[Seasonal variation and function-area difference of PAHs in road dust from Shanghai urban area]

Seasonal variation and function-area difference of polycyclic aromatic hydrocarbons (PAHs) in road dust from Shanghai centre area were studied, and the probable reasons were also discussed. The result showed that the accumulation level of PAHs varied significantly from winter to summer, namely, and the concentrations of total PAHs and the homologues in winter were higher than that in summer. Total PAH concentrations (t-PAH) in winter samples ranged from 9176 to 32,573 ng x g(-1), with a mean value of 20,648 ng x g(-1), whereas they varied from 6875 to 27,766 ng x g(-1) in summer, with an average of 14098 ng x g(-1). The individual PAHs composition ranged from 50 (acenaphthylene) to 3162 (indeno (1,2,3,-cd) pyrene) ng x g(-1) in winter, and 3 (acenaphthene) to 1485 (indeno(1,2,3,-cd) pyrene) ng x g(-1) in summer. The results exhibited that the levels showed a great rise from summer to winter. The difference of PAHs concentrations in road dust from functional areas were also obvious, that is, in winter, PAHs concentrations in road dust at industrial area (ID), commercial area (CO) and traffic area (TR) were much higher than those in other areas, with t-PAH mean concentration of 31 163, 24 932 and 18 815 ng x g(-1) resepectively, while city park (CP) and public lawn (PL) had the lowest level (7885, 8036 ng x g(-1)). In summer, the lowest concentration (7942 ng x g(-1)) appeared in CP, however, TR, ID and CO were the most polluted areas, with t-PAH mean concentration of 14,528, 14,247 and 11,523 ng x g(-1), respectively. The concentration of PAH homologues raised gradually with the ring number or molecular weight. Seasonal variation and function-area difference of PAHs in road dust from urban area correlated with both their sources and their physical and chemical characteristics.