浙江三门湾表层沉积物重金属含量分布、赋存形态及生态风险评价

Distribution,speciation and ecological risk assessment of heavymetals in the surface sediments of Sanmen Bayin Zhejiang

以三门湾表层沉积物为研究对象,对5种重金属(Zn、Cr、Cd、Cu、Pb)的含量分布、赋存形态进行分析,并运用潜在生态危害指数法、Risk Assessment Code(RAC)法、次生相与原生相比值法对重金属生态风险进行了评价。结果表明:三门湾表层沉积物重金属的含量分布整体表现为湾内高于湾外海域,人类活动是主要影响因素。运用BCR法对沉积物中重金属进行分级提取,结果显示Zn、Cd、Cr、Cu均以残渣态为主要赋存形态(Zn:79.20%~84.25%、Cr:93.24%~96.16%、Cd:34.71%~57.58%、Cu:66.06%~79.51%),而Pb以可还原态为主(56.58%~76.44%)。评价结果中,潜在生态危害指数法和次生相与原生相比值法均显示湾内的重金属污染比湾外严重,而RAC法指出Pb污染为湾外高于湾内海域;潜在生态危害指数法和RAC均指出Cd是主要污染元素;在次生相与原生相比值法中Pb则是主要危害元素,Cd次之。

Surface sediment samples were collected from Sanmen Bay in Zhejiang Province.The distribution of total concentration of five heavy metals（Zinc,Chromium,Cadmium,Copper,and Lead）was determined,and their speciation was investigated using BCR extraction method.The pollution level and ecological hazard of these heavy metals were evaluated with three methods：Potential Ecological Risk Index（Eir）,Risk Assessment Code（RAC）,Ratio of Secondary and Primary Phase（RSP）.The distribution of five metals show that the total concentrations in inner bay are higher than those out of the bay.The results of metal speciation in surface sediment show that the residual fraction of four metals are predominated except for Pb,of which Zn accounts for 79.20%~84.25%,Cr accounts for 93.24%~96.16%,Cd accounts for 34.71%~57.58%,and Cu accounts for 66.06% ~79.51%,respectively.The dominated fraction of Pb is the part bounded to amorphous Fe and Mn oxides and hydroxides,which accounts for 56.58%~76.44%.The evaluation results indicate that Cd is the primary element in the area according to Potential Ecological Risk Index,and which is consistent with that by the Risk Assessment Code method.However,Pb is evaluated to be the primary element with potential ecological threat according to the Ratio of Secondary and Primary Phase,and followed by Cd.