AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Model Analysis of Aerosol Reaction Chamber Studies of Aqueous Aerosol SOA (aaSOA) Formation
ANDREW SUMNER, Joseph Woo, V. Faye McNeill, Columbia University
Abstract Number: 745 Working Group: Aerosol Chemistry
Abstract The reactive uptake of glyoxal by wet aerosols is believed to be a significant source of secondary organic aerosol (SOA). Several recent laboratory studies have been performed with the goal of characterizing this process, but there has not been consensus on the effects of photochemistry on SOA growth and the identities of the product species formed.
We recently developed GAMMA (Gas Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas-phase and detailed aqueous aerosol-phase chemistry. We applied GAMMA to simulate recent aerosol chamber studies of SOA formation by the uptake of glyoxal by wet aerosol under dark and irradiated conditions (Galloway et al. 2009, 2011; Volkamer et al. 2009). We achieved closure to within 10% between simulated SOA growth and the results of most of the experiments with the same model of gas-aerosol equilibrium and aqueous chemistry.
Based on our analysis, SOA growth is dominated by reversible uptake of glyoxal as described by Henry’s Law, independent of photochemistry. Our results show that while some organic acids, organosulfates, and other oxidation products are formed under irradiated conditions, these product species contribute negligible aerosol mass. Under irradiated conditions, the photochemical destruction of gas-phase glyoxal may perturb the gas-aerosol equilibrium, leading to decreased SOA production during batch mode aerosol chamber experiments.