土壤对城市雨水径流中污染物的削减作用

Soil Reduction Foundtion of Pollutants in Urban Rainwater Runoff

[目的]分析城市雨水径流在土壤中的净化情况及径流污染物对土壤环境造成的影响。[方法]在充分了解陕西省西安市某地土壤特性和当地雨水径流水质的基础上,模拟城市土壤表层系统和雨水径流装置,研究雨水径流中的污染物在下渗过程中土壤表层对它们的削减作用及土壤基本理化性质的变化。[结果]在土壤层厚度为20cm,雨水渗透量为6 000ml,径流时间3h的条件下,裸土和绿地表层土壤对模拟雨水中各污染物的去除率均达到40%以上;土壤的密度及pH值基本未发生变化,氮的含量由原土的54.95mg/kg分别增加到65.10(绿地)和68.60mg/kg(裸土),有效磷的含量由原土的59.23mg/kg变化到82.39mg/kg(裸土)和39.93mg/kg(绿地),有机质的含量由原土的18.32mg/kg变化到19.28mg/kg(裸土)和14.04mg/kg(绿地)。[结论]绿地对雨水径流处理效果较好。在渗流过程中,土壤对氨氮的截留效果较为明显,短时间内土壤基本物理性质变化不大。

[Objective]To analyze the decontamination condition of urban rainwater in soil and the effect of rainwater runoff pollutants on soil environmental.[Methods]Based on full understand of soil properties and the quality of runoff in Xi＇an City of Shaanxi Province,the urban soil system and rainwater runoff device were simulated to analyze the reducting functions of topsoil on rainwater runoff pollutants in the process of infiltration,and the change of the basic physical and chemical properties of soil.[Results]As the soil layer thickness was 20 cm,total rainwater penetration was 6 000 ml,and the runoff time was 3h,the removal rate achieved above 40% both in bare soil and green fields systems on simulated rainwater pollutants.The soil density and pH value did not changed.But for the content of nitrogen,effective phosphorus,and soil organic matter,from in the original soil to green fields and bare soil,they changed from 54.95mg/kg to 65.10mg/kg and68.60mg/kg,59.23mg/kg to 82.39 mg/kg and 39.93 mg/kg,18.32 mg/kg to 19.28 mg/kg and 14.04mg/kg,respectively.[Conclusion]The effect of green fields on runoff water treatment is significant.In the process of infiltration,soil present significant effect on removal of ammonia nitrogen,and soil basic physical properties show little change within a short time.