PAHs in organic film on glass window surfaces from central Shanghai, China: Distribution, sources and risk assessment

Polycyclic aromatic hydrocarbons (PAHs) concentrations were analysed in the organic film on the glass surfaces of different functional areas in central Shanghai. Concentration levels of total PAHs in the organic film ranged from 1,348.5 to 4,007.9 ng m^-2. The concentration of PAHs was lowest in parks and green spaces (1,348.5 ng m^-2) and highest in traffic zones (4,007.9 ng m^-2). A concentration gradient of total PAHs was observed as follows: traffic zones > commercial areas > cultural and educational areas > parks and green spaces. The distribution of PAHs was characterised by 3-4 ring PAHs in the study areas. The most abundant PAHs were phenanthrene (20.5 %), fluorene (16.7 %), pyrene (12.4 %) and chrysene (Chry) (11.2 %). The mass of the bulk film was composed of organic and inorganic compounds and ranged from 246 to 1,288 mg m^-2. The bulk film thickness varied from 144 to 757 nm in the different functional areas. The ratios of An/178 and Fl/202 and principal component analysis suggested that PAHs came mainly from the mixed sources of fossil fuel, coal and incomplete combustion of biomass. Benzo[a]anthracene (BaA)/Chry is not suitable for use as a tracer for the transmission process of PAHs because of the rapid depletion of BaA in the organic film by photooxidation during daylight hours. The concentration of benzo[a]pyrene equivalent (BaPeq) varied from 21 to 701 ng g^-1, and the major carcinogenic contributors of the 16 PAHs were BaP, DahA, B[b/k]F and InP, accounting for 83 % of BaPeq.