Hydrocarbons in the surficial sediments of Lakes St. Clair,Erie, and Ontario

Although the long-term effects and the fate of petroleum hydrocarbons in marine and freshwater environments are not fully understood, it is generally recognized that much of the oil released by accidental spills or by various land sources ends up in the sediment where it may remain for at least several years The present study was undertaken to collect some initial data on the hydrocarbon concentrations in surficial sediments of lakes St Clair, Erie, and Ontario The distribution of hydrocarbons in these lakes followed the general patterns found for a number of contaminants, in that the distribution tended to coincide with the outlines of the sedimentary basins The highest concentrations were found in the Western Basin of Lake Erie and in the inshore zone around the west end of the lake, suggesting major inputs from the Detroit River Apart from some spots of high concentration around known dumping grounds, the concentrations gradually diminish toward the east The distribution pattern in Lake Ontario may be more readily ascribed to water circulation patterns than to any specific source around the lake The hydrocarbon levels were found to be significantly lower than those in Lake Erie in Lake St Clair only trace quantities of hydrocarbons were found, suggesting either low inputs or low sedimentation/accumulation rates due to its shallowness Although the present survey was limited to the top 3 cm of the sediments, the resulting distribution patterns indicate the western end of Lake Erie as the area with the heaviest hydrocarbon loadings The results may also facilitate the selection of specific areas where core sampling coupled with more complete analysis of the extracts could yield significant information on the long-term accumulation of anthropogenic hydrocarbons, and on their persistence and transformations in Great Lakes sediments