Distribution, Sources, and Risk Assessment of PAHs in Organic Films on Glass Window Surfaces Along the Urban-Rural Gradient in Shanghai, China

To analyze the pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) in organic films on glass surfaces along the urban-rural gradient in Shanghai, 35 organic film samples were collected in March 2014, and the PAHs were quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that the average thicknesses of the organic films were in the order of urban > rural > suburban. In urban areas, the PAH concentration in organic films on glass surfaces (5592 ng/m(2)) was much higher than that in films from suburban (2313 ng/m(2)) and rural (2306 ng/m(2)) areas. T-PAHs (total concentration of 16 PAH monomers) and BghiP showed a good positive correlation, indicating that automobile exhaust emissions greatly contribute to the PAH concentration in the organic films. The PAH monomers were mostly Phe, Fl, Pyr, and Chry in urban, suburban, and rural areas. The BaA/Chry ratio was not suitable for determining the migration distance of PAHs, and it is necessary to further study the degradation mechanism of PAHs in organic films on glass surfaces. Straw burning greatly influences the PAH concentration in rural areas. The average TEQ concentrations in urban, suburban, and rural areas were 781 ng/g, 258 ng/g, and 211 ng/g, respectively. Because people spend most of their time indoors, the exposure risk toward PAHs on glass surfaces cannot be ignored.