青狮潭水库底泥重金属污染特征及潜在生态风险

Pollution characteristics and potential ecological risk assessment of heavy metals in sediments of Qingshitan Reservoir

广西桂林青狮潭水库由东湖和西湖两部分组成,为了研究青狮潭水库底泥重金属污染分布特征及潜在生态风险,测定了青狮潭水库不同位置底泥中5种重金属(As,Cd,Cr,Hg,Pb)的含量,并通过地累积指数法和潜在生态风险指数法评价了重金属的污染程度和潜在生态风险。结果表明:东湖底泥中As和Cd含量较西湖高,西湖Hg和Pb含量高于东湖;底泥中Cr主要来源于成土母质,船只通行是造成Pb污染的主要原因;东湖底泥中As和Cd可能主要来源于东江上游煤矿开采;西湖底泥中As,Cd,Hg与营养元素间存在显著相关性,其来源可能与周边农业活动和前期水库内网箱养鱼有关;根据地累积指数,重金属污染强度排序为Cd,As,Pb,Hg,Cr,Cd和As为主要污染元素;重金属潜在生态风险大小排序为Cd,Hg,As,Pb,Cr;东湖底泥重金属潜在生态风险强于西湖。

In order to analyze the distribution and potential ecological risk of heavy metals in sediments of Qingshitan Reservoir, five kinds of heavy metals （As, Cd, Cr, Hg, Pb） were measured in different sites in the reservoir and the pollution degree and potential ecological risk of heavy metals were assessed by geo - accumulation index and potential ecological risk index, re- spectively. The results indicate that the contents of As and Cd in the sediments of East Lake are higher than that of West Lake, but the content of Hg and Pb in West Lake is larger; Cr in sediment mainly comes from soil parent materials; vessel traffic is the main cause of Pb pollution in the reservoir; As and Cd in the sediment of East Lake may mainly come from coal mining in the up- stream of the Dongjiang River; in the sediments of West Lake, As, Cd and Hg have strong relation with nutrient content, dedu- cing that it derived from agricultural activities and cage fish farming in previous time. According to the index of geo - accumulation, heavy metal pollution intensity is in the order Cd , As , Pb ,Hg , Cr; Cd and As are the main pollution elements in the sediments; in addition, the potential ecological risk of heavy metals is ranked as follows： Hg, As, Pb, Cr, Cd; the potential ecological risk of East Lake is greater than West Lake.