AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Volatility Change during Droplet Evaporation of Pyruvic Acid
SARAH SUDA PETTERS, Thomas Hilditch, Sophie Tomaz, Rachael E.H. Miles, Jonathan P. Reid, Barbara Turpin, University of North Carolina at Chapel Hill
Abstract Number: 886 Working Group: Aerosol Chemistry
Abstract Atmospheric water-soluble organic gases such as pyruvic acid are produced in large quantities by photochemical processing of biogenic hydrocarbons and undergo water-mediated reactions in aerosols and hydrometeors. These reactions can contribute to aerosol mass by forming less volatile compounds. However, the additional aerosol mass contributed by aqueous reactions is highly uncertain because models use simplified partitioning mechanisms based on fixed yields or limited laboratory experiments for these systems. Here we experimentally determine the evolution of volatility distributions of pyruvic acid using both the Vibrating Orifice Aerosol Generator (VOAG) and an electrodynamic balance (EDB). Pyruvic acid was evaporated with and without oxidation by OH radicals. The evaporation behavior of oxidized mixtures was consistent with expectations based on known volatilities of reaction products. However, more surprisingly, independent VOAG and EDB evaporation experiments conducted without oxidation also resulted in stable residual particles; the estimated volume yield was 10–30% of the initial pyruvic acid. Yields varied with temperature and pyruvic acid concentration under cloud, fog, and aerosol-relevant conditions. The formation of low volatility products, likely cyclic dimers, suggests that pyruvic acid accretion reactions occurring during droplet evaporation could contribute to aerosol mass in the atmosphere.