Long Range Transport of Toxic Organic Contaminants to the North American Great Lakes

Swain, Wayland; Mullin, M; Filkins, John

Studies of persistent organic contaminants made for the Upper Lakes Reference Group of the International Joint Commission in 1974-1976 indicated increased levels of organic contamination in flesh of fish taken from the vicinity of Isle Royale in Lake Superior. These findings led to a preliminary study of polychlorinated biphenyl (PCB) compounds in atmospheric precipitation deposited in Siskiwit Lake on Isle Royale. Subsequent studies reported here support the earlier findings but show signficant shifts in observed concentrations. Initially, these altered values were thought to be the result of increasing environmental concentrations of PCBs. The use of refined analytical procedures suggests, however, that the apparent changes are a function of the co-occurrence of derivatives of the pesticide toxaphene within the analytical spectrum of the PCB fraction. A comparison of the older data from Siskiwit Lake with those acquired from contemporary analytical procedures suggests that it is likely that derivatives of toxaphene may have been enumerated with PCB peaks, thus being inadvertently reported as total PCB. Based on results obtained with high resolution capillary chromatography, apparent increases in concentrations of PCB compounds in 1980 packed column chromatography samples are undoubtedly a function of historic analytical limitation, rather than an absolute change in environmental concentrations of the PCB compounds.