Heavy Metals Pollution and Its Potential Ecological Risk of the Sediments in Three Gorges Reservoir During Its Impounding Period
三峡库区蓄水运用期表层沉积物重金属污染及其潜在生态风险评价

In order to investigate the heavy metals concentrations and their potential ecological risks of sediments in Three Gorges Reservoir during its impounding period,24 sediment samples were collected from both the mainstream and tributaries for analyzing Cu,Pb,Zn,Cd,Ni,Cr,As and Hg.The index of geoaccumulation and the potential ecological risk index were then employed to evaluate the pollution degree of heavy metals in the sediments.The results indicate that the average contents of heavy metals in Three Gorges Reservoir: Cr is 86.31 mg·kg-1,Ni is 46.81 mg·kg-1,Cu is 76.03 mg·kg-1,Zn is 137.63 mg·kg-1,Cd is 0.75 mg·kg-1,Pb is 59.40 mg·kg-1,As is 18.07 mg·kg-1,Hg is 0.109 mg·kg-1,respectively.Average concentrations of heavy metals in sediments of Three Gorges Reservoir are relatively higher than those in sediment background of Yangtze River.The assessment by geoaccumulation index indicates that the pollution degree of heavy metals is: Cd>Pb>Cu>As>Zn>Ni>Hg>Cr.The assessment by potential ecological risk index show that the potential ecological risk intensity caused by heavy metals is: Cd>Hg>Cu>As>Pb>Cr>Zn,and Cd is the predominant element among them.In general,it is not significantly polluted during the impounding of Three Gorges Reservoir.