American Association for Aerosol Research - Abstract Submission

AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA

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Secondary Organic Aerosol Formation from Naphthalene and Methylnaphthalene Photooxidation

CHIA-LI CHEN, Mary Kacarab, Ping Tang, David R. Cocker III, University of California, Riverside

     Abstract Number: 491
     Working Group: Aerosol Chemistry

Abstract
Polycyclic aromatic hydrocarbons (PAHs) play a significant role in semivolatile gas-phase emissions from anthropogenic sources, which include incomplete combustion emissions, wood-burning, and may be a major “missing” source of SOA. Secondary organic aerosols can be formed from oxidation of PAHs and their contributions to ambient fine particulate matter are not well understood. Large uncertainties in PAH derived SOA, fine particle aging properties, SOA formation mechanisms and their gas-particle transformation reaction pathway in the atmosphere promote further investigation. The characteristics of SOA formation from oxidation of PAHs such as naphthalene and methylnaphthalene under the absence and presence of NOx conditions were conducted in the UCR CE-CERT chamber. SOA composition characteristics were identified by the HR-ToF-AMS, particle size distributions, particle density, SOA yield and particle volatility were obtained. SOA formations from naphthalene and methylnaphthalene photoxidation were found to favor higher SOA yields under H2O2 conditions more so than high NOx and low NOx conditions. The characteristic indicator of m/z 44 (CO2+) dominated the total organic aerosol formation and f44 and O/C ratio increased during the course of experiment from naphthalene and methylnaphthalene photooxidation. In addition, the VRF (Volume Remaining Fraction) increased from 20% to 88% which indicates that low volatility aerosols aged with reaction time. This research will provide a foundation for the prediction of SOA formation from PAH precursors.