高州水库表层沉积物重金属污染特征及生态风险评价

为全面了解高州水库(石骨库区和良德库区)表层沉积物重金属污染水平及其潜在的生态风险，在高州水库及其入库支流采集沉积物样品15个，分析Cu，Pb，Zn，Cr，Ni，Cd，Mn和As共8种重金属的含量水平及其分布特征.采用地累积指数(I_geo)、潜在生态危害指数(RI)及基于生物效应浓度的评价法,对高州水库及其支流表层沉积物重金属污染进行分析和评价.结果表明:高州水库及入库支流沉积物中重金属含量水平变动趋势基本一致，顺序依次为w(Zn)>w(Cr)>w(Pb)>w(Mn)>w(Ni)>w(Cu)>w(As)>w(Cd)，w(Cd)和w(Cr)空间分布不均匀；地累积指数显示，8种重金属污染程度处于无污染至中度污染，污染程度强弱顺序为Zn>Cd>Cr>Ni>Pb≈Cu>Mn≈As；潜在生态风险指数显示，高州水库及其入库支流表层沉积物重金属污染处于中等生态危害程度；基于沉积物质量基准的评价结果显示，高州水库沉积物重金属对生物的急性毒性效应不明显.水库上游支流沉积物中重金属的毒性应引起有关部门重视. 

Pollution Characteristics and Ecological Risk Assessment of Heavy Metals in Surface Sediments from Gaozhou Reservoir, Guangdong Province

The concentrations and distribution characteristics of eight heavy metals(Zn,Pb,Cu,Ni,Cd,Cr,Mn and As) were analyzed in fifteen surface sediment samples from Gaozhou Reservoir and its tributaries in South China,in order to comprehensively evaluate pollution levels of heavy metals in the surface sediments and their potential ecological risk in Gaozhou Reservoir(Shigu Reservoir area and Liangde Reservoir area).Heavy metal pollution in the sediments from Gaozhou Reservoir and its tributaries was analyzed and evaluated using geoaccumulation index(Igeo),potential ecological risk index(RI),and Sediment Quality Guideline(SQG),based on effect range low(ERL) effect range median(ERM) values and threshold effect level(TEL) probable effect level(PEL) values.The results indicated that the concentrations of heavy metals in the sediments from Gaozhou Reservoir and its tributaries had similar variation trends,with the order of contamination level being Zn>Cr>Pb>Mn>Ni>Cu>As>Cd.The degree of Cd and Cr spatial fluctuation appeared to be higher than other heavy metals in the surface sediments.According to the geoaccumulation index,the pollution degree of heavy metals in the surface sediments from Gaozhou Reservoir and its tributaries ranged from no pollution to moderate pollution,with the order of pollution degree being: Zn>Cd>Cr>Ni>Pb≈Cu >Mn≈As.The potential ecological risk index indicated that the degree of heavy metal pollution in the surface sediments from Gaozhou Reservoir and its tributaries represented moderate ecological harm.The biological acute toxicity effect of heavy metals in the sediments of Gaozhou Reservoir was not obvious,based on two different sets of Sediment Quality Guidelines(ERL ERM and TEL PEL).The total toxic units of heavy metals in the surface sediments from the Pengqing River,an upstream tributary of Gaozhou Reservoir,were higher than those of the other sites.The results suggested that attention should be paid to the potential toxic risk of upstream tributaries.