[PAH sources in road runoff system in Beijing].

In this study, road runoff, rainwater, ground sediment and roadside tree water samples were collected from three types of roads in Beijing in 2006. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs). The average PAH concentrations in each media in May-June were generally higher than those in July-August. Factor analysis indicated that PAHs in road runoff were mainly from ground sediment, and rainwater and roadside tree water also had certain influence to road runoff. Multiple regression analysis indicated that PAHs in ground sediment and road runoff mainly come from vehicular emission at the vehicle way and branch road, and at the bicycle way, the contributions of vehicular emission and coal combustion were equal. PAHs in rain were mainly from coal/oil combustion, and PAHs in roadside tree water were dominated by vehicular emission source.