Quality of Groundwater Used for Public Supply in the Continental United States: A Comprehensive Assessment

This article references 72 other publications.

1. 1

   Moore, J. W. Balancing the needs of water use; Springer Verlag, 1989.

   Google Scholar

   There is no corresponding record for this reference.
2. 2

   Maupin, M. A.; Kenny, J. F.; Hutson, S. S.; Lovelace, J. K.; Barber, N. L.; Linsey, K. S. Estimated use of water in the United States in 2010; U.S. Geological Survey, 2014.  DOI: 10.3133/cir1405 .

   Google Scholar

   There is no corresponding record for this reference.
3. 3

   Johnson, T. D.; Belitz, K.; Kauffman, L. J.; Watson, E.; Wilson, J. T. Populations using public-supply groundwater in the conterminous US 2010; Identifying the wells, hydrogeologic regions, and hydrogeologic mapping units. Sci. Total Environ. 2022, 806, 150618,  DOI: 10.1016/j.scitotenv.2021.150618

   Google Scholar

   3

   Populations using public-supply groundwater in the conterminous U.S. 2010; Identifying the wells, hydrogeologic regions, and hydrogeologic mapping units

   Johnson, Tyler D.; Belitz, Kenneth; Kauffman, Leon J.; Watson, Elise; Wilson, John T.

   Science of the Total Environment (2022), 806 (Part_2), 150618CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)

   Most Americans receive their drinking water from publicly supplied sources, a large portion of it from groundwater. Mapping these populations consistently and at a high resoln. is important for understanding where the resource is used and needs to be protected. The results show that 269 million people are supplied by public supply, 107 million are supplied by groundwater and 162 million are supplied by surface water. The population using public supply drinking water was mapped in two ways: the census enhanced method (CEM) evenly distributes the population across populated census blocks, and the urban land-use enhanced method (ULUEM) distributes the population only to certain urban land use designations. In addn., a two-dimensional polygon dataset was created for the conterminous U. S. that identifies 177 unique Hydrogeol. Mapping Units (HMUs) with similar hydrogeol. characteristics. The HMUs do not overlap, but they can delineate areas where stacked hydrogeol. regions (HRs) contribute drinking water from below the surface. HRs are waterbearing geol. regions identified as either a principal aquifers (PA) or secondary hydrogeol. regions (SHR). Within each HMU, the wells were used to det. the proportion of each HR that is providing groundwater to the HMU. In 63% of the HMUs, a single HR is providing water to the public supply wells located within it, while the rest of the HMUs show that the wells are tapping up to a max. of four stacked HRs. In total, groundwater from 108 HRs provide drinking water for public supply, six of which provide more than 50% of the groundwater used for public supply drinking water. The aquifer serving the largest no. of equiv. people (>17 million) is the glacial aquifer. The HR providing the greatest no. of people per km2 is the Biscayne aquifer in Florida at nearly 453 people per km2.

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4. 4

   Johnson, T. D.; Belitz, K.; Lombard, M. A. Estimating domestic well locations and populations served in the contiguous US for years 2000 and 2010. Sci. Total Environ. 2019, 687, 1261– 1273,  DOI: 10.1016/j.scitotenv.2019.06.036

   Google Scholar

   4

   Estimating domestic well locations and populations served in the contiguous U.S. for years 2000 and 2010

   Johnson, Tyler D.; Belitz, Kenneth; Lombard, Melissa A.

   Science of the Total Environment (2019), 687 (), 1261-1273CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)

   Domestic wells provide drinking water supply for approx. 40 million people in the United States. Knowing the location of these wells, and the populations they serve, is important for identifying heavily used aquifers, locations susceptible to contamination, and populations potentially impacted by poor-quality groundwater. The 1990 census was the last nationally consistent survey of a home's source of water, and has not been surveyed since. This paper presents a method for projecting the population dependent on domestic wells for years after 1990, using information from the 1990 census along with population data from subsequent censuses. The method is based on the "domestic ratio" at the census block-group level, defined here as the no. of households dependent on domestic wells divided by the total population. Anal. of 1990 data (>220,000 block-groups) indicates that the domestic ratio is a function of the household d. As household d. increases, the domestic ratio decreases, once a household d. threshold is met. The 1990 data were used to develop a relationship between household d. and the domestic ratio. The fitted model, along with household d. data from 2000 and 2010, was used to est. domestic ratios for each decadal year. In turn, the no. of households dependent on domestic wells was estd. at the block-group level for 2000 and 2010. High-resoln. census-block population data were used to refine the spatial distribution of domestic-well usage and to convert the data into population nos. The results are presented in two downloadable raster datasets for each decadal year. It is estd. that the total population using domestic-well water in the contiguous U. S. increased 1.5% from 1990 to 2000 to a total of 37.25 million people and increased slightly from 2000 to 2010 to 37.29 million people.

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5. 5

   U.S. Geological Survey Hydrologic Atlas 730; Reston, VA, Miller, J. A., Ed.; 2000,  DOI: 10.3133/ha730 .

   Google Scholar

   There is no corresponding record for this reference.
6. 6

   U.S. Environmental Protection Agency. National Primary Drinking Water Regulation Table ; 2022. https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulation-table (accessed 2022-06-16).

   Google Scholar

   There is no corresponding record for this reference.
7. 7

   U.S. Environmental Protection Agency. Summary of the Safe Drinking Water Act ; 2022. https://www.epa.gov/laws-regulations/summary-safe-drinking-water-act (accessed 2022-09-28).

   Google Scholar

   There is no corresponding record for this reference.
8. 8

   U.S. Environmental Protection Agency. Human Health Benchmarks for Pesticides ; 2022. https://ordspub.epa.gov/ords/pesticides/f?p=HHBP:home (accessed 2022-06-16).

   Google Scholar

   There is no corresponding record for this reference.
9. 9

   Norman, J. E.; Toccalino, P. L.; Morman, S. A. Health-Based Screening Levels for evaluating water-quality data, 2nd ed; 2018. https://water.usgs.gov/water-resources/hbsl/ (accessed 2022-06-15).

   Google Scholar

   There is no corresponding record for this reference.
10. 10

    U.S. Environmental Protection Agency. Drinking Water Contaminant Candidate List (CCL) and Regulatory Determination ; 2022. https://www.epa.gov/ccl (accessed 2022-06-16).

    Google Scholar

    There is no corresponding record for this reference.
11. 11

    Rowe, G. L.; Belitz, K.; Essaid, H. I.; Gilliom, R. J.; Hamilton, P. A.; Hoos, A. B.; Lynch, D. D.; Munn, M. D.; Wolock, D. W. Design of Cycle 3 of the National Water-Quality Assessment Program, 2013–2022: Part 1: Framework of Water-Quality Issues and Potential Approaches. U. S. Geological Survey Open-File Report 2009–1296 ; 2010. DOI: 10.3133/ofr20091296 .

    Google Scholar

    There is no corresponding record for this reference.
12. 12

    DeSimone, L. A.; McMahon, P. B.; Rosen, M. R. The quality of our Nation’s waters: Water quality in principal aquifers of the United States, 1991–2010. U.S. Geological Survey Circular 162 ; 2015. DOI: 10.3133/cir1360 .

    Google Scholar

    There is no corresponding record for this reference.
13. 13

    DeSimone, L. A. Quality of Water from Domestic Wells in Principal Aquifers of the United States, 1991–2004. U.S. Geological Survey Scientific Investigations Report 2008–5227 ; 2009. DOI: 10.3133/sir20095227 .

    Google Scholar

    There is no corresponding record for this reference.
14. 14

    Toccalino, P. L.; Hopple, J. A. The quality of our Nation’s waters: Quality of water from public-supply wells in the United States, 1993–2007: Overview of major findings. U. S. Geological Survey Circular 1346 ; 2010. DOI: 10.3133/cir1346 .

    Google Scholar

    There is no corresponding record for this reference.
15. 15

    Eberts, S. M.; Thomas, M. A.; Jagucki, M. L. The quality of our Nation’s waters: factors affecting public-supply-well vulnerability to contamination: understanding observed water quality and anticipating future water quality. U.S. Geological Survey Circular 1224 2013, 132, Report,  DOI: 10.3133/cir1224

    Google Scholar

    There is no corresponding record for this reference.
16. 16

    Hopple, J. A.; Delzer, G. C.; Kingsbury, J. A. Anthropogenic organic compounds in source water of selected community water systems that use groundwater, 2002–05. U. S. Geological Survey Scientific Investigations Report 2009–5200 ; 2009. DOI: 10.3133/sir20095200 .

    Google Scholar

    There is no corresponding record for this reference.
17. 17

    Degnan, J. R.; Kauffman, L. J.; Erickson, M. L.; Belitz, K.; Stackelberg, P. E. Depth of groundwater used for drinking-water supplies in the United States. U.S. Geological Survey Scientific Investigations Report 2021–5069 ; 2021. DOI: 10.3133/sir20215069 .

    Google Scholar

    There is no corresponding record for this reference.
18. 18

    Belitz, K.; Jurgens, B.; Landon, M. K.; Fram, M. S.; Johnson, T. Estimation of aquifer scale proportion using equal area grids: Assessment of regional scale groundwater quality. Water Resour Res. 2010, 46, W11550,  DOI: 10.1029/2010WR009321

    Google Scholar

    18

    Estimation of aquifer scale proportion using equal area grids: Assessment of regional scale groundwater quality

    Belitz, Kenneth; Jurgens, Bryant; Landon, Matthew K.; Fram, Miranda S.; Johnson, Tyler

    Water Resources Research (2010), 46 (11), W11550/1-W11550/14CODEN: WRERAQ; ISSN:0043-1397. (American Geophysical Union)

    The proportion of an aquifer with constituent concns. above a specified threshold (high concns.) is taken as a nondimensional measure of regional scale water quality. If computed on the basis of area, it can be referred to as the aquifer scale proportion. A spatially unbiased est. of aquifer scale proportion and a confidence interval for that est. are obtained through the use of equal area grids and the binomial distribution. Traditionally, the confidence interval for a binomial proportion is computed using either the std. interval or the exact interval. Research from the statistics literature has shown that the std. interval should not be used and that the exact interval is overly conservative. On the basis of coverage probability and interval width, the Jeffreys interval is preferred. If more than one sample per cell is available, cell declustering is used to est. the aquifer scale proportion, and Kish's design effect may be useful for estg. an effective no. of samples. The binomial distribution is also used to quantify the adequacy of a grid with a given no. of cells for identifying a small target, defined as a constituent that is present at high concns. in a small proportion of the aquifer. Case studies illustrate a consistency between approaches that use one well per grid cell and many wells per cell. The methods presented in this paper provide a quant. basis for designing a sampling program and for utilizing existing data.

