Concentrations and distributions of polychlorinated biphenyls, including non-ortho congeners, in mink populations from southern Ontario

Concentrations and distributions of polychlorinated biphenyls and organochl orines were quantified in 79 wild mink livers as part of a study to assess the Else of mink as biomonitors of organic contaminants in wetlands. Sample s were collected from fifteen southern Ontario townships, including townshi ps bordering the Great Lakes and further inland to quantify the relative im portance of the Great Lakes food webs an contaminant levels observed in fer al mink populations. The mink population in Mersea Township (Chatham Distri ct), bordering Lake Erie, was found to have significantly higher concentrat ions (1,797 mu g/kg total PCB, wet weight) of many of the contaminants quan tified. Reach Township (Lindsay District), inland from Lake Ontario, had si gnificantly lower concentrations (39 mu g/kg total PCB, wet weight). Multiv ariate analysis of organochlorine data demonstrated little spatial differen ce among PCB congener distribution patterns, except a greater proportion of total PCB was contributed by PCB 118 in mink taken from Wainfleet (Niagara District) and Reach Townships. The more toxic non-ortho PCBs were rarely f ound above levels of detection (0.05 mu g/kg), and PCBs 126 and 118 represe nted over 90% of the estimated TEQ. In the more contaminated areas, PCB con centrations were sufficiently high to potentially affect the fitness of min k populations.