中文摘要：

选取北京和石家庄两个监测点,于2014年冬季进行了PM（2.5）样品采集,分析研究了PM（2.5）及水溶性离子组分污染特征,并应用WRF-CAMx模型对采样时段进行了模拟,分析了观测期间PM（2.5）和二次离子组分区域传输贡献情况.结果表明,采样期间北京PM（2.5）质量浓度为（116.6±87.0）μg/m^3.水溶性离子质量浓度为（45.3±40.6）μg/m^3.其中SO4^2-、NO3^-和NH4＋质量浓度分别为（13.3±13.6）μg/m^3、（14.8±15.1）μg/m^3和（9.1±7.2）μg/m^3;石家庄污染水平高于北京,PM（2.5）浓度为（267.7±166.7）μg/m^3.总水溶性离子、SO4^2-、NO3^-和NH4＋质量浓度分别（111.8±104.3）μg/m^3、（36.6±36.5）μg/m^3、（28.5±29.3）μg/m^3和（25.5±29.8）μg/m^3.两处采样点SOR与NOR分别为0.12、0.10（北京）和0.11、0.14（石家庄）,冬季大气氧化性相对较弱,非均相氧化是主要二次转化原理.数值模拟结果显示,北京、石家庄城区1月PM（2.5）受区域传输贡献分别为28.1%和28.3%,高浓度时段外来源贡献有所上升.二次离子中两地NO3^-传输作用均强于SO4^2-.

英文摘要：

In this study, PM2.5 samples were collected in Beijing and Shijiazhuang in winter, 2014. The characteristics of PM2.5 and its water-soluble ions component were investigated. Then the WRF-CAMx modeling system was developed to examine the regional transportation impact of PMz5 and secondary inorganic species within the same period of sample collection. The result showed the concentration of PMz5 in Beijing during sample collecting period was （116.6±87.0）μg/m3. Total water-soluble ions concentration was （45.3±40.6）μg/m3, and the concentration of SO42, NO3 and NH4＋ were （13.3±13.6）μg/m3, （14.8±15.1）μg/m3and （9.1±7.2）μg/m3, respectively. The PM2.5 pollution in Shijiazhuang was more serious than Beijing, which could be found through the result that the concentration of PM2.5 in Shijiazhuang was （267.7±166.7）μg/m3. The concentration of total water-soluble ions, SO42, NO3 and NH4＋ were （111.8±104.3）μg/m3, （36.6±36.5）μg/m3, （28.5±29.3）μg/maand （25.5±29.8）μg/m3, respectively. SOR and NOR in two sites was 0.12, 0.10 （Beijing） and 0.11, 0.14 （Shijiazhuang）, respectively. Atmospheric oxidation effect in winter was relatively weaker. Heterogeneous oxidation was the mainly mechanism of aerosol reaction. The simulation results showed the contribution of regional transportation to urban area of Beijing and Shijiazhuang in January was 28.1% and 28.3%, respectively, and the increased regional contribution were found during heavy pollution period. The regional transportation contribution of NO3- was much higher than that of SO42- in both sites.