Effects of activated carbon on reductive dechlorination of PCBs by organohalide respiring bacteria indigenous to sediments.
Polychlorinated biphenyls (PCBs) have accumulated in aquatic sediments due to their inherent chemical stability and their presence poses a risk due to their potential toxicity in humans and animals. Granular activated carbon (GAC) has been applied to PCB contaminated sediment sites to reduce the aqueous concentration by sequestration thus reducing the PCB exposure and toxicity to both benthic and aquatic organisms. However, it is not known how the reduction of PCB bioavailability by adsorption to GAC affects bacterial transformation of PCBs by indigenous organohalide respiring bacteria. In this study, the impact of GAC on anaerobic dechlorination by putative organohalide respiring bacteria indigenous to sediment from Baltimore Harbor was examined. It was shown that the average Cl/biphenyl after dehalogenation of Aroclor 1260 was similar between treatments with and without GAC amendment. However, GAC caused a substantial shift in the congener distribution whereby a smaller fraction of highly chlorinated congeners was more extensively dechlorinated to mono- through tri-chlorinated congeners compared to the formation of tri- through penta-chlorinated congeners in unamended sediment. The results combined with comparative sequence analysis of 16S rRNA gene sequences suggest that GAC caused a community shift to putative organohalide respiring phylotypes that coincided with more extensive dechlorination of ortho and unflanked chlorines. This shift in activity by GAC shown here for the first time has the potential to promote greater degradation in situ by promoting accumulation of less chlorinated congeners that are generally more susceptible to complete mineralization by aerobic PCB degrading bacteria.
Goucher College, Department of Biological Sciences, 1021 Dulaney Valley Road, Baltimore, MD 21204, USA. Electronic address: birthe.kjellerup@goucher.edu.
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Kjellerup
Institute of Marine and Environmental Technology, Columbus Center, University of Maryland, 701 E. Pratt Street, Baltimore, MD 21202, USA.
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Naff
Goucher College, Department of Biological Sciences, 1021 Dulaney Valley Road, Baltimore, MD 21204, USA.
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Edwards
University of Maryland Baltimore County, Department of Civil and Environmental Engineering, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
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Ghosh
Center for Urban Waters, University of Washington-Tacoma, 326 East D Street, Tacoma, WA 98421, USA.
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Baker
Institute of Marine and Environmental Technology, Columbus Center, University of Maryland, 701 E. Pratt Street, Baltimore, MD 21202, USA.
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Sowers
D001140:Aroclors / Q000737:chemistry / Q000378:metabolism; D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D002140:California; D002606:Charcoal; D019015:Geologic Sediments / Q000382:microbiology*; D054879:Halogenation; D008396:Maryland; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism
D001140:Aroclors; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; C026987:aroclor 1260; D002606:Charcoal; D011078:Polychlorinated Biphenyls
Granulated activated carbon; Organohalide respiring bacteria; Polychlorinated biphenyls (PCBs); Sediment