[Size distribution of polycyclic aromatic hydrocarbons (PAHs) in different function zones of Guangzhou in autumn, China].

Size distribution of aerosol samples collected from two urban locations (Liwan and Wushan) and a suburban location (Xinken) in Guangzhou (South China) in autumn using Micro-Orifice Uniform Deposit Impactor (MOUDI) were analyzed for 13 polycyclic aromatic hydrocarbons (PAHs) by gas chromatography with mass selective detection (GC-MS). Bimodal distribution was found for 3- and 4-ring PAHs and unimodal for 5-, 6- and 7-ring PAHs. Different PAH size distribution models were found for urban and suburban. PAHs associated with larger particles in suburban than in urban, and different aging processes of aerosols can account for it. Adsorption behavior may be the main mechanism controlled the size distribution of PAHs in urban, and adsorption, absorption and multilayer adsorption may all play a part in suburban. For the diagnostic ratios of PAHs with the same molecular weight, large differences were found between the range of 1-2.5 microm and 0.1-0.56 microm. The concentrations of 13 PAHs were 39 ng/m3 in Xinken, 71-94 ng/m3 in Wushan and 32-154 ng/m3 in Liwan, and 5-7 ring PAHs were the most abundant.