Distribution and Ecological Risk Assessment of Heavy Metals in Sediments of Chaohu Lake

Chaohu Lake is one of the five largest fresh lakes in China.The sediments of Chaohu Lake and some of its tributary rivers were sampled and analyzed for the contents of heavy metals(Cd,Cr,Pb,Cu,Zn,Mn,Fe) in order to know their spatial distribution and the potential ecological hazard.The results indicated that the levels of heavy metals in the sediments of the rivers(esp.the Nanfei River) were even higher than those of the lake.Among the heavy metals, their levels followed a decreasing order of FeMnZnCrPbCuCd.Concerning the vertical distribution, the concentration of heavy metals decreased along with the increasing of depth, and the highest level is presented in the layer 0～8 cm of depth.The potential ecological risk index was used to evaluate metals pollution in sediments of Chaohu Lake.By means of the risk assessment methodology, based on available data, it was demonstrated that Nanfei River was exposed to a very high potential ecological risk.Among the analyzed heavy metals, Cd exhibited the highest pollution degree at the most of the sampling points.The other points were under a low potential ecological risk.