HA5 Bioaccumulation and Biomagnifications
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() Biomagnification of Perfluoroalkyl Contaminants in the Lake Ontario Food Web.

Martin, J1, Whittle, D2, Muir, D3, Mabury, S1, 1 University of Toronto, Toronto, ON, Canada2 Department of Fisheries and Oceans, Burlington, ON, Canada3 Environment Canada, Burlington, ON, Canada

ABSTRACT- Perfluorooctane sulfonate (PFOS) is a persistent and bioaccumulative perfluorinated acid recently detected in humans and wildlife worldwide that has alerted scientists to the environmental fate of other fluorinated organic contaminants. More recently a homologous series of perfluoroalkyl carboxylates (PFCAs) was detected in the Arctic, but the breadth of global contamination has not yet been explored. In this study we determined PFOS, the homologous series of PFCAs ranging from 8-15 carbons in chain length, and the PFOS-precursor heptadecafluorooctane sulfonamide (FOSA) in various organisms from a food web of Lake Ontario. The organisms analyzed included a top predator fish, lake trout (Salvelinus namaycush), three forage fish species including rainbow smelt (Osmerus mordax), slimy sculpin (Cottus cognatus), and alewife (Alosa pseudoharengus), and two invertebrates Diporeia (Diporeia hoyi) and Mysis (Mysis relicta). A striking finding was that the highest concentrations for all fluorinated contaminants were detected in the benthic macroinvertebrate Diporeia, which occupies the lowest trophic level of all organisms analyzed. Perfluorinated acid concentrations in Diporeia were often 10-fold higher than in Mysis, a predominantly pelagic feeder, suggesting that a major source of perfluoroalkyl contaminants to Lake Ontario biota is the sediment, not the water. PFOS was the dominant acid in all samples, but long-chain PFCAs, ranging in length from 8 to 15 carbons were also detected in most samples between <0.5 and 90 ng/g. Among Mysis and the more pelagic fish species (e.g. excluding Diporeia and sculpin) there was evidence for biomagnification, but the influence of foraging on highly contaminated Diporeia and sculpin by these fish may have overestimated trophic magnification factors (TMFs), which ranged from 0.51 for FOSA to 5.88 for PFOS. By accounting for the known diet composition of lake trout, it was shown that bioaccumulation was indeed occurring at the top of the food web for all perfluoroalkyl compounds except PFOA.

Key words: biomagnification, bioaccumulation, perfluorinated, PFOS

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