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19. 19

    Belitz, K.; Fram, M. S.; Johnson, T. D. Metrics for Assessing the Quality of Groundwater Used for Public Supply, CA, USA: Equivalent-Population and Area. Environ. Sci. Technol. 2015, 49 (14), 8330– 8338,  DOI: 10.1021/acs.est.5b00265

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    19

    Metrics for Assessing the Quality of Groundwater Used for Public Supply, CA, USA: Equivalent-Population and Area

    Belitz, Kenneth; Fram, Miranda S.; Johnson, Tyler D.

    Environmental Science & Technology (2015), 49 (14), 8330-8338CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)

    Data from 11000 public supply wells in 87 study areas were used to assess the quality of nearly all of the groundwater used for public supply in California. Two metrics were developed for quantifying groundwater quality: area with high concns. (km2 or proportion) and equiv.-population relying upon groundwater with high concns. (no. of people or proportion). Concns. are considered high if they are above a human-health benchmark. When expressed as proportions, the metrics are area-weighted and population-weighted detection frequencies. On a statewide-scale, ∼20% of the groundwater used for public supply has high concns. for one or more constituents (23% by area and 18% by equiv.-population). On the basis of both area and equiv.-population, trace elements are more prevalent at high concns. than either nitrate or org. compds. at the statewide-scale, in eight of nine hydrogeol. provinces, and in about three-quarters of the study areas. At a statewide-scale, nitrate is more prevalent than org. compds. based on area, but not on the basis of equiv.-population. The approach developed for this paper, unlike many studies, recognizes the importance of appropriately weighting information when changing scales, and is broadly applicable to other areas.

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20. 20

    McMahon, P. B.; Belitz, K.; Reddy, J. E.; Johnson, T. D. Elevated Manganese Concentrations in United States Groundwater, Role of Land Surface-Soil-Aquifer Connections. Environ. Sci. Technol. 2019, 53 (1), 29– 38,  DOI: 10.1021/acs.est.8b04055

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    20

    Elevated Manganese Concentrations in United States Groundwater, Role of Land Surface-Soil-Aquifer Connections

    McMahon, Peter B.; Belitz, Kenneth; Reddy, James E.; Johnson, Tyler D.

    Environmental Science & Technology (2019), 53 (1), 29-38CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)

    Chem. data from 43 334 wells were used to examine the role of land surface-soil-aquifer connections in producing elevated Mn concns. (>300 μg/L) in the USA groundwater. Elevated concns. of Mn and dissolved org. C (DOC) in groundwater are assocd. with shallow, anoxic water tables and soils enriched in org. C, suggesting soil-derived DOC supports Mn redn. and mobilization in shallow groundwater. Mn and DOC concns. are higher near rivers than farther from rivers, suggesting river-derived DOC also supports Mn mobilization. Anthropogenic N may also affect Mn concns. in groundwater. In parts of the northeastern USA contg. poorly buffered soils, ∼40% of the samples with elevated Mn concns. have a pH of <6 and elevated concns. of nitrate relative to samples with pH ≥6, suggesting acidic recharge produced by the oxidn. of NH4+ in fertilizer helps mobilize Mn. An estd. 2.6 million people potentially consume groundwater with elevated Mn concns., the highest densities of which occur near rivers and in areas with org. C rich soil. Results indicate land surface-soil-aquifer connections play an important role in producing elevated manganese concns. in groundwater used for human consumption.

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    McMahon, P. B.; Brown, C. J.; Johnson, T. D.; Belitz, K.; Lindsey, B. D. Fluoride occurrence in United States groundwater. Sci. Total Environ. 2020, 732, 139217,  DOI: 10.1016/j.scitotenv.2020.139217

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    Fluoride occurrence in United States groundwater

    McMahon, Peter B.; Brown, Craig J.; Johnson, Tyler D.; Belitz, Kenneth; Lindsey, Bruce D.

    Science of the Total Environment (2020), 732 (), 139217CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)

    Data from 38,105 wells were used to characterize fluoride (F) occurrence in untreated United States (U.S.) groundwater. For domestic wells (n = 11,032), water from which is generally not purposely fluoridated or monitored for quality, 10.9% of the samples have F concns. >0.7 mg/L (U.S. Public Health Service recommended optimal F concn. in drinking water for preventing tooth decay) (87% are <0.7 mg/L); 2.6% have F > 2 mg/L (EPA Secondary Maximum Contaminant Level, SMCL); and 0.6% have F > 4 mg/L (EPA MCL). The data indicate the biggest concern with F in domestic wells at the national scale could be one of under consumption of F with respect to the oral-health benchmark (0.7 mg/L). Elevated F concns. relative to the SMCL and MCL are regionally important, particularly in the western U.S. Statistical comparisons of potentially important controlling factors in four F-concn. categories (<0.1-0.7 mg/L; >0.7-2 mg/L; >2-4 mg/L; >4 mg/L) at the national scale indicate the highest F-concn. category is assocd. with groundwater that has significantly greater pH values, TDS and alky. concns., and well depths, and lower Ca/Na ratios and mean annual pptn., than the lowest F-concn. category. The relative importance of the controlling factors appears to be regionally variable. Three case studies illustrate the spatial variability in controlling factors using groundwater-age (groundwater residence time), water-isotope (evaporative concn.), and water-temp. (geothermal processes) data. Populations potentially served by domestic wells with F concns. <0.7, >0.7, >2, and >4 mg/L are estd. to be ∼28,200,000, ∼3,110,000; ∼522,000; and ∼172,000 people, resp., in 40 principal aquifers with at least 25 F analyses per aquifer.

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    Musgrove, M. The occurrence and distribution of strontium in US groundwater. Appl. Geochem. 2021, 126, 104867,  DOI: 10.1016/j.apgeochem.2020.104867

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    22

    The occurrence and distribution of strontium in U.S. groundwater

    Musgrove, MaryLynn

    Applied Geochemistry (2021), 126 (), 104867CODEN: APPGEY; ISSN:0883-2927. (Elsevier Ltd.)

    Groundwater samples from 32 principal aquifers across the United States (U.S.) provide a broad spatial scope of the occurrence and distribution of strontium (Sr) and are used to assess environments and factors that influence Sr concn. Strontium is a common trace element in soils, rocks, and water and is ubiquitous in groundwater with detectable concns. in 99.8% of samples (n = 4,824; median = 225μg/L). Concns. in 2.3% of samples exceeded the 4,000μg/L health-based screening level. The relative importance of controlling factors on Sr concn. are spatially variable and partly dependent on the type of groundwater well. Three case settings illustrate controls on Sr concn. For drinking-water supply wells, most high concns. (>4,000μg/L) were measured in samples from carbonate aquifers that resulted from water-rock interaction with Sr-bearing rocks and minerals. High Sr concns. from monitoring wells were more common in unconsolidated sand and gravel aquifers in arid or semi-arid setting where shallow groundwater is affected by irrigation and evaporative concn. of dissolved constituents in combination with lithol. or applied Sr sources. Upwelling saline groundwater is also a source of Sr in some locations. Total dissolved solids concn. is an indicator of high Sr in all settings. S. are potentially supplied water from public-supply wells with high Sr concn., ∼86% of whom use carbonate aquifers.

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    Lindsey, B. D.; Belitz, K.; Cravotta, C. A.; Toccalino, P. L.; Dubrovsky, N. M. Lithium in groundwater used for drinking-water supply in the United States. Sci. Total Environ. 2021, 767, 144691,  DOI: 10.1016/j.scitotenv.2020.144691

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    23

    Lithium in groundwater used for drinking-water supply in the United States

    Lindsey, Bruce D.; Belitz, Kenneth; Cravotta, Charles A. III; Toccalino, Patricia L.; Dubrovsky, Neil M.

    Science of the Total Environment (2021), 767 (), 144691CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)

    Lithium concns. in untreated groundwater from 1464 public-supply wells and 1676 domestic-supply wells distributed across 33 principal aquifers in the United States were evaluated for spatial variations and possible explanatory factors. Concns. nationwide ranged from <1 to 396μg/L (median of 8.1) for public supply wells and <1 to 1700μg/L (median of 6μg/L) for domestic supply wells. For context, lithium concns. were compared to a Health Based Screening Level (HBSL, 10μg/L) and a drinking-water only threshold (60μg/L). These thresholds were exceeded in 45% and 9% of samples from public-supply wells and in 37% and 6% from domestic-supply wells, resp. However, exceedances and median concns. ranged broadly across geog. regions and principal aquifers. Concns. were highest in arid regions and older groundwater, particularly in unconsolidated clastic aquifers and sandstones, and lowest in carbonate-rock aquifers, consistent with differences in lithium abundance among major lithologies and rock weathering extent. The median concn. for public-supply wells in the unconsolidated clastic High Plains aquifer (central United States) was 24.6μg/L; 24% of the wells exceeded the drinking-water only threshold and 86% exceeded the HBSL. Other unconsolidated clastic aquifers in the arid West had exceedance rates comparable to the High Plains aquifer, whereas no public supply wells in the Biscayne aquifer (southern Florida) exceeded either threshold, and the highest concn. in that aquifer was 2.6μg/L. Multiple lines of evidence indicate natural sources for the lithium concns.; however, anthropogenic sources may be important in the future because of the rapid increase of lithium battery use and subsequent disposal. Geochem. models demonstrate that extensive evapn., mineral dissoln., cation exchange, and mixing with geothermal waters or brines may account for the obsd. lithium and assocd. constituent concns., with the latter two processes as major contributing factors.

