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Folders: ROOT > ScienceBase Catalog > National Water-Quality Assessment Project > Groundwater Studies > Groundwater Assessment & Mapping ( Show all descendants )

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Concentrations of inorganic constituents, dissolved organic carbon (DOC), tritium, per- and polyfluoroalkyl substances (PFAS), volatile organic compounds (VOCs), and pharmaceuticals were measured in groundwater samples collected from 254 wells in 2019 and 2020. Concentrations of inorganic constituents, DOC, VOCs, and pharmaceuticals were measured at the U.S. Geological Survey (USGS) National Water Quality Laboratory in Lakewood, Colorado. Concentrations of tritium were measured at the USGS Tritium Laboratory in Menlo Park, California. Concentrations of PFAS were measured at SGS Laboratory in Orlando, Florida. In addition, several geospatial parameters were determined, including: percentages of selected land uses...
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This data release documents three Microsoft Excel tables that contain data for understanding environmental tracer concentrations in groundwater of the High Plains aquifer system. Results of dissolved-gas modeling using environmental tracer concentrations (tritium, tritiogenic helium-3, and radiogenic helium-4), for the sample network (VPFS, vertical flow path study) are described. Dissolved gas modeling results (ModOut) contains detailed information on the calibration of dissolved gas models to measured dissolved-gas concentrations (neon, argon, krypton, xenon, and nitrogen). Calibration was done using methods described by Aeschbach-Hertig and others (1999 & 2000) with modifications to include nitrogen gas (Weiss,...
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Lithium concentrations in untreated groundwater from 1,464 public-supply wells, 1,676 domestic-supply wells, and 1,560 monitoring wells distributed across 33 principal aquifers in the United States were evaluated for spatial variations and possible explanatory factors. For context, lithium concentrations are compared to a drinking-water only threshold (60 micrograms per liter) and a Health-Based Screening Level (HBSL, 10 micrograms per liter). These thresholds were exceeded in 9% and 45% of samples from public-supply wells and in 6% and 37% from domestic-supply wells, respectively. Exceedances were most frequent for arid regions and older groundwater. Groundwater lithium concentrations were highest in unconsolidated...
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Categorical classification of groundwater age based on concentrations of tritium (3H) in groundwater can provide useful information for the assessment and understanding of groundwater resources. These data present a three-part groundwater age classification system for the continental United States based on tritium thresholds that vary in space and time: modern (recharged after 1952), if the measured value is larger than an upper threshold; premodern (recharged prior to 1953) if the measured value is smaller than a lower threshold; or mixed if the measured value is between the two thresholds. Inclusion of spatially-varying that vary geographically on the basis of the location of the sample rather than a single threshold...
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High radium (Ra) concentrations in potable portions of the Cambrian-Ordovician (C-O) aquifer system were investigated using water-quality data and environmental tracers ( 3H, 3Hetrit, SF6 , 14C and 4Herad) of groundwater age from 80 public-supply wells (PSWs). Groundwater ages were estimated by calibration of tracers to lumped parameter models and ranged from modern (1 Myr) in the most downgradient, confined portions of the potable system. More than 80 and 40 percent of mean groundwater ages were older than 1000 and 50,000 yr, respectively. Anoxic, Fe-reducing conditions and increased mineralization develop with time in the aquifer system and mobilize Ra into solution resulting in the frequent occurrence of combined...
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The location of a point (or pixel) within the conterminous U.S. can be assigned based on its position relative to the Nation’s stream network. Two metrics are recognized: lateral position (LP) and distance from stream to divide (DSD). And given that a point can have different positions in different hydrologic orders the term multi-order hydrologic position (MOHP) is used to describe the ensemble of hydrologic positions. LP and DSD were developed for nine hydrologic orders across the conterminous U.S. (Belitz and others, 2019; Moore and others, 2019). Four case studies are presented here that were used for evaluating the utility of MOHP in the context of random forest machine learning (Belitz and others, 2019)....
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Chemical data from 43,334 wells were used to examine the role of land surface-soil-aquifer connections in producing elevated manganese concentrations (>300 µg/L) in United States (U.S.) groundwater. Elevated manganese and dissolved organic carbon (DOC) concentrations were associated with shallow water tables and organic-carbon rich soils, suggesting soil-derived DOC supported manganese reduction. Manganese and DOC concentrations were higher near rivers than farther from rivers, suggesting river-derived DOC also supported manganese reduction. Anthropogenic nitrogen may also affect manganese concentrations in groundwater. In parts of the northeastern U.S. containing poorly buffered soils, ~40% of the samples with...
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Water samples from 50 domestic wells located <1 kilometer (km) (proximal) and >1 km (distal) from shale-gas wells in upland areas of the Marcellus Shale region were analyzed for chemical, isotopic and groundwater-age tracers. Uplands were targeted because natural mixing with brine and hydrocarbons from deep formations is less common in those areas compared to valleys. Methane (CH4) -isotope and pre-drill CH4 data indicate one proximal sample (5 percent of proximal samples) contains thermogenic CH4 (2.6 milligrams per liter (mg/L)) associated with shale-gas production. Chloride (Cl), bromide (Br), lithium (Li), and neon-20 (20Ne)/argon-36 (36Ar) data suggest that CH4 leaked from a nearby gas well in a gas phase....
In 2018, groundwater samples were collected from aquifers in the Williston Basin in parts of eastern Montana, western North Dakota, and northwestern South Dakota. This dataset includes quality-control data for volatile organic compounds that include data for source-solution blanks and field blanks. The dataset also includes data for sulfur hexafluoride in environmental samples of groundwater.


    map background search result map search result map Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA Data for Elevated Manganese Concentrations in United States Groundwater, Role of Land Surface-Soil-Aquifer Connections Data for Tritium as an Indicator of Modern, Mixed and Premodern Groundwater Age Data Release for Hydrocarbons in Upland Groundwater, Marcellus Shale Region, Northeastern Pennsylvania and Southern New York, USA Point data for four case studies related to testing of multi-order hydrologic position Dissolved Gas and Tracer Concentrations for the High Plains Aquifer, Vertical Flowpath Study Network Quality-Control Data for Volatile Organic Compounds and Environmental Sulfur-Hexafluoride Data for Groundwater Samples from the Williston Basin, USA Inorganic Constituent and Ancillary Data for Evaluation of Lithium in Groundwater in the United States, 1991-2018 Geochemical and Geospatial Data for Per- and Polyfluoroalkyl Substances (PFAS) in Groundwater Used as a Source of Drinking Water in the Eastern United States Data Release for Hydrocarbons in Upland Groundwater, Marcellus Shale Region, Northeastern Pennsylvania and Southern New York, USA Dissolved Gas and Tracer Concentrations for the High Plains Aquifer, Vertical Flowpath Study Network Quality-Control Data for Volatile Organic Compounds and Environmental Sulfur-Hexafluoride Data for Groundwater Samples from the Williston Basin, USA Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA Geochemical and Geospatial Data for Per- and Polyfluoroalkyl Substances (PFAS) in Groundwater Used as a Source of Drinking Water in the Eastern United States Data for Tritium as an Indicator of Modern, Mixed and Premodern Groundwater Age Point data for four case studies related to testing of multi-order hydrologic position Data for Elevated Manganese Concentrations in United States Groundwater, Role of Land Surface-Soil-Aquifer Connections Inorganic Constituent and Ancillary Data for Evaluation of Lithium in Groundwater in the United States, 1991-2018