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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.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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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.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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California GAMA Special Study: An isotopic and dissolved gas investigation of nitrate source and transport to a public supply well in California's Central Valley

Description: This study investigates nitrate contamination of a deep municipal drinking water production well in Ripon, CA to demonstrate the utility of natural groundwater tracers in constraining the sources and transport of nitrate to deep aquifers in the Central Valley. The goal of the study was to investigate the origin (source) of elevated nitrate and the potential for the deep aquifer to attenuate anthropogenic nitrate. The site is ideal for such an investigation. The production well is screened from … more
Date: April 14, 2010
Creator: Singleton, M. J.; Moran, J. E.; Esser, B. K.; Roberts, S. K. & Hillegonds, D. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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California GAMA Program: Sources and Transport of Nitrate in Groundwater in the Livermore Valley Basin, California

Description: A critical component of the State Water Resource Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program is to assess the major threats to groundwater resources that supply drinking water to Californians (Belitz et al., 2004). Nitrate concentrations approaching and greater than the maximum contaminant level (MCL) are impairing the viability of many groundwater basins as drinking water sources Source attribution and nitrate fate and transport are therefore the focus of speci… more
Date: November 18, 2005
Creator: Beller, H; Eaton, G F; Ekwurzel, B. E.; Esser, B. K.; Hu, Q.; Hudson, G. B. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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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.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Uncertainties associated with the definition of a hydrologic source term for the Nevada Test Site

Description: The U.S. Department of Energy, Nevada Operations Office (DOE/NV) Environmental Restoration Division is seeking to evaluate groundwater contamination resulting from 30 years of underground nuclear testing at the Nevada Test Site (NTS). This evaluation requires knowledge about what radioactive materials are in the groundwater and how they are transported through the underground environment. This information coupled with models of groundwater flow (flow paths and flow rates) will enable prediction… more
Date: May 1, 1995
Creator: Smith, D. K.; Esser, B. K. & Thompson, J. L.
Item Type: Refine your search to only Report
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.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Radionuclide Decay and In-growth Technical Basis Document

Description: The purpose of this report is to assess the decay and in-growth of radionuclides from the radionuclide source term (RST) deposited by underground nuclear weapons tests conducted at the NTS from 1951 through 1992. A priority of the Underground Test Area (UGTA) project, administered by the Environmental Restoration Division of NNSA/NV, was to determine as accurately as possible a measure of the total radionuclide inventory for calculation of the RST deposited in the subsurface at the Nevada Test … more
Date: July 1, 2003
Creator: Kersting, A. B.; Finnegan, D. L.; Tompson, A. F. B.; Esser, B. K.; Smith, D. K.; Zavarin, M. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Colloid-Facilitated Transport of Low-Solubility Radionuclides: A Field, Experimental, and Modeling Investigation

Description: For the last several years, the Underground Test Area (UGTA) program has funded a series of studies carried out by scientists to investigate the role of colloids in facilitating the transport of low-solubility radionuclides in groundwater, specifically plutonium (Pu). Although the studies were carried out independently, the overarching goals of these studies has been to determine if colloids in groundwater at the NTS can and will transport low-solubility radionuclides such as Pu, define the geo… more
Date: February 1, 2003
Creator: Kersting, A. B.; Reimus, P. W.; Abdel-Fattah, A.; Allen, P. G.; Anghel, I.; Benedict, F. C. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Nitrate Biogeochemistry and Reactive Transport in California Groundwater: LDRD Final Report

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 sources… more
Date: February 24, 2006
Creator: Esser, B. K.; Beller, H.; Carle, S.; Cey, B.; Hudson, G. B.; Leif, R. et al.
Item Type: Refine your search to only Report
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.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Enhanced ocean observational capability

Description: Coastal oceans are vital to world health and sustenance. Technology that enables new observations has always been the driver of discovery in ocean sciences. In this context, we describe the first at sea deployment and operation of an inductively coupled plasma mass spectrometer (ICPMS) for continuous measurement of trace elements in seawater. The purpose of these experiments was to demonstrate that an ICPMS could be operated in a corrosive and high vibration environment with no degradation in p… more
Date: January 10, 2000
Creator: Volpe, A. M. & Esser, B. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Hydrologic resources management program. FY 1995 progress report

Description: This report presents the results of FY 1995 technical studies conducted by the Lawrence Livermore National Laboratory (LLNL) as part of the Hydrology and Radionuclide Migration Program (HRMP), a multi-agency program sponsored by the U.S. Department of Energy, Nevada Operations Office (DOE/NV), to address the environmental consequences of nuclear weapons testing at the Nevada Test Site (NTS). A priority is to better characterize the complex near-field environment in order to assess and predict t… more
Date: March 1, 1996
Creator: Smith, D. K.; Esser, B. K. & Kenneally, J. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Analysis of Savannah Survey Sediment Collections of 30 Sep 04

Description: This report summarizes laboratory radiochemical analyses of sediment samples collected by the Defense Threat Reduction Agency during the DoD Savannah Survey operations of Sep 04. The analytic goal was to determine if Wassaw Sound sediment collections of 30 Sep 04 display evidence for local anthropogenic uranium, as distinct from the recognized regional background stemming from the Savannah River Site (SRS). Radiochemical methods were selected to maximize detection sensitivity for such anthropog… more
Date: December 3, 2004
Creator: Wimer, N. G.; Hutcheon, I. D.; Esser, B. K. & Ramon, E. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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