AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Size Distribution Dynamics Reveal the Importance of Particle-Phase Chemistry in Organic Aerosol Formation
Manabu Shiraiwa, LINDSAY YEE, Katherine Schilling, Christine Loza, Jill Craven, Andreas Zuend, Paul Ziemann, John Seinfeld, California Institue of Technology
Abstract Number: 458 Working Group: Aerosol Chemistry
Abstract Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality and public health. Particle size distribution is a key in determining their optical properties and cloud condensation nuclei activity. The dominant portion of organic aerosols is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosol (SOA). Combining chamber experiments and kinetic flux modeling, here we show that particle-phase chemistry needs to be considered for accurate prediction of size distribution as well as mass concentration and carbon oxidation state of SOA. The particle-phase reaction mainly proceeds at the surface and its reaction products contribute to SOA mass substantially. Chamber experiments with aldehyde injection strongly confirm that the particle-phase reactions with organic hydroperoxides forming peroxyhemiacetals can lead to large increase in SOA mass. The results highlight the need for consideration of particle-phase chemistry and size distribution dynamics in atmospheric aerosol models.