M8 PM Chiral Chemistry: Toxicology of Environmental Contaminants and Phase Transfer
Monday, 14 November 2005: 1:50 PM - 5:30 PM in 337-338

(MOR-1117-759673) Chiral polychlorinated biphenyls in the aquatic food web of Lac la Biche, Alberta.

Morrissey, Joshua¹, Wong, Charles¹, ¹ University of Alberta, Edmonton, AB, Canada

ABSTRACT- Enantiomeric fractions (EFs) of chiral pollutants are useful indicators of biotransformation in the environment. The aquatic food web of Lac la Biche (LLB), Alberta has undergone significant changes, ranging from hypereutrophication to population loss of walleye from over-fishing. The dramatic decrease in the numbers of walleye has resulted in a population explosion of double-crested cormorants, which have replaced walleye as the top predator in this system. Population control measures are currently in place to reduce the numbers of double crested cormorants at LLB. Chiral polychlorinated biphenyls (PCBs) were studied in the aquatic food web of LLB in order to assess the changing dynamics of this food web. Invertebrates, forage fish (e.g., yellow perch, spottail shiners, white suckers), predatory fish (including northern pike) and cormorant eggs, chicks, and adults were collected in 2004. Samples were extracted for organochlorine pesticides and analyzed by chiral gas chromatography/mass spectrometry (GC/MS), while stable carbon and nitrogen ratios were used to determine feeding and trophic structure. Preliminary results which show racemic EFs of chiral PCBs in yellow perch indicate that stereoselective biotransformation of PCBs is not occurring in the lower food web of LLB, while possible changes in EF at higher trophic levels may indicate the occurrence of biotransformation in this food web.

Key words: bioaccumulation, biotransformation, chiral PCBs, food webs