渭河中下游河道沉积物重金属污染生态风险评价

以渭河中下游河道沉积物为研究对象,在分析12个干流采样点和7个一级支流采样点沉积物中Pb,Zn,Cr,Cu,Co和Ni六种重金属元素含量变化的基础上,采用Hakanson潜在生态风险指数法对河道沉积物重金属污染的生态风险程度进行了评价。渭河中下游河道19个采样点沉积物中Pb,Zn,Cr,Cu,Co和Ni六种重金属元素含量均不同程度超过了陕西省土壤重金属背景值,除Pb外,支流沉积物中其他五种重金属的平均含量都低于干流沉积物;Hakanson潜在生态风险评价结果显示,渭河中下游采样点的六种重金属元素单项生态风险指数均小于40,综合潜在生态风险指数均小于50,潜在生态风险处于较低水平,表明渭河中下游河道沉积物中重金属富集量小,基本不构成生态风险。

Assessing Heavy Metal Pollution Risk of Sediment in the Channel of the Middle and Lower Reaches of Weihe River

In order to understand the variations in sediment heavy metal pollution in the channel of middle and lower reaches of Weihe River,12 sampling sites in main river channel and 7 sampling sites in tributary river channel were chosen.The changes in contents of Pb,Zn,Cr,Cu,Co and Ni in sediments were analyzed and the ecological risk assessment of heavy metals in sediment was conducted by using the method of potential ecological risk index invented by Hakanson.All heavy metal contents in sediment were higher than the soil background values of Shaanxi Province in all sampling sites.Except for Pb,the contents of the other five heavy metals in the sampling sites of the main river channel were higher than in the sampling sites of the tributary river channel.The results from the method of potential ecological risk index invented by Hakanson indicated that the single potential ecological risk index of all measured heavy metals in all sampling sites was lower than 40 and the integrated potential ecological risk index of all sampling sites was lower than 50.The potential ecological risk of heavy metals in channel of the middle and low reaches of Weihe River was at the low level.These results implied that the heavy metal accumulation was low and the potential ecological risk of all measured heavy metals hardly existed in the channel of the middle and lower reaches of Weihe River.