嘉兴市河网重金属污染特征及生态风险评价

Pollution characteristics and ecological risk assessment of heavy metals in Jiaxing River Network,Zhejiang Province, China

为了研究嘉兴市河网重金属污染分布特征,于2019年4月和7月采集了50个点位的地表水样和沉积物的样品,分析测定了9种重金属,并采用内梅罗综合污染指数和潜在生态危害指数法对地表水样和表层沉积物的生态危害程度进行评价.结果表明,地表水中部分点位Pb超过GB 3838—2002《地表水环境质量标准》Ⅲ类标准.沉积物中9种重金属整体高于浙江省土壤背景值:4月份以Zn、Cu、Cr和Cd的超标最为严重,7月份以Cd和Hg超标最为严重,有机质可能对沉积物重金属元素的含量起到重要的控制作用.内梅罗综合污染指数法评价结果表明,地表水中重金属整体污染程度偏低,主要潜在贡献因子为Pb.潜在生态风险评估表明沉积物中4月份的污染高于7月份,Hg和Cd为主要污染贡献因子,不同等级的风险水平主要与Hg和Cd贡献较大密切相关.

In order to study the distribution characteristics of heavy metal pollution in Jiaxing river network,water samples and sediment samples from 50 sampling sites from Jiaxing river network were collected in April and July 2019,and 9 heavy metals were analyzed.Nemero comprehensive pollution index and potential ecological hazard index method were employed to evaluate the degree of ecological risk of surface water and surface sediments.The results showed that heavy metals Pb of partial sites in surface water of Jiaxing river network exceedⅢlevel of the Environmental Quality Standard for surface water(GB 3838—2002).All the elements of 9 heavy metals in the surface sediment were higher than the background values in soils of Zhejiang province.The heavy metals Zn,Cu,Cr and Cd were the most serious pollution in April while Cd and Hg in July.The organic matter may play an important role in controlling the concentration of heavy metals in the surface sediments.The Nemero comprehensive pollution index showed that the overall pollution level of heavy metals in surface water was low,and Pb was the potential pollution factor.The potential ecological risk assessment showed that the pollution in the surface sediments in April was higher than that in July,and Hg and Cd were the main factors contribute to the pollution.The risk of different levels in surface sediments were mainly related to the greater contribution of Hg and Cd.