Molecular Composition, Absorption, and Oxidative Potential of Urban Burning Aerosols

Qiaorong Xie, Katherine Hopstock, Kevin Ridgway, Jamie Cast, Shantanu Jathar, Alexander Laskin, Christian L'Orange, Sergey Nizkorodov, LUIS RUIZ ARMENTA, University of California, Irvine

     Abstract Number: 100
     Working Group: Aerosol Chemistry

Abstract
Wildfires are an increasingly prevalent natural disaster worldwide, affecting our climate through smoke plume radiative effects and human health through smoke exposure. The number of large fires (10,000 acres or more) within the United States and the total area consumed has increased since the early 2000s. This increase is fueled by the onset of climate change and increased anthropogenic activities associated with housing developments in at-risk locations at the wild-land urban interface (WUI). While extensive work has investigated the molecular composition of biomass-burning aerosol (BBOA), the contribution from urban-burning aerosol (UBA) remains to be discovered. This poster overviews the molecular composition, absorption, and oxidative properties of UBA samples collected during the summer 2022 Burning Homes and Structural Materials (BHASMA) Campaign. During this campaign, materials (e.g., Structural wood, carpeting, and insulation) typical for a North American house were burned in smoldering pyrolysis or combustion. The chromophoric and molecular analysis of UBA done through liquid chromatography coupled with a photodiode array and high-resolution mass spectrometry (HPLC-PDA-HRMS) remains ongoing. Still, it suggests that in addition to well-known BBOA tracers, species such as levoglucosan and lignin decomposition products, plastics, and plasticizers are present in these samples. These additional chemical agents may alter the chemistry compared to BBOA studied in the past. In addition, we investigated the stability of chromophores with respect to solar UV exposure. Initial results indicate photobleaching and photoenhancement effects observed after UV aging for up to 6 hours and suggest untreated woods may experience this effect the most. This effect may depend on chemical treating agents applied to materials during manufacturing. Lastly, preliminary results collected from the dithiothreitol (DTT) assay, representative of antioxidant depletion in cells, suggest that treated wood and manufactured materials have higher OPDTT. This again implies that the manufacturing process alters UBA composition compared to previously studied BBOA.