广州秋季不同功能区大气颗粒物中PAHs粒径分布

利用MOUDI^TM级联分段式采样器采集了秋季广州市区(荔湾采样点和五山采样点)及郊区(新垦采样点)3个采样点的气溶胶样品并使用GC-MS分析了样品中13种多环芳烃的含量.发现3～4环的多环芳烃呈双峰分布,5～7环的多环芳烃呈单峰分布.广州市区和郊区的多环芳烃具有不同粒径分布模式;相对于城区,郊区的多环芳烃存在于更大的颗粒物中,这可能是气溶胶的陈化过程不同导致的.城区的多环芳烃可能主要受吸附作用控制,而郊区的多环芳烃则可能受多种机制控制,如吸附作用、吸收作用和多层吸附.诊断参数值在粒径1～2.5μm和0.1～0.56μm存在较大差异;从浓度上看新垦13种多环芳烃的总浓度为39ng/m³,五山为71～94ng/m³,荔湾为32～154 ng/m³;从组成上看广州市大气颗粒物种多环芳烃以5～7环为主.

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.