衡水湖岸带重金属潜在生态风险评价及其对道路径流污染物的截留效应

Assessment of The Potential Ecological Risk of Heavy Metals in The Riparian Zone of Hengshui Lake and Its Interception Effect on Road Runoff Pollutants

湿地岸带对地表径流污染物具有显著的截留作用。为探讨湿地岸带对道路径流污染物的截留效应以及湿地岸带的潜在生态风险,测定衡水湖四周道路降尘和岸带土壤的重金属含量,并采用多种指数对岸带的潜在生态风险进行评价。结果表明:道路降尘和岸带土壤重金属含量均低于农用地土壤污染风险值。结合单因子指数、内梅罗指数和地质累积指数可知,衡水湖四周道路存在轻微的铅、镉和锌污染,岸带在靠近道路排水渠的表层土壤存在轻微的镉和锌污染。道路和岸带的潜在生态风险指数均小于150,表明衡水湖道路降尘和岸带重金属的潜在生态风险为轻微。岸带表层土壤的铅、镉、锌和铁含量由公路至水面表现出较明显的下降趋势,下层土壤的镉、锌含量显著低于表层土壤,表明岸带在水平方向和垂直方向对重金属都具有较好的截留效应。

The wetland riparian zone has a significant interception effect on surface runoff pollutants.In order to explore the interception effect of the riparian zone on road runoff pollutants and the potential ecological risk of the riparian zone,we measured the heavy metal contents in road dust samples and soil samples of the riparian zone around Hengshui Lake,and evaluated the potential ecological risk of the riparian zone by using a variety of indexes.The results showed that the contents of heavy metal elements in road dust samples and soil samples was lower than the risk value of soil pollution in agricultural land.Combined with the single factor index,the Nemerow index and the geo-accumulation index,it can be seen that there are slight Pb pollution,Cd pollution and Zn pollution on the roads around Hengshui Lake,and there are slight Cd pollution and Zn pollution on the surface soil in the riparian zone near the road drainage channel.The potential ecological risk index of the road and the riparian zone is less than 150,indicating that there was a slight potential ecological risk in the road dust and the riparian zone of Hengshui Lake.The Pb,Cd,Zn and Fe elements of the riparian zone showed a significant decline from the highway to the water,and the contents of Cd and Zn elements for the subsoil are significantly lower than that of the topsoil samples,indicating that the riparian zone has a good interception effect for heavy metal elements in horizontal and vertical directions.