Soot大气化学演化过程及其混合气溶胶形成机制研究

In recent years in China, photochemical pollution and haze episodes have occurred more frequently. High levels of ozone and atmospheric fine particles have become serious environmental problems, and as a major component of atmospheric aerosol particles, soot (black carbon aerosol) pollution shows an increasing trend. Soot plays an important role in human health, air quality, climate change and atmospheric chemistry. However, a little concern has been paid to atmospheric chemical evolution of soot and its role in atmospheric chemical processes up to now. Here we study atmospheric chemical evolution of soot and formation mechanism of its mixed aerosol by using various measurement techniques and monitoring instruments such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and flow tube reactor. Based on the investigations on various atmospheric chemical processes in the presence of soot, we will elucidate the effects of soot on the heterogeneous conversion processes of atmospheric trace gases such as SO2 and NO2 on mineral dust surfaces and the photolysis processes of adsorbed nitrate or nitrate solution, explore the influence mechanisms, potential heterogeneous conversion pathways, and its further influences on the conversions of other atmospheric species, clarify possible roles in atmospheric oxidation capacity and the formation of atmospheric secondary particle and ozone, and its potential impacts on air pollution, and finally reveal the atmospheric chemical evolution processes of soot and the formation mechanisms of its mixing states. This study not only helps to further understand the heterogeneous reaction of atmospheric aerosol, towards a more comprehensive understanding of the atmospheric chemical processes of atmospheric trace gases, but also helps to explore the formation mechanisms of atmospheric aerosols and ozone during air pollution episodes. This study also provides important information for the government to formulate air pollution control strategy and policy.

近年来我国大气污染事件频发，高浓度O3和细粒子污染成为严重环境问题，作为气溶胶重要组份的黑碳气溶胶污染也日益加重。黑碳气溶胶对空气质量、气候变化和大气化学具有重要作用，但目前对soot的大气化学演化及其在大气化学过程中作用研究不足。本项目拟用漫反射傅立叶变换红外光谱、流动管反应器和外场观测设备等手段开展soot大气化学演化过程及其混合气溶胶形成机制研究。通过考察soot对大气化学过程的影响，阐明soot对SO2、NO2等大气非均相转化过程和对吸附态或溶液中硝酸盐光解的影响、影响机制、潜在转化途径，以及这种影响所带来的对其他物种大气转化的进一步影响等，澄清soot对大气氧化性、大气二次粒子和O3形成等可能作用，进而揭示soot大气化学演化过程及其混合态形成机制。此研究可丰富对大气非均相反应认识，有助于探索大气污染事件中气溶胶和O3形成机制，也有助于为我国大气污染控制和决策制定提供重要科学依据

近年来我国大气污染事件时有发生，高浓度O3和细粒子污染成为严重环境问题。作为气溶胶重要组份的黑碳气溶胶对空气质量、气候变化和大气化学具有重要作用，其污染也日益加重。但目前对soot的大气化学演化及其在大气化学过程中作用研究不足。本研究基于实验室模拟和外场观测系统地研究了表面活性物种对SO2和NO2非均相反应的影响和影响机制、不同形貌氧化铁的非均相反应性能、soot和生物质燃烧烟尘对SO2在矿尘气溶胶表面非均相转化的影响、新鲜和不同方法老化的柴油soot及其有机溶剂萃取液对NO2非均相反应的影响、不同条件下的硝酸盐光化学、soot 对吸附态或溶液中硝酸盐光解反应的影响、硝酸盐光化学对大气SO2和典型有机醛、酸非均相转化以及液相硫酸盐形成的影响、甲苯、乙烯和soot对硝酸盐光解产生O3的影响、以及外场观测如伴随生物质燃烧的上海大气污染事件特征的研究、灰霾事件中液相非均相反应的倾向性研究等，发现了一系列新颖的结果。这些工作大大加深了对soot和生物质燃烧烟尘的大气化学行为、大气SO2和NO2的非均相过程、硝酸盐光化学及其对臭氧形成影响、以及它们之间相互影响的认识，丰富了大气非均相化学，有助于揭示soot大气化学演化过程及其混合态形成机制，有助于澄清soot对大气氧化性、大气二次气溶胶形成和臭氧形成等可能的作用及其作用机制，可为大气模式研究或大气化学模式发展提供更多更细致的相关数据或理论依据，为大气化学的发展做出了应有的贡献。同时，我们也发现耦合生物质燃烧的上海大气污染事件特征、上海灰霾事件中硝酸盐污染的增长趋势，以及灰霾事件中液相非均相反应的倾向性，如高硝酸盐污染的灰霾事件有利于SO2的液相非均相氧化等。上述研究不仅弥补相关研究的不足，而且为我国城市大气污染控制和决策制定提供科学依据。