昌黎黄金海岸保护区表层海域沉积物中重金属的赋存形态特征及生态风险评价

Speciation characteristics and ecological risk assessment of heavy metals in the surface sea sediments of the Changli Gold Coast Reserve

为了解昌黎黄金海岸保护区表层海域沉积物中重金属的污染状况,采用欧共体标准物质局(Community Bureau of Reference,简称BCR)提出的三级4步提取法分析了沉积物中Cr、Pb、Cu、Zn、Ni的形态特征,并利用次生相原生相分布比值法(Ratio of secondary phrase and primary phrase)和潜在生态风险指数法(Potential ecological hazard index method)对沉积物重金属进行生态风险评价。结果表明,研究区5种重金属含量超过中国浅海沉积物环境背景值;5种金属均以残渣态为主,次生相中,Cu和Ni以可氧化态为主,Cr、Pb、Zn以可还原态为主。次生相原生相分布比值法表明:元素Pb和Ni为保护区表层沉积物中主要的污染元素,Cu、Cr和Zn则较为轻微。潜在生态风险指数法表明:5种金属元素潜在风险指数按顺序依次为Ni>Pb>Cu>Cr>Zn,在各点位均属于低风险级,环境危害较小。

In order to figure out heavy metal pollution in the surface sea sediments of the Changli Gold Coast Reserve,the chemical speciation of heavy metals(Cr,Pb,Cu,Zn and Ni)in the surface sea sediments was determined by using the latest version of the 3-step sequential extraction procedure recommended by European Community Bureau of Reference(BCR).The ecological risk of heavy metals was assessed by adopting the ratio of secondary phase to primary one and the potential ecological hazard index method.The results indicated that the content of the above five heavy metals exceed background value in China.All of these five metals existed mainly in the form of residual.In the secondary phase,Cu and Ni were mainly composed with oxidizable faction,while other elements were mainly distributed in reducible faction.RSP results showed that in the surface sea sediments Pb and Ni were the primary elements with high ecological risk while Cu,Cr and Zn were with relatively slight risk.According to the comprehensive assessment results obtained after using the potential ecological hazard index method,the five metals’ecological risk degree can be sequenced as Ni>Pb>Cu>Cr>Zn.