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    McMahon, P. B.; Belitz, K.; Barlow, J. R. B.; Jurgens, B. C. Methane in aquifers used for public supply in the United States. Appl. Geochem. 2017, 84, 337– 347,  DOI: 10.1016/j.apgeochem.2017.07.014

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    24

    Methane in aquifers used for public supply in the United States

    McMahon, P. B.; Belitz, K.; Barlow, J. R. B.; Jurgens, B. C.

    Applied Geochemistry (2017), 84 (), 337-347CODEN: APPGEY; ISSN:0883-2927. (Elsevier Ltd.)

    In 2013 to 2015, 833 public supply wells in 15 Principal aquifers in the U. S. were sampled to identify which aquifers contained high methane concns. (>1 mg/L) and det. the geol., hydrol., and geochem. conditions assocd. with high concns. This study represents the first national assessment of methane in aquifers used for public supply in the U. S. and, as such, advances the understanding of the occurrence and distribution of methane in groundwater nationally. Methane concns. >1 and > 10 mg/L occurred in 6.7 and 1.1% of the samples, resp. Most high concns. occurred in aquifers in the Atlantic and Gulf Coastal Plain regions and upper Midwest. High methane concns. were most commonly assocd. with Tertiary and younger aquifer sediments, old groundwater (>60 years), and concns. of oxygen, nitrate-N, and sulfate <0.5 mg/L. Concns. of methane were also pos. correlated (p < 0.05) with dissolved org. carbon and ammonium. Case studies in Florida, Texas, and Iowa were used to explore how regional context from this data set could aid our understanding of local occurrences of methane in groundwater. Regional data for methane, Br/Cl ratios, sulfate, and other parameters helped identify mixing processes involving end members such as wastewater effluent-impacted groundwater, saline formation water, and pore water in glacial till that contributed methane to groundwater in some cases and supported methane oxidn. in others.

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    Szabo, Z.; Stackelberg, P. E.; Cravotta, C. A. Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States. Environ. Sci. Technol. 2020, 54 (12), 7236– 7249,  DOI: 10.1021/acs.est.0c00192

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    25

    Occurrence and Geochemistry of Lead-210 and Polonium-210 Radionuclides in Public-Drinking-Water Supplies from Principal Aquifers of the United States

    Szabo, Zoltan; Stackelberg, Paul E.; Cravotta, Charles A.

    Environmental Science & Technology (2020), 54 (12), 7236-7249CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)

    On the basis of lifetime cancer risks, lead-210 (210Pb) and polonium-210 (210Po) ≥ 1.0 and 0.7 pCi/L (picocuries per L), resp., in drinking-water supplies may pose human-health concerns. 210Pb and 210Po were detected at concns. greater than these thresholds at 3.7 and 1.5%, resp., of filtered untreated groundwater samples from 1263 public-supply wells in 19 principal aquifers across the United States. Nationally, 72% of samples with radon-222 (222Rn) concns. > 4000 pCi/L had 210Pb ≥ 1.0 pCi/L. 210Pb is mobilized by alpha recoil assocd. with the decay of 222Rn and short-lived progeny. 210Pb concns. ≥ 1.0 pCi/L occurred most frequently where acidic groundwaters inhibited 210Pb readsorption (felsic-cryst. rocks) and where reducing alk. conditions favored dissoln. of iron-manganese- (Fe-Mn-) oxyhydroxides (which adsorb 210Pb) and formation of lead-carbonate complexes (enhancing lead (Pb) mobility). 210Po concns. ≥ 0.7 pCi/L occurred almost exclusively in confined Coastal Plain aquifers where old (low percent-modern carbon-14) groundwaters were reducing, with high pH (>7.5) and high sodium/chloride (Na/Cl) ratios resulting from cation exchange. In high-pH environments, aq. polonium (Po) is poorly sorbed, occurring as dihydrogen polonate (H2PoO3(aq)) or, under strongly reducing conditions, as a hydrogen-polonide anion (HPo-). Fe-Mn- and sulfate-redn. and cation-exchange processes may mobilize polonium from mineral surfaces. Po2+ occurrence in low-to-neutral-pH waters is attenuated by adsorption.

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    Bexfield, L. M.; Toccalino, P. L.; Belitz, K.; Foreman, W. T.; Furlong, E. T. Hormones and Pharmaceuticals in Groundwater Used As a Source of Drinking Water Across the United States. Environ. Sci. Technol. 2019, 53 (6), 2950– 2960,  DOI: 10.1021/acs.est.8b05592

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    26

    Hormones and Pharmaceuticals in Groundwater Used As a Source of Drinking Water Across the United States

    Bexfield, Laura M.; Toccalino, Patricia L.; Belitz, Kenneth; Foreman, William T.; Furlong, Edward T.

    Environmental Science & Technology (2019), 53 (6), 2950-2960CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)

    This is the first large-scale, systematic assessment of hormone and pharmaceutical occurrence in groundwater used for drinking across the United States. Samples from 1091 sites in Principal Aquifers representing 60% of the vol. pumped for drinking-water supply had final data for 21 hormones and 103 pharmaceuticals. At least one compd. was detected at 5.9% of 844 sites representing the resource used for public supply across the entirety of 15 Principal Aquifers, and at 11.3% of 247 sites representing the resource used for domestic supply over subareas of nine Principal Aquifers. Of 34 compds. detected, one plastics component (bisphenol A), three pharmaceuticals (carbamazepine, sulfamethoxazole, and meprobamate), and the caffeine degradate 1,7-dimethylxanthine were detected in more than 0.5% of samples. Hydrocortisone had a concn. greater than a human-health benchmark at 1 site. Compds. with high soly. and low Koc were most likely to be detected. Detections were most common in shallow wells with a component of recent recharge, particularly in cryst.-rock and mixed land-use settings. Results indicate vulnerability of groundwater used for drinking water in the U.S. to contamination by these compds. is generally limited, and exposure to these compds. at detected concns. is unlikely to have adverse effects on human health.

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27. 27

    Bexfield, L. M.; Belitz, K.; Lindsey, B. D.; Toccalino, P. L.; Nowell, L. H. Pesticides and Pesticide Degradates in Groundwater Used for Public Supply across the United States: Occurrence and Human-Health Context. Environ. Sci. Technol. 2021, 55 (1), 362– 372,  DOI: 10.1021/acs.est.0c05793

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    27

    Pesticides and pesticide degradates in groundwater used for public supply across the United States: Occurrence and human-health context

    Bexfield, Laura M.; Belitz, Kenneth; Lindsey, Bruce D.; Toccalino, Patricia L.; Nowell, Lisa H.

    Environmental Science & Technology (2021), 55 (1), 362-372CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)

    This is the first assessment of groundwater from public-supply wells across the United States to analyze for >100 pesticide degradates and to provide human-health context for degradates without benchmarks. Samples from 1204 wells in aquifers representing 70% of the vol. pumped for drinking supply were analyzed for 109 pesticides (active ingredients) and 116 degradates. Among the 41% of wells where pesticide compds. were detected, nearly two-thirds contained compd. mixts. and three-quarters contained degradates. Atrazine, hexazinone, prometon, tebuthiuron, four atrazine degradates, and one metolachlor degradate were each detected in >5% of wells. Detection frequencies were largest for aquifers with more shallow, unconfined wells producing modern-age groundwater. To screen for potential human-health concerns, benchmark quotients (BQs) were calcd. by dividing concns. by the human-health benchmark, when available. For degradates without benchmarks, estd. values (estd. benchmark quotients (BQE)) were first calcd. by assuming equimolar toxicity to the most toxic parent; final anal. excluded degradates with likely overestimated toxicity. Six pesticide compds. and 1.6% of wells had concns. approaching levels of potential concern (individual or summed BQ or BQE values >0.1), and none exceeded these levels (values >1). Therefore, although pesticide compds. occurred frequently, concns. were low, even accounting for mixts. and degradates without benchmarks.

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28. 28

    Bexfield, L. M.; Belitz, K.; Fram, M. S.; Lindsey, B. D. Volatile organic compounds in groundwater used for public supply across the United States: Occurrence, explanatory factors, and human-health context. Sci. Total Environ. 2022, 827, 154313,  DOI: 10.1016/j.scitotenv.2022.154313

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    28

    Volatile organic compounds in groundwater used for public supply across the United States: Occurrence, explanatory factors, and human-health context

    Bexfield, Laura M.; Belitz, Kenneth; Fram, Miranda S.; Lindsey, Bruce D.

    Science of the Total Environment (2022), 827 (), 154313CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)

    This systematic assessment of occurrence for 85 volatile org. compds. (VOCs) in raw (untreated) groundwater used for public supply across the United States (U.S.), which includes 43 compds. not previously monitored by national studies, relates VOC occurrence to explanatory factors and assesses VOC detections in a human-health context. Samples were collected in 2013 through 2019 from 1537 public-supply wells in aquifers representing 78% of the vol. pumped for public drinking-water supply. Lab. detection limits for VOCs generally were less than 0.1 μg/L. Detections were reported for 36% of the sampled principal-aquifer area (38% of sampled wells) and were most common in wells in shallow, unconfined aquifers in urban areas that produce high proportions of modern-age and oxic groundwater. The disinfection byproduct trichloromethane (chloroform) was the most commonly detected VOC assocd. primarily with anthropogenic sources (24% of the sampled area, 25% of sampled wells), followed by the gasoline oxygenate Me tert-Bu ether (8.4% of area, 11% of wells). Carbon disulfide (12% of area, 14% of wells) was examd. sep. because of likely substantial contributions from natural sources. Newly monitored VOCs were each detected in <1% of the sampled area. Although detections of 1,4-dioxane in this first national study of its occurrence in raw groundwater were rare, measured concns. exceeded the most stringent (non-enforceable) human-health benchmark in 0.5% of the sampled area (9 wells). Two wells had exceedances of enforceable benchmarks for tetrachloroethylene and trichloroethylene, and 50 wells total (representing 2.0% of the sampled area, 3.3% of sampled wells) had combined VOC concns. exceeding 10% of benchmarks of any type. Compared with previous national findings, this study reports lower rates of VOC detection, but confirms widespread anthropogenic influence on groundwater used for public supply, with relatively few concns. of individual VOCs or mixts. that approach or exceed human-health benchmarks.

