中文摘要：

为比较北京城区与远郊区大气颗粒物中水溶性无机离子的组成特征,2012年4月,利用Andersen分级撞击式采样器同时在2个采样点进行大气颗粒物分级采样,样品采用离子色谱分析.结果表明,城区和上甸子大气颗粒物中水溶性无机离子总浓度分别为（83.7±48.9） μg·m^-3和（75.5±52.9） μg·m^-3,NO3-、SO42-和NH4＋是最主要的水溶性无机离子,分别占总离子浓度的81.2%和84.2%.粒径分布显示,Mg2＋和Ca2＋在5.8—9.0 μm的粒径范围出现峰值,Na＋、NH4＋、Cl-在0.43—1.1 μm和4.7—9.0μm的粒径范围出现双峰,K＋、NO3-和SO42-在0.65—2.1 μm的粒径范围出现峰值.后向轨迹簇分析表明,气团来自南方时,城区和上甸子二次离子浓度分别为（92.4±40.0） μg·m^-3和（95.0±35.4） μg·m^-3,来自其他方向时,分别为（24.0±10.8） μg·m^-3和（13.3±10.6） μg·m^-3.

英文摘要：

In order to investigate the characteristics of water-soluble inorganic ions in particulate matter （PM） at urban and rural sites in Beijing, PM samples were collected with Thermo Scientific Andersen impactors at both sites. The water-soluble inorganic ions were analyzed by IC.The results showed that the concentrations of the total water-soluble inorganic ions at urban and rural sites were （83.7±48.9） μg·m^-3 and （75.5±52.9） μg·m^-3. NO3-, SO42- and NH4＋ were the major ions in particulate matter at both sites, which accounted 81.2% and 84.2% of all the ions. Furthermore, Mg2＋and Ca2＋ were mainly associated with coarse particles with a peak at 5.8—9.0 μm, Na＋, NH4＋and Cl- had a multi-mode distribution, with peaks at 0.43—1.1 μm and 4.7—9.0 μm. K＋, NO3- and SO42- were mainly associated with fine particles with a peak at 0.65—2.1 μm. The backward air mass trajectory analysis suggested that the concentrations of secondary ion were （92.4±40.0） μg·m^-3 and （95.0±35.4） μg·m^-3 when the air mass came from the south, and （24.0±10.8） μg·m^-3 and （13.3±10.6） μg·m^-3 when the air mass came from the other directions at urban and rural sites.