Chemical Characterization of Water-Soluble Organic Gases from Combustion of African Biomass in Cloud Water Mimics as Precursors to Secondary Organic Aerosol

CADE CHRISTENSEN, Vaios Moschos, Megan Mouton, MarkieSha James, Marc Fiddler, Solomon Bililign, Barbara Turpin, Jason Surratt, University of North Carolina at Chapel Hill

     Abstract Number: 218
     Working Group: Aerosols, Clouds and Climate

Abstract
Wildfire biomass burning (BB) occurrences have been on the rise because of climate change in recent years. BB originating from the African continent has been grossly understudied despite estimates of nearly 50% of all organic carbon emissions being attributed to Africa. Gaseous emissions from BB have the potential to partition into cloud water droplets, undergo oxidation chemistry, and lead to formation of secondary organic aerosol (SOA). To better understand the potential of these emissions to form SOA, this study aims to chemically characterize the freshly generated water-soluble gaseous emissions from native sub-Saharan African plants. Mist chambers were used to mimic cloud droplets and collect gaseous emissions by flowing fresh lab-generated BB emissions through a mist and allowing water-soluble gases to partition into the droplets. Emissions generated from ten unique African biomass fuels were collected to determine emission profiles dependent on fuel type, as well as a mixture of fuels was combusted to mimic a wildfire event that is common to the African continent. Reverse-phase liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight tandem mass spectrometry (RPLC-ESI-HR-QTOF-MS/MS) was used to analyze the collected emissions. Accurate mass obtained from the QTOF allowed for chemical formula identification, while fragmentation analysis provided insights into functional groups present and potential structures for many compounds. These results will help incorporate impacts of African wildfire emissions in our assessment of atmospheric processes and allow for future studies on aqueous oxidation of these emissions leading to potential SOA formation.