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29. 29

    Jurgens, B. C.; Faulkner, K.; McMahon, P. B.; Hunt, A. G.; Casile, G.; Young, M. B.; Belitz, K. Over a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination. Communications Earth and Environment 2022,  DOI: 10.1038/s43247-022-00473-y

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    There is no corresponding record for this reference.
30. 30

    Brown, C. J.; Barlow, J. R. B.; Cravotta, C. A.; Lindsey, B. D. Factors affecting the occurrence of lead and manganese in untreated drinking water from Atlantic and Gulf Coastal Plain aquifers, eastern United States-Dissolved oxygen and pH framework for evaluating risk of elevated concentrations. Appl. Geochem. 2019, 101, 88– 102,  DOI: 10.1016/j.apgeochem.2018.10.017

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    30

    Factors affecting the occurrence of lead and manganese in untreated drinking water from Atlantic and Gulf Coastal Plain aquifers, eastern United States-Dissolved oxygen and pH framework for evaluating risk of elevated concentrations

    Brown, Craig J.; Barlow, Jeannie R. B.; Cravotta, Charles A., III; Lindsey, Bruce D.

    Applied Geochemistry (2019), 101 (), 88-102CODEN: APPGEY; ISSN:0883-2927. (Elsevier Ltd.)

    Groundwater samples collected during 2012 and 2013 from public-supply wells screened in the Atlantic and Gulf Coastal Plain aquifers of the eastern and southeastern U. S. rarely contained lead or manganese concns. that exceeded drinking-water limits, despite having corrosive characteristics. Data indicate that the occurrence of dissolved lead and manganese in sampled groundwater, prior to its distribution or treatment, was related to several explanatory factors including the presence of source minerals, hydrol. position along the flow path, water-rock interactions, and assocd. geochem. conditions such as pH and dissolved oxygen (DO) concns. Elevated concns. of lead compared to health-based benchmarks were assocd. with groundwater that is acidic (pH ≤ 6.5), oxygenated (DO ≥ 2 mg/L), and closer to recharge zones (relatively young water). Elevated concns. of manganese were assocd. with groundwater that is acidic to neutral (pH ≤ 7.5), has low DO (<2 mg/L), and further from recharge zones (relatively old). Under these geochem. conditions, minerals that could sequester lead or manganese tended to be undersatd., and adsorption by hydrous ferric oxide was limited. Under neutral to alk. pH conditions, pptn. of impure calcium carbonate or phosphate compds. contg. traces of lead or manganese (solid solns.) could maintain low concns. of the trace elements. Addnl., adsorption of lead or manganese cations by hydrous ferric oxides (HFO) could be another attenuating factor where conditions are oxidizing and dissolved inorg. carbon concns. are relatively low. A DO/pH framework was developed as a screening tool for evaluating risk of elevated lead or manganese, based on the occurrence of elevated lead and manganese concns. and the corresponding distributions of DO and pH in the Atlantic and Gulf Coastal Plain aquifers. Validation of the DO/pH framework was accomplished using an independent national dataset that showed consistent results for elevated lead (pH ≤ 6.5; DO ≥ 2 mg/L) and manganese (pH ≤ 7.5; DO < 2 mg/L).

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31. 31

    Degnan, J. R.; Lindsey, B. D.; Levitt, J. P.; Szabo, Z. The relation of geogenic contaminants to groundwater age, aquifer hydrologic position, water type, and redox conditions in Atlantic and Gulf Coastal Plain aquifers, eastern and south-central USA. Sci. Total Environ. 2020, 723, 137835,  DOI: 10.1016/j.scitotenv.2020.137835

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    31

    Relation of geogenic contaminants to groundwater age, aquifer hydrologic position, water type, and redox conditions in Atlantic and Gulf Coastal Plain aquifers, eastern and south-central USA

    Degnan, James R.; Lindsey, Bruce D.; Levitt, Joseph P.; Szabo, Zoltan

    Science of the Total Environment (2020), 723 (), 137835CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)

    Groundwater age distributions developed from carbon-14 (14C), tritium (3H), and helium-4 (4He) concns., along with aquifer hydrol. position, water type, and redox conditions, were compared to geogenic contaminants of concern (GCOC) from 252 public-supply wells in six Atlantic and Gulf Coastal Plain unconsolidated-sediment aquifers. Concns. of one or more GCOCs in 168 (67%) wells exceeded MCLs (max. contaminant levels), SMCLs (secondary MCLs), or HBSLs (health-based screening levels). Human-health benchmark thresholds (MCLs or HBSLs) were exceeded in 31 (12%) wells, and included 0.8% for fluoride (F), 2.4% for arsenic (As), 4% for lead-210 (210Pb), and 4.8% for polonium-210 (210Po). Values of pH increase with age and were outside the SMCL in 31% of wells (23% < 6.5 and 7.5% > 8.5, SMCL). Among GCOCs with concns. that increased significantly with groundwater age, the frequency of sentry threshold exceedances (i.e., one-half of MCL, SMCL, or HBSL) included 40% for dissolved solids (DS), 12% for chloride (Cl), 3.6% for F, 4.4% for As, and 9.1% for 210Po. Iron (Fe) concns. did not correlate with groundwater age, but exceeded sentry thresholds in 29% of wells. Groundwater age, water types, redox, pH, and GCOCs varied because of unique hydrogeol. features of the aquifers (recharge locations and geometry). As expected, primarily confined aquifers had young, oxic, low to near-neutral pH water near the outcrop (recharge area), and older, reduced, high pH water deeper and farther along flow paths. However, unique aquifer hydrogeol. conditions, such as multiple-recharge zones produced anomalous patterns of young and old groundwater at varying depths and locations along flow paths. Evidence for this variability is seen in disequil. patterns in the progression of the chem. evolution of groundwater with hydrol. position. When hydrogeol. differences are considered, groundwater age combined with hydrol.-position data, can provide a strong basis for inferring potential occurrence of GCOCs.

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32. 32

    Erickson, M. L.; Yager, R. M.; Kauffman, L. J.; Wilson, J. T. Drinking water quality in the glacial aquifer system, northern USA. Sci. Total Environ. 2019, 694, 133735,  DOI: 10.1016/j.scitotenv.2019.133735

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    32

    Drinking water quality in the glacial aquifer system, northern USA

    Erickson, M. L.; Yager, R. M.; Kauffman, L. J.; Wilson, J. T.

    Science of the Total Environment (2019), 694 (), 133735CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)

    Groundwater supplies 50% of drinking water worldwide, but compromised water quality from anthropogenic and geogenic contaminants can limit usage of groundwater as a drinking water source. Groundwater quality in the glacial aquifer system, USA (GLAC), is presented in the context of a hydrogeol. framework that divides the study area into 17 hydrogeol. terranes. Results are reported at aquifer-system scale and regional (terrane) scale. This paper presents a quant. assessment of groundwater quality in the GLAC using data from numerous sources for samples collected 2005-2013, compared to health-based and aesthetic (non-health) benchmarks, and evaluated with areal and population metrics. Concns. above a benchmark are considered high. Trace elements are widespread across the study area, with an estd. 5.7 million people relying on groundwater with high concns. of one or more trace elements; manganese and arsenic are most often at high concn. Nitrate is found at high concn. in 4.0% of the study area, serving about 740 thousand people. Org. compds. including pesticides and volatile org. compds. are high in 2.0% of the assessed study area, with about 870 thousand people relying on groundwater with high concns. of an org. compd. High arsenic and manganese concns. occur primarily in the terranes with thick, stratigraphically complex, fine-grained glacial sediment, coincident with groundwater under reducing conditions (indicated by iron concns. >100 μg/L); high nitrate is uncommon in those same terranes. When nitrate is high in thick, fine-grained, complex terranes, though, it is much more commonly assocd. with groundwater under more oxidizing conditions. Common geogenic trace elements occur at high concn. due to characteristic geol. and geochem. conditions. Conversely, anthropogenic nitrate and org. compds. are introduced at or near the land surface. High concns. of nitrate or org. compds. are generally limited to areas in proximity where people live and use the chems.

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33. 33

    Rosecrans, C. Z.; Musgrove, M. Water Quality of groundwater used for public supply in principal aquifers of the western United States. U.S. Geological Survey Scientific Investigations Report 2020–5078 2020,  DOI: 10.3133/sir20205078

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    There is no corresponding record for this reference.
34. 34

    U.S. Geological Survey. California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project ; 2022. https://webapps.usgs.gov/gama/ (accessed 2022-06-20).

    Google Scholar

    There is no corresponding record for this reference.
35. 35

    Michielssen, S.; Vedrin, M. C.; Guikema, S. D. Trends in microbiological drinking water quality violations across the United States. Environ. Sci.: Water Res. Technol. 2020, 6 (11), 3091– 3105,  DOI: 10.1039/D0EW00710B

    Google Scholar

    35

    Trends in microbiological drinking water quality violations across the United States

    Michielssen, Senne; Vedrin, Matthew C.; Guikema, Seth D.

    Environmental Science: Water Research & Technology (2020), 6 (11), 3091-3105CODEN: ESWRAR; ISSN:2053-1419. (Royal Society of Chemistry)

    This study analyzed temporal trends in health-based drinking water quality violations, and both temporal and geog. trends in microbiol. drinking water quality violations for U. S. public water systems. We esp. focused on microbiol. regulations that apply to all public water systems, i.e., the total coliform rule (TCR), which became effective in 1990, and its successor, the revised total coliform rule (RTCR), which was implemented in 2016. By using the U. S. Environmental Protection Agency (EPA)'s Safe Drinking Water Information System, we detd. that changes in regulations greatly impacted temporal trends in health-based violations. TCR health-based violations were the most common type of health-based violation, partly because the TCR required more monitoring than any other regulation and was one of the few rules that applied to transient non-community water systems, which make up a large fraction of all public water systems and often have limited resources. As expected by the U. S. EPA, the implementation of the RTCR caused an immediate decrease in the no. of health-based violations due to specific changes in what constitutes a health-based violation under the RTCR vs. the TCR. The no. and severity of health-based coliform violations varied with system size and type, and this imbalance was exacerbated under the RTCR. Notably, while very small public water systems and transient non-community water systems already had more violations per system than their counterparts, this disparity was amplified upon adoption of the RTCR. Geog. analyses showed that the Great Lakes region had high nos. of total health-based coliform violations. While fewer data exist to analyze violations normalized by the no. of systems, an initial exploration of health-based coliform violations per system resulted in different geog. patterns. We conclude with a discussion of the potential benefits of future predictive modeling to identify public water systems that would benefit from tech. and financial assistance to improve their water quality.

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36. 36

    Pennino, M. J.; Compton, J. E.; Leibowitz, S. G. Trends in Drinking Water Nitrate Violations Across the United States. Environ. Sci. Technol. 2017, 51 (22), 13450– 13460,  DOI: 10.1021/acs.est.7b04269

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    36

    Trends in Drinking Water Nitrate Violations Across the United States

    Pennino, Michael J.; Compton, Jana E.; Leibowitz, Scott G.

    Environmental Science & Technology (2017), 51 (22), 13450-13460CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)

    Drinking water max. contaminant levels (MCL) are established by the U.S.EPA to protect human health. Since 1975, U.S. public water suppliers have reported MCL violations to the national Safe Drinking Water Information System (SDWIS). This study assessed temporal and geog. trends for violations of the 10 mg nitrate-N L-1 MCL in the conterminous U.S. We found that the proportion of systems in violation for nitrate significantly increased from 0.28% to 0.42% of all systems between 1994 and 2009 and then decreased to 0.32% by 2016. The no. of people served by systems in violation decreased from 1.5 million in 1997 to 200,000 in 2014. Periodic spikes in people served were often driven by just one large system in violation. On av., Nebraska and Delaware had the greatest proportion of systems in violation (2.7% and 2.4%, resp.), while Ohio and California had the greatest av. annual no. of people served by systems in violation (278,374 and 139,149 people, resp.). Even though surface water systems that serve more people have been improving over time, groundwater systems in violation and av. duration of violations are increasing, indicating persistent nitrate problems in drinking water.

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    Scanlon, B. R.; Fakhreddine, S.; Reedy, R. C.; Yang, Q.; Malito, J. G. Drivers of Spatiotemporal Variability in Drinking Water Quality in the United States. Environ. Sci. Technol. 2022, 56 (18), 12965– 12974,  DOI: 10.1021/acs.est.1c08697

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    37

    Drivers of Spatiotemporal Variability in Drinking Water Quality in the United States

    Scanlon, Bridget R.; Fakhreddine, Sarah; Reedy, Robert C.; Yang, Qian; Malito, John G.

    Environmental Science & Technology (2022), 56 (18), 12965-12974CODEN: ESTHAG; ISSN:1520-5851. (American Chemical Society)

    Approx. 10% of community water systems in the United States experience a health-based violation of drinking water quality; however, recently allocated funds for improving United States water infrastructure ($50 billion) provide an opportunity to address these issues. The objective of this study was to examine environmental, operational, and sociodemog. drivers of spatiotemporal variability in drinking water quality violations using geospatial anal. and data analytics. Random forest modeling was used to evaluate drivers of these violations, including environmental (e.g., landcover, climate, geol.), operational (e.g., water source, system size), and sociodemog. (social vulnerability, rurality) drivers. Results of random forest modeling show that drivers of violations vary by violation type. For example, arsenic and radionuclide violations are found mostly in the Southwest and Southcentral United States related to semiarid climate, whereas disinfection byproduct rule violations are found primarily in Southcentral United States related to system operations. Health-based violations are found primarily in small systems in rural and suburban settings. Understanding the drivers of water quality violations can help develop optimal approaches for addressing these issues to increase compliance in community water systems, particularly small systems in rural areas across the United States.

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    Nigra, A. E.; Chen, Q.; Chillrud, S. N.; Wang, L.; Harvey, D.; Mailloux, B.; Factor-Litvak, P.; Navas-Acien, A. Inequalities in Public Water Arsenic Concentrations in Counties and Community Water Systems across the United States, 2006–2011. Environ. Health Perspect. 2020, 128 (12), 127001,  DOI: 10.1289/EHP7313

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    38

    Inequalities in Public Water Arsenic Concentrations in Counties and Community Water Systems across the United States, 2006-2011

    Nigra Anne E; Factor-Litvak Pam; Navas-Acien Ana; Chen Qixuan; Chillrud Steven N; Mailloux Brian; Wang Lili; Harvey David; Mailloux Brian; Factor-Litvak Pam

    Environmental health perspectives (2020), 128 (12), 127001 ISSN:.

    BACKGROUND: In the United States, nationwide estimates of public drinking water arsenic exposure are not readily available. We used the U.S. Environmental Protection Agency's (EPA) Six-Year Review contaminant occurrence data set to estimate public water arsenic exposure. We compared community water system (CWS) arsenic concentrations during 2006-2008 vs. after 2009-2011, the initial monitoring period for compliance with the U.S. EPA's [Formula: see text] arsenic maximum contaminant level (MCL). OBJECTIVE: Our objective was to characterize potential inequalities in CWS arsenic exposure over time and across sociodemographic subgroups. METHODS: We estimated 3-y average arsenic concentrations for 36,406 CWSs (98%) and 2,740 counties (87%) and compared differences in means and quantiles of water arsenic (via quantile regression) between both 3-y periods for U.S. regions and sociodemographic subgroups. We assigned CWSs and counties MCL compliance categories (High if above the MCL; Low if below) for each 3-y period. RESULTS: From 2006-2008 to 2009-2011, mean and 95th percentile CWS arsenic (in micrograms per liter) declined by 10.3% (95% CI: 6.5%, 14.1%) and 11.5% (8.3%, 14.8%) nationwide, by 11.4% (4.7%, 18.1%) and 16.3% (8.1%, 24.5%) for the Southwest, and by 36.8% (7.4%, 66.1%) and 26.5% (12.1%, 40.8%) for New England, respectively. CWSs in the High/High compliance category (not MCL compliant) were more likely in the Southwest (61.1%), served by groundwater (94.7%), serving smaller populations (mean 1,102 persons), and serving Hispanic communities (38.3%). DISCUSSION: Larger absolute declines in CWS arsenic concentrations at higher water arsenic quantiles indicate declines are related to MCL implementation. CWSs reliant on groundwater, serving smaller populations, located in the Southwest, and serving Hispanic communities were more likely to continue exceeding the arsenic MCL, raising environmental justice concerns. These estimates of public drinking water arsenic exposure can enable further surveillance and epidemiologic research, including assessing whether differential declines in water arsenic exposure resulted in differential declines in arsenic-associated disease. https://doi.org/10.1289/EHP7313.

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    Spaur, M.; Lombard, M. A.; Ayotte, J. D.; Harvey, D. E.; Bostick, B. C.; Chillrud, S. N.; Navas-Acien, A.; Nigra, A. E. Associations between private well water and community water supply arsenic concentrations in the conterminous United States. Sci. Total Environ. 2021, 787, 147555,  DOI: 10.1016/j.scitotenv.2021.147555

    Google Scholar

    39

    Associations between private well water and community water supply arsenic concentrations in the conterminous United States

    Spaur, Maya; Lombard, Melissa A.; Ayotte, Joseph D.; Harvey, David E.; Bostick, Benjamin C.; Chillrud, Steven N.; Navas-Acien, Ana; Nigra, Anne E.

    Science of the Total Environment (2021), 787 (), 147555CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)

    Geogenic arsenic contamination typically occurs in groundwater as opposed to surface water supplies. Groundwater is a major source for many community water systems (CWSs) in the United States (US). Although the US Environmental Protection Agency sets the max. contaminant level (MCL enforceable since 2006: 10μg/L) for arsenic in CWSs, private wells are not federally regulated. We evaluated county-level assocns. between modeled values of the probability of private well arsenic exceeding 10μg/L and CWS arsenic concns. for 2231 counties in the conterminous US, using time invariant private well arsenic ests. and CWS arsenic ests. for two time periods. Nationwide, county-level CWS arsenic concns. increased by 8.4μg/L per 100% increase in the probability of private well arsenic exceeding 10μg/L for 2006-2008 (the initial compliance monitoring period after MCL implementation), and by 7.3μg/L for 2009-2011 (the second monitoring period following MCL implementation) (1.1μg/L mean decline over time). Regional differences in this temporal decline suggest that interventions to implement the MCL were more pronounced in regions served primarily by groundwater. The strong assocn. between private well and CWS arsenic in Rural, American Indian, and Semi Urban, Hispanic counties suggests that future research and regulatory support are needed to reduce water arsenic exposures in these vulnerable subpopulations. This comparison of arsenic exposure values from major private and public drinking water sources nationwide is crit. to future assessments of drinking water arsenic exposure and health outcomes.

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    Scott, J. Computerized stratified random site-selection approaches for design of a ground-water-quality sampling network. U.S. Geological Survey Water Resources Investigations Report 90–4101 1990.  DOI: 10.3133/wri904101 .

