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GEOPHYSICAL RESEARCH LETTERS,
VOL. 33,
L05810,
doi:10.1029/2005GL025164,
2006
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
Abstract
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.
Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906); 1041 Geochemistry: Stable isotope geochemistry (0454, 4870); 1615 Global Change: Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912).
Read Full Article (file size: 189028 bytes) Cited by
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.
Copyright 2006 by the American Geophysical Union.
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