基于单颗粒物分析技术的沙尘气溶胶细粒子内部混合特性研究

Fine dust aerosols have been of great concern due to its long-range transport, which has an important impact on global biogeochemical cycles and climate change. Knowledge of particle mixing state is vital for the evaluation of the climate and health impacts of aerosols. Particle physical, optical, hygroscopic, and toxicological properties strongly depend on how chemical species are mixed within individual particles. Thus it is of great value to study the mixing state of single particles. Based on reviewing the characteristics of mixing state between dust particles and pollution particles, we will make field compaigns on dust events of spring in a typical city in northern China, by using the combination of different observation methods especially the aerosol time-of-flight mass spectrometer technique. We will concentrate more on the internal mixing characteristics of single particles, including the major species and mixing states of particles in dust events. In addition, the major species and mixing states of sulfate and nitrate particles will be paid more attention to during the dust events. The results from this work will help to make sure how the single dust particles mixed before, during, and after dust events, indicating the variation of internal mixing state of single particles in dust events. It will help understand the variation of dust aerosols during the long-range transport, as well as the effects to global biogeochemical cycles and climate changes.

由于沙尘气溶胶细粒子能在大气中进行长距离传输，对全球生物地球化学循环和气候环境产生着重要影响。而气溶胶细粒子不同化学成分之间的混合特征直接影响着其物理、光学、吸湿性和毒性特征，因此研究单颗粒物水平的气溶胶内混合状态对于气溶胶的气候和健康效应研究具有非常重要的意义。本项目拟在总结我国沙尘气溶胶细粒子混合污染特征已有成果的基础上，应用先进的气溶胶单颗粒物粒径及化学组分实时在线测量(ATOFMS)技术，结合膜采样及离线化学分析方法，对我国北方春季沙尘事件中的气溶胶细粒子及其主要成分的内部混合特性进行研究。项目将针对硫酸盐、硝酸盐、有机气溶胶和元素碳等细粒子在沙尘发生前后混合特征的变化进行深入探讨，揭示矿物气溶胶与污染气溶胶的主要存在形式和混合特征，从单粒子水平阐述我国城市污染物与沙尘混合并相互作用机制，揭示沙尘期间气溶胶单颗粒物的内部变化特征，真实反映沙尘气溶胶的内混合污染规律。

由于沙尘气溶胶细粒子能在大气中进行长距离传输，对全球生物地球化学循环和气候环境产生着重要影响。而气溶胶细粒子不同化学成分之间的混合特征直接影响着其物理、光学、吸湿性和毒性特征，因此研究单颗粒物水平的气溶胶内混合状态对于气溶胶的气候和健康效应研究具有非常重要的意义。本项目在总结我国沙尘气溶胶细粒子混合污染特征已有成果的基础上，应用先进的气溶胶单颗粒物粒径及化学组分实时在线测量(ATOFMS)技术，对我国北方春季沙尘事件中的气溶胶细粒子及其主要成分的内部混合特性进行研究，针对硫酸盐、硝酸盐、有机气溶胶和元素碳等细粒子在沙尘发生前后混合特征的变化进行了探讨，结果表明沙尘颗粒物中矿物元素多与硝酸盐呈内部混合，如Dust_Fe、Dust_Ca和Dust_Si；而Dust_Al则出现与硫酸盐和硝酸盐混合的特性；同时针对典型重污染过程的污染特征及二次颗粒物SNA的季节变化特征进行了分析，为后续重污染过程的发生、发展与特征分析开展持续研究提供了初步结果和借鉴。