    Google Scholar

    There is no corresponding record for this reference.
41. 41

    Arnold, T. L.; DeSimone, L.; Bexfield, L. M.; Lindsey, B.; Barlow, J. R.; Kulongoski, J.; Musgrove, M.; Kingsbury, J. A.; Belitz, K. Groundwater Quality Data from the National Water Quality Assessment Project, May 2012 through December 2013. U.S. Geological Survey Data Series 997 2016,  DOI: 10.3133/ds997

    Google Scholar

    There is no corresponding record for this reference.
42. 42

    Arnold, T.; Bexfield, L. M.; Musgrove, M.; Lindsey, B. D.; Stackelberg, P. E.; Barlow, J. R.; DeSimone, L. A.; Kulongoski, J. T.; Kingsbury, J. A.; Ayotte, J. D. Groundwater-quality data from the National Water-Quality Assessment Project, January through December 2014 and select quality-control data from May 2012 through December 2014. U.S. Geological Survey Data Series 1063 2017,  DOI: 10.3133/ds1063

    Google Scholar

    There is no corresponding record for this reference.
43. 43

    Arnold, T.; Bexfield, L.; Musgrove, M.; Lindsey, B.; Stackelberg, P.; Lindsey, B.; Barlow, J.; Kulongoski, J.; Belitz, K. Datasets from Groundwater-Quality and Select Quality-Control Data from the National Water-Quality Assessment Project, January through December 2015 and Previously Unpublished Data from 2013- 2014. U.S. Geological Survey Data Series 1087 2018,  DOI: 10.3133/ds1087

    Google Scholar

    There is no corresponding record for this reference.
44. 44

    Arnold, T.; Bexfield, L. M.; Musgrove, M.; Erickson, M. L.; Kingsbury, J. A.; Degnan, J. R.; Tesoriero, A. J.; Kulongoski, J. T.; Belitz, K. Groundwater-quality and select quality-control data from the National Water-Quality Assessment Project, January through December 2016, and previously unpublished data from 2013 to 2015. U.S. Geological Survey Data Series 1124 2020,  DOI: 10.3133/ds1124

    Google Scholar

    There is no corresponding record for this reference.
45. 45

    Kingsbury, J. A.; Bexfield, L. M.; Arnold, T.; Musgrove, M.; Erickson, M. L.; Degnan, J. R.; Tesoriero, A. J.; Lindsey, B. D.; Belitz, K. Groundwater-quality and select quality-control data from the National Water-Quality Assessment Project, January 2017 through December 2019. U.S. Geological Survey Data Series 1136 2021,  DOI: 10.3133/ds1136

    Google Scholar

    There is no corresponding record for this reference.
46. 46

    Koterba, M. T.; Wilde, F. D.; Lapham, W. W. Ground-Water Data-Collection Protocols and Procedures for the National Water-Quality Assessment Program: Collection and Documentation of Water-Quality Samples and Related Data. U.S. Geological Survey Open-File Report 95–399; USGS Publications Warehouse, 1995. DOI: 10.3133/ofr95399 .

    Google Scholar

    There is no corresponding record for this reference.
47. 47

    Lapham, W. W.; Wilde, F. D.; Koterba, M. T. Ground-Water Data-Collection Protocols and Procedures for the National Water-Quality Assessment Program: Selection, Installation, and Documentation of Wells, and Collection of Related Data. U.S. Geological Survey Open-File Report 95–398; USGS Publications Warehouse, 1995. DOI: 10.3133/ofr95398 .

    Google Scholar

    There is no corresponding record for this reference.
48. 48

    U.S. Geological Survey. National Field Manual for the Collection of Water-Quality Data. Techniques of Water-Resources Investigations, Book 9 ; 2015. DOI: 10.3133/twri09 .

    Google Scholar

    There is no corresponding record for this reference.
49. 49

    Zomer, R.; Trabucco, A.; van Straaten, O.; Bossio, D. Carbon, land and water: A global analysis of the hydrologic dimensions of climate change mitigation through afforestation/reforestation; IWMI, 2006.

    Google Scholar

    There is no corresponding record for this reference.
50. 50

    Zomer, R. J.; Trabucco, A.; Bossio, D. A.; Verchot, L. V. Climate change mitigation: A spatial analysis of global land suitability for clean development mechanism afforestation and reforestation. Agriculture, ecosystems & environment 2008, 126 (1–2), 67– 80,  DOI: 10.1016/j.agee.2008.01.014

    Google Scholar

    There is no corresponding record for this reference.
51. 51

    Middleton, N.; Thomas, D. S. G. World atlas of desertification; United Nations Environment Programme., Copublished in the US, Central and South America by John Wiley, London; New York, 1997. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&local_base=BVB01&doc_number=007862306&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA

    Google Scholar

    There is no corresponding record for this reference.
52. 52

    Johnson, T. D.; Belitz, K. Assigning land use to supply wells for the statistical characterization of regional groundwater quality: Correlating urban land use and VOC occurrence. J. Hydrol 2009, 370 (1–4), 100– 108,  DOI: 10.1016/j.jhydrol.2009.02.056

    Google Scholar

    52

    Assigning land use to supply wells for the statistical characterization of regional groundwater quality: Correlating urban land use and VOC occurrence

    Johnson, Tyler D.; Belitz, Kenneth

    Journal of Hydrology (Amsterdam, Netherlands) (2009), 370 (1-4), 100-108CODEN: JHYDA7; ISSN:0022-1694. (Elsevier B.V.)

    Summary: Many national and regional groundwater studies have correlated land use "near" a well, often using a 500 m radius circle, with water quality. However, the use of a 500 m circle may seem counterintuitive given that contributing areas are expected to extend up-gradient from wells, and not be circular in shape. The objective of this study was to evaluate if a 500 m circle is adequate for assigning land use to a well for the statistical correlation between urban land use and the occurrence of volatile org. compds. (VOCs). Land use and VOC data came from 277 supply wells in four study areas in California. Land use was computed using ten different-sized circles and wedges (250 m to 10 km in radius), and three different-sized "searchlights" (1-2 km in length). We define these shapes as contributing area surrogates (CASs), recognizing that a simple shape is at best a surrogate for the actual contributing area. The presence or absence of correlation between land use and the occurrence of VOCs was evaluated using Kendall's tau (τ). Values of τ were within 10% of one another for wedges and circles ranging in size from 500 m to 2 km, with correlations remaining statistically significant (p < 0.05) for all CAS sizes and shapes, suggesting that a 500 m circular CAS is adequate for assigning land use to a well. Addnl. evaluation indicated that urban land use is autocorrelated at distances ranging from 8 to 36 km. Thus, urban land use in a 500 m CAS is likely to be predictive of urban land use in the actual contributing area.

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53. 53

    Falcone, J. A. U.S. conterminous wall-to-wall anthropogenic land use trends (NWALT), 1974–2012. U.S. Geological Survey Data Series 948 2015 45. DOI: 10.3133/ds948 .

    Google Scholar

    There is no corresponding record for this reference.
54. 54

    McMahon, P. B.; Chapelle, F. H. Redox processes and water quality of selected principal aquifer systems. Ground Water 2008, 46 (2), 259– 271,  DOI: 10.1111/j.1745-6584.2007.00385.x

    Google Scholar

    54

    Redox processes and water quality of selected principal aquifer systems

    McMahon, P. B.; Chapelle, F. H.

    Ground Water (2008), 46 (2), 259-271CODEN: GRWAAP; ISSN:0017-467X. (Blackwell Publishing, Inc.)

    Redn./oxidn. (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 obsd. ecol. succession of electron acceptors such as dissolved oxygen, nitrate, and sulfate and threshold concns. of these substrates needed to support active microbial metab. Similarly, the utilization of solid-phase electron acceptors such as Mn(IV) and Fe(III) is indicated by the prodn. of dissolved manganese and iron. An internally consistent set of threshold concn. 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 org. compds.) 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 concns. explained many water quality trends obsd. 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 chem. parameters included in the framework, those parameters should be included in routine water quality monitoring programs whenever possible.

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    Jurgens, B. C.; McMahon, P. B.; Chapelle, F. H.; Eberts, S. M. An Excel workbook for identifying redox processes in ground water. U.S. Geological Survey Open-File Report 2009–1004 2009,  DOI: 10.3133/ofr20091004

    Google Scholar

    There is no corresponding record for this reference.
56. 56

    U.S. Environmental Protection Agency. Integrated Risk Information System . 2022. https://www.epa.gov/iris (accessed 2022-07-21).

    Google Scholar

    There is no corresponding record for this reference.
57. 57

    U.S. Environmental Protection Agency. 2018 Edition of the Drinking Water Standards and Health Advisories Tables. Office of Water, U.S. Environmental Protection Agency: Washington, DC, 2018, https://www.epa.gov/system/files/documents/2022-01/dwtable2018.pdf (accessed June 19, 2022).

    Google Scholar

    There is no corresponding record for this reference.
58. 58

    Jurgens, B. C.; Parkhurst, D. L.; Belitz, K. Assessing the Lead Solubility Potential of Untreated Groundwater of the United States. Environ. Sci. Technol. 2019, 53 (6), 3095– 3103,  DOI: 10.1021/acs.est.8b04475

    Google Scholar

    58

    Assessing the Lead Solubility Potential of Untreated Groundwater of the United States

    Jurgens, Bryant C.; Parkhurst, David L.; Belitz, Kenneth

    Environmental Science & Technology (2019), 53 (6), 3095-3103CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)

    In the U.S., about 44 million people rely on self-supplied groundwater for drinking water. Because most self-supplied homeowners do not treat their water to control corrosion, drinking water can be susceptible to lead (Pb) contamination from metal plumbing. To assess the types and locations of susceptible groundwater, a geochem. reaction model that included pure Pb minerals and solid solns. of calcite (CaxPb1-xCO3) and apatite [CaxPb5-x(PO4)3(OH; Cl; F)] was developed to est. the lead soly. potential (LSP) for over 8300 untreated groundwater samples collected from domestic and public-supply sites between 2000 and 2016 in the U.S. The LSP is the calcd. amt. of Pb metal that could dissolve at 25°C before a Pb-bearing mineral ppts. About 33% of untreated groundwater samples had LSP greater than 15μg/L-the USEPA action level for dissolved plus particulate forms of Pb. Five percent of samples had high LSP (above 300μg/L) and tended to occur in the eastern and southeastern U.S. Measured Pb concns. above 15μg/L were rarely detected (<1%) but always coincided with high LSP values. Future work will provide a better understanding of the relation between water chem., Pb-mineral formation, and dissolved Pb concns. in tap water.

