冬季二次硫酸盐在矿尘颗粒物表面形成过程的研究

Winter is the season when haze pollution occurs frequently in China, and the studies suggest that explosive growth of secondary fine particles is the main cause, usually accompanied with high relative humidity and steady weather. Field studies show that sulfate increases significantly or even explosively during the severe haze pollution period, which plays an important role in the rapid growth of PM2.5. However, the mechanism of explosive growth of sulfate under both low temperature and high RH condition is still far from clear. Therefore, the project prepares to carry out the research on the heterogeneous formation of sulfate on minerals. The heterogeneous reactions of SO2 on the surface of several typical mineral dusts to form sulfate will be studied under winter temperature conditions in Beijing-Tianjin-Hebei (BTH) region(-20℃- 10℃), and the influence of several environmental factors, such as RH and light, will also be discussed. The reaction kinetic parameters will be determined and micro-mechanism for the reaction will be speculated reasonably. These will be helpful to evaluate the contribution of the heterogeneous reactions on minerals to the rapid formation of secondary sulfates. Further, this research would be favourable to get a deep understanding on more complicated processes of secondary aerosol formation.

冬季是我国霾污染的高发季节，研究表明灰霾成因主要是二次细粒子爆发性增长，通常伴随静稳天气及较高湿度。外场观测显示，硫酸盐在重污染期间会有极大增长甚至呈现爆发式增长，对PM2.5快速增长起到非常重要的作用。然而现阶段对于冬季低温高湿条件下硫酸盐爆发性增长的微观机制还不清楚。本项目针对京津冀地区冬季重霾频发的情况，拟深入开展矿尘颗粒物表面二次硫酸盐非均相形成过程的研究。实验室模拟研究京津冀冬季温度范围内（T：-20℃-10℃）高相对湿度条件下（RH：60%-90%），多种环境要素（光照、混合组分等）对SO2在典型矿尘表面反应形成硫酸盐过程的影响，得到相关非均相反应过程的动力学参数，推测微观反应机制，为评估矿尘颗粒物非均相反应对二次硫酸盐快速形成的贡献提供数据支持，也为进一步研究更为复杂的大气二次气溶胶非均相形成过程奠定基础。

本项目围绕SO2在颗粒物表面的非均相反应，研究了SO2在不同相对湿度、不同温度、光照条件下在粉煤灰、二氧化钛等颗粒物表面发生的非均相反应过程，研究了SO2氧化生成硫酸盐的影响机制，为非均相反应对二次硫酸盐快速形成的贡献提供数据支持，也为模式计算提供更为精确的物理化学参数；同时研究了金属氧化物表界面非均相降解反应机制，将有助于提出符合我国实际环境条件的典型反应性有机物非均相降解转化过程和机理。