滇西沘江沉积物剖面重金属元素分布特征

Distributing characteristics of heavy metal elements in the sediment profiles of Bijiang River,western Yunnan,China

采用连续提取法测定流经兰坪金顶铅锌矿区的沘江3个沉积物剖面中重金属元素的含量,分析Pb、Zn、Cd和As在流域的分布特征和在沉积物剖面中的分布特征。结果表明,距矿山75km的河段沉积物中,浅层沉积物中4种金属元素均污染严重,金顶铅锌矿是沉积物中重金属元素的主要来源,随着矿山开发规模的不断扩大,污染程度加深。4种重金属元素中Cd活性态比例高,且污染程度最强、范围最广、深度最大,Zn、Pb次之,As污染相对较轻、范围较小。潜在生态危害指数法研究结果表明,浅层沉积物中重金属元素表现出中等—很强的生态风险性,产生生态危害的主要重金属元素是Cd,其后依次是Pb、As和Zn。

Heavy metals in the sediments profiles of Bijiang River are analyzed by sequential extraction procedure,and the distribution and the speciation analysis of heavy metals show that 75km section of the Bijiang River away from Jinding Pb-Zn deposit is polluted by heavy metals in the sediments,and Cd pollution is much worse.Assessment of these ecological risks shows that the potential ecological hazards of heavy metals in the upper sediment are middle to very high degree.The main factor causing ecological hazards is Cd,and then followed by Pb,As,zn.