北京大气气溶胶中水溶性离子的粒径分布和垂直分布

Size Distributions and Vertical Distributions of Water Soluble Ions of Atmospheric Aerosol in Beijing

2004-09在北京325m气象塔的8、80、240m3个不同高度，利用Andersen分级采样器同步进行了大气气溶胶采样．样品用离子色谱（IC）进行了分析．结果表明，SO4^2-，NH4^＋、NO3^-、K^＋的浓度在0．43—1．1μm出现峰值；Ca^2＋、Mg^2＋的浓度在4．7—5．8μm出现峰值；Na^＋，Cl^-的浓度在0．65—1．1μm和4．7—5．8μm出现峰值．观测期间，二次离子（SO4^2-，NH4^＋、NO3^-）的峰值从“凝结模态”向“液滴模态”移动，高湿度可能是形成液滴模态的重要原因．二次离子（SO4^2-，NH4^＋、NO3^-）随着高度升高，浓度有增加的趋势；Ca^2＋、Mg^2＋在80m出现高值；K^＋、Na^＋、Cl^-的垂直分布比较均匀．

In order to research on the vertical distribution of atmospheric aerosol, aerosol samples were simultaneously collected with cascade sampler at 8, 80, 240m of 325m meteorological tower during September 2004, in Beijing. The water soluble ionic concentrations were analyzed by IC. It shows that there are three types size distribution： （i） ions whose mass resided mainly within the accumulation mode with the peak at 0.43 - 1.1μm（SO4^2-,NH4^＋、NO3^-、K^＋ ）, ① ions whose mass resided mainly within coarse particles with the peak at 4.7 - 5.8 μm（Ca^2＋、Mg^2＋ ）, ② ions which were two modes with the peak at 0.65 - 1.1 μm and 4.7 - 5.8 μm（Na^＋,Cl^- ）. The concentration of ions such as SO4^2-,NH4^＋、NO3^- increase with the height rising. The concentration of ions such as Ca^2＋、Mg^2＋. have the peak at 80 m. The concentration of ions such as K^＋、Na^＋、Cl^- have uniform distributions at different height.