ORGANOCHLORINE INSECTICIDES AND PCB IN THE SEDIMENTS OF LAKE-HURON (1969) AND GEORGIAN-BAY AND NORTH-CHANNEL (1973)

Surficial and core sediments were collected from the main body of Lake Huron in 1969 and Georgian Bay and North Channel in 1973. These were analysed for organochlorine insecticides and PCB. Residues of organochlorines were higher in the twelve depositional basins in Lake Huron and Georgian Bay than in sediment in the nondepositional zones. PCB was present at similar concentrations to ΣDDT; with mean levels of 13 and 10 ng/g for PCB and ΣDDT in the main body of Lake Huron and 11 and 5 ng/g for PCB and ΣDDT in Georgian Bay. Residues of PCB varied from 9-33 ng/g in the 12 basins. With respect to ΣDDT, both parent DDT and its two metabolites were present in sediment at a mean residue of 7.8 ng/g for the whole lake. The main lake had residues of 10.2 ng/g while Georgian Bay had 5.8 ng/g and North Channel 4.1 ng/g in keeping with use patterns since 1943. HEOD was present in only 5.7% of sediment samples from main Lake Huron, 30% from Georgian Bay and 15% from North Channel. The highest residues 1.7 ng/g occurred in the North Channel. No chlordane was detected, however, heptachlor epoxide was identified in 8.5% of sediments collected in Lake Huron, 23% from Georgian Bay and 14% in North Channel. Endosulfan appeared in 4% of samples from both Georgian Bay and North Channel. © 1979.