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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...
Geochemistry has contributed significantly to the understanding of ground-water systems over the last 50 years. Historic advances include development of the hydrochemical facies concept, application of equilibrium theory, investigation of redox processes, and radiocarbon dating. Other hydrochemical concepts, tools, and techniques have helped elucidate mechanisms of flow and transport in ground-water systems, and have helped unlock an archive of paleoenvironmental information. Hydrochemical and isotopic information can be used to interpret the origin and mode of ground-water recharge, refine estimates of time scales of recharge and ground-water flow, decipher reactive processes, provide paleohydrological information,...
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This data release documents eight Microsoft Excel tables; four which contain data for understanding groundwater ages in the South East Coastal Plain (SECP), Coastal Lowlands (CLOW) and Mississippi Embayment and Texas Coastal Uplands (METX) aquifer systems and four that describe the data fields. Results described include dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, and radiogenic helium-4), mean age and age distribution, and carbon-14 geochmical modeling results Dissolved gas modeling results (DGmodel) contains detailed information on the calibration of dissolved gas models to dissolved gas concentrations (neon, argon, krypton, xenon, and...
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This data release documents nine Microsoft Excel tables that contain data for understanding groundwater ages in the Glacial aquifer system. Results for the three sample networks (PAS, principal aquifer study; MSS, modeling support study; FPS, flow path study) are described by three tables each: dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), and results for the mean age and age distribution. Tables are labeled by network and data type (as described below) separated by an underscore (_). For example, dissolved gas modeling results from the PAS network is label ‘PAS_NGmodel’. Dissolved gas modeling results...
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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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This data release documents two Microsoft Excel tables; one contains data for understanding groundwater ages in the Spanish Valley watershed, and one that describe the data fields. Mean ages and age distributions from 19 groundwater samples were estimated in support of an evaluation of the groundwater resources of the Spanish Valley watershed (Masbruch and others, 2019). Individual groundwater well and spring vulnerability to land-surface contamination and changes in hydraulic conditions (for example, water extraction or reduced recharge) can be assessed using environmental tracer-based groundwater age. The detailed interpretation of groundwater age reported here supplements the apparent tracer ages of Masbruch...
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This data release documents three Microsoft Excel tables that contain estimates of tritium in precipitation data for the continental United States. Table 1 contains estimates of tritium in precipitation for precipitation stations located in the continental United States. Measured precipitation data are formatted in regular font while correlated data are italicized. Table 2 contains tritium in precipitation for ninety-six 2-degree latitude by 5-degree longitude quadrangles covering the continental U.S. Latitudes are north of the equator and longitudes are west of the prime meridian. Please see the processing steps below and the main manuscript for additional details on the results presented in this table. Table 3...
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Groundwater age is an important indicator of groundwater susceptibility to anthropogenic contamination and a key input to statistical models for forecasting water quality. Numerical models can provide estimates of groundwater age, enabling interpretation of measured age tracers. However, to extend to national-scale groundwater systems where numerical models are not routinely available, a more efficient metamodeling approach can provide a less precise but widely applicable estimate of groundwater age, trained to make forecasts based on predictor variables that can be measured independent of numerical models. We trained gradient-boosted regression tree statistical metamodels to MODFLOW/MODPATH derived groundwater...
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Continuous monitoring and discrete water-quality sampling were coupled in a karst aquifer to assess drivers and timescales of water-quality change. Water-quality data included environmental tracers of groundwater age (tritium [3H], tritiogenic helium-3 [3He-trit], sulfur hexafluoride [SF6], carbon-14 [14C], and radiogenic helium-4 [4He-rad]). All water quality data is available from the U.S. Geological Survey NWIS database (U.S. Geological Survey, 2019). Groundwater ages were estimated by calibration of environmental tracers to lumped parameter models of groundwater age for multiple samples collected at six groundwater wells using the program TracerLPM (Jurgens and others, 2012). The final estimates for mean groundwater...
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This data release documents four Microsoft Excel tables; one contains data for understanding water ages, one contains noble gas model data, two that describe the data fields. Results described include environmental tracer concentrations (tritium, tritiogenic helium-3, choloroflourocarbons, and radiogenic helium-4), mean age and age distribution, noble gas concentrations, and groundwater recharge conditions. Mean age and age distribution results (LPM) contain final models of groundwater age by calibration of lumped parameter models to tracer concentrations (Jurgens and others, 2012). Please see the main manuscript for additional details on the results presented in this table. Noble gas model results (CEmodel) contain...
