Reinterpreting the importance of oxygen-based biodegradation in chloroethene-contaminated groundwater

Ground Water Monitoring and Remediation
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Abstract

Chlororespiration is common in shallow aquifer systems under conditions nominally identified as anoxic. Consequently, chlororespiration is a key component of remediation at many chloroethene-contaminated sites. In some instances, limited accumulation of reductive dechlorination daughter products is interpreted as evidence that natural attenuation is not adequate for site remediation. This conclusion is justified when evidence for parent compound (tetrachloroethene, PCE, or trichloroethene, TCE) degradation is lacking. For many chloroethene-contaminated shallow aquifer systems, however, nonconservative losses of the parent compounds are clear but the mass balance between parent compound attenuation and accumulation of reductive dechlorination daughter products is incomplete. Incomplete mass balance indicates a failure to account for important contaminant attenuation mechanisms and is consistent with contaminant degradation to nondiagnostic mineralization products like CO2. While anoxic mineralization of chloroethene compounds has been proposed previously, recent results suggest that oxygen-based mineralization of chloroethenes also can be significant at dissolved oxygen concentrations below the currently accepted field standard for nominally anoxic conditions. Thus, reassessment of the role and potential importance of low concentrations of oxygen in chloroethene biodegradation are needed, because mischaracterization of operant biodegradation processes can lead to expensive and ineffective remedial actions. A modified interpretive framework is provided for assessing the potential for chloroethene biodegradation under different redox conditions and the probable role of oxygen in chloroethene biodegradation.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Reinterpreting the importance of oxygen-based biodegradation in chloroethene-contaminated groundwater
Series title Ground Water Monitoring and Remediation
DOI 10.1111/j.1745-6592.2011.01344.x
Volume 31
Issue 4
Year Published 2011
Language English
Publisher National Ground Water Association
Publisher location Westerville, OH
Contributing office(s) South Atlantic Water Science Center
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Ground Water Monitoring and Remediation
First page 50
Last page 55
Country United States