Accumulation of dechlorination daughter products: A valid metric of chloroethene biodegradation |
| |
Authors: | Paul M Bradley Frank H Chapelle |
| |
Institution: | South Carolina Water Science Center, Columbia, South Carolina |
| |
Abstract: | In situ reductive dechlorination of perchloroethene (PCE) and trichloroethene (TCE) generates characteristic chlorinated (cis‐dichloroethene cis‐DCE] and vinyl chloride VC]) and nonchlorinated (ethene and ethane) products. The accumulation of these daughter products is commonly used as a metric for ongoing biodegradation at field sites. However, this interpretation assumes that reductive dechlorination is the only chloroethene degradation process of any significance in situ and that the characteristic daughter products of chloroethene reductive dechlorination persist in the environment. Laboratory microcosms, prepared with aquifer and surface‐water sediments from hydrologically diverse sites throughout the United States and amended with 1,2‐14C] TCE, 1,2‐14C] DCE, 1,2‐14C] DCA, or 1,2‐14C] VC, demonstrated widely variable patterns of intermediate and final product accumulation. In predominantly methanogenic sediment treatments, accumulation of 14C‐DCE, 14C‐VC, 14C‐ethene, and 14C‐ethane predominated. Treatments characterized by significant Fe(III) and/or Mn(IV) reduction, on the other hand, demonstrated substantial, and in some cases exclusive, accumulation of 14CO2 and 14CH4. These results suggest that relying on the accumulation of cis‐DCE, VC, ethene, and ethane may substantially underestimate overall chloroethene biodegradation at many sites. © 2007 Wiley Periodicals, Inc. * 1 This article is a U.S. government work and, as such, is in the public domain in the United States of America. |
| |
Keywords: | |
|
|