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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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This data release consists of data (in four tables) for assessing the time scales of arsenic variability in three production wells in New Hampshire; tables that describe the data fields in the data tables are also included in the data release. High-frequency (every 5 to 15 minutes) and bi-monthly water-quality monitoring of a bedrock-aquifer domestic well (425651070573701), a bedrock-aquifer public-supply well (425400070545401), and a glacial-aquifer public-supply well (425311070535801) was completed between 2014 and 2018. Concentrations of arsenic and other geochemical constituents and dissolved gases, as tracers of groundwater age, were measured on a bimonthly basis; physicochemical data, including specific conductance,...
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Residence time distribution (RTD) is a critically important characteristic of groundwater flow systems; however, it cannot be measured directly. RTD can be inferred from tracer data with analytical models (few parameters) or with numerical models (many parameters). The second approach permits more variation in system properties but is used less frequently than the first because large-scale numerical models can be resource intensive. With the data and computer codes in this data release users can (1) reconstruct and run 115 General Simulation Models (GSMs) of groundwater flow, (2) calculate groundwater age metrics at selected GSM cells, (3) train a boosted regression tree model using the provided data, (4) predict...
A new groundwater dating procedure using the transient atmospheric signal of the environmental tracers SF5CF3, CFC-13, SF6, and CFC-12 was developed. The analytical procedure determines concentrations of the four tracers in air and water samples. SF5CF3 and CFC-13 can be used to date groundwaters in some environments where the CFCs and SF6 have previously failed because these new tracers have increasing atmospheric input functions, no known terrigenic source, and are believed to be stable under reducing conditions. SF5CF3 has a dating range from 1970 to modern; the mixing ratio (mole fraction) in North American air has increased from the detection limit of 0.005 parts per trillion (ppt) to the 2006 mole fraction...
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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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Groundwater age distribution and susceptibility to natural and anthropogenic contaminants were assessed for selected principal aquifers of the Western United States: the Central Valley aquifer system (CVAL), the Basin and Range basin-fill aquifers (BNRF), the Rio Grande aquifer system (RIOG), the High Plains aquifer (HPAQ), the Columbia Plateau basaltic-rock aquifers (CLPT), and the Colorado Plateaus aquifers (COPL). Groundwater ages were estimated by calibration of environmental tracers (tritium, tritiogenic helium-3, chlorofluorocarbons, sulfur hexafluoride, carbon-14 and radiogenic helium-4) to lumped parameter models (LPMs) for 1,353 samples from 1,182 sample locations. Groundwater samples were collected from...
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This data release documents two Microsoft Excel tables that contain data for understanding tracer concentrations and groundwater age in the Columbia Plateau aquifer system. Results for geochemical correction of carbon-14, and lumped parameter modeling of groundwater age for the sample network (VPFS, vertical flow path study) are described. Geochemical carbon-14 correction results (RFG) describe geochemical correction of carbon-14 in dissolved inorganic carbon (DIC) for groundwater age dating. Datasets includes measured water parameters and chemistry, model parameter inputs, and final corrected carbon-14 in DIC. Geochemical correction was completed using the revised Fontes and Granier model of Han and Plummer (2013)....
Thirty water-supply drinking-water wells were sampled during fall 2018 for a set of constituents including PFAS. Groundwater samples were sent to Maxxam Laboratories (RTI Laboratory contract) to be analyzed for eighteen PFAS using USEPA 537m method. Groundwater age data were collected and analyzed as well in the USGS Reston, Va. laboratory. Quality-control samples including equipment and field blanks, sequential replicate samples, and laboratory spikes, were collected to evaluate and estimate potential contamination bias and measure variability from water-quality data-collection processes. No PFAS were detected in equipment or field blanks indicating that selected equipment, cleaning, sampling, and handling procedures...
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This data release provides additional data collected since the original publication of: Busenberg, Eurybiades, Plummer, L.N., Coplen, T.B., Doughten, M.W., Widman, P.K., Casile, G.C., Wayland, J.E., and Nelms, D.L., 2014, A 19-year record of chemical and isotopic composition of water from springs of the Shenandoah National Park, Virginia, 1995–2014: U.S. Geological Survey Data Series 893, 11 p., http://dx.doi.org/10.3133/ds893. ISSN 2327-638X (online) This data release represents to original 2014 U.S. Geological Survey Data Series along with additional data collected in Shenandoah National Park up to April 18, 2017. The data release consists of two files: a spreadsheet consisting of multiple worksheets, and a data...
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In 2013, water-quality and age-date tracer samples were collected at wells located along two flow paths in the Memphis aquifer, southwest Tennessee, as part of the National Water Quality Assessment (NAWQA) Project of the National Water-Quality Program to better understand the vulnerability of the aquifer to contamination.. Each flow path began in the aquifer outcrop area (shallow well depths) and ended at public supply wells (deep well depths) in Memphis, TN in the confined parts of the aquifer. This data release includes results for samples collected as part of this study and information for additional wells that provided supplemental data near the end of each flow path to support the findings in "Fraction of young...


