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AGU: Geophysical Research Letters

 

Index Terms

  • Atmospheric Composition and Structure: Aerosols and particles
  • Geochemistry: Stable isotope geochemistry
  • Global Change: Biogeochemical cycles, processes, and modeling

Abstract

Isotopic constraints on non-photochemical sulfate production in the Arctic winter

Justin R. McCabe

Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA

Joel Savarino

Laboratoire de Glaciologie et Geophysique de l'Environnement CNRS/UJF, St. Martin d'Heres, France

Becky Alexander

Department of Atmospheric Sciences, University of Washington, Seattle, Washington, USA

Sunling Gong

Air Quality Research Branch (ARQM), Atmospheric Environment Service, Toronto, Ontario, Canada

Mark H. Thiemens

Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA

The oxygen isotopic composition (Δ17O) of non-seasalt sulfate (NSS) aerosol was measured in samples from Alert, Canada over one year (July 1999–June 2000) and used to quantify the S(IV) oxidants. Measurements of Δ17O in NSS are used to evaluate the relative contributions of O3, H2O2, and OH oxidation leading to the formation of SO4 2− compared to a model of Feichter et al. (1996). The isotopic values suggest that there is a twofold overestimate of ozone oxidation in the model during winter. The isotopic composition is consistent with 10 to 18% contribution from a non-photochemical oxidation pathway, likely Fe3+/Mn2+-catalyzed O2 oxidation, during the dark Arctic winter. Isotopic evidence also invokes a 3 to 10% contribution of a mass dependent oxidant during springtime Arctic ozone depletion events.

Received 15 November 2005; accepted 2 February 2006; published 9 March 2006.

Citation: McCabe, J. R., J. Savarino, B. Alexander, S. Gong, and M. H. Thiemens (2006), Isotopic constraints on non-photochemical sulfate production in the Arctic winter, Geophys. Res. Lett., 33, L05810, doi:10.1029/2005GL025164.

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