Atmos. Chem. Phys. Discuss., 10, 11081-11107, 2010
www.atmos-chem-phys-discuss.net/10/11081/2010/
doi:10.5194/acpd-10-11081-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Heterogeneous uptake of gaseous hydrogen peroxide by Gobi and Saharan dust aerosols: a potential missing sink for H2O2 in the troposphere
M. Pradhan, G. Kyriakou, A. T. Archibald, A. C. Papageorgiou, M. Kalberer, and R. M. Lambert
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK

Abstract. The first direct laboratory measurements of gaseous hydrogen peroxide uptake by authentic Gobi and Saharan dust aerosol particles as a function of relative humidity (RH) have been carried out in an entrained aerosol flow tube coupled to a chemical ionization mass spectrometer. Gobi dust shows uptake coefficients, γH2O2= (3.33±0.26)×10−4 at 15% RH rising to γH2O2=(6.03±0.42)×10−4 at 70% RH; the corresponding values for Saharan dust are systematically higher (γH2O2=(6.20±0.22)×10−4 at 15% RH rising to γH2O2=(9.42±0.41)×10−4 at 70% RH). High resolution X-ray photoelectron spectroscopy (XPS) measurements of the surface chemical composition of the two mineral dust samples together with published water adsorption isotherms of their principal constituents enables rationalization of these observations, which are relevant to nighttime tropospheric chemistry. A box model study performed by incorporating the experimentally determined data set reveals that uptake of H2O2 onto dust can be an important loss process for this species which has been, until now, poorly constrained.

Citation: Pradhan, M., Kyriakou, G., Archibald, A. T., Papageorgiou, A. C., Kalberer, M., and Lambert, R. M.: Heterogeneous uptake of gaseous hydrogen peroxide by Gobi and Saharan dust aerosols: a potential missing sink for H2O2 in the troposphere, Atmos. Chem. Phys. Discuss., 10, 11081-11107, doi:10.5194/acpd-10-11081-2010, 2010.
 
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