干旱区绿洲城郊排污渠沉积物重金属污染与释放特征

Heavy metal contamination and release characteristics of sediments in oasis of arid area and suburban drainage ditch

在白银市城郊东大沟沿程采集了8个沉积物样品,采用Tessier五步连续提取法和静态释放试验研究了沉积物中重金属的污染特征及在不同离子强度条件下沉积物中重金属的释放规律.结果表明:(1)东大沟沉积物中Cd、Cu、Pb、Zn的含量均超过了甘肃省土壤元素背景值,其平均值分别为背景值的128.83、12.71、26.90、17.99倍.(2)沉积物中Cd和Cu主要以残渣态和有机结合态存在,Zn主要以有机结合态和铁锰氧化物结合化态存在,Pb主要以铁锰氧化物结合态存在;沉积物中重金属的活性顺序为Zn>Pb>Cd>Cu.(3)随着离子强度的增大,沉积物中Cu、Pb、Zn的释放量随之增加,沉积物中Cd的释放量则是先增加后减少.

Eight representative sediment samples were collected from Dongdagou, Baiyin. Tessier five-step sequential extraction and static release test method were conducted to study the pollution characteristics of heavy metals, and the release of heavy metals in different ionic strength conditions was also studied. The results showed that： （1） concentrations of Cd, Cu, Pb and Zn in the sediments were higher than the soil elements background values in Gansu province, and the average concentrations of Cd, Cu, Pb and Zn were 128.83, 12.71, 26.90 and 17.99 times higher. （2）The main forms of Cd and Cu were residual form（RES） and organic form （OM） ; the main forms of Zn were organic form （OM） and Fe-Mn oxides bonded form （FMO） ; and the main form of Pb was oxides bonded form（FMO）. The activities of heavy metals in descending order were Zn〉Pb〉Cd〉Cu. （3） With the increase of ionic strength, the release quantities of Cu,Zn and Pb increased, and the release quantities of Cd increased first and decreased later.