and water from the shallower wells shows evidence of anthropogenic nutrient inputs. Aquifer recharge is derived from either the mountain front or seepage from the Rio Grande. Dissolved-gas data indicate that the middle, deep, and aquifer-test pumping, and water-supply wells have cooler recharge temperatures than the shallower wells. Inferred groundwater age varies by method but indicates that the deeper, aquifer-test pumping, and water-supply wells have older water, as much as 15,000 years before present. Results indicate that the water-supply wells draw primarily from the middle and deeper portions of the aquifer system below the clay units and have not been affected by the contaminant plume, although some data indicate a potential for modern water entering some of the deeper and water-supply wells.

@article{doi103133sir20215076,
    author = "Travis, Rebecca E. and Bell, Meghan T. and Linhoff, Benjamin and Beisner, Kimberly R.",
    title = "Utilizing multiple hydrogeologic and anthropogenic indicators to understand zones of groundwater contribution to water-supply wells near Kirtland Air Force Base Bulk Fuels Facility in southeast Albuquerque, New Mexico",
    year = "2021",
    journal = "Scientific investigations report",
    abstract = "First posted October 4, 2021 For additional information, contact: Director, New Mexico Water Science Center U.S. Geological Survey 6700 Edith Blvd. NE Albuquerque, NM 87113 In 1999, a jet-fuels release was discovered at the Bulk Fuels Facility on Kirtland Air Force Base, Albuquerque, New Mexico. Contaminants had reached the water table and migrated north-northeast toward water-supply wells. Monitoring wells were installed downgradient from the facility to determine the primary zones of groundwater production for water-supply wells and assess contaminant presence. The monitoring wells are screened within the Santa Fe Group aquifer system, which includes clay units, at depths as great as 445 meters below land surface, and were categorized as water table, shallow, middle, deep, and aquifer-test pumping wells. Water-supply wells are screened across multiple water-bearing units within the aquifer system. All wells were sampled for major ions, trace elements, nutrients, stable isotopes, dissolved gases, tritium, carbon isotopes, and chlorofluorocarbons. The deeper and water-supply wells have evidence of longer groundwater residence times, as much as thousands of years, and water from the shallower wells shows evidence of anthropogenic nutrient inputs. Aquifer recharge is derived from either the mountain front or seepage from the Rio Grande. Dissolved-gas data indicate that the middle, deep, and aquifer-test pumping, and water-supply wells have cooler recharge temperatures than the shallower wells. Inferred groundwater age varies by method but indicates that the deeper, aquifer-test pumping, and water-supply wells have older water, as much as 15,000 years before present. Results indicate that the water-supply wells draw primarily from the middle and deeper portions of the aquifer system below the clay units and have not been affected by the contaminant plume, although some data indicate a potential for modern water entering some of the deeper and water-supply wells.",
    url = "https://doi.org/10.3133/sir20215076",
    doi = "10.3133/sir20215076",
    openalex = "W3204657834",
    references = "doi103133sir20115182"
}

The concentrations of U in natural waters are usually low, being typically less than 4 μg/L in river water, around 3.3 μg/L in open seawater, and usually less than 5 μg/L in groundwater. Higher concentrations can occur in both surface water and groundwater and the range spans some six orders of magnitude, with extremes in the mg/L range. However, such extremes in surface water are rare and linked to localized mineralization or evaporation in alkaline lakes. High concentrations in groundwater, substantially above the WHO provisional guideline value for U in drinking water of 30 μg/L, are associated most strongly with (i) granitic and felsic volcanic aquifers, (ii) continental sandstone aquifers especially in alluvial plains and (iii) areas of U mineralization. High-U groundwater provinces are more common in arid and semi-arid terrains where evaporation is an additional factor involved in concentrating U and other solutes. Examples of granitic and felsic volcanic terrains with documented high U concentrations include several parts of peninsular India, eastern USA, Canada, South Korea, southern Finland, Norway, Switzerland and Burundi. Examples of continental sandstone aquifers include the alluvial plains of the Indo-Gangetic Basin of India and Pakistan, the Central Valley, High Plains, Carson Desert, Española Basin and Edwards-Trinity aquifers of the USA, Datong Basin, China, parts of Iraq and the loess of the Chaco-Pampean Plain, Argentina. Many of these plains host eroded deposits of granitic and felsic volcanic precursors which likely act as primary sources of U. Numerous examples exist of groundwater impacted by U mineralization, often accompanied by mining, including locations in USA, Australia, Brazil, Canada, Portugal, China, Egypt and Germany. These may host high to extreme concentrations of U but are typically of localized extent. The overarching mechanisms of U mobilization in water are now well-established and depend broadly on redox conditions, pH and solute chemistry, which are shaped by the geological conditions outlined above. Uranium is recognized to be mobile in its oxic, U(VI) state, at neutral to alkaline pH (7–9) and is aided by the formation of stable U–CO3(±Ca, Mg) complexes. In such oxic and alkaline conditions, U commonly covaries with other similarly controlled anions and oxyanions such as F, As, V and Mo. Uranium is also mobile at acidic pH (2–4), principally as the uranyl cation UO22+. Mobility in U mineralized areas may therefore occur in neutral to alkaline conditions or in conditions with acid drainage, depending on the local occurrence and capacity for pH buffering by carbonate minerals. In groundwater, mobilization has also been observed in mildly (Mn-) reducing conditions. Uranium is immobile in more strongly (Fe-, SO4-) reducing conditions as it is reduced to U(IV) and is either precipitated as a crystalline or ‘non-crystalline’ form of UO2 or is sorbed to mineral surfaces. A more detailed understanding of U chemistry in the natural environment is challenging because of the large number of complexes formed, the strong binding to oxides and humic substances and their interactions, including ternary oxide-humic-U interactions. Improved quantification of these interactions will require updating of the commonly-used speciation software and databases to include the most recent developments in surface complexation models. Also, given their important role in maintaining low U concentrations in many natural waters, the nature and solubility of the amorphous or non-crystalline forms of UO2 that result from microbial reduction of U(VI) need improved quantification. Even where high-U groundwater exists, percentage exceedances of the WHO guideline value are variable and often small. More rigorous testing programmes to establish usable sources are therefore warranted in such vulnerable aquifers. As drinking-water regulation for U is a relatively recent introduction in many countries (e.g. the European Union), testing is not yet routine or established and data are still relatively limited. Acquisition of more data will establish whether analogous aquifers elsewhere in the world have similar patterns of aqueous U distribution. In the high-U groundwater regions that have been recognized so far, the general absence of evidence for clinical health symptoms is a positive finding and tempers the scale of public health concern, though it also highlights a need for continued investigation.