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    Smedley, P. L.; Kinniburgh, D. G. A review of the source, behaviour and distribution of arsenic in natural waters. Appl. Geochem. 2002, 17 (5), 517– 568,  DOI: 10.1016/S0883-2927(02)00018-5

    Google Scholar

    59

    A review of the source, behaviour and distribution of arsenic in natural waters

    Smedley, P. L.; Kinniburgh, D. G.

    Applied Geochemistry (2002), 17 (5), 517-568CODEN: APPGEY; ISSN:0883-2927. (Elsevier Science Ltd.)

    A review. The range of As concns. found in natural waters is large, ranging from less than 0.5 μg l-1 to more than 5000 μg l-1. Typical concns. in freshwater are less than 10 μg l-1 and frequently less than 1 μg l-1. Rarely, much higher concns. are found, particularly in groundwater. In such areas, more than 10% of wells may be 'affected' (defined as those exceeding 50 μg l-1) and in the worst cases, this figure may exceed 90%. Well-known high-As groundwater areas have been found in Argentina, Chile, Mexico, China and Hungary, and more recently in West Bengal (India), Bangladesh and Vietnam. The scale of the problem in terms of population exposed to high As concns. is greatest in the Bengal Basin with more than 40 million people drinking water contg. 'excessive' As. These large-scale 'natural' As groundwater problem areas tend to be found in two types of environment: firstly, inland or closed basins in arid or semi-arid areas, and secondly, strongly reducing aquifers often derived from alluvium. Both environments tend to contain geol. young sediments and to be in flat, low-lying areas where groundwater flow is sluggish. Historically, these are poorly flushed aquifers and any As released from the sediments following burial has been able to accumulate in the groundwater. Arsenic-rich groundwaters are also found in geothermal areas and, on a more localized scale, in areas of mining activity and where oxidn. of sulfide minerals has occurred. The As content of the aquifer materials in major problem aquifers does not appear to be exceptionally high, being normally in the range 1-20 mg kg-1. There appear to be two distinct 'triggers' that can lead to the release of As on a large scale. The first is the development of high pH (>8.5) conditions in semi-arid or arid environments usually as a result of the combined effects of mineral weathering and high evapn. rates. This pH change leads either to the desorption of adsorbed As (esp. As(V) species) and a range of other anion-forming elements (V, B, F, Mo, Se and U) from mineral oxides, esp. Fe oxides, or it prevents them from being adsorbed. The second trigger is the development of strongly reducing conditions at near-neutral pH values, leading to the desorption of As from mineral oxides and to the reductive dissoln. of Fe and Mn oxides, also leading to As release. Iron (II) and As(III) are relatively abundant in these groundwaters and SO4 concns. are small (typically 1 mg l-1 or less). Large concns. of phosphate, bicarbonate, silicate and possibly org. matter can enhance the desorption of As because of competition for adsorption sites. A characteristic feature of high groundwater As areas is the large degree of spatial variability in As concns. in the groundwaters. This means that it may be difficult, or impossible, to predict reliably the likely concn. of As in a particular well from the results of neighboring wells and means that there is little alternative but to analyze each well. Arsenic-affected aquifers are restricted to certain environments and appear to be the exception rather than the rule. In most aquifers, the majority of wells are likely to be unaffected, even when, for example, they contain high concns. of dissolved Fe.

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60. 60

    Nordstrom, D. K.; Smedley, P. L. Fluoride in groundwater; The Groundwater Project, 2022.

    Google Scholar

    There is no corresponding record for this reference.
61. 61

    Langmuir, D. Aqueous Environmental Geochemistry; Prentice Hall: Upper Saddle River, NJ, 1997.

    Google Scholar

    There is no corresponding record for this reference.
62. 62

    Hobday, D. K.; Galloway, W. E. Groundwater processes acid sedimentary uranium deposits. Hydrogeol J. 1999, 7 (1), 127– 138,  DOI: 10.1007/s100400050184

    Google Scholar

    There is no corresponding record for this reference.
63. 63

    Jurgens, B. C.; Fram, M. S.; Belitz, K.; Burow, K. R.; Landon, M. K. Effects of Groundwater Development on Uranium: Central Valley, California, USA. Ground Water 2010, 48 (6), 913– 928,  DOI: 10.1111/j.1745-6584.2009.00635.x

    Google Scholar

    63

    Effects of groundwater development on uranium: Central Valley, California, USA

    Jurgens, Bryant C.; Fram, Miranda S.; Belitz, Kenneth; Burow, Karen R.; Landon, Matthew K.

    Ground Water (2010), 48 (6), 913-928CODEN: GRWAAP; ISSN:0017-467X. (Wiley-Blackwell)

    Uranium (U) concns. in groundwater in several parts of the eastern San Joaquin Valley, California, have exceeded federal and state drinking water stds. during the last 20 years. The San Joaquin Valley is located within the Central Valley of California and is one of the most productive agricultural areas in the world. Increased irrigation and pumping assocd. with agricultural and urban development during the last 100 years have changed the chem. and magnitude of groundwater recharge, and increased the rate of downward groundwater movement. Strong correlations between U and bicarbonate suggest that U is leached from shallow sediments by high bicarbonate water, consistent with findings of previous work in Modesto, California. Summer irrigation of crops in agricultural areas and, to lesser extent, of landscape plants and grasses in urban areas, has increased PCO2 concns. in the soil zone and caused higher temp. and salinity of groundwater recharge. Coupled with groundwater pumping, this process, as evidenced by increasing bicarbonate concns. in groundwater over the last 100 years, has caused shallow, young groundwater with high U concns. to migrate to deeper parts of the groundwater system that are tapped by public-supply wells. Continued downward migration of U-affected groundwater and expansion of urban centers into agricultural areas will likely be assocd. with increased U concns. in public-supply wells. The results from this study illustrate the potential long-term effects of groundwater development and irrigation-supported agriculture on water quality in arid and semiarid regions around the world.

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    Nolan, J.; Weber, K. A. Natural Uranium Contamination in Major US Aquifers Linked to Nitrate. Environ. Sci. Tech Let 2015, 2 (8), 215– 220,  DOI: 10.1021/acs.estlett.5b00174

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    64

    Natural Uranium Contamination in Major U.S. Aquifers Linked to Nitrate

    Nolan, Jason; Weber, Karrie A.

    Environmental Science & Technology Letters (2015), 2 (8), 215-220CODEN: ESTLCU; ISSN:2328-8930. (American Chemical Society)

    Groundwater geochem. data collected from 2 major US aquifers, High Plains (HP) and Central Valley (CV), revealed naturally occurring groundwater U exceeding the US EPA max. contaminant level (MCL =30 μg/L) across 22375 Km2 where 1.9 million people live. Anal. of geochem. parameters revealed a moderately strong correlation between U and nitrate, a common groundwater contaminant, as well as alky. and Ca (Spearman's rho (ρ) ≥0.30; p <0.001). Nitrate is recognized to alter U soly. by oxidative dissoln. of reduced U(IV) minerals. Approx. 78% of areas where U concns. were interpolated above the MCL were correlated to the presence of nitrate (Pearson's r ≥0.5; p <0.05). Shallow groundwater was detd. to be the most susceptible to co-contamination (HP, ρ =0.46; CV, ρ =0.52). Together, these results indicate that nitrate, a primary contaminant, should be considered as a factor leading to secondary groundwater U contamination in addn. to the recognized role of alky. and Ca.

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    Smedley, P. L.; Kinniburgh, D. G. Molybdenum in natural waters: A review of occurence, distributions and controls. Appl. Geochem. 2017, 84, 387– 432,  DOI: 10.1016/j.apgeochem.2017.05.008

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    65

    Molybdenum in natural waters: A review of occurrence, distributions and controls

    Smedley, Pauline L.; Kinniburgh, David G.

    Applied Geochemistry (2017), 84 (), 387-432CODEN: APPGEY; ISSN:0883-2927. (Elsevier Ltd.)

