Microbial Responses to Trace Elements and Nutrients in the St. Lawrence River

Abstract

Abstract Over 100 surface sediment samples from Lac St. Louis (St. Lawrence River) were examined for various microbial physiological types and densities. These organisms were correlated to the concent rat ions of trace elements (Ni, Co, Cr, V, Cu, Pb, Zn, As, Fe, Mn and Ti) and nutrients (P and organic matter). Results indicated a relationship between bacterial densities and trace element concentrations. Data also suggested there was an apparent indication of bacterial inhibit ion due to toxic substances in the lake sediment. Generally, high and low bacterial density zones existed in the sediment with low bacterial density zones being associated with high concentrations of trace elements. Because of the relationships and the distribution of trace elements and organic matter, the lake bottom exhibited a heterogeneous nature. The availability of trace elements in the surface sediments was assessed by determination of chemical species of the trace elements in solutions obtained by elutriation of the sediment with distilled water. Data and methodology are presented.