土壤-植物系统对径流污染物截留的影响因子分析

Factors Affecting Runoff Pollutants Trapping in Soil-Plant System

通过比较3种土壤-植物系统,分析确定了植被条件、污染物浓度、进水流量和坡度对地表径流污染物去除率的影响。研究结果表明:植被条件、进水浓度、进水流量和坡度对污染物去除率的影响因污染物的存在状态和性质不同而变化;颗粒态污染物SS、PP和CODMn的截留特征受4种因素的影响显著,"土壤-紫花苜蓿"和"土壤-高羊茅"系统的污染物去除率显著优于对照系统,并随进水浓度、进水流量和坡度增加而降低;溶解态污染物NO-3-N、NH+4-N和TDP的净化效果受植被条件和进水浓度的影响显著,"土壤-高羊茅"系统的污染物去除率显著优于"土壤-紫花苜蓿"和对照系统,NO-3-N去除率在中等浓度时最高,NH+4-N和TDP去除率随浓度增加而显著增加,NO-3-N去除率受进水流量影响显著,随进水流量增加而降低,NH+4-N去除率受坡度影响显著,随坡度的增加而降低。研究得出在构建土壤-植物系统的实践中,应根据上游污染源区污染状况及受纳水体水质要求设计净化系统,并选种地表密集生长的植被及适当降低系统坡度来提高土壤-植物系统的环境功能。

The effects of vegetation type, pollutant concentration, flow velocity and slope on runoff pollutant removal efficiency were studied by comparing three kinds of soil-plant systems, namely ＂soil- alfalfa＂ system, ＂soil-tall fescue＂ system and control system with no vegeta- tion. Results indicated that the influence of vegetation type, pollutant concentration, flow velocity and slope on pollutant removal efficiency varies with the status and nature of pollutants. The trapping of particulate pollutant SS （suspended solid）, PP（particulate phosphorus） and CODMh is affected by the above mentioned four parameters obviously. The particulate pollutant removal efficiencies in the ＂soil-alfalfa＂ sys- tem and ＂soil-tall fescue＂ system were significantly superior to the control system, and decreased with the increasing of influent concentra- tion, influent flow rate and slope. The removal efficiencies of dissolved pollutant NO^-N, NH^-N and TDP（total dissolved phosphorus） were affected by vegetation type and influent concentration significantly. The dissolved contaminant removal efficiency in the ＂soil-tall fescue＂ system was better than the ＂soil-alfalfa＂ system as well as the control system. Nitrate removal rate reached highest in moderate concentration. The removal efficiencies of NH^-N and TDP increased with the increase of their concentrations. Nitrate removal rate decreased remarkably with increasing influent flow rate. The removal rate of NH2-N decreased significantly with increasing slope of soil system. It was concluded through the investigation that while constructing soil-plant system to control runoff pollutants, the upstream pollution status and the receiving water quality requirement should be considered, a dense growth of surface vegetation should be selected, and the slope of the soil system should be lowered to improve contaminant trapping function of soil-plant system.