CHARACTERIZATION OF PARTICULATE POLLUTION BY AEROSOL MASS SPECTROMETRY
Herring, Courtney Leigh
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Atmospheric aerosols impact human health, climate, and air pollution and arrive in the atmosphere by countless number of sources. One of the largest uncertainties in understanding these impacts is due to limitations in our understanding of the organic aerosol (OA) components. To understand this complex mixture of thousands of compounds accurate high-resolution chemical speciation is needed. An Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS or HR-AMS) was deployed in two separate month-long studies to measure atmospheric particulate pollution. The first study, at the Lovelace Respiratory Research Institute (LRRI), focused on the measurement of gasoline and diesel engine exhaust under various loads and dilutions in controlled chamber experiments. HR-AMS data demonstrated clean signal associated with 53 polycyclic aromatic hydrocarbon (PAH) compounds. PAHs are of interest due to their carcinogenic implication and negative health effects especially when associated with submicron particles. From this work a novel methodology was developed for quantifying these compounds by their molecular ion signal (P-MIP). In the second study, conducted in Yakima, WA, ambient wintertime pollution was characterized and the OA components were deconvolved using positive matrix factorization (PMF). This investigation resulted in the identification of two new amine associated factors which were identified by mass spectra peaks from six dominant amine ions (C3H8N+, C2H6N2+, C4H10N+, C3H8N2+, C5H12N+, and C6H14N+). Amine ions are of interest to atmospheric research because of their implications on climate and formation of new particles. The unifying implication from both studies was the utilization of the HR-AMS to identify atmospheric pollutants that continue to generate ongoing research interests (due to their impacts on climate, pollution, or human health) and are typically difficult to measure by the HR-AMS. Additionally, included in this dissertation are four examples of science/engineering related inquiry-based lessons that were developed to relate well with my own Master’s research field and implemented into three high school science and math classrooms over the course of a two year NSF STEM Fellowship. Lastly, a two-year long case study following qualitative and quantitative data from 296 students one of these activities provides examples of the positive impact by these types of developed activities.