Organochlorine Compounds in Lake Superior: Chiral Polychlorinated Biphenyls and Biotransformation in the Aquatic Food Web

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• 作者：Charles S. Wong ; Scott A. Mabury ; D. Michael Whittle ; Sean M. Backus ; Camilla Teixeira ; David S. DeVault ; Charles R. Bronte ; and Derek C. G. Muir
• 刊名：Environmental Science & Technology
• 出版年：2004
• 出版时间：January 1, 2004
• 年：2004
• 卷：38
• 期：1
• 页码：84 - 92
• 全文大小：135K
• 年卷期：v.38,no.1(January 1, 2004)
• ISSN：1520-5851

文摘

The enantiomeric composition of seven chiral PCBcongeners was measured in the Lake Superior aquaticfood web sampled in 1998, to determine the extent ofenantioselective biotransformation in aquatic biota. All chiralPCB congeners studied (CBs 91, 95, 136, 149, 174, 176,and 183) biomagnified in the Lake Superior aquatic foodweb, based on biomagnification and food web magnificationfactors greater than unity. PCB atropisomers wereracemic in phytoplankton and zooplankton, suggesting nobiotransformation potential toward PCBs for these lowtrophic level organisms. However, Diporeia and mysids hadsignificantly nonracemic residues for most chiral congenersstudied. This observation suggests that these macrozooplankton can stereoselectively metabolize chiral congeners.Alternatively, macrozooplankton obtained nonracemicresidues from feeding on organic-rich suspended particlesand sediments, which would imply that stereoselectivemicrobial PCB biotransformation may be occurring in LakeSuperior sediments at PCB concentrations far lowerthan that previously associated with such activity. Widelynonracemic PCB residues in forage fish (lake herring,rainbow smelt, and slimy sculpin) and lake trout suggesta combination of both in vivo biotransformation and uptakeof nonracemic residues from prey for these species.Minimum biotransformation rates, calculated from enantiomermass balances between predators and prey, suggestmetabolic half-lives on the order of 8 yr for CB 136 in laketrout and 2.6 yr for CB 95 in sculpins. This result suggeststhat significant biotransformation may occur for metabolizable PCB congeners over the lifespan of these biota. Thisstudy highlights the potential of chiral analysis to studybiotransformation processes in food webs.