Study On The Occurrence And Release Of Organic Pollutants In Urban Road Dust And Rainfall Runoff

With the accelerating of urbanization process,the impermeable area of city's road has increased,exacerbated the accumulation of pollutants in the road dust,which made the road dust become one of the most widely distributed pollution carriers in the urban area.Urban–rural fringe is the frontier of urban expansion and the most dynamic area in urban region but less knowledge was paid on the status of regional.In this study,the occurrence and environmental risk of SVOCs?16 kinds of PAHs as the main pollutants?and 55kinds of VOCs accumulated from road dust in urban–rural fringe was systimetially studied and compared with other land use tape areas?ie commercial area,industrial park,residential area,traffic area and leisure area?.And further analyzed the pollution of PAHs in rainfall runoff.The average concentration distribution of?16PAHs in road dust is:traffic area>urban–rural fringe>commercial area>residential area>industrial park>leisure area.The pollution of PAHs in road dust in the urban–rural fringe is second only to the traffic area.Motor vehicle traffic is an important factor affecting the accumulation of PAHs in road dust.The release behavior of PAHs from road dust to the water phase is very limited,Only NAP,PHE,FLA and PYR were detected.Due to the greater solubility,the release rate of NAP was higher than the other three PAHs.A total of 17 VOCs were detected in road dust,including a variety of benzene seeies,two halogenated alkanes and MTBE.The concentration range of total VOCs in road dust in the study area was 1.85–7.56 mg/kg,which is relatively small.The area with relatively high leves of VOCs in road dust in commercial area and industrial park.The road dust deposits a various pollutants.These pollutants will migrate with the runoff under rainfall conditions and eventually be transported to the urban water system.The concentration of PAHs in rainfall runoff varies greatly in different areas and under different rainfall conditions,which is closely related to the surrounding environment,the pre-rainfall accumulation of pollutants and the rainfall conditions.In the runoff,the particulate phase has more PAHs than the dissolved phase.For PAHs with different ring numbers,the PAHs content of the 4-ring and 3-ring is the most,and the 6-ring accounts for the least.The risk of cancer caused by PAHs in the road dust of the urban–rural fringe is higher and second only to the traffic area.Children's health risk of exposure to PAHs in urban road dust are much greater than adults.The non-carcinogenic risk of VOCs in road dust is relatively low,but due to its exchangeability with air and water pollution,attention should also be paid.The total toxic equivalent of PAHs in the runoff of the three roads of W.2^nd Ring Rd,Dongcheng District Hutong and Huayuanqiao road exceeds the limit value of B[a]P in the Integrated discharge standard of water pollutants,which will bring high risk to the urban water system and should be paid attention to.This study provides basic support for urban surface pollution control and risk assessment.