CADMIUM ACCUMULATION IN EURASIAN WATERMILFOIL PLANTS

The aquatic vascular plant Eurasian watermilfoil (Myriophyllum spicatu m L.) was investigated for its potential to take up Cd from nutrient-r ich water in a short-term growth and harvest regime. Eurasian watermil foil plants were grown in and harvested weekly from 0.10 M Hoagland nu trient solutions containing concentrations of Cd from 0.04 to 7.63 mu g Cd mL(-1). Dry weights of plants significantly decreased when expose d to 7.63 mu g Cd mL(-1). For both 0.04 and 1.03 mu g Cd mL(-1) treatm ent the greatest concentration of Cd in plants occurred during the fir st two weeks. The greatest Cd concentration of Cd in plants for the 7. 63 mu g Cd mL(-1) treatment occurred during week one and decreased thr ough week 2. Tissue P concentration in control plants increased over t ime but did not increase significantly over time when plants were expo sed to 0.04 and 1.03 mu g Cd mL(-1) levels. Tissue P concentration dec reased over time when plants were exposed to 7.63 mu g Cd mL(-1). Stem length, root dry weights, and root number significantly increased ove r time in control plants and in those exposed to the 0.04 and 1.03 mu g Cd mL(-1) treatments. Plants treated with 7.63 mu g Cd mL(-1) did no t grow. These results suggest that Eurasian watermilfoil would be usef ul for absorbing Cd from nutrient-rich water when the solution concent ration was in the range of 0.04 to 7.63 mu g Cd mL(-1). However, in so lutions having the highest concentration of Cd, the harvest regime wou ld have to sustain plant vigor, avoid tissue Cd loss, and realize maxi mum uptake of Cd from solution.