当前中国大气复合污染日趋严重，大气臭氧的形成机制表现出与发达国家不同的特征。其中，大气中气态亚硝酸（HONO）浓度极高，并通过HONO光解反应生成大量OH从而对O3的形成产生重大影响。然而，模式模拟低估了实际观测中高浓度的HONO，这说明存在未知的HONO来源。已有研究表明非均相反应可能是HONO在大气中的重要来源，然而目前的研究还很有限，无法解释高浓度HONO的来源。因此，本项目针对我国城市复合污染特点，拟对北京市实际大气中的HONO含量进行实时测量，获得HONO浓度与光照、温度、相对湿度、气溶胶表面积浓度及谱分布、气态前体物之间的相关性，推导HONO产生的关键参数，输入到实验室模拟中，系统研究HONO在气溶胶表面的非均相生成和去除过程，获得反应动力学参数，分析反应前后气溶胶表面物理化学性质的变化，为HONO的非均相生消过程提供基础数据，也有助于拓展对我国复合型污染OH来源的认识。

In the increasingly serious air pollution complex situation in China, the formation mechanism of atmospheric ozone exhibits different characteristics from that of the developed countries. In particular，the concentrations of gaseous nitrous (HONO) is very high in the atmosphere. The photolysis of HONO significantly impacts the formation of O3. However, the models fail to reproduce unexpected high concentrations of HONO observed in the field studies, indicating the existence of new, yet unknown, sources of HONO. Heterogeneous processes thought to be the major source of HONO in the atmosphere, intensively studied in the laboratory and several mechanisms of HONO formation on aerosol and ground surface have been proposed. Even so the mechanisms of HONO formation in the atmosphere are still not completely understood. Therefore, this project intends to measure the concentrations of HONO in Beijing, obtain the correlation of the HONO with sunlight, temperature, relative humidity, aerosol surface area, and gaseous precursors. Key parameters can be derived to lead the investigations of laboratory studies. Systematically investigating the heterogeneous processes of the formation and loss of HONO, probing the kinetic parameters, the changes of physical chemistry properties of aerosols before and after the reactions can provide essential information for the source and sink of HONO and scientific support for deep understanding of the source of OH in China with air pollution complex situation.