Chlorinated Organic Residues in Fish, Water, and Precipitation from the Vicinity of Isle Royale, Lake Superior

Abstract

Studies of persistent organic contaminants for the Upper Lakes Reference Group of the International Joint Commission indicated increased levels of organic contamination in the flesh of fish taken from the vicinity of Isle Royale on Lake Superior. Significant increases in levels of organic residues in Lake Superior fish near Isle Royale were observed in lean lake trout, Salvelinus namaycush, and in fat lake trout, Salvelinus namaycush siscowet.Siskiwit Lake, a deep cold lake on Isle Royale, well removed from the direct influences of man, was selected as a control site for studies on Lake Superior. Values for several organic residues in the flesh of fish from Siskiwit Lake were significantly higher than corresponding fish from Lake Superior. Polychlorinated biphenyls were nearly double the Lake Superior mean value, and p,p-DDE showed a more than 10 fold increase in Siskiwit Lake.These findings lead to a preliminary study of the transport of polychlorinated biphenyl compounds in atmospheric precipitation. Data from the Isle Royale area are compared with metropolitan sites and with those of other investigators.