东江沉积物重金属分布特征及污染评价

Distribution characteristics and pollution assessments of heavy metals in Dongjiang river sediments

采用ICP-MS对东江河流沉积物中的重金属进行分析,发现东江沉积物中Cu、Zn、Cd、Hg等重金属呈现相同的变化特点,高值区和低值区基本一致。东江流域沉积物的重金属污染物主要是Cu、Zn、Cd、Hg、Pb,其平均含量分别为157.29、213.21、0.98、0.42、50.77mg.kg-1,均高于中国大陆沉积物背景值。地累积指数法和Hakanson潜在生态危害指数法对东江流域沉积物污染程度和生态危害程度的评价结果显示,东江沉积物中地累积指数从大到小的顺序为Cd、Cu、Zn、Hg、Pb;从总的污染程度来看,东江沉积物中各重金属对生态风险影响程度从大到小的顺序为Hg、Cd、Cu、Pb、Zn;从总的生态风险指数上看,整个东江流域除处于上游的河源市段生态风险低外,处于中游的惠州段生态风险为"较高",处于下游的东莞段生态风险为"极高"。

Heavy metals in sediments from Dongjiang River were detected by ICP-MS.The results showed that the distribution characteristics of these heavy metals,including Cu,Zn,Cd,Hg,were similar,and the sites with higher and lower value were approximately in accordance.Cu,Zn,Cd,Hg,Pb were the main heavy metal pollutants.The average contents of these heavy metals in the sediments were 157.29,213.21,0.98,0.42,50.77 mg·kg-1 respectively,which exceeded the sediment background value in China.The degree of pollution was evaluated by the index of geoaccumulation and the index of the Hakanson ecological risk.The results showed that the geoaccumulation of the pollutants in Dongjiang River was in the order： Cd,Cu,Zn,Hg,Pb,while the ecological risk degree of the pollutants was in the order： Hg,Cd,Cu,Pb,Zn.On the whole,in Dongjiang River,the potential ecological risk of sediments from upstream（Heyuan） was at low level,middle stream（Huizhou） at relatively high level,and downstream（Dongguan） at very high level.