Heavy Metal Pollution in the Surface Sediment of Dan River and Its Ecological Risk Assessment

The concentrations of heavy metals(Mn,Zn,Cu,Pb,Cd,Cr,Hg,As)in the surface sediment of Dan River and its main tributaries were determined by using atomic absorption spectrometry(AAS)and atomic fluorescence spectrometry(AFS),and the toxic effects and sediment pollution assessment were conducted systematically by using Sediment Quality Guidelines(SQG),Hakanson Potential Ecological Risk Index.Moreover,the underlying source of heavy metal was analyzed.The results indicated that the average concentrations of Mn,Zn,Cu,Pb,Cd,Cr,Hg,As were 115.1,18.78,8.46,6.49,2.85,60.6,0.047,14.22 mg·kg-1 respectively.Base on the SQG,the surface sediment in Dan River was moderately contaminated by Cd,As and Cr since their concentrations were just between lowest effect leve(lLE-L)and severe effect leve(lSE-L)values,which could be result in negative biota effects in the watersheds.Except for As and Cr,other heavy metal elements found the most obvious positive correlation.These heavy metals had a common trend and the same pollution source.Industrial waste was one of the most important anthropogenic emission sources of trace elements and an important source of heavy metals mainly.Compared to the soil background values of Shanxi,the heavy metals in Dan River sediments showed more higher ecological risk,and the ecological risk of the heavy metals,arranged from the highest to lowest pollution degree,was as follows CdHgAsPbCrCuZn.On the basis of analysis of potential ecological risk factor and ecological risk index of the heavy metals,it suggested that Gaoping City,Bagong River,Shuidong were the most polluted sites.This study would provide scientific basis for the prevention,control of pollution,and environmental management in Dan River.