Using chiral polychlorinated biphenyl (PCB) congeners as probes to understand biotransformations in food webs offers significant insights but also challenges.  Our studies of aquatic and riparian food webs at a Superfund Site in the northwestern corner of South Carolina have shown atropisomeric PCBs to be valuable tracers.  The Superfund Site within the Lake Hartwell watershed provides a unique field site because 1) PCBs are the only contaminants, 2) there is limited development, and 3) the current remediation consists of natural attenuation through sedimentation.  Here, we present results of three studies that suggest several levels of metabolism can occur in both aquatic and riparian food webs.  The first study found that microbial communities that colonize basal resources of the stream system (e.g., fine benthic organic matter, coarse particulate organic matter, and biofilms) produce different enantiomeric fractions (EF).  Transfer of atropisomers from these basal resources suggested through changes in EF that <i>in vivo</i> biotransformation occurs in successive trophic levels.  In a second study, historical differences in EF values for four atropisomeric PCB congeners (CB 91, 95, 136, and 149) were observed in bluegills and largemouth bass between 1994 and 2004 that suggest distinct metabolic pathways between the prey and predator.  The last study considered the links as observed with EFs among invertebrate larvae in PCB-contaminated sediment, riparian spiders, and riparian amphibians.  The collection of studies highlights the value of using persistent organic pollutants that are also chiral to understand contaminant biotransformation in complex food webs as well as points to future directions for laboratory studies.

Enantioselective biotransformation of chiral PCBs in aquatic to riparian food webs

249th National Meeting (2015)

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