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Dechlorination of Individual Congeners in Aroclor 1248 as Enhanced by Chlorobenzoates, Chlorophenols, and Chlorobenzenes
Ist Teil von
Journal of Microbiology and Biotechnology, 2008, 18(10), , pp.1701-1708
Ort / Verlag
Seoul: Korean Society for Applied Microbiology
Erscheinungsjahr
2008
Quelle
Free E-Journal (出版社公開部分のみ)
Beschreibungen/Notizen
Previous investigations showed that three classes of haloaromatic compounds (HACs: chlorobenzoates, chlorophenols, and chlorobenzenes) enhanced the reductive dechlorination of Aroclor 1248, judging from the overall extent of reduction in Cl atoms on the biphenyl. In the present study, we further investigated the kind of polychlorinated biphenyl (PCB) congeners involved in the enhanced dechlorination by four isomers belonging to each class (2,3-, 2,5-, 2,3,5-, and 2,4,6-chlorobenzoates; 2,3-, 3,4-, 2,5-, and 2,3,6-chlorophenols; and 1,2-, 1,2,3-, 1,2,4-, and penta-chlorobenzencs). Although the PCB congeners involved in the enhanced dechlorination varied with the HACs, the enhancement primarily involved para-dechlorination of the same congeners (2,3,4'-, 2,3,4,2'-plus 2,3,6,4'-, 2,5,3',4'- plus 2,4,5,2',6'-, and 2,3,6,2',4'-chlorobiphenyls), regardless of the HACs. These congeners are known to have low threshold concentrations for dechlorination. To a lesser extent, the enhancement also involved meta dechlorination of certain congeners with high threshold concentrations. There was no or less accumulation of 2,4,4'- and 2,5,4'-chlorobiphenyls as final products under HAC amendment. Although the dechlorination products varied, the accumulation of ortho-substituted congeners, 2-, 2,2'-, and 2,6-chlorobiplienyls, was significantly higher with the HACs, indicating a more complete dechlorination of the highly chlorinated congeners. Therefore, the present results suggest that the enhanced dechlorination tinder HAC enrichment is carried out through multiple pathways, sonic of which may be universal, regardless of the kind of HACs, whereas others may be HAC-specific.