Organic and Inorganic Contaminants in the St. Lawrence River: Some Preliminary Results on Their Distribution

Abstract

Abstract Volatile hydrocarbons (VHC’s) have been measured at many locations in the St. Lawrence River, Several concentrations of VHC’s were higher than those measured at other polluted Great Lakes sites, e.g. the St. Clair River. Tributaries to the St. Lawrence River were found to be significant sources of VHC’s. Cadmium in the St. Lawrence River is mostly found in dissolved (bioavailable) forms as compared to the Mississippi River where dissolved cadmium accounts for about 10% of the total cadmium. The major sources of cadmium appear to be in the Montreal area. Although the analytical results show local impairment in water quality, intensive sampling is required to pinpoint sources and/or quantify loadings, However, none of the VHC or cadmium concentrations exceed water quality guidelines or objectives. In fact there are no guidelines for most VHC’s. Nevertheless, the concentrations of VHC’s and cadmium found should have no toxic effect on aquatic organisms. The results of this study indicate that there are major sources of VHC’s and cadmium in Quebec. For example, inputs on the southwestern portion of Lac St.Louis may be a major source of perchloroethylene, and effluents in the vicinity of the Montreal STP may be a major source of cadmium. U.S. tributaries, e.g. the Grassy River, may also be a significant source of VHC’s.