AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Observed Ambient Gas-particle Partitioning of Tracers for Biogenic Oxidation
GABRIEL ISAACMAN-VANWERTZ, Lindsay Yee, Nathan Kreisberg, Rebecca Wernis, Joshua Moss, Susanne Hering, Suzane de Sá, Scot Martin, Lizabeth Alexander, Brett Palm, Weiwei Hu, Pedro Campuzano-Jost, Douglas Day, Jose-Luis Jimenez, Matthieu Riva, Jason Surratt, Juarez Viegas, Antonio O. Manzi, Eric Edgerton, Karsten Baumann, Rodrigo A. F. Souza, Paulo Artaxo, Allen H. Goldstein, University of California at Berkeley, Berkeley, CA, USA
Abstract Number: 369 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Exchange of atmospheric organic compounds between gas and particle phases is an important process in particle formation, but is poorly understood due to a lack of simultaneous measurements in both phases of individual compounds. Measurements of particle- and gas-phase organic compounds are presented here for the southeastern U.S. and central Amazonia. Known isoprene oxidation products contribute 8% and 15% on average to particle-phase organic mass at these sites, but are also observed to have substantial gas-phase concentrations contrary to many models that treat these compounds as non-volatile. Observed gas-particle partitioning of approximately 100 known and newly observed oxidation products is not well explained by environmental factors (e.g. temperature). Instead, compounds with high vapor pressures have a higher particle fraction than expected. This demonstrates that gas-particle partitioning of biogenic oxidation products is driven by chemical processes such as the formation of low-volatility mass (e.g. accretion products, inorganic-organic adducts) that may in some cases be measured as individual compounds. Uncertainty in the characterization of this mass challenges the use of equilibrium to model partitioning of individual species, but average particle fractions for a given compound are observed to be consistent within ~25% across measurement sites.