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Using Nitrogen and Oxygen Isotope Compositions of Nitrate to Distinguish Contaminant Sources in Hanford Soil and Groundwater.

DE2008940585

Publication Date	2008
Personal Author	Conrad, M.; Bill, M.
Page Count	9
Abstract	The nitrogen ((delta)(sup 15)N) and oxygen ((delta)(sup 18)O) isotopic compositions of nitrate in the environment are primarily a function of the source of the nitrate. The ranges of isotopic compositions for nitrate resulting from common sources are outlined in Figure 1 from Kendall (1998). As noted on Figure 1, processes such as microbial metabolism can modify the isotopic compositions of the nitrate, but the effects of these processes are generally predictable. At Hanford, nitrate and other nitrogenous compounds were significant components of most of the chemical processes used at the site. Most of the oxygen in nitrate chemicals (e.g., nitric acid) is derived from atmospheric oxygen, giving it a significantly higher (delta)(sup 18)O value (+23.5(per thousand)) than naturally occurring nitrate that obtains most of its oxygen from water (the (delta)(sup 18)O of Hanford groundwater ranges from -14(per thousand) to -18(per thousand)). This makes it possible to differentiate nitrate from Hanford site activities from background nitrate at the site (including most fertilizers that might have been used prior to the Department of Energy plutonium production activities at the site). In addition, the extreme thermal and chemical conditions that occurred during some of the waste processing procedures and subsequent waste storage in select single-shell tanks resulted in unique nitrate isotopic compositions that can be used to identify those waste streams in soil and groundwater at the site (Singleton et al., 2005; Christensen et al., 2007). This report presents nitrate isotope data for soil and groundwater samples from the Hanford 200 Areas and discusses the implications of that data for potential sources of groundwater contamination.
Keywords	Hanford reservation Nitrates Fertilizers Radioactive waste processing Groundwater contamination Plutonium Soils Oxygen Nitrogen Nitric acid
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Lawrence Berkeley National Lab., CA.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200908

Using Nitrogen and Oxygen Isotope Compositions of Nitrate to Distinguish Contaminant Sources in Hanford Soil and Groundwater.

Using Nitrogen and Oxygen Isotope Compositions of Nitrate to Distinguish Contaminant Sources in Hanford Soil and Groundwater.
DE2008940585

Publication Date	2008
Personal Author	Conrad, M.; Bill, M.
Page Count	9
Abstract	The nitrogen ((delta)(sup 15)N) and oxygen ((delta)(sup 18)O) isotopic compositions of nitrate in the environment are primarily a function of the source of the nitrate. The ranges of isotopic compositions for nitrate resulting from common sources are outlined in Figure 1 from Kendall (1998). As noted on Figure 1, processes such as microbial metabolism can modify the isotopic compositions of the nitrate, but the effects of these processes are generally predictable. At Hanford, nitrate and other nitrogenous compounds were significant components of most of the chemical processes used at the site. Most of the oxygen in nitrate chemicals (e.g., nitric acid) is derived from atmospheric oxygen, giving it a significantly higher (delta)(sup 18)O value (+23.5(per thousand)) than naturally occurring nitrate that obtains most of its oxygen from water (the (delta)(sup 18)O of Hanford groundwater ranges from -14(per thousand) to -18(per thousand)). This makes it possible to differentiate nitrate from Hanford site activities from background nitrate at the site (including most fertilizers that might have been used prior to the Department of Energy plutonium production activities at the site). In addition, the extreme thermal and chemical conditions that occurred during some of the waste processing procedures and subsequent waste storage in select single-shell tanks resulted in unique nitrate isotopic compositions that can be used to identify those waste streams in soil and groundwater at the site (Singleton et al., 2005; Christensen et al., 2007). This report presents nitrate isotope data for soil and groundwater samples from the Hanford 200 Areas and discusses the implications of that data for potential sources of groundwater contamination.
Keywords	Hanford reservation Nitrates Fertilizers Radioactive waste processing Groundwater contamination Plutonium Soils Oxygen Nitrogen Nitric acid
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Lawrence Berkeley National Lab., CA.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200908