大气中烯烃及芳香烃与OH自由基反应速率常数的测定及评估

大气中烯烃及芳香烃可被OH自由基氧化，进一步反应生成臭氧和二次有机气溶胶，对人体健康以及大气环境产生重要影响。目前大部分烯烃及芳香烃和OH自由基之间的反应动力学研究以惰性气体为底气开展，不同实验室获得的速率常数存在显著差异（有的高达2个数量级），所获速率常数在实际大气中应用存在极大不确定性。本研究拟采用相对速率常数法，通过烟雾箱实验开展不同背景气（空气及惰性气体）及温度条件下混合体系中烯烃及芳香烃与OH自由基之间反应速率常数的研究，阐明空气及温度对混合体系中烯烃及芳香烃与OH自由基之间反应速率常数的影响；开展单一烯烃及芳香烃在空气环境下与OH自由基反应速率常数的测定，验证混合体系所获反应速率常数的可靠性。该项目的实施为科学评估烯烃及芳香烃的大气寿命及其环境影响提供新的科学依据。

Atmospheric oxidative removal of alkenes and aromatics is mainly initiated by gas phase reaction with the hydroxyl radical (OH), and their degradation in the atmosphere can form a series of secondary pollutants, such as ozone and organic aerosol, which have wide-ranging impacts on human health and atmosphere. Almost all gas-phase kinetics of OH reactions with alkenes and aromatics were based on the inert gas as the bath gas, and the gas-phase rate coefficients of OH reactions with alkenes and aromatics obtained from various laboratories were significantly different. In addition, there is great uncertainty about the application of the obtained gas-phase rate coefficients of OH reactions with alkenes and aromatics in air condition. Based upon established relative rate concepts, the gas-phase rate coefficients of hydroxyl radical reactions with alkenes and aromatics by using simulative systems in smog chamber under different bath gas and temperature conditions will be determined, and the various factors (bath gas and temperature) affecting the gas-phase rate coefficients will be elucidated. This project will establish an experimental technique capable of measuring rate coefficients for large numbers of OH+alkenes/aromatics reactions simultaneously, and the accuracy of the obtained rate coefficients can be proved by the gas-phase rate coefficients of hydroxyl radical reactions with a single alkene/aromatic. The project applied will provide a novel and practical scientific idea for assessing the atmospheric lifetime and atmospheric environmental impact of alkenes and aromatics.