广西北海近岸海域表层沉积物中重金属分布特征及生态风险评价

Distribution and Potential Ecological Risk Assessment of Heavy Metals in Surface Sediments from Beihai Offshore Area,Guangxi,China

通过采集广西北海近岸海域表层沉积物的样品并进行重金属含量分析,结果表明:Cu、Pb、Cd、Zn、Cr、Hg、As 7种元素的空间变异系数都超过0.4,各重金属空间波动程度的顺序为Hg>Cd>Zn>As>Cr>Pb>Cu;从空间分布上看,重金属含量的高值点大多数分布在离岸较近的海域,并受沉积物粒度效应的控制;表层沉积物中Cr的污染程度最大,其环境效应不容忽视;区域上重金属的潜在生态危害系数大小顺序为As>Hg>Cd>Cr>Pb>Cu>Zn;各采样站位重金属的潜在生态危害系数(Eir)均远小于40,潜在生态危害指数(RI)也远远小于150,属于低生态危害范畴。

The concentrations of heavy metals （Cu, Pb, Cd, Zn, As, Cr and Hg ） in the surface sediment samples collected from Beihai offshore area,Guangxi,China, were determined. Accordingly, the analysis for space distribution of these heavy metals was carried out and their integrated pollution effects were evaluated by the technique of Hakanson ecological risk. The result shows that the concentrations of Cu,Pb, Cd, Zn, Hg and As have large variation range,which indicates that the six heavy metals are discretely distributed. The highest variation coefficients is found in Hg,and the order of variation coefficient is Hg）Cd）Zn 〉As〉Cr〉Pb〉 Cu. Spatially,the higher concentration of heavy metals appears near Beihai City,and it is also controlled by the size of sediments. The accumulation coefficients of heavy metals and the ecological risk assessment indicate that the offshore area in Beihai has slight potential ecological risk.