中文摘要：

2002年8月14—24日在临安采集气溶胶样品，对气溶胶质量和离子成分的尺度分布进行分析。结果表明：SO4^2-主要集中在粒径〈2．1μm的细粒子中，约占所有尺度段上SO4^2-质量总和的94％；细粒子（PM2t）中，ρ（SO4^2-）和ρ（NH4^＋）最高，二者之和占所分析离子质量浓度总和的89％。利用公共多尺度空气质量模式（CMAQ）的过程分析对影响硫酸盐气溶胶分布特征的主要因子进行定量评估，结果表明：经过云内液相氧化和湿清除形成硫酸盐气溶胶的速率为0．19μg（m^3·h），其对硫酸盐气溶胶的贡献最大；SO2液相氧化反应中速率最大的是H2O5[5．26μg／（m^3·h）]，其次是O2[4．14μg／（m^3·h）]和O3（1．56μg/（m^3·h）]。模拟分析证明，采样期间研究区域SO4^2-主要是由上海及其以南的浙江沿海一带通过SO2云内与H2O2和O2的液相氧化反应生成。通过模式敏感性试验发现，在个例的风场配置下，上海排放的SO2对临安地区的SO2和硫酸盐的贡献率分别达15％和22％。

英文摘要：

Aerosol samples were taken in Lin＇an city from 2002-08-14 to 2002-08-24 in order to analyze the size distributions of aerosol mass and ionic components. The results indicated that SO4^2- with size less than 2.1μm accounted for 94 % of the total mass in all size ranges. In fine particles （PM2t）, SO4^2- and NH4^＋ had the largest mass concentrations and accounted for 89% of the total mass of all analyzed ionic components. The Community Muhiscale Air Quality （CMAQ） model was used to analyze the main factors affecting distribution of sulfate aerosol. The results indicated that the sulfate formation rate through in-cloud aqueous oxidation and wet deposition was 0.19 μg/（m^3·h）, which was 2.5 times the rate of sulfur gas condensation. Among the SO2 aqueous oxidations, H2O2 had the largest reaction rate 5.26μg/（m^3·h）, followed by O2 4.14μg/（ m^3·h） and O3 1.56μg/（m^3·h）. This proved that SO4^2- in Lin＇an was produced via the in-cloud aqueous oxidations of SO2 by H2O2 and O2 over Shanghai and the coastal region of Zhejiang. A sensitivity test was applied by shutting down SO2 emissions in Shanghai, and it was found that SO2 emitted from Shanghai accounted for 15% and 22% of SO2 and SO4^2- in Lin＇ an, respectively.