大气氧化性增强是当前我国细颗粒物污染和近地面高浓度臭氧问题的核心驱动力，全面解析大气氧化能力成为掌握区域性复合型大气污染形成机制的关键。活性卤素物种直接参与大气自由基生消过程，影响许多重要物种的源和汇，在大气对流层化学中起着十分重要的作用。但目前关于活性卤素物种及其化学行为的探讨十分有限，其在大气氧化性与复合污染中的角色作用如何亟待研究。本项目拟利用差分吸收光谱技术在上海城区与近海岛屿开展BrO和IO浓度的全面监测，摸清我国东部地区海、陆边界层中活性卤素物种浓度水平及其变化特征。基于化学模型模拟，量化活性卤素物种对自由基收支平衡与大气氧化性的影响。结合观测资料与空气污染案例，诊断不同污染程度和环境条件下BrO、IO的关键化学行为，特别是在大气复合污染过程中的作用机制。该研究不仅有利于弥补我国卤素化学研究的相关空白，而且对揭示大气自由基化学、区域复合污染形成机制具有十分积极、重要的意义。

Currently, the enhancement of atmospheric oxidation capacity is the core driving force of fine particle and ground surface ozone pollution in China. Comprehensive knowledge on the atmospheric oxidation capacity is the key to grasp the formation mechanism of regional complex air pollution. Reactive halogen species (RHS) are not only directly involved in the processes of atmospheric radical production and loss, but also can affect the sources and sinks of many important species. Therefore, RHS are considered to play a significant role in the tropospheric chemistry. However, there were rare researches focusing on the RHS and their chemical behaviors. Activities of RHS in the atmospheric oxidation capacity and complex pollution are need to be further explored urgently. In this study, the Differential Optical Absorption Spectroscopy (DOAS) method will be utilized to measure the BrO and IO concentrations at costal urban area and offshore island, respectively. Then the typical RHS levels in the continental and marine boundary layer of China eastern area are characterized along with its temporal variations. The impacts of RHS on the radical budget and atmospheric oxidation capacity are quantified based on the simulation by chemical transport model. Coupled with measured data and air pollution episodes, we will further diagnose the crucial chemical behavior of BrO and IO under different atmospheric conditions, especially for the interaction mechanism during the complex air pollution evolution. This study is beneficial to make up the gaps of related halogen chemistry research in China, and also critical to reveal the atmospheric radical chemistry and formation mechanism of regional complex air pollution.