春、夏季长江口海水、沉积物及生物体中重金属含量及其评价

Concentrations and assessment of heavy metals in seawater,sediments and aquatic organisms at Yangtze River estuary in spring and summer

根据2009年5月(春季)、8月(夏季)长江口海域的环境调查资料,分析了长江口及其临近海域水相、表层沉积物及生物体内的6种重金属含量及分布特征,利用单因子指数法对污染状况进行了评价,并就污染来源进行了探讨。结果表明:研究海域春季表层水体中以Cu和Hg污染为主,超标率均为30%,而底层则主要为Hg污染,超标率为35%,Zn和Pb除个别站位超标外,其它站位状况良好;夏季表、底层水体中重金属污染以Cu、Zn和Hg污染较为严重,各重金属质量浓度约为春季水体中的2倍。研究海域春季表层沉积物中重金属污染状况由大到小依次为Cd、As、Cu、Zn、Pb、Hg,夏季表层沉积物中重金属污染状况由大到小依次为Cd、Cu、As、Hg、Zn、Pb,春、夏季沉积物中各重金属质量分数有所差异,总体表现为春季高于夏季。生物体内重金属质量分数状况较好,均符合各类食品安全标准。春、夏季沉积物对重金属的富集能力有所不同;但总体表现为春季富集能力高于夏季,这可能与泥沙再悬浮造成的重金属重新释放有关;鱼类和甲壳类对不同重金属的富集能力有所差异,鱼类对重金属的富集能力由大到小依次为Cd、Pb、Cu、Zn、Hg、As,而甲壳类对重金属的富集能力由大到小依次为Pb、Cd、Hg、Zn、Cu、As。

Heavy metals in seawater,sediments and aquatic organisms（fishes and crustacean） were determined and simply assessed using single factor index based on the data obtained from two cruises in the Yangtze River estuary in May and August,2009,in addition,the possible sources of contaminants had been discussed.Results showed that both the Cu and Hg concentrations in the surface seawater in May had an overtaking rate of 30%,the bottom water was mainly polluted by Hg,with an overtaking rate of 35%,part of the stations were contaminated by Zn and Pb;in August,both of the surface water and bottom water were contaminated majorly by Cu,Zn and Hg,with the concentration of each heavy metal two times as many as that in May.The descending order of heavy metal pollution in the sediments in May was CdAsCuZnPbHg,while in August was CdCuAsHgZnPb,the overall level of heavy metals in sediments in May was higher than that in August.Concentrations of heavy metals in aquatic organisms turned out to meet the food safety standards.As resuspension in sediments may have an impact on the release of heavy metals from sediments,the enrichment coefficients of heavy metal in sediments fluctuated greatly in May and August;the descending order of enrichment coefficients in fish ranked as CdPbCuZnHgAs,while in crustacean was PbCdHgZn CuAs.