氏 名 孫
す ん翠
す い枝
じ所 属 理工学研究科 分子物質化学専攻 学 位 の 種 類 博士（理学）
学 位 記 番 号 理工博 第
292号 学位授与の日付 平成
31年
3月
25日 課程・論文の別 学位規則第４条第１項該当
学 位 論 文 題 名
Chemical and Physical Characterization of Aerosols in East Asia Based on Mass Spectrometry and Electron Microscopy質量分析法と電子顕微鏡解析に基づく東アジアにおけるエアロゾル の化学的・物理的特性の研究
(英文
)論 文 審 査 委 員 主査 教 授 竹川 暢之 委員 教 授 城丸 春夫 委員 准教授 大浦 泰嗣
委員
教 授 持田 陸宏（名古屋大学宇宙環境研究所）
【論文の内容の要旨】
Aerosols are suspensions of solid or liquid particles in the air. The anthropogenic activities can increase the concentration of ambient aerosols, having significant influences on human health and air quality. Aerosols can alter the radiative balance of the atmosphere by efficiently scattering solar radiation and also by acting as cloud condensation nuclei (CCN). These effects have significant impacts on regional and global climate. Black carbon (BC) aerosols are emitted from incomplete combustion of fossil fuel and biomass, which can significantly contribute to global warming because of its strong absorption efficiency for visible solar radiation. The mixing state of BC-containing particles is an important parameter for characterizing the radiative effects of aerosols. However, variability in the concentrations and mixing state of BC are poorly understood because measurements of these parameters are limited.
In general, aerosol measurements can be categorized into online and offline analysis methods. The online analysis provides real-time measurements of aerosols with high temporal resolution. However, chemical species that can be quantified by online methods are generally limited. Calibration of online methods during field experiments is also an important issue. The offline analysis involves the collection of particles on a substrate and analysis of the particles in the laboratory. Although the
offline analysis can provide detailed information on chemical species, temporal resolution and representativeness of samples are often limiting factors for the interpretation of the results, especially when aerosol concentrations show large temporal/spatial variability.
The major objectives of this study are to improve the quantification method for online aerosol mass spectrometry and to characterize the chemical and physical properties of ambient aerosols in Asian outflow based on online aerosol mass spectrometer and offline electron microscopy analysis. Chapter 1 (introduction of this study) gives the fundamentals of aerosol formation processes and a brief review of techniques for aerosol measurement. Chapter 2 (experimental methods used in this research) describes experimental details of the laser-induced incandescence - mass spectrometric analyzer (LII-MS) and transmission electron microscopy (TEM). A new calibration method for a particle mass spectrometer using polydispersed aerosols combined with an optical particle sizer has been developed. Chapter 3 discusses details of the operation procedure and laboratory evaluation of the new calibration method using the LII-MS. This method has been successfully deployed in a field experiment in Taiwan. Chapter 4 presents and discusses results from the field experiment in Taiwan.
The combination of the online and offline techniques provides detailed insights into chemical composition and mixing state of aerosol particles. Results from the LII-MS measurement showed that the averaged mass fraction of sulfate and nitrate internally mixed with BC was ~9% and ~11%, respectively, in regionally polluted air. The TEM analysis showed that the number fraction of aerosol particles internally mixed with BC was ~5-26% and ~1-23% for core-shell and attached types, respectively. The physical and chemical processes affecting the variability in the mixing state are discussed. Our findings provide a new constraint for three-dimensional models that can resolve the mixing state of aerosol particles to accurately estimate the radiative impact of BC.
Chapter 5 summarizes the conclusions and future perspective of this research.
