Removal of Polycyclic Aromatic Hydrocarbons by Extensive Green Roof
【Abstract】In this study, four pilot 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 roof, the reference roof and rainfall. The results show that, in eight monitored rainfall events, the average PAHs mass concentration in the effluent of these four facilities was 145, 166, 151 and 160 ng·L−1and that of asphalt roof and reference roof was 900 and 270 ng·L−1, respectively. The PAHs mass concentrations discharged from four simulation facilities were significantly lower than that of asphalt roof and reference roof. From the perspective of the mass load control, all the four simulation facilities could effectively control roof runoff PAHs load with an average load reduction rate of 71.76% compared with the reference roof. Interception and adsorption by green roof substrates were the main way to remove PAHs. Facilities' PAHs removal efficiency could be improved by increasing the substrate thickness with the same substrate composition. Transforming traditional asphalt roof into extensive green roof was an effective way to control the emission of PAHs in roof runoff.
【Keywords】 roof runoff; extensive green roof; PAHs; sponge city; low impact development (LID);
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