map background search result map search result map Well characteristics, water quality and age-date tracer data for wells along two regional flow paths in the Memphis aquifer, southwest Tennessee A multi-year record of chemical and isotopic composition of water from springs of the Shenandoah National Park, Virginia Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA: Table 1. Dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), and results for the mean age of groundwater by calibration of lumped parameter models to tracer concentrations. Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA: Table 2. Detailed information on the calibration of dissolved gas models to dissolved gas concentrations (neon, argon, krypton, xenon, and nitrogen). Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA: Table 3. Detailed information on calculations of environmental tracer data. Dissolved Gas, Environmental Tracer Concentrations, and Lumped Parameter Modeling Results for Groundwater Age Dating in the Glacial Aquifer System, Conterminous United States Data and Scripts for Metamodeling for Groundwater Age Forecasting in the Lake Michigan Basin Data for Tritium deposition in precipitation in the United States, 1953 - 2012 Data for Groundwater Age and Susceptibility of Poorly Consolidated Sedimentary Aquifers of the United States Gulf Coast: Results from the Southeast Coastal Plain (SECP), Coastal Lowland (CLOW), Mississippi Embayment and Texas Coastal Upland (METX) Principal Aquifer Networks Data for Tritium as an Indicator of Modern, Mixed and Premodern Groundwater Age Data for assessing the susceptibility of groundwater used for drinking water supply from selected principal aquifers of the Western United States, 2004-2018 Data for timescales of water-quality change in a karst aquifer, south-central Texas Data for Time Scales of Arsenic Variability and the Role of High-Frequency Monitoring at Three Water-Supply Wells in New Hampshire, USA Lumped parameter models of groundwater age, Spanish Valley Watershed, Grand and San Juan Counties, Utah Lumped parameter models of groundwater age and noble gas models of recharge conditions in support of Groundwater and Surface-Water Resources near Red Fleet Reservoir, Uintah County, Utah Lumped parameter models of groundwater age from the Columbia Plateau Aquifer, Vertical Flowpath Study Network Data for three-dimensional distribution of groundwater residence time metrics in the glaciated United States using metamodels trained on general numerical simulation models Data in support of the occurrence and distribution of per- and polyfluoroalkyl substances in sampled source water of public drinking-water supplies in the surficial aquifer in Delaware, 2018 Lumped parameter models of groundwater age and noble gas models of recharge conditions in support of Groundwater and Surface-Water Resources near Red Fleet Reservoir, Uintah County, Utah Lumped parameter models of groundwater age, Spanish Valley Watershed, Grand and San Juan Counties, Utah Well characteristics, water quality and age-date tracer data for wells along two regional flow paths in the Memphis aquifer, southwest Tennessee Data for Time Scales of Arsenic Variability and the Role of High-Frequency Monitoring at Three Water-Supply Wells in New Hampshire, USA A multi-year record of chemical and isotopic composition of water from springs of the Shenandoah National Park, Virginia Data in support of the occurrence and distribution of per- and polyfluoroalkyl substances in sampled source water of public drinking-water supplies in the surficial aquifer in Delaware, 2018 Data for timescales of water-quality change in a karst aquifer, south-central Texas Lumped parameter models of groundwater age from the Columbia Plateau Aquifer, Vertical Flowpath Study Network Data and Scripts for Metamodeling for Groundwater Age Forecasting in the Lake Michigan Basin Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA: Table 1. Dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), and results for the mean age of groundwater by calibration of lumped parameter models to tracer concentrations. Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA: Table 2. Detailed information on the calibration of dissolved gas models to dissolved gas concentrations (neon, argon, krypton, xenon, and nitrogen). Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA: Table 3. Detailed information on calculations of environmental tracer data. Data for Groundwater Age and Susceptibility of Poorly Consolidated Sedimentary Aquifers of the United States Gulf Coast: Results from the Southeast Coastal Plain (SECP), Coastal Lowland (CLOW), Mississippi Embayment and Texas Coastal Upland (METX) Principal Aquifer Networks Dissolved Gas, Environmental Tracer Concentrations, and Lumped Parameter Modeling Results for Groundwater Age Dating in the Glacial Aquifer System, Conterminous United States Data for assessing the susceptibility of groundwater used for drinking water supply from selected principal aquifers of the Western United States, 2004-2018 Data for three-dimensional distribution of groundwater residence time metrics in the glaciated United States using metamodels trained on general numerical simulation models Data for Tritium deposition in precipitation in the United States, 1953 - 2012 Data for Tritium as an Indicator of Modern, Mixed and Premodern Groundwater Age