活性含氮化合物非均相/多相反应及其对区域空气质量的影响研究

This project focuses on the unsolved problems existing in the research of the heterogeneous and multiphase reactions of the reactive nitrogen-containing compounds. Combined with the actual air pollution condition in our country, laboratory simulation focusing on the heterogeneous and multiphase reactions of the reactive nitrogen-containing compounds will be carried out. A series of methods and instruments will be used to reveal new mechanisms and the influence of reaction condition and coexisting components. The synergistic effect of SO2 and NO2 will be systematically investigated. The uptake coefficients as well as the reaction rate constants will be accurately measured, which will be further used to establish the parameterization scheme suitable for atmospheric pollution condition in China. In addition, the research results will be compiled in CMAQ model with new module. Consequently, the effect of these heterogeneous and multiphase reactions on the sources and sinks of reactive nitrogen-containing compounds will be assessed, in particularly on the contribution of HONO and secondary nitrate aerosol, as well as the formation of other secondary aerosol. Our country is facing serious problems of complex air pollution which makes the atmospheric fine particles (PM2.5) and O3 appear alternately. Since the formation of PM2.5 and O3 are closely related to the atmospheric chemistry of nitrogen oxides, therefore, the research of this project are useful for understanding the causes of complex air pollution, and could provide a scientific basis for cooperative control of PM2.5 and O3 in our country.

本项目针对活性含氮化合物非均相/多相反应研究中存在的问题，并结合我国实际大气复合污染现状，拟开展活性含氮化合物非均相/多相反应的实验室研究，通过多种研究手段揭示活性含氮化合物非均相/多相反应的新机制，考察环境条件和共存组分的影响，深入系统研究NO2和SO2共存反应中的复合效应，准确测量反应的摄取系数和速率常数，构建适合于我国大气污染条件的参数化方案，将所得研究结果用于CMAQ新的模块，以准确评估非均相/多相反应对活性含氮化合物源汇平衡的影响，重点关注对HONO和二次硝酸盐的贡献，以及对其他二次颗粒物生成的影响。当前我国面临严峻的大气污染问题，大气复合污染使得大气细粒子(PM2.5)和O3问题交替出现，而PM2.5和O3的形成都与氮氧化物密切相关，因此，本项目的研究有助于深入认识我国大气复合污染的成因，并为PM2.5和O3的协同控制提供科学依据。

活性含氮化合物是大气中重要的污染物，与O3和PM2.5的形成都密切相关。因此，准确认识活性含氮化合物参与的大气化学过程，是评估大气中含氮化合物的科学依据，也是揭示大气复合污染成因的关键步骤之一。本项目开展了典型活性氮物种在大气中转化的机制研究，对NO2在不同颗粒物表面的摄取系数进行了测量，系统分析了影响非均相摄取系数的关键因素，阐明不同研究方法对于非均相摄取系数的影响作用；开展了NO-NO2与SO2在矿质颗粒物表面非均相反应过程中复合效应的深入研究，从分子水平揭示了复合效应机制，阐明了SO2-硫酸盐转化与NO-NO2循环过程的耦合关系，测量了SO2共存条件下NO和NO2的摄取系数，提出了非均相复合效应可能是无光照条件下大气氧化性重要来源；探索了不同矿质颗粒物表面硝酸盐光解的规律，揭示了影响表面硝酸盐光解的主要原因，发现了硝酸盐阳离子的碱性对于NO2和HONO产率的决定性影响，阐明了SO2、NH3和H2O对不同环境条件下硝酸盐光解的影响机制；发现了硝酸盐混合颗粒物吸水过程中，弱酸置换强酸的化学机制，提出了HNO3在矿质颗粒物表面非均相反应与水吸附-脱附过程的耦合造成HNO3的大气循环过程；初步构建了NO2非均相反应动力学的参数化方案，并应用于CMAQ模型评估不同反应机制对HONO和二次气溶胶形成的贡献。研究结果为深入认识大气活性含氮化合物的迁移转化及其环境影响提供了重要科学依据。