Aqueous chemistry and its role in secondary organic aerosol (SOA) formation 1Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, USA
10 Nov 2010
2Department of Chemistry, Sonoma State University, Rohnert Park, CA, USA
3Institute of Marine and Coastal Sciences, Rutgers University, Rutgers/NOAA CMER Program, New Brunswick, NJ, USA
Received: 22 May 2010 – Published in Atmos. Chem. Phys. Discuss.: 09 June 2010 Abstract. There is a growing understanding that secondary organic aerosol (SOA) can
form through reactions in atmospheric waters (i.e., clouds, fogs, and
aerosol water). In clouds and wet aerosols, water-soluble organic products
of gas-phase photochemistry dissolve into the aqueous phase where they can
react further (e.g., with OH radicals) to form low volatility products that
are largely retained in the particle phase. Organic acids, oligomers and
other products form via radical and non-radical reactions, including
hemiacetal formation during droplet evaporation, acid/base catalysis, and
reaction of organics with other constituents (e.g., NH4+).
Revised: 15 October 2010 – Accepted: 07 November 2010 – Published: 10 November 2010
This paper provides an overview of SOA formation through aqueous chemistry,
including atmospheric evidence for this process and a review of radical and
non-radical chemistry, using glyoxal as a model precursor. Previously
unreported analyses and new kinetic modeling are reported herein to support
the discussion of radical chemistry. Results suggest that reactions with OH
radicals tend to be faster and form more SOA than non-radical reactions. In
clouds these reactions yield organic acids, whereas in wet aerosols they
yield large multifunctional humic-like substances formed via radical-radical
reactions and their O/C ratios are near 1.
Citation: Lim, Y. B., Tan, Y., Perri, M. J., Seitzinger, S. P., and Turpin, B. J.: Aqueous chemistry and its role in secondary organic aerosol (SOA) formation, Atmos. Chem. Phys., 10, 10521-10539, doi:10.5194/acp-10-10521-2010, 2010.