AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Particle Acidity Effects on SOA Formation from Toluene Oxidation in the Presence of NOx under Dry and Humid Conditions
DAO HUANG, Yunle Chen, Steve Kim, Nga Lee Ng, Zhejiang University
Abstract Number: 191 Working Group: Aerosol Chemistry
Abstract Toluene is estimated to be one of the most important precursors of SOA in urban areas and some rural areas due to its relatively high concentration and SOA yields. Particle acidity is considered to be an important factor in aerosol formation as it may affect SOA yield and composition. For toluene SOA formation, the particle acidity effect is under debate although most studies tend to support that particle acidity has little impact on aromatic SOA formation. Furthermore, little is known about toluene SOA composition in the presence of seeds of different acidity. In this study, ammonium sulfate seeds and ammonium sulfate+sulfuric acid seeds were used in the photo-oxidation of toluene in the presence of NOx under dry and humid conditions. A high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a high-resolution chemical ionization time-of-flight mass spectrometer coupled with a filter inlet for gas and aerosol (FIGAERO-CIMS) were used to measure the particle composition under different conditions. Our experimental results indicate that particle acidity have insignificant impact on toluene SOA yields. We also compared particle-phase compositions in the presence of seeds of different acidity.