Rate Measurements of Reactions Between Aldehydes and Amines Applied to Clouds and Aerosol

DAVID O. DE HAAN (1), Hiromi Takano (1), Vanessa A. Blasic (1), Jacob J. Turley (1)

(1) University of San Diego

     Abstract Number: 713
     Last modified: May 14, 2010

Abstract
Reactive uptake of glyoxal and methylglyoxal by clouds and aerosol may be a significant source of secondary organic aerosol material in the global atmosphere. We report NMR measurements of aqueous-phase reactions of methylglyoxal and glyoxal with ammonium sulfate and a variety of amine compounds found in atmospheric particles. Reaction kinetics and temperature- and pH-dependent rate constants are extracted from the data and used to predict reaction rates in clouds and aerosol. Preliminary results indicate that glyoxal reacts mainly with methylamine, while methylglyoxal reacts mainly with amino acids in marine clouds and with ammonium sulfate and amino acids in terrestrial clouds. All of these reactions produce nitrogen-containing oligomers, some of which absorb visible light and would be categorized as brown carbon. While measured bulk-phase reaction rates are slow, reaction rates in evaporating aerosol droplets are several orders of magnitude faster, as observed by aerosol mass spectrometry. Accretion reactions involving amines could therefore be an important aerosol-phase sink for glyoxal and methylglyoxal in the particle phase.