松花江沉积物重金属形态赋存特征研究

Speciation of Heavy Metals in Sediment of the Songhua River,Northeast of China

采用Tessier连续提取法分析了松花江表层沉积物中Cu、Pb、Zn、Mn4种重金属的赋存形态,并结合次生相富集系数法,探讨了沉积物中重金属的潜在生态风险及来源。结果表明,沉积物中Cu以残渣态为主(高于50%),其次为有机质结合态,从上游至下游,沉积物中Cu形态的稳定程度逐渐增加;沿程所有沉积物样品中可交换态Pb的含量均高于当地沉积物背景值,存在较高的可迁移性和二次释放风险;在二松大部分江段和松花江干流,Zn主要以比较稳定的残渣态存在,不存在二次释放污染水体的风险;Mn的有效态含量均在流域沉积物背景值范围之内。对重金属次生相富集系数的研究表明,沿程沉积物中Cu、Pb均有一定程度的富集,主要来源于人为输入;Zn在二松中下游的哈达湾至松原江段有一定的富集,其余江段人为输入的Zn较少;沉积物中的Mn主要为自然来源。

The chemical partitioning of Cu, Pb, Zn and Mn in the surface sediments of Songhua River were determined by the Tessier sequential extraction method. The chemical speciation charaeteristies, pollution state and potential ecological effects of the heavy metals were discussed combining with the phase enrichment factors analysis. The results showed that Cu mainly existed in residual fraction, aceounting for more than 50% of its total content; and the organic fraction ranked the second. The stability of Cu in the downstream sediments was higher than that of the upstream sediment. In all the sediment samples, the eontent of exchangeable fraction of Pb was higher than its background value, which was easily mobile and could bring ecological risk to the water eeological system again, and should be paid more attention to. Zn in most sediment of the secondary Songhua River and the Songhua River was mainly associated with the residual fraction, and then would not pollute the river heavily. The content of effective Mn was lower than its baekground value of Mn in Songhua River. The results of phase enriehment factors analysis indicated that Cu and Pb accumulated in the sediment to some degree, while Zn pollution mainly existed from the Seeond Songhua River to the Main Songhua River in comparison, Zn showed less pollution in the other area of the river. Mn showed no pollution in the surface sediments of the River.