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in creator/contributor: "Esser, B. K."  
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Dissolved gas and isotopic tracers of denitrification

Description: We present results from field studies in California (USA) where tritium-helium age dating is used in conjunction with major gases (N{sub 2}, O{sub 2}, CH{sub 4}, CO{sub 2}), noble gases (He, Ne, Ar, Kr, Xe), and stable isotopes ({sup 15}N/{sup 14}N, {sup 18}O/{sup 16}O) in order to document nitrate loading and denitrification associated with confined animal agricultural operations and septic systems. Preliminary results show that in-field extraction of the full suite of dissolved gases will be … more
Date: February 28, 2008
Creator: Singleton, M. J.; Moran, J. E.; Esser, B. K.; McNab, W. W.; Carle, S. F. & Cey, B. D.
Partner: UNT Libraries Government Documents Department
open access

Evidence for Groundwater Contamination Vulnerability in California?s Central Valley

Description: The California Water Resources Control Board, in collaboration with the US Geological Survey and Lawrence Livermore National Laboratory, has implemented a program to assess the susceptibility of groundwater resources. Advanced techniques such as groundwater age dating using the tritium-helium method, extensive use of oxygen isotopes of the water molecule ({delta}{sup 18}O) for recharge water provenance, and analysis of common volatile organic compounds (VOCs) at ultra-low levels are applied wit… more
Date: December 13, 2005
Creator: Moran, J. E.; Leif, R.; Esser, B. K. & Singleton, M. J.
Partner: UNT Libraries Government Documents Department
open access

Saturated Zone Denitrification at California Dairies

Description: Denitrification can effectively mitigate the problem of high nitrate concentrations in groundwater under dairy operations by reducing nitrate to N{sub 2} gas, at sites where biogeochemical conditions are favorable. We present results from field studies at central California dairies that document the occurrence of saturated-zone denitrification in shallow groundwater using biomolecular indicators, stable isotope compositions of nitrate, and measurements of dissolved excess N{sub 2} gas. Excess N… more
Date: February 27, 2006
Creator: Singleton, M. J.; Esser, B. K.; Moran, J. E.; McNab, W. W. & Beller, H. R.
Partner: UNT Libraries Government Documents Department
open access

Simulation of Nitrate Biogeochemistry and Reactive Transport in a California Groundwater Basin

Description: Nitrate is the number one drinking water contaminant in the United States. It is pervasive in surface and groundwater systems, and its principal anthropogenic sources have increased dramatically in the last 50 years. In California alone, one third of the public drinking-water wells has been lost since 1988 and nitrate contamination is the most common reason for abandonment. Effective nitrate management in groundwater is complicated by uncertainties related to multiple point and non-point source… more
Date: January 16, 2004
Creator: Tompson, A. B.; Kane, S. R.; Beller, H. R.; Hudson, G. B.; McNab, W. W.; Moran, J. E. et al.
Partner: UNT Libraries Government Documents Department
open access

Sources of groundwater nitrate revealed using residence time and isotope methods

Description: Nitrate concentrations approaching and greater than the maximum contaminant level (MCL) are impairing the viability of many groundwater basins as drinking water sources. Nitrate isotope data are effective in determining contaminant sources, especially when combined with other isotopic tracers such as stable isotopes of water and tritium-helium ages to give insight into the routes and timing of nitrate inputs to the flow system. This combination of techniques is demonstrated in Livermore, CA, wh… more
Date: October 7, 2004
Creator: Moore, K. B.; Ekwurzel, B.; Esser, B. K.; Hudson, G. B. & Moran, J. E.
Partner: UNT Libraries Government Documents Department
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