用于径流污染削减的土地处理设施内土壤重金属污染研究

通过对一处植草沟-表面流人工湿地联合径流处理设施内的水体及土壤样品进行采样分析,研究土地处理设施内土壤重金属污染风险和径流截流净化机制间的关系。研究结果表明,径流内重金属的水体-土壤迁移,是其在土地处理设施内脱除的主要途径,但这带来了不可忽视的土壤重金属富集现象。与周边自然土壤相比,径流土地处理设施内土壤主要重金属(Fe、Mn、Ph、Cu、Zn及As)的平均浓度上升了1.5~2.9倍,带来了严重的负面环境风险。其在具备深度水质净化能力的土地处理设施单元内(如人工湿地)尤为严重。同时设施内重金属水体-土壤迁移的强度显著受到水体理化环境,特别是氧化还原水平的调控,厌氧及强还原性环境会进一步提高土壤重金属二次释放及向周边环境迁移的风险。

Study on Runoff Pollution Reduction of Soil Heavy Metal Pollution in Land Treatment Facilities

Through the sampling analysis on the water and soil samples in the runoff treatment facilities combined with a grassing trough and surface flow constructed wetland,this paper studies the relationship between the soil heavy metal pollution risk and the runoff interception purification mechanism in land treatment facilities.The study result shows that the water-soil translocation of heavy metals in runoff is the main way to remove it in the land treatment facilities,but this will bring the phenomenon of soil heavy metal enrichment which cannot be neglected.Compared with the surrounding natural soil,the average concentrations of the main metals(Fe,Mn,Ph,Cu,Zn and As)in the soil of runoff land treatment facilities go up 1.5 to 2.9 times,which bring the serious negative environmental risk,and are particularly serious in the land treatment facilities(i.e.constructed wetland)with the advanced water quality purification capacity.At the same time,the intensity of heavy metal water-soil translocation in the facilities is obviously affected by the physicochemical environment of water.Especially,the regulation of oxidoreduction level,and the anaerobic and strong reducibility environment will further increase the secondary release of soil heavy metal and the risk of translocation to the surrounding environment.