粗放型绿色屋顶基质层对降雨出流水质影响

为研究粗放型绿色屋顶基质层对雨水出流N、P、COD和SS淋失的影响，根据华中地区降雨强度和水质实际情况，构建了3种不同基材配方的绿色屋顶基质层，在9场模拟暴雨下进行绿色屋顶的基质出流水质监测。结果表明:本试验各绿色屋顶设施对TN、NH₄+-N、NO₃--N和SS都有较好的削减作用，但对TP和PO₄3--P淋失现象明显，绿色屋顶的出流中以颗粒态P和溶解态N为主；去除出流中SS，对净化COD效果显著；生物炭的添加对出流污染物有明显的控制作用，能有效缓解降雨初期污染物浓度高的问题，同时能显著增加植物地上部生物量；厚度为5 cm的绿色屋顶出流水中N和COD较10 cm厚度低，但其SS出流平均浓度偏高，且植物后期不能维持良好的长势。粗放型绿色屋顶设施运行稳定后截污效应良好，具有较高的可行性和广阔的应用前景。

EFFECT OF SUBSTRATE COMPOSITION OF EXTENSIVE GREEN ROOF ON WATER QUALITY OF RAINFALL OUTFLOW

In order to study the effect of substrate composition of extensive green roof on the leaching of N, P, COD and SS from rainwater, three green roof models with different substrate compositions were constructed according to rainfall intensity and water quality in central China, and the water quality monitoring of green roof was carried out under 9 simulated rainstorms. The results showed that the green roof facilities in this experiment could reduce TN, NH₄+-N, NO₃--N and SS, but the leaching of TP and PO₄3--P was obvious. The outflow of green roof was mainly particulate phosphorus and dissolved nitrogen; removal of SS from the effluent had significant effect on COD purification; the addition of biochar had obvious controlling effect on the outflow pollutants, which could effectively alleviate the problems of high concentration of pollutants in the initial stage of rainfall, and significantly increase the aboveground biomass of plants; the average concentration of N and COD in the effluent from green roof of 5 cm thick was lower than that of 10 cm thick, but the SS effluent was higher, and the plants could not maintain good growth in the later stage of rainfall. The extensive green roof facility had good pollution interception effect after stable operation, and high feasibility and broad application prospects.