Characterizing Oxidized North American Fire Emissions and Their Aqueous/Multiphase Atmospheric Transformations Through the FIREX Campaign
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). SOA formation through aqueous-phase chemistry of WSOGs, known to be present in wildfire emissions, such as glycolaldehyde or phenols, remains unclear. Furthermore, most oxidized organic constituents of biomass burning (BB) emissions still remain unidentified and may represent a major 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, 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 identified in the gas-phase emissions from BB of the western U.S. fuel types. Amongst these compounds, potential precursors of aqSOA were selected based on their atomic O/C ratio, water solubility, abundance and potential reactivity toward hydroxyl (OH) radical using literature data. These results indicated the high potency of BB as a source of aqSOA. 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 using both ion chromatography (IC) and high-resolution quadrupole time-of-flight mass spectrometry equipped with electrospray ionization (ESI-HR-QTOFMS). The presence of potential reactive compounds was evaluated by oxidizing these samples with OH radical (H2O2/UV). Known precursors of aqSOA, such as acetic and glycolic acids, were identified in those samples. The formation of low-volatility organics, such as oxalic and pyruvic acids, through OH oxidation also indicates the potential formation of aqSOA from BB emissions during wildfires.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.A31C2193T
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0360 Radiation: transmission and scattering;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0368 Troposphere: constituent transport and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE