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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,...
Categories: Publication;
Types: Citation;
Tags: Hydrochemical modelin,
geochemistry,
groundwater age
This data release documents three Microsoft Excel tables (and corresponding comma separated data files) that contain estimates of tritium in precipitation data for the continental United States. Versions of this data release contain additional tritium data for more recent years. The current version has tritium data through 2022. 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...
Categories: Data,
Data Release - In Progress;
Tags: Tritium,
USGS Science Data Catalog (SDC),
continental United States,
groundwater,
groundwater age,
Groundwater age distributions and susceptibility to natural and anthropogenic contaminants were assessed for selected wells, streambed piezometers, and springs in southeastern Minnesota. The data provide information to understand how long it will take to observe groundwater quality improvements from best management practices implemented at land surface to reduce losses of nitrate (and other chemicals) from agricultural practices. Nineteen water samples were collected from ten wells, three streambed piezometers, and four springs between August 2020 and September 2022. Two of these samples are field replicate samples collected from a spring site and a well site. A child item contains historical data from 15 water...
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...
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...
This data release codifies and attributes explanatory variables that could potentially influence groundwater quality at 50 groundwater wells used for domestic water supply and 43 groundwater sites used for public water supply in the U.S. Geological Survey’s Priority Basin Project Redding-Red Bluff shallow aquifer (NSV-SA) study unit in 2018-2019 and Northern Sacramento Valley public-supply (NSV-PA) study unit in 2007, respectively. Water quality from domestic and public-supply groundwater sites was assessed as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) program. The NSV-SA and NSV-PA study units include domestic and public-supply wells within...
We computed mean groundwater ages and age distributions at eight wells by calibrating lumped parameter models (LPMs) to concentrations of tracers (3H, CFCs, SF6) in samples using the computer program TracerLPM (Jurgens and others, 2012). We also measured 14C but all samples contained ancient carbonate from the limestone bedrock, and we were unable to resolve the atmospherically-derived 14C sufficiently to use it as a tracer. Tritium was below the detection level in two of the eight well-water samples, indicating the water was recharged prior to about 1950. Groundwater from the other six wells could be fitted to LPMs that were either piston flow models (PFM), exponential – piston flow models (EPM), or binary mixing...
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...
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...
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...
The Captain Jack Superfund site near Ward, Colorado hosts extensive interconnected underground mine workings, which drain via the Big Five Adit. Drainage from the adit has historically been acidic with elevated concentrations of metals. In 2018 the U.S. Environmental Protection Agency (EPA) utilized a subsurface remediation strategy consisting of the installation of a hydraulic bulkhead within the workings to preclude drainage out of the mine. To understand the processes occurring during water impoundment within the mine workings, the U.S. Geological Survey (USGS), in cooperation with EPA, completed water-quality sampling and analysis during 2020 as water was impounded within the mine workings. The USGS sampling...
Categories: Data;
Types: Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Boulder County,
Colorado,
Geochemistry,
Hydrology,
USGS Science Data Catalog (SDC),
The U.S. Geological Survey collected groundwater samples from 17 wells in the Indio subbasin (CA basin designation 7-21.01) of the Coachella Valley and surface water samples from two sites representing sources of recharge to the Indio subbasin in 2021. These samples are intended to provide inorganic water quality data, particularly total dissolved solids (TDS), within areas of the Indio subbasin not sampled for the Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater used for domestic and small system drinking water supplies in Coachella Valley (CODA). Other areas of special interest for the Indio salinity study were nearby managed aquifer...
Categories: Data;
Types: Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: California,
Coachella Valley,
Geochemistry,
Groundwater,
Groundwater age,
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...
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...
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...
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,...
Groundwater age distributions and susceptibility to natural and anthropogenic contaminants were assessed for selected wells across Minnesota. The data provide information to understand how long it will take to observe groundwater quality improvements from best management practices implemented at land surface to reduce losses of nitrate (and other chemicals) from agricultural practices. A total of 13 age estimates were done on samples collected from 8 wells between July 1996 and May 1997. Groundwater ages were estimated from dissolved gas (argon and nitrogen) and environmental tracer data (tritium, chlorofluorocarbons, and tritiogenic helium-3) from field samples using the equations available in TracerLPM (an Excel®...
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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