CADMIUM, COPPER AND LEAD IN AQUATIC MACROPHYTES IN SHOAL LAKE (MANITOBA-ONTARIO)

Cadmium, copper and lead concentrations were surveyed in several species of submerged aquatic macrophytes in a Precambrian Shield Lake. Values were variable within each species and interspecific differences in metal concentration were not significant over the season as a whole. Cadmium concentration increased during the season in Potamogeton foliosus and Myriophyllum exalbescens, while copper and lead declined in P. foliosus. No identifiable seasonal trends were seen in P. zosteriformis and P. robbinsii. In P. foliosus, copper and lead concentrations increased with water depth. Few significant correlations were found between metal concentrations in the shoots and each of several water chemistry parameters, temperature, and shoot chlorophyll, soluble sugar and starch content. Roots yielded greater metal concentration than shoots.