AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Understanding the Role of Aerosols in the Lifecycle of Organic Carbon through Multiple Generations of Aging
GABRIEL ISAACMAN-VANWERTZ, Jonathan Franklin, Christopher Lim, Paola Massoli, Andrew Lambe, John B. Nowak, Timothy Onasch, Manjula Canagaratna, Joseph Roscioli, Scott Herndon, John Jayne, Douglas Worsnop, Luping Su, Daniel Knopf, Pawel Misztal, Caleb Arata, Allen H. Goldstein, Jesse Kroll, Massachusetts Institute of Technology
Abstract Number: 332 Working Group: Aerosol Chemistry
Abstract Emissions of organic carbon to the atmosphere undergo oxidation reactions to yield hundreds of products, forming a multiphase, chemically dynamic system of organic aerosol and gas-phase products that span a wide range of volatilities. Throughout atmospheric aging, organic aerosol acts as an intermediate reservoir for carbon, formed by condensation of low-volatility gases and eventually deposited or re-volatilized through fragmentation. A complete understanding of the fate and transformations of organic carbon in the atmosphere therefore requires a detailed quantitative description of both gas- and particle-phase carbon, but attempts to understand the evolution of carbon through atmospheric oxidation has in nearly all cases resulted in a large fraction of “missing” or unidentified carbon. This has resulted in significant uncertainty in the budget and fluxes of organic aerosol, due in part to difficulties measuring semi-volatile organic compounds, which partition easily between the gas phase and the organic aerosol mass and are therefore susceptible to sampling-related losses. In our work, a large suite of state-of-the-art mass spectrometric and spectroscopic instrumentation was brought to bear on the simulated multi-day atmospheric aging of common biogenic emissions. Organic carbon across all volatilities and functionalities was measured, from aerosols to high-volatility gases, including CO and CO2. New chemical ionization and electron-impact ionization mass spectrometric instruments allowed for the characterization and quantification of low-volatility gases and semi-volatile compounds to understand both their transition into and their formation from organic aerosols. By observing all carbon through multiple generations of oxidation, we examine the relationships between particles and lower-volatility gases with unprecedented detail and place them in the context of current simplified (i.e. two-dimensional) model frameworks, providing a more complete understanding of the evolution of organics in the atmosphere.