Influence of Cadmium Input on the Nutritional Properties in Overlying Water of Eutrophic Lakes

The characteristics of nutrient in eutrophic lakes, Lake Donghu and Lake Nanhu, Wuhan City, were investigated with the input of cadmium (Cd) at lab scale. To investigate the influence of Cd concentrations to nitrogen and phosphorus transference, we simulated the condition of Lake Nanhu and Lake Donghu in PVC columns, and the concentrations of import Cd to overlying water were designed as 0 mg/L, 5 mg/L, 50mg/L. The results showed Cd could reduce the TP concentration of the overlying water and inhibit the release of phosphorous from the sediments. The eutrophication degree of Lake Nanhu was more serious, so was effect of Cd. However, the TP release from sediments between Cd-5 and Cd-50 treatments didn´t exhibit obvious difference. The inhibition of Cd to the release of soluble phosphate was apparent as also. The higher the Cd concentration input in the overlying water, the stronger the inhibition to release of soluble phosphate from lake sediments imposed. The influence of Cd to the variation of TN and ammonia nitrogen in overlying water seemed negligibly, but as for Lake Nanhu which was more eutrophied, the TN released from sediments for Cd-0 treatment was more than Cd-5 and Cd-50 treatments.