Absorption Spectra and Brown Carbon Chromophores in Particles Emitted by Burning Structural Materials

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

     Abstract Number: 667
     Working Group: Aerosol Chemistry

Abstract
Fires at the wildland-urban interface (WUI) are increasingly prevalent worldwide. From these fires, large amounts of carbonaceous aerosol particles consisting of black carbon (BC) and brown carbon (BrC) are released into the urban atmosphere. While the BC and BrC emissions from biomass burning have been thoroughly characterized, the chemical composition of aerosols emitted from WUI fires is still poorly understood. Once in the atmosphere, organic compounds in aerosol particles undergo complex chemical transformations affecting their chemical and physical properties. In the case of BrC, the most critical property affected by this chemical aging is the absorption coefficient, which determines the amount of radiative energy trapped by aerosols. This poster reports preliminary findings from the ongoing Burning Homes And Structural MAterials (BHASMA) campaign, focusing on light-absorption coefficients and the chemical composition of smoke released by model WUI fires. Various urban materials, such as structural wood, manufactured wood, sheathing/insulation, siding, roofing, carpet, and electrical wiring commonly found in American households, are burned in two modes: pyrolysis at reduced oxygen level or flaming in presence of normal amount of oxygen. Aerosol particles from the simulated burning of these materials are collected on filters. The chemical composition is analyzed using liquid chromatography coupled with a photodiode array and high-resolution mass spectrometry (HPLC-PDA-HRMS), which separates compounds on a reverse-phase column, detects chromophoric species by their enhanced light absorption and identifies them by a formula using mass spectrometry. This poster is submitted as a late-breaking one as the BHASMA campaign is currently ongoing (June-July 2023), and the first results should be available by the time of the AAAR meeting.