有效态与TCLP法评价沉积物重金属生态环境风险

Assessment of ecological risk of heavy metals in sediment by effective state and TCLP

采集了河道沉积物样品,测定了沉积物中重金属的有效态,并采用TCLP法测定了Cd、Pb和Zn的含量,同时开展了生态环境风险评价。结果表明,根据农产品产地土壤重金属污染程度的分级标准,该河段沉积物中Cd超标率为60%,Zn的超标率为20%,Pb的含量都在安全值范围内。沉积物中三种重金属的均为低风险。TCLP提取沉积物中Cd、Pb和Zn含量,与国际标准值对比发现,沉积物中上下游的两个样品Cd含量大于国际标准值;所有沉积物样品中的Pb、Zn的含量均大于国际标准值。内梅罗综合污染指数结果表明,调查区域河段的沉积物为重度污染。根据有效态和TCLP提取的重金属含量评价结果表明,两种评价方法存在一些差异,但综合两种评价结果,该河流流域确实存在污染的风险。

The samples of river sediment were collected,the effective states of heavy metals in sediment were determined,the contents of CD,Pb and Zn were determined by TCLP method,and the risk assessment of ecological environment was carried out.The results show that according to the classification standard of heavy metal pollution degree in the soil of agricultural products producing area,the over standard rate of CD,Zn and Pb in the sediment of the reach is 60%,20%and within the safe value range.All of the three heavy metals in the sediment are of low risk.The content of CD,Pb and Zn in the sediment extracted by TCLP was compared with the international standard value.It was found that the content of Cd in the two samples in the middle,upper and lower reaches of the sediment was higher than the international standard value;the content of Pb and Zn in all sediment samples was higher than the international standard value.The results of Nemero comprehensive pollution index show that the sediments in the investigated river reach are heavily polluted.According to the evaluation results of the heavy metal content extracted from the effective state and TCLP,there are some differences between the two evaluation methods,but the risk of pollution does exist in the river basin.