The Accumulation And Transfer Processes And Ecological Risk Assessment Of PAHs In Road Dust From Shanghai

As a set of POPs (Persistent Organic Pollutants), PAHs (Polycyclic Aromatic Hydrocarbons) are semi-volatilized, toxic, persistent in the environment for long period of time, and biomagnify as they move up through the food chain, and can also lead to cancer, abnormality and genic mutation, so they are of great concern. Especially during the last few years more and more Chinese scientists began to study on PAHs. The corrosion to biological system of urban road dusts is convert, potential, and persistent, moreover, some particles of urban road dusts can threaten human's health and sometimes cause death. Urban road dusts is not only the important sink of PAHs, meanwhile, they probably can transport to air, in some certain conditions, by volatilization and resuspension, and also can be washed to water bulk by surface runoff, to be the second pollution source of PAHs. Taking Shanghai city as an example, seasonal variation and the difference in functional districts of PAHs in urban road dusts in Shanghai central area have been discussed systematically, then the distribution principle of PAHs among urban media and the dominant factors influencing the environmental biogeochemistry of PAHs and the influencing mechanism in urban area, the source of PAHs in urban road dusts, have been analyzed, the dry deposition flux of PAHs in Shanghai central area has also been calculated using a modified model, at last, their ecological risk assessement has been given, which will provide scientific bases for urban environmental protection and management.The results have shown that all the 16 kinds of PAHs that EPA priority control have been detected with a large amount. Total PAHs concentration in winter samples ranged from 6450.828~92834.521ng/g, with a mean value of 19140.898ng/g, while it in summer samples ranged from 5632.086 ~ 27765.727ng/g, averaged in 13329.578ng/g. The seasonal variation was obvious that both total PAHs and single PAH concentrations were higher in winter samples than that in summer samples.In various functional districts in summer samples, park samples had the lowest PAHs concentration, university, residential areas and gas stations were also lower, while industrial areas and traffic areas were most polluted, the reason why...