Degradation of Ã-hexachlorocyclohexane and organochlorine contaminant fate in High Arctic lakes

• Main Author: Helm, Paul Anthony
• Format: Thesis
• Language: English
• Published: 1999
• Subjects: Arctic; Baffin Island; Lawrence River; Tagish; Arctic marine mammals; Baffin; Beluga; Beluga whale; Beluga*; ringed seal
• Online Access: http://hdl.handle.net/1807/12947; http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0003/MQ45581.pdf

grantor: University of Toronto Polychlorinated naphthalenes (PCNs) are a class of persistent organic pollutants (POPS) used prior to and in similar applications to polychlorinated biphenyls (PCBs). PCNs have a planar structure like non-/mono-'ortho ' PCBs and chlorinated dioxins (PCDDs) resulting in similar biomagnification properties and modes of toxicity. PCNs are proposed additions to the list of restricted and banned substances under the UNECE-Long-Range Transboundary Atmospheric Pollutants (LRTAP)-POPs Protocol. Research conducted as part of this thesis has improved our knowledge of the environmental occurrence and behaviour of PCNs and non-/mono-' ortho' PCBs from an atmospheric perspective in the Great Lakes and Arctic regions of North America. Analytical methods were improved by using a cyclodextrin-based GC column to resolve coeluting penta- and hexaCNs which have varying degrees of toxicity and which bioaccumulate. Elevated PCN levels were observed in air of urban areas relative to over the Great Lakes and in the Arctic. Current combustion sources contributed up to 55% of the PCNs in air in north Toronto while evaporative emissions were the predominant source in the downtown. Over-lake PCN concentrations were highest for L. Ontario compared to L. Huron, L. Superior, and the upper St. Lawrence River and estimates of air-water gas exchange showed triCNs volatilize from L. Ontario while tetraCNs are near equilibrium. PCNs in air collected at arctic monitoring stations at Alert, NU, Tagish, YK, and Dunai, Russia, varied seasonally with higher levels in winter coinciding with transport of air masses from Eurasia and were correlated with anthropogenic sulfate concentrations. At Resolute, NU, PCN and non-/mono-'ortho' PCB concentrations were temperature-dependent, suggesting regional or local sources influence levels. PCNs contributed as much or more dioxin toxic equivalents than non-/mono-'ortho' PCBs in urban and arctic air. PCNs were higher in beluga whale than ringed seal blubber collected near Baffin Island. The occurrence of PCNs in arctic marine mammals demonstrates their persistence and ability to accumulate through the food web. These results strengthen the argument for the addition of PCNs to the UNECE POPS Protocol by providing monitoring data from remote regions and by illustrating the contributions due current sources in addition to past-use evaporative sources. M.A.Sc.