Secondary Organic Bulk and Molecular Aerosol Yields and Product Identification and Quantification using HPLC technique from the OH and NO3 initiated Photooxidation of 5 BBVOCs

MELINDA SCHUENEMAN, Douglas Day, Demetrios Pagonis, Pedro Campuzano-Jost, Seonsik Yun, Olivia Jenks, Dongwook Kim, Marla DeVault, Paul Ziemann, Joost de Gouw, Jose-Luis Jimenez, CIRES, University of Colorado, Boulder

     Abstract Number: 336
     Working Group: Aerosol Chemistry

Abstract
Wildfires are increasing in frequency and intensity in recent years due to an expanding population, increased land clearing for agriculture, and climate change. Wildfires emit a wide array of gas- and particle-phase species into the atmosphere, therein leading to complex physical and chemical composition of species present in wildfire smoke. This complexity can not always be explained with ambient atmospheric measurements alone, leading to a need to understand individual or mixed wildfire components in a simplified system. Chamber experiments were conducted for five known biomass burning (BB) -emitted volatile organic compounds (VOCs): phenol, catechol, styrene, furfural, and methyl furfural. For these experiments, multiple particle-phase instruments (EESI-HR-ToF, HR-AMS-ToF, SMPS) and gas-phase instruments were operated (Vocus-ToF and Iodide CIMS). Each VOC was reacted with either the hydroxyl (OH in a high NOx environment) or nitrate (NO3) radical. The former involves a series of “lights on” steps, where OH is formed and reacted with the existing VOC and oxidation products, forming SOA. SOA yields were quantified for all five VOCs, and SOA yield curves were fitted to a VBS. Matching literature observations, phenolic compounds like catechol and phenol had high SOA yields across multiple C* bins. The lesser-studied species furfural, styrene, and methyl furfural also had substantial SOA formation potential. Molecular yields were also found for the more abundant products in each system where direct or indirect calibrations could be performed. Indirect calibrations involved a coupling of the HPLC technique with the EESI and AMS, where we separated individual particle components (extracted from a filter) by their solubility and polarity. Individual species are then re-aerosolized and measured with the EESI and AMS.