黄、东海表层沉积物重金属赋存形态及风险评价

Speciation and Ecological Assessment of Heavy Metals in Surface Sediments of the Yellow Sea and East China Sea

利用Teissier 5步连续提取法分析了黄、东海6个表层沉积物样品中重金属Zn、Pb、Ni、V、Fe和Mn的赋存形态,并基于富集因子评价法、地质累积指数评价法和酸提取态比重风险评价法对6种重金属的污染现状和潜在生态风险进行了初步评价。各重金属的含量分布依次为:Fe>Mn>Zn>V>Ni>Pb。Ni、Zn、V和Fe两两之间均呈现很好的正相关,表明这些元素污染具有同源性。赋存形态分析表明,V、Fe、Zn和Ni主要以残渣态存在,Pb和Mn在可提取态和残渣态比例相当。铁锰氧化物结合态和碳酸盐结合态是非残渣态Pb和Mn的主要存在形式。富集因子评价法和地质累积指数评价法结果显示,Pb、V、Fe和Mn主要受自然来源影响,未受到人类活动的影响。Ni和Zn受到轻微人类活动影响。酸提取态比重风险评价结果显示,Pb和Mn风险评价为中风险,易从沉积物重新释放进入水体形成二次污染。

The speciation of Zn,Pb,Ni,V,Fe and Mn of six surface sediments from the Yellow Sea(YS)and the East China Sea(ECS)was determined using the Tessier sequential extraction procedure(SEP).The pollution levels of six heavy metals were evaluated by the ecological risk assessment(enrichment factor(EF),geoaccumulation index(I geo)and acid-soluble fraction).The distributions of heavy metals followed the order of Fe>Mn>Zn>V>Ni>Pb.The good positive relationship between Ni,Zn,V and Fe indicates the same pollution source.Sequential extractions suggested that V,Fe,Zn and Ni were mainly associated with residual fractions,and the amounts of non-residual fractions of Pb and Mn were equal to that of the residual fractions.In non-residual fractions,Fe-Mn oxides fraction and carbonate fraction were the main fractions.The EF values and I geo values indicated that Pb,V,Fe and Mn were mainly from the terrestrial input while Ni and Zn were slightly polluted by exterior input.The results of ecological risk assessment from acid-soluble fraction demonstrated moderately polluted for Pb and Mn,which are likely to be released from sediments and lead to the second pollution to the aquatic environment.