Transport of Toxic substances into Lake Superior by Suspended Solids

Abstract

A primary threat to Great Lakes sport and commercial fisheries arises from contamination problems due to the introduction of certain xenobiotic chemicals in aquatic environments. Of particular concern are hydrophobic organic chemicals and heavy metals which bioaccumulate in aquatic animals. Fish bioaccumulation of toxic and/or carcinogenic substances can occur from water, suspended particles, sediments and through food chains (Byran, 1979). The threat of toxic substance contamination is likely to continue in the foreseeable future because of serious hazardous wastes disposal problems in the Great Lakes Basin (IJC, 1979) and the widespread dispersion of pollutants via the atmosphere (Eisenreich, 1981). Pollutants enter water systems from a variety of point and nonpoint sources, including surface runoff, atmospheric input, municipal and industrial discharges and vessel operations. The hydrophobic character of many organic pollutants and the affinity of heavy metals for colloidal material cause association with sediments and suspended solids such as clays, detritus material and various biomass forms (Baker, 1980). Suspended particles can represent a major river-lake transport host for chemical compounds such as chlorinated hydrocarbons (Shear and Watson, 1977). Finely divided colloidal-type particles such as clays can be transported to deep regions of lake basin areas (Leland et tl-, 1973; Baker, 1980). Some contaminants associated with sediments are resistant to biodegradation.