Elucidation of the Mechanisms and Environmental Relevance of cis-Dichloroethene and Vinyl Chloride Biodegradation

Abstract

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CSIA of TCE and Daughter Products With Multiple Sources, Multiple Attenuation Mechanisms, and Low Ethene

“…As shown in Exhibit 2, at fEAFB there were some wells with very reducing geochemistry as evidenced by their <0.1 mg/L sulfate and >1 mg/L of methane, but there were other wells that were not nearly so reducing and contained up to 11 mg/L of sulfate and less than 0.1 mg/L of methane. Biodegradation of VC could occur through direct oxidation rather than reduction (Bradley, 2011;Bradley & Chapelle, 2011;Cox, 2010;Dijk et al, 2000;Gossett, 2010). Abiotic degradation (i.e., biogeochemical degradation) of the TCE and/or cDCE without production of VC (Brown et al, 2007(Brown et al, , 2009Ferrey et al, 2004) could also contribute to the attenuation processes.…”

“…The geochemistry indicated reducing conditions throughout most of the plume, and the prevailing wisdom suggested that the only biodegradation active under such conditions was reductive dechlorination. However, remediation professionals now recognize the significance of abiotic degradation and even oxidative processes under reducing conditions (Bradley, 2011;Bradley & Chapelle, 2011;Cox, 2010;Dijk et al, 2000;Gossett, 2010). CSIA data were collected to review MNA at fEAFB, in part because CSIA is sensitive to all degradation: abiotic degradation, biodegradation, reductive dechlorination, and oxidation.…”