Assessing the Impact of Atmospheric Photochemical Aging on Organic Aerosol Tracers Derived From Burning African Biomass Relevant to Botswana
ADRIENNE LAMBERT, Cade Christensen, Vaios Moschos, Megan Mouton, MarkieSha James, Marc Fiddler, Barbara Turpin, Solomon Bililign, Jason Surratt,
University of North Carolina at Chapel Hill Abstract Number: 252
Working Group: Aerosol Chemistry
AbstractAs a result of climate change, wildfires are becoming increasingly frequent and intense, leading to the production of biomass burning (BB)-derived organic aerosols (BBOA). These fine aerosol particles can have negative impacts on human health. Despite accounting for over 50% of worldwide BB emissions, there is a lack of systematic laboratory studies analyzing organic aerosol tracers derived from the burning of African biomass. This study aims to examine how atmospheric photochemical aging alters the chemical composition of freshly-generated BBOA tracers from well-known and abundant African biomass fuels, especially those relevant to Botswana. Gas chromatography interfaced to electron ionization quadrupole mass spectrometry (GC/EI-MS) was used to analyze aerosol filters collected from both fresh and photochemically-aged BB emissions of six different biomass fuel types (i.e., Botswana fuel mixture,
Cordia africana,
Baikiaea plurijuga,
Acacia erioloba,
Colophospermum mopane, and Ethiopian cow dung) generated from a furnace that mimicked smoldering conditions. The furnace effluent was injected into the NCA&T smog chamber at a constant relative humidity of 70% ± 3%. The abundances of 17 known BBOA tracer compounds (e.g., levoglucosan, mannosan, coniferyl alcohol, lactic acid, etc.) were compared between the fresh and photochemically-aged BB emissions from each of the 6 fuel types, and significant differences were found. In addition, a number of ambient fine particulate matter samples collected from Botswana at the start of the southern hemisphere fire season were also analyzed by GC/EI-MS in order to identify the BBOA tracers from our laboratory studies. Our results will likely help to increase our fundamental understanding of the chemical transformations of BB emissions in Botswana after atmospheric photochemical aging.