长江中游典型湖泊重金属分布及其风险评价——以大通湖为例

DISTRIBUTION AND RISK EVALUATION OF HEAVY METALS IN TYPICAL LAKES IN MIDDLE REACHES OF THE YANGTZE RIVER——TAKING THE DATONG LAKE FOR EXAMPLE

水域环境是水生生物赖以生存及渔业资源持续健康发展的基础。水环境中重金属的含量直接关系到水产品的质量和安全。为评估长江中游典型湖泊的渔业水环境,本研究以大通湖为例,测定了其湖水及沉积物重金属含量,采用地质累积指数法与潜在生态危害指数法对沉积物重金属的污染状况进行了评价,并对长江中游典型湖泊沉积物重金属污染状况及环境风险进行了评估。结果表明:大通湖水中As、Cd、Cu、Pb和Zn的含量均符合国家渔业水质标准要求,除S7、S17、S33和S39点位Zn的含量属国家地表水Ⅱ类以外,其他所有点位的5种重金属的含量均低于国家地表水I类标准。大通湖沉积物中As、Cd、Cr、Cu、Pb和Zn的含量均高于相应元素的洞庭湖背景值,呈现累积富集的趋势,但各重金属的污染程度及潜在生态危害均较低。除个别湖泊的个别重金属处于中度污染外,长江中游湖泊沉积物的重金属污染程度较轻。

Water environment is the foundation for aquatic organisms to survival and for fisheries resources to develop sustainably and healthily.The content of heavy metals in water environment is directly related to the quality and safety of aquatic products.To appraise the water environment of typical lakes in the middle reaches of the Yangtze River,content of heavy metals in water and sediment of the Datong Lake was measured,the pollution of sediment heavy metals was evaluated by the methods of geoaccumulation index and potential ecological risk index,and the pollution and the potential ecological risk of sediment heavy metals for typical lakes in the middle ranches of the Yangtze River were also estimated in the present study.The results showed that the content of As,Cd,Cu,Pb and Zn in water of the Datong Lake all met the water quality standard for fisheries.Except for the content of Zn for S7,S17,S33and S39which belonged to the grade II surface water,the content of 5heavy metals analyzed for all samples was within the range of environmental quality standard for grade I surface water.The content of As,Cd,Cr,Cu,Pb and Zn in sediment of the Datong Lake was all higher than their corresponding background values for the area of the Dongting Lake,which indicated that there was growing tendency of accumulation for above 6heavy metals in sediment of the Datong Lake.However,the result showed that the pollution arose from heavy metals in sediment of the Datong Lake was still lighter judged by the methods of geoaccumulation index and potential ecological risk index.The pollution resulted from sediment heavy metals in the typical lakes in the middle ranch of the Yangtze River were lower overall,except for several heavy metals in few lakes which showed slight higher pollution.