Laboratory Chemical Characterization of Fresh and Aged Bioaerosols
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Authors
Bahdanovich, Palina
Issue Date
2025
Type
Dissertation
Language
en_US
Keywords
aging , bioaerosol , chemical composition , mass spectrometry
Alternative Title
Abstract
Bioaerosols are biological aerosol particles in the atmosphere, such as pollen, fungi, algae, and bacteria, with sizes ranging from a few nanometers to hundreds of micrometers. The importance of bioaerosols has been growing due to climate change, however, their chemistry and atmospheric fate are still largely unexplored. The contribution of bioaerosols and their organic compounds to the atmospheric organic carbon load, and their role in cloud physics and atmospheric processes should be studied further. To address this knowledge gap, this dissertation investigates the chemical composition of water-soluble extracts of various types of bioaerosols and the effects of laboratory aging, such as exposure to simulated solar radiation and OH radicals. The bioaerosols chosen for chemical characterization were lodgepole pine pollen, rabbitbrush pollen, western gall rust fungi, hay Bacillus bacteria, Pedobacter bacteria, and Spirulina alga. Using various analytical techniques, such as gas chromatography – mass spectrometry (GC-MS), ultra-high performance liquid chromatography – mass spectrometry (UPLC-MS), ultraviolet-visible-near-infrared spectrophotometry (UV-Vis-NIR), proton nuclear magnetic resonance spectroscopy (1H-NMR), and Fourier-transform infrared spectroscopy (FTIR), organic species (saccharides, amino acids, and fatty acids) and functional groups of these bioaerosols were determined. Chemical analysis showed that the saccharide glucose was common between all analyzed bioaerosol extracts, and the major contribution of organic species in pollen was from saccharides. Laboratory aging was performed on lodgepole pine pollen and Spirulina alga using the Suntest CPS solar simulator. These bioaerosols were exposed to (1) simulated solar radiation, ranging from 300 to 800 nanometers, and (2) OH radicals formed by hydrogen peroxide through photolysis. Functional groups were compared before and after aging using 1H-NMR and FTIR spectroscopy to uncover the chemical transformation and changes in polarity of the bioaerosols. FTIR results showed an overall increase of polar functional groups in the two bioaerosols after aging with simulated solar radiation. Though 1H-NMR showed no significant changes after simulated solar aging, the functional group distribution transformed dramatically after exposure to OH radicals. In summary, this research was instrumental in understanding the contribution of various organic compounds to bioaerosol chemistry and the transformation of bioaerosols after exposure to atmospheric aging.