    Molybdenum is an essential trace element for human, animal and plant health and has played an important part in the evolution of life on earth. Nonetheless, exposure to the element can be harmful and although the evidence for symptoms in humans is sparse, it has been linked with a no. of health conditions in animal models. Molybdenum is present in trace quantities (1-10 mg/kg) in most rocks and soils and at concns. less than, and often orders of magnitude less than, 10 μg/L in most freshwaters. It is the most abundant transition metal in open seawater (10 μg Mo/L) owing to the dominance, and low chem. reactivity, of the molybdate ion (MoO2-4). The 2011 WHO Guidelines for Drinking-Water Quality (fourth edition) advised a health-based value of 70 μg/L for Mo but this is no longer promulgated as a formal guideline value as WHO consider such concns. to be rarely found in drinking water. This is indeed usually the case, but there are instances where currently-used drinking waters do exceed 70 μg Mo/L. We therefore recommend more routine measurement of Mo in water, at least on a reconnaissance scale, in order to improve knowledge on occurrence in water used for potable supply. Where multi-element anal. procedures are already used (e.g. ICP-MS), the marginal cost of adding Mo to the list of elements to be analyzed should not be great. We have reviewed nine areas in the world where high concns. of Mo in freshwater, and in some cases drinking water, have been found: Argentina, Jordan, Qatar, Ethiopia, UK, USA (three) and Chile. These represent a range of geochem. environments. A common theme of the high-Mo occurrences is (i) oxic, alk. conditions where, as for seawater, the Mo occurs as the stable molybdate ion; groundwater in oxic, alk. conditions within volcanogenic sediments can have exceptionally high Mo concns. (up to hundreds of μg/L) where felsic volcanic ash is present; (ii) anoxic, non-sulphidic waters where Mo can be released to soln. by reductive dissoln. of Mn and Fe oxides or by release from degrdn. of org. matter, notably within high-Mo org.-rich muds, black shales or oil shales; or (iii) surface waters or groundwater impacted by metal sulfide mining and/or mineralization, in particular occurrences of porphyry deposits. Under such conditions, Mo concns. can reach several tens to several hundreds of μg/L and while not all are otherwise suitable for drinking water, some are. Much of the basic geochem. of Mo in oxic natural environments is now quite well understood. Critically, its behavior is redox-sensitive like its near neighbors in the Periodic Table, W and V. At the near-neutral pH values characteristic of most natural waters, Mo is rather weakly sorbed and formation of Mo minerals is either not indicated or is extremely slow. Molybdenum becomes less mobile when converted to thiomolybdates under the strongly reducing conditions found in some present-day ocean basins (e.g. the Black Sea), fjords, stratified lakes and confined aquifers. This leads to concns. of around 100 mg Mo/kg or more in black shales and other org.-rich mudstones. However, despite the many studies of these water bodies and the importance of Mo as a palaeoredox indicator, the mechanism of the highly-efficient and diagnostic scavenging of Mo in euxinic (H2S-rich) waters remains uncertain. Possibilities include the formation of an as yet unidentified Mo-Fe-S mineral or solid soln., or the scavenging by some pre-existing solid such as a sulfide or oxide mineral, or org. matter. The possible role of dispersed and reduced natural org. matter has become more prominent in recent years but this has proven difficult to quantify and the mechanism of binding is poorly understood. Molybdenum isotope studies now play an important role in constraining reaction pathways. At a more fundamental level, there is a lack of up-to-date thermodn. and kinetic data for many of the reactions of importance for Mo in the natural environment and this limits the ability of current geochem. models to predict its fate and transport. This is particularly true for the strongly reducing conditions where Mo partitions to the solid phase, leading to the formation of the Mo-rich shales. Even the existence of reduced aq. Mo species (e.g. in the Mo(V) and Mo(III) oxidn. states) in natural waters is uncertain. These uncertainties will only be resolved with focused lab. expts. using the benefits of modern instrumentation, combined where necessary with supporting mol. dynamics calcns. The mobility of Mo in aq. systems has to date received far more attention in the marine than the freshwater setting. The value of Mo speciation as an indicator of redox conditions and of stable-isotopic variations as a tracer, can have more value in the arena of environment and health, and studies of the element's mobility in aq. systems can be useful for themes varying from radioactive waste disposal, sustainability of unconventional hydrocarbon exploitation and wider surficial pollution.

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    Szabo, Z.; dePaul, V. T.; Fischer, J. M.; Kraemer, T. F.; Jacobsen, E. Occurrence and geochemistry of radium in water from principal drinking-water aquifer systems of the United States. Appl. Geochem. 2012, 27 (3), 729– 752,  DOI: 10.1016/j.apgeochem.2011.11.002

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    66

    Occurrence and geochemistry of radium in water from principal drinking-water aquifer systems of the United States

    Szabo, Zoltan; de Paul, Vincent T.; Fischer, Jeffrey M.; Kraemer, Thomas F.; Jacobsen, Eric

    Applied Geochemistry (2012), 27 (3), 729-752CODEN: APPGEY; ISSN:0883-2927. (Elsevier Ltd.)

    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 physiog. provinces of the USA and analyzed for concns. 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 detd., or in 3.15% (40 of 1266) of the samples in which at least one isotope concn. (226Ra or 228Ra) was detd. The max. concn. 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 cryst. rocks (granitic, metamorphic) of New England, the Mesozoic basins of the Appalachian Piedmont, the Gulf Coastal Plain, and the glacial sands and gravels (highest concns. in New England). The concn. of Ra was consistently controlled by geochem. properties of the aquifer systems, with the highest concns. most likely to be present where, as a consequence of the geochem. environment, adsorption of the Ra was slightly decreased. The result is a slight relative increase in Ra mobility, esp. 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 concns. of Fe or Mn, and in places, high concns. 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 concns. of the Ra radioisotopes was acidic (low pH), and had in places, high concns. 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 concns. of combined Ra occurred. Concns. 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 concns. Concns. of 224Ra and 226Ra were significantly correlated to those of 228Ra (Spearman's rank correlation coeff., +0.236 and +0.326, resp.). Activity ratios of 224Ra/228Ra in the water samples were mostly near 1 when concns. of both isotopes were greater than or equal to 0.037 Bq/L (1 pCi/L), the level above which anal. results were most reliable. Co-occurrence among these highest concns. of the Ra radionuclides was most likely in those PAs where chem. conditions are most conducive to Ra mobility (e.g. acidic North Atlantic Coastal Plain). The concns. 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 concns. of 224Ra are enhanced in soln. relative to those of 228Ra by alpha recoil from the aquifer matrix. Rapid adsorption of the two Ra isotopes (controlled by the alk. and oxic aquifer geochem.) 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.

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    Arndt, M. Evaluation of gross alpha and uranium measurements for MCL compliance ; 2010. https://www.waterrf.org/resource/evaluation-gross-alpha-and-uranium-measurements-mcl-compliance-0 (accessed August 9, 2022).

    Google Scholar

    There is no corresponding record for this reference.
68. 68

    Welch, A. H.; Szabo, Z.; Parkhurst, D. L.; VanMetre, P. C.; Mullin, A. H. Gross-beta activity in ground water: Natural sources and artifacts of sampling and laboratory analysis. Appl. Geochem. 1995, 10 (5), 491– 503,  DOI: 10.1016/0883-2927(95)00020-8

    Google Scholar

    68

    Gross-beta activity in ground water: natural sources and artifacts of sampling and laboratory analysis

    Welch, Alan H.; Szabo, Zoltan; Parkhurst, David L.; Van Metre, Peter C.; Mullin, Ann H.

    Applied Geochemistry (1995), 10 (5), 491-503CODEN: APPGEY; ISSN:0883-2927. (Elsevier)

    Gross-beta activity has been used as an indicator of beta-emitting isotopes in water since at least the early 1950s. Originally designed for detection of radioactive releases from nuclear facilities and weapons tests, anal. of gross-beta activity is widely used in studies of naturally occurring radioactivity in ground water. Analyses of about 800 samples from 5 ground-water regions of the United States provide a basis for evaluating the utility of this measurement. The data suggest that measured gross-beta activities are due to (1) long-lived radionuclides in ground water,a nd (2) ingrowth of beta-emitting radionuclides during holding times between collection of samples and lab. measurements. Although 40K and 228Ra appear to be the primary sources of beta activity in ground water, the sum of 40K plus 228Ra appears to be less than the measured gross-beta activity in most ground-water samples. The difference between the contribution from these radionuclides and gross-beta activity is most pronounced in ground water with gross-beta activities >10 pCi/L, where these 2 radionuclides account for less than one-half the measured gross-beta activity. One exception is ground water from the Coastal Plain of new Jersey, where 40K plus 228Ra generally contribute most of the gross-beta activity. In contrast, 40K and 228Ra generally contribute most of beta activity in ground water with gross-beta activities <1 pCi/L. The gross-beta technique does not measure all beta activity in ground water. Although 3H contributes beta activity to some ground water, it is driven from the sample before counting and therefore is not detected by gross-beta measurements. Beta-emitting radionuclides with half-lives shorter than a few days can decay to low values between sampling and counting. Although little is known about concns. of most short-lived beta-emitting radionuclides in environmental ground water (water unaffected by direct releases from nuclear facilities and weapons tests), their activities are expected to be low. Ingrowth of beta-emitting radionuclides during sample holding times can contribute to gross-beta activity, particularly in ground water with gross-beta activities >10 pCi/L. Ingrowth of beta-emitting progeny of 238U, specifically 234Pa and 234Th, contributes much of the measured gross-beta activity in groundwater from 4 of the 5 areas studied. Consequently, gross-beta activity measurements commonly overestimate the abundance of beta-emitting radionuclides actually present in ground water. Differing sample holding times before anal. lead to differing amts. of ingrowth of the two progeny. Therefore, holding times can affect obsd. gross-beta measurements, particularly in ground water with 238U activities that are moderate to high compared with the activity of 40K plus 228Ra. Uncertainties assocd. with counting efficiencies for beta particles with different energies further complicate the interpretation of gross-beta measurements.

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69. 69

    Dubrovsky, N. M.; Burow, K. R.; Clark, G. M.; Gronberg, J.; Hamilton, P. A.; Hitt, K. J.; Mueller, D. K.; Munn, M. D.; Nolan, B. T.; Puckett, L. J. The quality of our Nation’s waters─Nutrients in the Nation’s streams and groundwater, 1992–2004. U.S. Geological Survey Circular 1350 2010, (2), 174,  DOI: 10.3133/cir1350

    Google Scholar

    There is no corresponding record for this reference.
70. 70

    Zogorski, J. S.; Carter, J. M.; Ivahnenko, T.; Lapham, W. W.; Moran, M. J.; Rowe, B. L.; Squillace, P. J.; Toccalino, P. L. Volatile organic compounds in the nation’s ground water and drinking-water supply wells. U.S. Geological Survey Circular 1292 2006, 101,  DOI: 10.3133/cir1292

    Google Scholar

    There is no corresponding record for this reference.
71. 71

    U.S. Environmental Protection Agency. Secondary Drinking Water Standards: Guidance for Nuisance Chemicals ; 2022. https://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals (accessed 2022-06-23).

    Google Scholar

    There is no corresponding record for this reference.
72. 72

    U.S. Environmental Protection Agency. Provisional Peer-Reviewed Toxicity Values for Lithium ; 2008, https://cfpub.epa.gov/ncea/pprtv/documents/Lithium.pdf (accesed September 28, 2022).

    Google Scholar

    There is no corresponding record for this reference.