海州湾连岛周边海域沉积物重金属污染评价

Assessment of heavy metal pollution in sediments of the sea area around the Liandao island of Haizhou bay

本文测定了海州湾连岛周边海域21个表层沉积物中重金属元素(Cd、Cr、Cu、Pb和Hg)和类金属(As)的含量,通过克里金插值法得到重金属含量的空间分布,采用地累积指数法和潜在生态风险指数法评价了重金属污染程度和风险等级。结果表明:仅Cu的平均含量超过GB 18668-2002《海洋沉积物质量》中规定的1类标准;Cu和Pb的空间变异系数为114.66%和108.44%,空间离散度较强。重金属污染程度从大到小依次为Cd>Pb>Cu>As>Hg>Cr,其中Cd、Cu和Pb为偏中度污染,As和Hg为轻度污染,Cr无污染;整体潜在生态风险等级已达中等级风险,其中连岛南部海域港口附近重金属污染为高等级风险,表层沉积物的生态风险主要由Cd元素引起。

The total 21 surface sediment samples were collected in the sea area around Liandao island, which is located in Haizhou bay, Jiangsu province, China. The heavy metals(Cd, Cr, Cu, Pb and Hg) contents and the metal-like arsenic(As) content were determined. The spatial distribution maps of heavy metals and metal-like As were obtained by using Kriging interpolation method. The pollution degree and risk grade of heavy metals and metal-like As were assessed by ground accumulation index and potential ecological risk index respectively.The results were indicated that the average content of heavy metal Cu was higher than the Class 1 standard according to the Marine Sediment Quality(GB 18668-2002). The variation coefficients of heavy metal Cu and Pb were 114.66% and 108.44% respectively. Therefore, they had strong spatial dispersion. The pollution degree of heavy metals and metal-like As ranked from large to small: Cd>Pb>Cu>As>Hg>Cr based on the analysis results of ground accumulation method, in which heavy metal Cd, Cu and Pb were the moderate pollution, As and Hg were mild pollution, and Cr was non-pollution. The overall potential ecological risk level in the sea area of Liandao island reached the medium level. There existed the high ecological risk level of heavy metals and metal-like As in the southern part of Liandao island. Further, the ecological risk of surface sediments was mainly caused by heavy metal Cd.