AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Secondary Organic Aerosol Formation on Wet Aerosols: Model Simulation and Implications
SIYUAN WANG, Jian Zhen Yu, Hong Kong University of Science & Technology
Abstract Number: 165 Working Group: Aerosol Chemistry
Abstract In recently years, a growing number of studies suggest that SOA formation via aqueous-particle processes may account for a significant fraction of the currently missing SOA [1]. Water-soluble organics, such as glyoxal, may undergo a series of aqueous-phase processes in aerosol liquid water that eventually lead to the formation of highly oxidized, high-molecular-weight compounds [2].
In the present study, an observation-based modeling work is conducted, incorporating state-of-the-art gas-/aqueous-phase mechanisms to evaluate SOA formation potential on wet aerosols. The model is driven by real-time ambient measurements (e.g. NMHCs, NOx, CO, Ozone, AMS) obtained in summer Hong Kong, located in sub-tropical Asia with high relative humidity. The modeling results indicate that the SOA formed via aqueous-particle processes could account for 1/5 of total SOA in summer. Major aqueous-phase products include C2-C4 di-carboxylic acids, oligomers and organosulfates. The simulated effective Henry’s law constant of glyoxal, effective SOA formation rate relative to glyoxal and reactive uptake coefficient of glyoxal all fall in the respective ranges reported in the literatures. Furthermore, we herein demonstrate that aqueous-particle processes may explain the formation of some di-carboxylic acids and organosulfate (glycolic acid sulfate and IEPOX-sulfate) observed in ambient aerosols.
This modeling work suggests the potential importance of aqueous-particle processes on SOA formation under humid conditions, which is currently not incorporated in air quality models yet. More detailed chemical speciation techniques for aerosol-phase components (e.g. di-carboxylic acids, organosulfates, oligomers) are in crucial need, in order to further evaluate these processes.
References
[1] Ervens, B., et al, Atmos. Chem. Phys., 2011, 11(21), 11069-11102.
[2] Lim, Y. B., et al, Atmos. Chem. Phys., 2010, 10(21), 10521-10539.