Tracking Sources of Unsaturated Zone and Groundwater Nitrate Contamination Using Nitrogen and Oxygen Stable Isotopes at the Hanford Site, Washington
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- 作者：Michael J. Singleton ; Katharine N. Woods ; Mark E. Conrad ; Donald J. DePaolo ; and P. Evan Dresel
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：May 15, 2005
- 年：2005
- 卷：39
- 期：10
- 页码：3563 - 3570
- 全文大小：343K
- 年卷期：v.39,no.10(May 15, 2005)
- ISSN：1520-5851
文摘
The nitrogen and oxygen isotopic compositions of nitratein pore water extracts from unsaturated zone (UZ) coresamples and groundwater samples indicate at least fourpotential sources of nitrate in groundwaters at the U.S. DOEHanford Site in south-central Washington. Naturalsources of nitrate identified include microbially producednitrate from the soil column (
15N of 4-8”, 18O of -9 to 2”)and nitrate in buried caliche layers (15N of 0-8”, 18Oof -6 to 42”). Isotopically distinct industrial sources of nitrateinclude nitric acid in low-level disposal waters (15N 
0”, 18O 23”) and co-contaminant nitrate in high-levelradioactive waste from plutonium processing (15N of8-33”, 18O of -9 to 7”). The isotopic compositions ofnitrate from 97 groundwater wells with concentrations up to1290 mg/L NO3- have been analyzed. Stable isotopeanalyses from this study site, which has natural andindustrial nitrate sources, provide a tool to distinguishnitrate sources in an unconfined aquifer where concentrationsalone do not. These data indicate that the most commonsources of high nitrate concentrations in groundwater atHanford are nitric acid and natural nitrate flushed out ofthe UZ during disposal of low-level wastewater. Nitrateassociated with high-level radioactive UZ contaminationdoes not appear to be a major source of groundwater nitrateat this time.
15N of 4-8”, 18O of -9 to 2”)and nitrate in buried caliche layers (15N of 0-8”, 18Oof -6 to 42”). Isotopically distinct industrial sources of nitrateinclude nitric acid in low-level disposal waters (15N 0”, 18O 23”) and co-contaminant nitrate in high-levelradioactive waste from plutonium processing (15N of8-33”, 18O of -9 to 7”). The isotopic compositions ofnitrate from 97 groundwater wells with concentrations up to1290 mg/L NO3- have been analyzed. Stable isotopeanalyses from this study site, which has natural andindustrial nitrate sources, provide a tool to distinguishnitrate sources in an unconfined aquifer where concentrationsalone do not. These data indicate that the most commonsources of high nitrate concentrations in groundwater atHanford are nitric acid and natural nitrate flushed out ofthe UZ during disposal of low-level wastewater. Nitrateassociated with high-level radioactive UZ contaminationdoes not appear to be a major source of groundwater nitrateat this time.