The Temporal And Spatial Variability And Source Analysis Of PAHs And PCBs In Precipitation And Dust Fall In Shanghai

With the acceleration of urbanization and industrialization process, environment issues are prominent in Shanghai, which is an important political, economic and cultural center of China. Atmospheric deposition is an important migration way of pollutants in atmosphere and into the ecosystem, at the same time, the persistent organic pollutants (POPs) were paid widespread attention due to its strong persistence and the effect of carcinogenesis, teratogenesis and mutagenesis, so the research of POPs in precipitation and dust fall of Shanghai need to be carried out promptly.This paper was supported by bidding project of Shanghai environmental protection bureau (2010-04), Major Science and Technology Program for Water Pollution Control and Treatment (Grant No.2009ZX07317-006) and National Natural Science Foundation (Grant No.40971259). The precipitation and dust fall in Shanghai were selected as the research objective and many methods were used in the research, such as statistics, analytical chemistry and physical geography. The temporal and spatial variability of PAHs and PCBs in precipitation and dust fall of Shanghai were analyzed, as well as source analysis and their ecological risks in environment. The main conclusions were as follows:(1) In precipitation, the concentrations of PAHs were between0.07-0.67μg·L-1, there was no obvious difference between different sample sites, but the variances were bigger in urban. The main structures of PAHs were2-4rings PAHs. At the same time, the fluxes of PAHs were between0.36～290.06μg·m-2·month-1, and the higher PAHs fluxes were found in summer.In dust fall, the concentrations of PAHs were varied from3.60μg·g-1to92.15μg·g-1. There was no obvious difference in different months, but the concentration in downtown sites were a little higher than in urban. Meanwhile, the main structure of PAHs in dust fall were4～6rings PAHs. The fluxes of PAHs in dust fall were varied from18.32μg·m-2·month-1to1288.08μg·m-2·month-1, and the higher PAHs fluxes were found in winter and spring.The dominant removal mechanism of PAHs in atmospheric deposition was dust fall in spring, autumn and winter, but precipitation in summer. Meanwhile, the burden of PAHs in atmospheric deposition, which was heavier in northern areas than in the southern areas of Shanghai, was about10.78t.(2) In precipitation, the concentrations of PCBs were varied from ND to0.49μg·L-The highest and lowest levels were found in December2010and April2011, however, there was no obvious difference between different sites. The main structure of PCBs was pentachlorodiphenyl, and the fluxes of PCBs were ND-23.11μg·m-2·month-1, which was dominant in June to August2011.In dust fall, the concentrations of PCBs were varied from ND to0.83μg·g-1, with the higher level in winer and spring. Meanwhile, the main structure of PCBs was pentachlorodiphenyl. The fluxes of PCBs were varied from ND to2.87μg·m-2·month-1, and the higher fluxes were found in winter and spring.The precipitation was as important as dust fall in apportion of PCBs in atmospheric deposition. And the burden of PCBs in atmospheric deposition, which were focus on November to December,2010and June to October,2011, was about0.22t.(3) In precipitation, the main sources of PAHs were the burning of the fossil fuel and wood in spring and autumn, but only the burning of wood and coal in winter and summer. The sources of PAHs in dust fall were similar with the precipitation, but there were the source of leak of oil and mix source. At the same time, the source of PCBs in precipitation and dust fall was residual of the history usage.(4)The toxic equivalent concentration (TEQ) of PAHs in precipitation and dust fall was varied from0.12ng·L-1to119.76ng·L-1and from0.33μg·g-1to13.04μg·g-1. The main environment risks of PAHs in precipitation and dust fall were in middle risk level, but the individual PAHs, such as Phe, and high rings PAHs, were in high risk level.The TEQ concentration of PCBs in precipitation and dust fall was ND-9.22ng-L and ND～20.28ng·g-1, respectively. In60%of samples, the concentrations of PCBs had exceeded the ERM, which showed the high ecological risk. While, most samples were in the middle risk level in spring and summer.