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Monitoring microbial dechlorination of tetrachloroethene (PCE) in groundwater using compound-specific stable carbon isotope ratios: Microcosm and field studies

Journal Article · · Environmental Science and Technology
DOI:https://doi.org/10.1021/es981282u· OSTI ID:687390
The determination of compound-specific stable isotope ratios is a promising new tool to assess biodegradation of organic compounds in groundwater. In this study, the occurrence of carbon isotope fractionation during dechlorination of tetrachloroethene (PCE) to ethene was evaluated in a PCE-contaminated aquifer and in a microcosm that was based on aquifer material from the site. In the microcosm, all dechlorination steps were accompanied by carbon isotope fractionation. The largest fractionation occurred during dechlorination of cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), resulting in a large enrichment of {sup 13}C in the remaining cDCE and VC. Stable carbon isotope ratios ({delta}{sup 13}C) of cDCE and VC increased from {minus}25.7 to {minus}1.5{per_thousand} and {minus}37.0 to {minus}2.5{per_thousand}, respectively. The {delta}{sup 13}C of ethene was initially {minus}60.2{per_thousand} and approached the {delta}{sup 13}C of the added PCE ({minus}27.3{per_thousand}) as dechlorination came to completion. A similar carbon isotope pattern was observed for PCE dechlorination at the field site. Strong enrichment of {sup 13}C in cDCE and VC during microbial dechlorination may serve as a powerful tool to monitor the last two dechlorination steps, which frequently determine the rate of complete dechlorination of chlorinated ethenes at field sites undergoing intrinsic bioremediation.
OSTI ID:
687390
Journal Information:
Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 16 Vol. 33; ISSN ESTHAG; ISSN 0013-936X
Country of Publication:
United States
Language:
English