Characterization and loading estimation of polycyclic aromatic hydrocarbons in road runoff from urban regions of Beijing, China.

This paper reports an initial study regarding our quantitative understanding of the characteristics of polycyclic aromatic hydrocarbon (PAH) contamination and loading estimation from road runoff in Beijing (China). The concentrations of 16 PAHs were measured in road runoff and rainwater in a composite commercial and residential catchment of Beijing in 2006. In road runoff samples, geometric mean concentrations of Sigma16 PAHs (the sum of 16 PAH concentrations) in the dissolved and particle phases were 548.2 and 3,872.2 ng/L, respectively, and in rainwater samples, the concentrations in the dissolved and particle phases were 172.9 and 274.6 ng/L, respectively. An analysis on spatial variation among the sampling sites showed that PAH concentrations at the branch road (with low traffic volume) were higher than those at the trunk road (with high traffic volume) and that PAH contamination at the bicycle lane was comparable to that at the vehicle lane. Dimensionless cumulative analyses indicated that first flush effect did not occur in all cases, but rather depended on storm event characteristics. According to the annual unit loading rate and the planned road area, the relative magnitude of PAH loading in road runoff was in the following order: Vehicle lane of trunk road > branch road > bicycle lane of trunk road.