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Accumulation of dechlorination daughter products: A valid metric of chloroethene biodegradation
Author(s) -
Bradley Paul M.,
Chapelle Frank H.
Publication year - 2007
Publication title -
remediation journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.762
H-Index - 27
eISSN - 1520-6831
pISSN - 1051-5658
DOI - 10.1002/rem.20140
Subject(s) - reductive dechlorination , microcosm , chemistry , biodegradation , vinyl chloride , environmental chemistry , chloride , enrichment culture , organic chemistry , geology , copolymer , polymer , paleontology , bacteria
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‐ 14 C] TCE, [1,2‐ 14 C] DCE, [1,2‐ 14 C] DCA, or [1,2‐ 14 C] VC, demonstrated widely variable patterns of intermediate and final product accumulation. In predominantly methanogenic sediment treatments, accumulation of 14 C‐DCE, 14 C‐VC, 14 C‐ethene, and 14 C‐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 14 CO 2 and 14 CH 4 . 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. * This article is a U.S. government work and, as such, is in the public domain in the United States of America.