Methylglyoxal Enhances Aerosol Cloud Nucleation

Neha Sareen (1), Allison N. Schwier (1), Terry L. Lathem (2), Athanasios Nenes (2), V. FAYE MCNEILL (1)

(1) Columbia University, (2) Georgia Institute of Technology

     Abstract Number: 238
     Last modified: April 30, 2010

Abstract
Methylglyoxal is a common tropospheric trace gas formed by the oxidation of anthropogenic and biogenic precursors such as toluene and isoprene. When absorbed into aqueous atmospheric aerosols, methylglyoxal is a potential precursor for secondary organic aerosol (SOA) formation through the formation of oligomers. The same species are strongly surface active, known to suppress surface tension in bulk aqueous solutions. Here we show that exposure of pure ammonium sulfate particles to gas-phase methylglyoxal in an aerosol reaction chamber depresses their critical supersaturation by up to 25%. Most of this CCN enhancement is a result of surface tension depression, presenting for the first time evidence that the gas phase can act as a reservoir of organics surfactants and enhance aerosol CCN activation in an unforeseen way.