AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Characterizing Oxidized North American Fire Emissions and Their Aqueous/Multiphase Atmospheric Transformations through the FIREX Campaign
SOPHIE TOMAZ, Tianqu Cui, Yuzhi Chen, Kenneth Sexton, Jason Surratt, Barbara Turpin, University of North Carolina at Chapel Hill
Abstract Number: 94 Working Group: There Must be Something in the Water: Cloud, Fog and Aerosol Aqueous Chemistry for Aerosol Production
Abstract Aqueous multiphase chemistry of water-soluble organic gases (WSOGs) is now recognized to be a potential and significant source of atmospheric secondary organic aerosol (SOA). However, SOA formation through aqueous-phase chemistry of wildfire emissions is not well understood. Furthermore, most oxidized organic constituents of biomass burning (BB) emissions remain unidentified and may represent a major missing source of atmospheric aqueous SOA (aqSOA). In the present work, we investigated the chemical composition of gas-phase emissions from the combustion of several western U.S. fuels, at the Fire Science Laboratory as part of FIREX (Fire Influence on Regional and Global Environments Experiment), using a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) equipped with iodide reagent ion chemistry. By using the HR-ToF-CIMS, more than 50 oxygen (O)-containing and 15 nitrogen (N)-containing organic compounds were characterized in the gas-phase emissions from BB of the western U.S. fuel types. From among these compounds, we selected potential precursors of aqSOA based on their atomic O/C ratio, water solubility, abundance and potential reactivity toward hydroxyl (OH) radical using literature data. The selected compounds such as oxo-butanoic and hydroxypropanoic acids, were oxidized in the aqueous phase in the presence of OH radical (H2O2/UV). We evaluated the formation of low-volatility organics using both ion chromatography (IC) and high-resolution electrospray ionization mass spectrometry (ESI-HR-MS). We compared these results with water samples collected during the FIREX experiments, by scrubbing gaseous emissions into water using mist chamber samplers. We investigated the composition of these samples and their reactivity toward OH. Reactive compounds were identified and were compared with those tested based on the HR-ToF-CIMS measurements of primary BB emissions.