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Dehydrochlorination of 1,1,1‐trichloroethane and pentachloroethane by microbially reduced ferruginous smectite
Author(s) -
CerviniSilva Javiera,
Kostka Joel E.,
Larson Richard A.,
Stucki Joseph W.,
Wu Jun
Publication year - 2003
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620220511
Subject(s) - clay minerals , chemistry , environmental chemistry , incubation , dithionite , anoxic waters , shewanella oneidensis , reductive dechlorination , biodegradation , mineralogy , organic chemistry , geology , bacteria , biochemistry , enzyme , paleontology
Reduction of structural Fe(III) in smectite clay minerals has been identified as a means to promote dechlorination of polychlorinated ethanes, but its environmental significance has yet to be fully assessed because Fe reduction has normally been achieved by agents uncommon in the environment (e.g., dithionite). This study reports the dehydrochlorination of pentachloroethane and 1,1,1‐trichloroethane in the presence of ferruginous smectite reduced by two cultures of microorganisms, Shewanella oneidensis strain MR‐1 (MR‐R) and an enrichment culture from rice paddy soils (PS‐R), in aqueous suspension under anoxic conditions. Microbially reduced ferruginous smectite facilitated dehydrochlorination of 1,1,1‐trichloroethane to 1,1‐dichloroethene with up to 60% conversion within 3 h of incubation time. In contrast, no formation of 1,1‐dichloroethene was observed after incubation of 1,1,1‐trichloroethane with chemically reduced ferruginous smectite for 24 h. Microbially reduced ferruginous smectite by MR‐R and PS‐R promoted the dehydrochlorination of pentachloroethane to tetrachloroethene by 80 and 15%, respectively, after 3 h of incubation time. The conversion of pentachloroethane to tetrachloroethene in the presence of chemically reduced ferruginous smectite after 24 h was 65%. These results indicate that structural Fe(II) in clay minerals has the potential to be an important reductant controlling the fate of organic chemicals in contaminated sediments.