粗放型绿色屋顶对多环芳烃的控制效果

构建4个粗放型绿色屋顶中试设施,考察不同基质组成的设施在实际降雨条件下出水中16种多环芳烃(PAHs)质量浓度并与降雨、沥青屋面径流、空白对照设施的出水进行对比.结果表明,8场监测降雨事件中,4种模拟屋面设施出流PAHs的平均质量浓度分别为145、166、151、160 ng·L~(-1),沥青屋面和空白对照设施出流PAHs的平均质量浓度分别为900 ng·L-1和270 ng·L~(-1),4个模拟设施出流PAHs质量浓度显著低于沥青屋面和空白对照设施;从质量负荷控制的角度,4个模拟设施均能有效控制屋面径流PAHs负荷,与空白屋面相比,平均负荷削减率为71.76%.绿色屋顶对PAHs的去除机制以基质材料的截留及吸附为主,同样基质配比的情况下,增加基质层厚度,能改善设施对PAHs的去除效果.将传统沥青屋面改造为粗放型绿色屋顶,有助于控制屋面径流PAHs排放.

Removal of Polycyclic Aromatic Hydrocarbons by Extensive Green Roofs

In this study,four pilot-scale extensive green roof facilities with different substrate compositions were developed. In 8 rainfall events, concentrations of 16 kinds of polycyclic aromatic hydrocarbons (PAHs) in effluent of these facilities were investigated and compared with effluents of asphalt roofing, the blank control roof and rain water. Average PAHs concentrations in the effluent of these four facilities, asphalt roofing and blank control facilities were 145, 166, 151, 160, 900, 270 ng·L^-1, respectively. The PAHs mass concentrations discharged by four simulation facilities were significantly lower than asphalt roofing and blank control roof. From the perspective of the mass loading control, all four simulation facilities could effectively control roof runoff PAHs load with an average load reduction rate of 71.76% compared with the blank control roof. Interception and adsorption by green roof substrates was the main removal way for PAHs. Facilities'' PAHs removal efficiency could be improved by increasing the substrate thickness with the same substrate composition. Transforming traditional asphalt roofing into extensive green roof was an effective way to control PAHs emissions from roof runoff.