下凹式绿地对城市降雨径流污染的削减效应

Reduction effect of sunken green space on urban rainfall-runoff pollution

以现场7次降雨14组径流污染监测数据为基础,探讨了下凹式绿地对城市降雨径流污染的削减效应,分析了径流污染负荷、绿地土壤与覆被植物、降雨历时等因素对污染削减率的影响.结果表明,当COD,NH4+-N和TP的浓度分别为56.0～216.0,0.27～2.97,0.20～0.95mg/L时,下凹式绿地对COD,NH4+-N和TP的平均削减率为52.21%,48.98%和47.35%.下凹式绿地对径流污染的削减过程可分为2个阶段:初期1h的径流污染削减率符合一级动力学模式,后期径流污染削减规律可用二级动力学模式表示.降雨历时增加可提高污染物削减率,当降雨历时约从3h增加到20h时,径流污染的综合削减率可从40%上升到65%.

Based on monitoring 14 rainfall-runoff samples in 7 rainfall events, the reduction effect of sunken green space on urban rainfall-runoff pollution was discussed, and effect of influent loading, soil and land cover of sunken green space, and rainfall duration on pollution reduction rate was analyzed. Sunken green space had a better decontamination efficiency when the event mean concentration of COD, NH4^＋-N and TP were 56.0-216.0, 0.27-2.97 and 0.20-0.95mg/L, respectively. The average removal rate of COD, NH4^＋-N and TP were 52.21%, 48.98% and 47.35%, respectively. The decontamination process could be divided into two periods. In the first one hour since rainfall, the relationship between the concentrations of COD, NH4^＋-N and TP in influent and effluent followed linear equation. And then, the pollution reduction rate agreed with second-order kinetic model. The pollution reduction rate increased with the extension of rainfall duration. The integrated pollution reduction rate of COD, NH4^＋-N and TP could increase from about 40 % to 65 % when rainfall duration increased from about 3 to 20 hours.