模拟降雨条件下污染土壤中重金属元素径流迁移特征

探明污染土壤中重金属元素随地表径流迁移特征,对于防控重金属污染物的迁移扩散具有重要意义。通过室内模拟降雨试验,研究不同降雨强度下(55,100,120mm/h)污染土壤中Cd、Pb和Cr随地表径流迁移的特征。结果表明:径流中3种重金属元素总量在产流的前20min内逐渐降低,随后趋于稳定;产流初期(产流10min内)颗粒态重金属占径流重金属总量的比例均在80%以上;随产流时间延长,颗粒态Cd和Cr对径流重金属的贡献率快速降低,其颗粒态/溶解态的比值范围分别为47.0～0.4和12.9～0.4,而Pb则主要以颗粒态的形式存在,溶解态Pb对其随径流迁移的贡献率可忽略不计;随降雨强度增大,径流中总Cd和Pb含量显著降低,而径流中总Cr含量以及溶解态重金属含量无明显变化规律。

Heavy Metals Loss Characteristics with Surface Runoff Under Simulated Rainfall Conditions in Contaminated Soil

The aim is to understand the loss characteristics of Cd,Pb,and Cr with surface runoff from heavy metals contaminated soil.Simulated rainfall experiments were carried out and there were three rain intensities treatments as 55,100,120 mm/h.The results indicated that the total contents of Cd,Pb,and Cr in runoff were sharply decreased within 20 min after runoff generation and then were tending towards stability.Within the first 10 min after runoff generation proportions of particulate heavy metals in total contents of heavy metals in runoff were over 80%.The proportions were gradually decreasing during the runoff process under the 3 rainfall intensities treatments.Within the extension of runoff time,the ratio of particulate Cd to dissolved Cd in runoff was ranged from 47.0 to 0.4,and the ratio of Cr was ranged from 12.9 to 0.4,respectively.However,particle bound Pb was the major form for the Pb lost along with the runoff,and the dissolved Pb in runoff could be ignored.Increase of rainfall intensity resulted in the decrease in total contents of Cd and Pb in runoff,however,no regularity change of total content of Cr and the contents of dissolved Cd and Cr in runoff was observed.