10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Multiphase Product Distributions for Aqueous-phase Oxidation of Water-soluble Organic Compounds in Bulk Solution and Submicron Particles
KEVIN NIHILL, Christopher Lim, James Rowe, Martin Breitenlechner, Alexander Zaytsev, Joshua L. Cox, Frank Keutsch, Jesse Kroll, MIT
Abstract Number: 848 Working Group: Aerosol Chemistry
Abstract Atmospheric aqueous-phase oxidation has been identified as a possible source of highly oxidized organic aerosol (OA) observed in the ambient atmosphere. Most laboratory experiments monitoring the oxidation of organic precursors in the aqueous phase have used bulk phase chemistry, but this may not accurately simulate partitioning or concentration conditions of fine particles in the ambient atmosphere. This is suggested by significant differences in the product distributions of experiments that compare oxidation of water-soluble organics in both the bulk and particle phases. This work serves to extend our understanding of atmospheric aqueous oxidation of water-soluble organic compounds by precisely measuring and comparing the aqueous-phase oxidation products of varying carbon-number polyols (water-soluble compounds with formula CnH2n+2On) in both the gas and aqueous phases. Through complementary measurements of oxidation products using an aerosol mass spectrometer (AMS) and two proton-transfer reaction time-of-flight mass spectrometers (high sensitivity PTR3s) – one for the gas phase, and one with a gas-phase denuder followed by a thermodesorption unit for aerosol volatilization – we seek to understand the full oxidation product distributions for a variety of polyols. In particular, a more thorough profile of gas-phase products will allow for an improved understanding of how partitioning and concentration effects in aqueous-phase oxidation impacts the chemistry of the atmosphere. Further, we can elucidate the dependence of gas-particle partitioning on the liquid water content (LWC) of the air mass, which may span many orders of magnitude in the atmosphere. This study underscores the need to reproduce atmospheric conditions in the laboratory in order to better characterize the influence of aqueous-phase oxidation on atmospheric organic chemistry.