Date of Award
5-28-2024
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
Atmospheric aerosols are ubiquitous indoors and outdoors and their impact on human life on Earth is extensive. Aerosol particles scatter and absorb solar radiation, are key in the formation of clouds and precipitation, and can affect the abundance and distribution of greenhouse and atmospheric trace gases by physicochemical multiphase processes, thus they play an important role in regulating regional and global climate. On the other hand, poor indoor and outdoor air quality associated with high particulate matter (PM) levels is among the leading health risks worldwide, affecting life quality and expectancy by increasing the risk of cancer, cardiovascular and respiratory diseases. Organic aerosols (OA) have been recognized to account for a significant portion of atmospheric PM covering a wide range of volatilities that encompass thousands of individual compounds. Therefore, the extent of aerosols impact on human life strongly depends on the volatility and chemical composition of the species that comprise the OA population. The work presented in this dissertation focuses on the improvement of OA characterization through the development of novel instrumentation and methods, and the application of these techniques to investigate the process influencing aerosols’ volatility and chemical composition variability. Chapter 2 discusses the challenges in recovering volatility information through thermal evaporation measurements alone and presents improvements in OA volatility characterization when combining thermal evaporation with thermal desorption gas chromatography-mass spectrometry. Chapter 3 focuses on the full development of a modified Semi-Volatile Thermal Desorption Aerosol Gas Chromatograph (SV-TAG) with an automatic calibration system. This version of the SV-TAG features a newly developed cell designed to improve the collection of intermediate volatility and semi-volatile gases and particles, extending the analytical capability of the instrument in the quantification of higher-volatility chemical species. This new instrument was deployed during the Alaskan Layered Pollution and Chemical Analysis (ALPACA) field campaign to help understand the dynamics of speciated gas-particle partitioning under extreme cold and dark conditions with results discussed in Chapter 4. The time-dependent chemical information provided by the SV-TAG also aided in the investigation of the major sources contributing to poor air quality during wintertime in this Arctic region, which is detailed in Chapter 5.
Language
English (en)
Chair
Brent Williams