二次有机气溶胶（SOA）包裹层对颗粒相PAHs非均相降解的影响。

多环芳烃（PAHs）是广泛分布在可吸入颗粒物中的一类强致癌性有机污染物，对人体健康构成严重威胁，因此在环境领域备受关注。研究显示：气溶胶颗粒表层的非均相化学过程是PAHs大气老化的一个重要通道，且颗粒形态和组分会对PAHs的非均相老化过程有显著影响。经气固相分配形成的包裹态二次有机气溶胶（SOA coating）是真实大气中常见的气溶胶形态之一，然而这种SOA coating是否会对颗粒相PAHs的非均相降解产生影响目前仍不清楚。因此，本项目拟利用多台在线质谱仪（真空紫外光电离有机气相质谱仪和气溶胶质谱仪等），同步监测气相、颗粒相组分及动态变化，研究不同来源VOCs反应形成的SOA包裹层对颗粒相PAHs非均相化学降解的影响。获得不同包裹层存在条件下，颗粒相PAHs的非均相降解动力学数据。研究结果对弄清复杂的SOA形态对颗粒相PAH的非均相降解的影响和综合评价SOA的健康风险具有重要意义。

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants with strongly carcinogenic property in the inhalable particles. Their occurrence constitutes a human health risk and are widely concerned in the environment. The heterogeneous chemistry process on the particle surface is reported to be one important pathway of particulate PAHs aged. Moreover, both morphology and component of aerosol particle have a significant impact on the heterogeneous degradation of particulate PAHs. In the real atmosphere, secondary organic aerosol coating(SOA coating) is ubiquitous particulate morphology. However, the effect of SOA coating on the heterogeneous degradation of PAHs is not clear yet. Thus, in this proposal, we plan to employ several online analysis instruments (VUV photoionzation VOCs mass spectrometer and Aerosol mass spectrometer, etc ) to monitor the evolution of the gas-phase and particle-phase species, so as to investigate the effect of SOA coating to the heterogeneous degradation of PAHs aerosol. The kinetics for heterogeneous reaction of PAHs aerosol by exposure to different oxidants will be obtained under different type of SOA coating. These results will be of significance in understanding the effect of complex SOA morphology on the heterogeneous reaction of particulate PAHs in the atmosphere and evaluating the health risk of SOA integrally.