@article{doi101016japgeochem2022105534,
    author = "Smedley, Pauline and Kinniburgh, D.G.",
    title = "Uranium in natural waters and the environment: Distribution, speciation and impact",
    year = "2022",
    journal = "Applied Geochemistry",
    abstract = "The concentrations of U in natural waters are usually low, being typically less than 4 μg/L in river water, around 3.3 μg/L in open seawater, and usually less than 5 μg/L in groundwater. Higher concentrations can occur in both surface water and groundwater and the range spans some six orders of magnitude, with extremes in the mg/L range. However, such extremes in surface water are rare and linked to localized mineralization or evaporation in alkaline lakes. High concentrations in groundwater, substantially above the WHO provisional guideline value for U in drinking water of 30 μg/L, are associated most strongly with (i) granitic and felsic volcanic aquifers, (ii) continental sandstone aquifers especially in alluvial plains and (iii) areas of U mineralization. High-U groundwater provinces are more common in arid and semi-arid terrains where evaporation is an additional factor involved in concentrating U and other solutes. Examples of granitic and felsic volcanic terrains with documented high U concentrations include several parts of peninsular India, eastern USA, Canada, South Korea, southern Finland, Norway, Switzerland and Burundi. Examples of continental sandstone aquifers include the alluvial plains of the Indo-Gangetic Basin of India and Pakistan, the Central Valley, High Plains, Carson Desert, Española Basin and Edwards-Trinity aquifers of the USA, Datong Basin, China, parts of Iraq and the loess of the Chaco-Pampean Plain, Argentina. Many of these plains host eroded deposits of granitic and felsic volcanic precursors which likely act as primary sources of U. Numerous examples exist of groundwater impacted by U mineralization, often accompanied by mining, including locations in USA, Australia, Brazil, Canada, Portugal, China, Egypt and Germany. These may host high to extreme concentrations of U but are typically of localized extent. The overarching mechanisms of U mobilization in water are now well-established and depend broadly on redox conditions, pH and solute chemistry, which are shaped by the geological conditions outlined above. Uranium is recognized to be mobile in its oxic, U(VI) state, at neutral to alkaline pH (7–9) and is aided by the formation of stable U–CO3(±Ca, Mg) complexes. In such oxic and alkaline conditions, U commonly covaries with other similarly controlled anions and oxyanions such as F, As, V and Mo. Uranium is also mobile at acidic pH (2–4), principally as the uranyl cation UO22+. Mobility in U mineralized areas may therefore occur in neutral to alkaline conditions or in conditions with acid drainage, depending on the local occurrence and capacity for pH buffering by carbonate minerals. In groundwater, mobilization has also been observed in mildly (Mn-) reducing conditions. Uranium is immobile in more strongly (Fe-, SO4-) reducing conditions as it is reduced to U(IV) and is either precipitated as a crystalline or ‘non-crystalline’ form of UO2 or is sorbed to mineral surfaces. A more detailed understanding of U chemistry in the natural environment is challenging because of the large number of complexes formed, the strong binding to oxides and humic substances and their interactions, including ternary oxide-humic-U interactions. Improved quantification of these interactions will require updating of the commonly-used speciation software and databases to include the most recent developments in surface complexation models. Also, given their important role in maintaining low U concentrations in many natural waters, the nature and solubility of the amorphous or non-crystalline forms of UO2 that result from microbial reduction of U(VI) need improved quantification. Even where high-U groundwater exists, percentage exceedances of the WHO guideline value are variable and often small. More rigorous testing programmes to establish usable sources are therefore warranted in such vulnerable aquifers. As drinking-water regulation for U is a relatively recent introduction in many countries (e.g. the European Union), testing is not yet routine or established and data are still relatively limited. Acquisition of more data will establish whether analogous aquifers elsewhere in the world have similar patterns of aqueous U distribution. In the high-U groundwater regions that have been recognized so far, the general absence of evidence for clinical health symptoms is a positive finding and tempers the scale of public health concern, though it also highlights a need for continued investigation.",
    url = "https://doi.org/10.1016/j.apgeochem.2022.105534",
    doi = "10.1016/j.apgeochem.2022.105534",
    openalex = "W4311183355",
    references = "doi101111j17456584200900635x"
}

