The concentrations of heavy metals were comparedin four dominant submerged macrophytes (Fig. 3). Significant difference was only found in Cd concentration among the submerged plants (po0.05). The Cd concentrationin C. demersum was significantly higher than that in Myriophyllum spicatum, but not significantly higher than that in Potamogeton maackianus and Stuckenia pectinata. The maximum values of As and Cd were 23 and 1.05 mgkg_1 in S. pectinata, respectively (Table2). The maximum percentages of Cr, Fe, and Ni in above-ground partsof C. demersum were 0.42 percent, 1.64 percent, and 0.27 percent, respectively (Table2).