Atmos. Chem. Phys. Discuss., 8, 20799-20838, 2008
www.atmos-chem-phys-discuss.net/8/20799/2008/
doi:10.5194/acpd-8-20799-2008
© Author(s) 2008. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Glyoxal uptake on ammonium sulphate seed aerosol: reaction products and reversibility of uptake under dark and irradiated conditions
M. M. Galloway1, P. S. Chhabra2, A. W. H. Chan2, J. D. Surratt3, R. C. Flagan2,4, J. H. Seinfeld2,4, and F. N. Keutsch1
1Dept. of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
2Dept. of Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
3Dept. of Chemistry, California Institute of Technology, Pasadena, CA, USA
4Dept. of Environmental Science and Engineering California Institute of Technology, Pasadena, CA, USA

Abstract. Chamber studies of glyoxal uptake onto neutral ammonium sulphate aerosol were performed under dark and irradiated conditions to gain further insight into processes controlling glyoxal uptake onto ambient aerosol. Organic fragments from glyoxal dimers and trimers were observed within the aerosol under dark and irradiated conditions; glyoxal oligomer formation and overall organic growth were found to be reversible under dark conditions. Analysis of high-resolution time-of-flight aerosol mass spectra provides evidence for irreversible formation of carbon-nitrogen (C-N) compounds in the aerosol. These compounds are likely to be imidazoles formed by reaction of glyoxal with the ammonium sulphate seed. To the authors' knowledge, this is the first time C-N compounds resulting from condensed phase reactions with ammonium sulphate seed have been detected in aerosol. Organosulphates were not detected under dark conditions. However, active oxidative photochemistry, similar to that found in cloud processing, was found to occur within aerosol during irradiated experiments. Organosulphates, carboxylic acids, and organic esters were identified within the aerosol. Our study suggests that both C-N compound formation and photochemical processes should be considered in models of secondary organic aerosol formation via glyoxal.

Citation: Galloway, M. M., Chhabra, P. S., Chan, A. W. H., Surratt, J. D., Flagan, R. C., Seinfeld, J. H., and Keutsch, F. N.: Glyoxal uptake on ammonium sulphate seed aerosol: reaction products and reversibility of uptake under dark and irradiated conditions, Atmos. Chem. Phys. Discuss., 8, 20799-20838, doi:10.5194/acpd-8-20799-2008, 2008.
 
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