Concentration characteristics and related ecological risk assessment in roof runoff in Shanghai

Roof runoff samples of three rainfall events were collected at three different sites in Shanghai during the rainy season of 2014.Samples were analyzed for PAHs in both particle phase and dissolved phase, including pollution characteristics, dynamic variation, source apportionment and ecological risk of PAHs. Results indicated that the dissolved PAHs concentrations varied from 33.9 to 581.5 ng/L, while the concentrations in the particle phase ranged from 134.6 to 27528 ng/L. PAHs concentrations differed in three sampling sites: tile roof > concrete roof > asphalt roof. Three and four rings PAHs were the dominant components. The EMC value of BaP was 17.4~378.5 ng/L, much higher than the applicable discharge standard of BaP in China. The PAHs in tile roof runoff originated mainly from vehicle emission and coal combustion, whereas the PAHs in concrete and asphalt roof runoff were mainly from vehicle emission, coal combustion and oil spill. The TEQ value of PAHs in roof runoff was 6.08~16.86 ng/L, much higher than the applicable discharge standard of China, which should be brought to the attention of relevant departments.