Date Thesis Awarded

5-2020

Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)

Department

Chemistry

Advisor

Rachel O'Brien

Committee Members

Christopher J. Abelt

Jon Kay

Kristin Wustholz

Abstract

Biomass burning organic aerosol (BBOA), organic aerosol that derived from burning of biomass fuels, has been a major research focus because of its special role in the global budget of atmospheric chemistry and radiative forcing. Due to its chemical complexity, there are gaps in our knowledge about the chemical aging processes of BBOA in the atmosphere. Since many photochemical aging experiments on BBOA are usually conducted for only a few hours, less is known about the photo-aging pathways of the system over an extended timescale. This study presents the analyses of three BBOA filter samples derived from three types of fuels that were photolytically aged over a timeframe of up to ~3.5 days. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Offline-Aerosol Mass Spectrometry (Offline-AMS) were used to measure the chemical changes in the aqueous sample extracts and evaluate how those changes can relate to their specific fuel type. This study finds an overall increase in oxidation states and decrease in the nitro group (NO₂) compounds in the samples. The level of levoglucosan, a tracer organic species of BBOA, is also observed to decrease in the sample mixture due to photolysis alone for the first time. Several unique chemical characteristics were observed for each sample, which possibly relate to their individual fuel type. In order to further support those observations and obtain a full picture of the chemical compositions of the samples, future studies will focus on examining the acetonitrile extracts of our samples, investigating the corresponding on-line AMS data set, and applying more analytical methods to the sample extracts.

Recommended Citation

Yu, Hongmin, "Chemical Transformation of Biomass Burning Organic Aerosols Due to Photolytic Aging" (2020). Undergraduate Honors Theses. William & Mary. Paper 1557.
https://scholarworks.wm.edu/honorstheses/1557