简单式绿色屋顶对雨水径流营养盐的调控效果研究

Effect of Extensive Green Roof on Regulation of Nutrients in Rainfall Runoff

基于天然降雨长期监测和人工模拟降雨实验,研究了3个简单式绿色屋顶实验装置雨水径流营养盐浓度、总量及削减能力的差异,分析了基质层和排水层材料选型及降雨量等对绿色屋顶径流营养盐调控效果的影响。结果表明:绿色屋顶出水NH4^+-N、NO3^--N和TP浓度高于普通混凝土屋面;选用不同排水层材料的绿色屋顶出水营养盐浓度差异不明显;而选用超轻量基质作为基质层材料时,绿色屋顶出水TP浓度较高,NH4^+-N浓度较低。绿色屋顶能削减部分径流中的NH4^+-N、NO3^--N和TP总量,不同基质层材料和排水层材料的绿色屋顶对不同营养盐总量削减效果无明显差异。除绿色屋顶自身不同结构层选型带来的差异外,降雨量和雨前干期是影响绿色屋顶出水NO3^--N和TP浓度、营养盐总量及总量削减率的重要因素。

The differences of nutrient concentration,nutrient total amount and reducing capacity of rainfall runoff in three extensive green roof experiments were explored by long-term monitoring of natural rainfall and artificial rainfall experiments,and the effect of substrate layer,drainage layer selection and precipitation on regulation of runoff nutrients of green roof were analyzed.The concentration of NH4^+-N,NO3^--N and TP in the green roof runoff was higher than that of the concrete roof.There was no significant difference in nutrient concentration of green roof effluent when different drainage layers were adopted.When ultra-light substrate was used as the substrate layer,the TP concentration of the green roof runoff was higher,but the NH4^+-N concentration was lower.Green roof could reduce part of the total amount of NH4^+-N,NO3^--N and TP in the runoff.Green roofs with different substrate layer and the drainage layer had no significant difference on different nutrient total amount reduction.In addition to the difference caused by the selection of different structural layers of the green roof,precipitation and prior dry period were important factors affecting NO3^--N and TP concentration,total nutrient amount and total reduction rate of green roof effluent.