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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...
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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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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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The Mississippi River Valley alluvial aquifer (MRVA) overlies and is bounded by several regional aquifers that make up the Mississippi embayment aquifer system (MEAS) in the central United States. The MRVA, which consists of Quaternary alluvium, is one of the most heavily pumped aquifers in the nation and is a major source of groundwater for irrigation. Large groundwater-level declines in portions of the aquifer have raised concerns about sustainable use of this important resource. An aquifer-scale assessment of groundwater-age categories based on tritium concentrations was completed to better understand groundwater availability and susceptibility. The presence of tritium, a radioactive isotope of hydrogen, in a...
    map background search result map search result map Data for Tritium as an Indicator of Modern, Mixed and Premodern Groundwater Age Data for timescales of water-quality change in a karst aquifer, south-central Texas Groundwater age categories based on tritium concentrations in samples collected from the Mississippi River Valley alluvial aquifer and aquifers of the Mississippi embayment principal aquifer system Data for Tritium deposition in precipitation in the United States, 1953 - 2023 (ver. 2.0, May 2023) Data for timescales of water-quality change in a karst aquifer, south-central Texas Groundwater age categories based on tritium concentrations in samples collected from the Mississippi River Valley alluvial aquifer and aquifers of the Mississippi embayment principal aquifer system Data for Tritium as an Indicator of Modern, Mixed and Premodern Groundwater Age Data for Tritium deposition in precipitation in the United States, 1953 - 2023 (ver. 2.0, May 2023)