Current use organohalogen contaminant distributions in seawater and trophodynamics in marine and terrestrial food chains of the Canadian Arctic

This thesis investigated the concentrations and bioaccumulation of current use organohalogen contaminants (OHCs) in the Canadian Arctic. Current use pesticides (CUPs), polybrominated diphenyl ethers (PBDEs), and alternative halogenated flame retardants (HFRs) were measured in seawater, and their bioaccumulation processes in polar bear (Ursus maritimus)-ringed seal (Pusa hispida) food chains in three locations across Nunavut (Canada) were assessed. Their bioaccumulation was also evaluated throughout the Arctic wolf (Canis lupus) food chain in the Bathurst Region of the Northwest Territories and Nunavut. Concentrations of OHCs in the terrestrial and marine organisms were relatively similar (low to sub ng g-1 lipid weight). Volumetric bioconcentration factors (BCFv) and bioaccumulation factors (BAFs) indicated effective uptake of the CUPs, PBDEs and some alternative HFRs by terrestrial and marine organisms. Biomagnification of some octaBDEs, the nona–decaBDEs and total PBDEs (PBDE) was evident in wolves and caribou (Rangifer tarandus groenlandicus), and these compounds (with BDE28/33 and the HFR) underwent a small degree of trophic magnification in that food chain [trophic magnification factors (TMFs) = 1.3–2.1]. The CUPs had very limited biomagnification, and along with the alternative HFRs, all underwent trophic dilution (decreasing concentrations with increasing trophic level) through the terrestrial food chain. In seawater, CUPs, PBDEs and select alternative HFRs were detected at low pg L-1 concentrations. In the marine food chains, there was differential biomagnification of chlorothalonil, -endosulfan and -endosulfan in polar bears (BMFs >1 in some locations). All other significant BMFs for CUPs across the three locations were in lower TL interactions (e.g., plankton:algae). Only two PBDEs (BDE17 and BDE154) exhibited any biomagnification in ringed seals, at Barrow and Rae Straits alone. At Cumberland Sound, all significant biomagnification occurred in capelin (Mallotus villosus), a transient fish (>1000 km range) that ranges into temperate zones. The TMFs of the OHCs indicated near-universal trophic dilution through the ringed seal food chains; only endosulfan sulfate magnified, and only through the poikilothermic portion of the marine food web. It is unlikely that the OHCs investigated here will undergo large-scale biomagnification through these food chains, most likely due to effective metabolic transformation and environmental degradation of the contaminants.