沙湖沉积物中重金属污染的分布特征及生态安全评价

Distribution characteristics of heavy metal pollution and evaluation of ecological risk in the sediments of Shahu Lake

沉积物是重金属元素的重要载体,为了摸清沙湖表层沉积物中重金属污染现状及其潜在生态危险,调查了湖区6个样点As、Hg、Cd、Cr、Cu、Pb、Zn的含量,并以工业最高背景值、土壤环境质量一级标准为参比值计算重金属富集系数。利用潜在生态危害指数法进行评价。结果表明湖区各采样点重金属含量均未超过工业最高背景值;除Cd外,其他重金属元素平均含量小于一级自然背景值。Cd的富集程度最高,富集顺序为:Cd>Pb>As>Cu>Cr>Zn>Hg;生态危害指数均远小于40,危害程度为轻微,各样点重金属风险程度由高到低为:主航道>养殖区>沙湖湖北>湖心>鸟岛>新码头。总体而言,沙湖重金属生态危害较小。但主航道、养殖区等区域已呈现出一定程度的重金属污染,说明这些区域人为干扰较多。

The sediment is the main carrier of heavy metal elements.In order to find out the pollution status and potential ecological risk of heavy metals in the surface sediments of Shahu,the content and accumulation of 6 heavy metals(As,Hg,Cd,Cr,Cu,Pb,Zn) in the whole lake area were investigated.The enrichment factors of heavy metals in sediments from different sampling sites were evaluated using the highest background value of the industry and the level of the natural background value of the soil as the reference value.The risk of heavy metals pollution in sediments was evaluated by the potential ecological risk index.The results showed that the average content of other heavy metals was less than that of the first level natural background value except for the Cd.The concentration of Cd in the sediments of Shahu lake was the highest,whose enrichment sequence was Cd>Pb>As>Cu>Cr>Zn>Hg.The ecological risk index was much less than 40,and the harm degree was slight.The risk of heavy metals was highest in the main channel.Overall,the ecological risk of heavy metals in Shahu was small.However,some heavy metal pollution has been shown in the main channel and the agricultural region,which indicated that these areas were more man-made interference.