城市绿地对雨水径流污染物的削减作用

为探究城市绿地调控城市降雨地表径流污染的有效性和可行性，采用室内土柱模拟试验，研究植被覆盖、径流污染物浓度、土壤层深度、地下水、水力负荷与停留时间对城市绿地削减污染物的影响。结果表明，在低、中和高3种 雨水径流污染物浓度水平（CODCR 为68、137、550 mg/L；TN是3.01、7.51、30.06 mg/L；TP为0.29、0.69、2.73 mg/L； NH+4是0.44、1.61、2.19 mg/L），水力负荷为3.5、3.0、2.5 cm/h，持续进水1 h条件下，城市绿地具有良好且稳定的污染削减能力，对CODCR 、TN、TP、NH+4的平均削减率分别达到41.52%、78.96%、84.68%，50.21%、70.23%、60.91%，73.18%、95.88%、94.99%，62.72%、55.16%、69.98%。受土壤复氧能力和水力停留时间的限制，绿地覆盖对污染物CODCR 与TN削减率的影响不明显。城市绿地污染削减率随着降雨地表径流污染物浓度的升高而呈现逐渐增加的趋势。城市绿地对雨水地表径流污染削减作用主要发生在深度35~65 cm土层内。城市绿地对低、中和高污染浓度水平各污染物削减率随着水力负荷的增加而降低。

Reduction of Urban Green Space on Stormwater Runoff Pollutant

In order to explore the effectiveness and feasibility of urban green space on regulating urban rainfall-runoff pollution, the simulated test of soil column was adopted to study the effects of vegetation cover, runoff pollution concentration, soil depth and groundwater, and hydraulic loading rate and residence time on reducing the pollutants by green space. The results indicate that green space has a good and stable ability to reduce three stormwater runoff pollution concentrations, which COD are 68, 137 and 550 mg/L, TN are 3.01, 7.51 and 30.06 mg/L, TP are 0.29, 0.69 and 2.73 mg/L, and NH+4 are 0.44, 1.61 and 2.19 mg/L respectively, with 3.5, 3.0 and 2.5 cm/h hydraulic loading rate respectively and continuous inflow 1h. The pollution reduction rates of COD, TN, TP and NH+4 by green space reach to 41.52%, 78.96% and 84.68%, 50.21%, 70.23% and 60.91%, 73.18%, 95.88% and 94.99%, and 62.72%, 55.16% and 69.98% respectively. Restricted by the soil reaeration capacity and hydraulic retention time, the effect of vegetation cover on pollution reduction rates of COD and TN is not significant. With the rainfall-runoff pollution concentration increased, the pollutant reduction rate of green space shows a gradually increasing trend. The reduction of green space on the stormwater runoff pollution mainly occurs in the soil depth of 35~65 cm. The reduction rate of each pollutant for the low, medium and high pollution concentration level decrease with the hydraulic loading rate increased.