@article{doi101016jjhazmat2022129473,
    author = "Korak, Julie A. and Mungan, Annabel L. and Watts, Landon T.",
    title = "Critical review of waste brine management strategies for drinking water treatment using strong base ion exchange",
    year = "2022",
    journal = "Journal of Hazardous Materials",
    url = "https://doi.org/10.1016/j.jhazmat.2022.129473",
    doi = "10.1016/j.jhazmat.2022.129473",
    openalex = "W4293074402",
    references = "doi101016japgeochem201406025"
}

Southern Kazakhstan is one of the fastest-growing regions of this country and continued development depends on a sustainable supply of freshwater for multiple purposes. Groundwater in Southern Kazakhstan occurs in a wide variety of hydrogeological conditions with varying levels of quality and vulnerability to contamination. The aim of this paper is to investigate the present groundwater quality through sampling and laboratory analysis of source water from public supply wells, compare results to hydrogeology and known contaminant sources, and indicate where future protections may be needed. Protection from surface-borne contaminants is mainly determined by the thickness of the vadose zone, depth of the groundwater level, presence, thickness and composition of aquifers, and mobility of pollutants. Forty-five wells were sampled, yielding 106 samples of groundwater presently used for drinking water, which were evaluated to investigate the occurrence of potential pollutants and hydrogeology of the region. Of the samples collected, 46 samples were used for analysis of inorganic water chemistry, 30 for individual indicators including metals, and 31 samples for determination of petroleum products. A contaminant inventory database and geospatial database aided the interpretation of the results and allowed the prediction of future water issues. Kazakhstan’s maximum permissible concentrations (MPCs) for metals were exceeded in areas associated with industrial enterprises, while fluoride and nitrate were more closely associated with mining and agricultural sources. Groundwater quality is dependent on hydrogeology and environmental contaminants resulting from historical land uses and must be regularly monitored for drinking water safety. Petroleum hydrocarbons were not detected in any of the drinking water sources.

@article{doi103390w15244240,
    author = "Tleuova, Zhanna and Snow, D. and Mukhamedzhanov, Murat and Ermenbay, Aray",
    title = "Relation of Hydrogeology and Contaminant Sources to Drinking Water Quality in Southern Kazakhstan",
    year = "2023",
    journal = "Water",
    abstract = "Southern Kazakhstan is one of the fastest-growing regions of this country and continued development depends on a sustainable supply of freshwater for multiple purposes. Groundwater in Southern Kazakhstan occurs in a wide variety of hydrogeological conditions with varying levels of quality and vulnerability to contamination. The aim of this paper is to investigate the present groundwater quality through sampling and laboratory analysis of source water from public supply wells, compare results to hydrogeology and known contaminant sources, and indicate where future protections may be needed. Protection from surface-borne contaminants is mainly determined by the thickness of the vadose zone, depth of the groundwater level, presence, thickness and composition of aquifers, and mobility of pollutants. Forty-five wells were sampled, yielding 106 samples of groundwater presently used for drinking water, which were evaluated to investigate the occurrence of potential pollutants and hydrogeology of the region. Of the samples collected, 46 samples were used for analysis of inorganic water chemistry, 30 for individual indicators including metals, and 31 samples for determination of petroleum products. A contaminant inventory database and geospatial database aided the interpretation of the results and allowed the prediction of future water issues. Kazakhstan’s maximum permissible concentrations (MPCs) for metals were exceeded in areas associated with industrial enterprises, while fluoride and nitrate were more closely associated with mining and agricultural sources. Groundwater quality is dependent on hydrogeology and environmental contaminants resulting from historical land uses and must be regularly monitored for drinking water safety. Petroleum hydrocarbons were not detected in any of the drinking water sources.",
    url = "https://www.mdpi.com/2073-4441/15/24/4240/pdf?version=1702273083",
    doi = "10.3390/w15244240",
    is_oa = "true",
    number = "24",
    pages = "4240",
    semanticscholar_citation_count = "13",
    semanticscholar_id = "35d82ff1830ccc9d1b19db8a0201543e62707136",
    volume = "15"
}