PH11 Bioaccumulation and Biotransformation of POPs
Exhibit Hall
8:00 AM - Thursday, 13 November 2003
(PH122) Contributions of atmospheric deposition to food chain biomagnification in the Chilliwack watershed of British Columbia, Canada.
Morrissey, C1, Bendell-Young, L1, Elliott, J2, 1 Dept. of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada2 Environment Canada, Canadian Wildlife Service, Delta, BC, Canada
ABSTRACT- Research on food chain contamination in remote arctic and lake ecosystems has revealed significant concentrations of persistent organic pollutants in fish and wildlife from long-range atmospheric sources. Biota occupying mountain streams are similarly exposed to organic contaminants from atmospheric deposition through runoff of contaminated snow pack and glaciers. Therefore, we assessed the extent to which atmospheric pollutants were contributing to food chain contamination in mountain streams of southwestern British Columbia, Canada, particularly the Chilliwack River watershed. Through analysis of American dipper (Cinclus mexicanus) eggs, invertebrates and salmon fry prey; we found that polychlorinated biphenyls (PCBs), DDE, hexachlorobenzene (HCB) and trans-nonachlor were the most commonly detected organic compounds in dipper eggs and prey. PCB and organochlorine patterns were highly consistent across sites within the Georgia Basin and between prey and dipper eggs, indicating common sources from atmospheric deposition to the region. Concentrations of total organochlorines and PCBs in dipper eggs were positively related to drainage area and collection year but not to elevation. Total PCBs in dipper eggs and prey were dominated by congeners 153, 138 and 180. No differences in egg congener patterns existed between Chilliwack egg samples and other Georgia Basin samples. However, principle component analysis revealed significant spatial differences between dipper eggs collected from the main stem of the Chilliwack River and those on smaller tributaries, primarily due to variation in the lower chlorinated PCBs 66 and 105. Biomagnification of atmospheric contaminants occurred between trophic levels for DDE, HCB, trans-nonachlor, and total PCBs with the highest biomagnification factors calculated for PCBs (183) and DDE (32). This study provides a benchmark for using a unique aquatic passerine, the American dipper, for biomonitoring persistent organic pollutants in mountain streams of western North America.
Key words: watersheds, POPs, food chain, bioaccumulation