Characterizing wintertime aerosol composition and sulfate formation in Fairbanks, Alaska

Davey, Ragen

dc.contributor.author	Davey, Ragen
dc.date.accessioned	2020-09-20T18:59:58Z
dc.date.available	2020-09-20T18:59:58Z
dc.date.issued	2020-05
dc.identifier.uri	http://hdl.handle.net/11122/11261
dc.description	Thesis (M.S.) University of Alaska Fairbanks, 2020	en_US
dc.description.abstract	The citizens of Fairbanks, Alaska are exposed to high levels of air pollutants throughout the winter months, causing the city to violate the Fine Particulate Matter (PM₂.₅) National Ambient Air Quality Standards set in place by the United States Environmental Protection Agency. Previous studies have shown the significant amount of sulfate aerosols particles observed in Fairbanks winters, but the formation mechanism of aerosols containing sulfate in the atmosphere is still unknown. While sulfate aerosol particle formation is commonly driven by oxidants including ·OH, H₂O₂ and O₃, these photochemical species are limited in Fairbanks winter months. This indicates sulfate aerosol particle formation may occur through a nontraditional pathway, and this project investigates one proposed mechanism in which transition metals may catalyze sulfate aerosol particle formation. We collected twelve full diurnal cycles over the winter months of 2019, using a particle-to-liquid sampler (PILS) at hourly time resolution. This PILS instrument creates an aqueous extract containing only the water-soluble components of the aerosol particles. These aqueous extracts were analyzed offline for inorganic and metal concentrations by ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS). This hourly dataset provides new insights in emissions, chemical processing and their coupling with boundary layer dynamics. We find a strong correlation between hourly sulfate and PM2.5 mass concentrations, but we do not find the strong evidence of transition metal ion (TMI) catalysis on sulfate formation. We also collected twelve sets of aerosol filters using Micro-Orifice Uniform Deposit Impactor (MOUDI) throughout the winter of 2019. These size-resolved filter samples suggest the presence of hydroxymethane sulfonate (HMS) in submicron particles when temperatures are below -30 °C (-22 °F), suggesting a new reservoir for sulfur compounds in Fairbanks winter and warranting further investigation.	en_US
dc.description.sponsorship	UAF, The Alaska Space Grant Program, Alaska NSF EPSCoR, URSA, Alaska Department of Environmental Conservation, and BLAST	en_US
dc.description.tableofcontents	Chapter 1: Introduction -- 1.1 Motivation and Background -- 1.2 Fairbanks PM₂.₅ Pollution -- 1.3 Sulfur Oxidation -- 1.4 Hypothesis. Chapter 2: Site Description -- 2.1 Fairbanks Meteorology -- 2.2 Sample site -- 2.3. NCore site -- 2.3.1 NCore Measurements -- 2.3.2 NCore Instrumentation. Chapter 3: Methods -- 3.1 Sample collection, preparation and preservation -- 3.1.1 Aqueous sample collection -- 3.1.2 Aqueous sample preservation -- 3.1.3 Blank samples and Internal Standard -- 3.2 Filter sample collection -- 3.3 Chemicals and reagents -- 3.4 Analytical methods -- 3.4.1 Ion analysis of aqueous samples -- 3.4.2 Metal analysis of aqueous samples -- 3.5 Data Analysis (Math Methods). Chapter 4: Results and Discussion: Inorganic Species -- 4.1 Sulfate Correlation -- 4.2 Statistical Species Correlation -- 4.3 SO₂ Correlation with PM₂.₅ -- 4.4 Median Diurnal Cycles -- 4.4.1 January Median Diurnal Cycle -- 4.4.2 February Median Diurnal Cycle -- 4.5 Inorganic Individual Diurnal Cycle Trends -- 4.5.1 Loss of Sulfate to PM₂.₅ Correlation -- 4.5.2 NH₄ is episodic -- 4.6 MOUDI Observations -- 4.6.1 Size distribution of Sulfate and PM₂.₅ -- 4.6.2 HMS in Fairbanks. Chapter 5: Results and Discussion: Metal Species -- 5.1 Sulfate Correlation to Metals -- 5.2 Strontium and Barium to Total PM₂.₅ -- 5.3 Zn Correlation with PM₂.₅ -- 5.4 ICP-MS versus IC discrepancies. Chapter 6: Conclusions and Future Work -- 6.1 Conclusions with Regard to this Thesis Study -- 6.2 Future Work -- References -- Appendices.	en_US
dc.language.iso	en_US	en_US
dc.subject	atmospheric aerosols	en_US
dc.subject	Alaska	en_US
dc.subject	Fairbanks	en_US
dc.subject	atmospheric sulfur compounds	en_US
dc.subject	atmospheric sulfur dioxide	en_US
dc.subject	air	en_US
dc.subject	pollution	en_US
dc.title	Characterizing wintertime aerosol composition and sulfate formation in Fairbanks, Alaska	en_US
dc.type	Thesis	en_US
dc.type.degree	ms	en_US
dc.identifier.department	Department of Chemistry and Biochemistry	en_US
dc.contributor.chair	Mao, Jingqiu
dc.contributor.committee	Simpson, William R.
dc.contributor.committee	Guerard, Jennifer J.