Air-Snow Interactions and Atmospheric Chemistry
Florent Dominé,1*
Paul B. Shepson2*
The presence of snow greatly perturbs the
composition of near-surface polar air, and the higher concentrations of
hydroxyl radicals (OH) observed result in a greater oxidative capacity of the lower atmosphere. Emissions of nitrogen oxides, nitrous acid,
light aldehydes, acetone, and molecular halogens have also been
detected. Photolysis of nitrate ions contained in the snow appears to
play an important role in creating these perturbations. OH formed in
the snowpack can oxidize organic matter and halide ions in the snow,
producing carbonyl compounds and halogens that are released to the
atmosphere or incorporated into snow crystals. These reactions modify
the composition of the snow, of the interstitial air, and of the
overlying atmosphere. Reconstructing the composition of past
atmospheres from ice-core analyses may therefore require complex
corrections and modeling for reactive species.
1 CNRS, Laboratoire de Glaciologie et
Géophysique de l'Environnement, B.P. 96, 54 Rue Molière,
38402 Saint Martin d'Hères cedex, France.
2 Department of Chemistry and Department of Earth
and Atmospheric Sciences, Purdue University, West Lafayette, IN 47907, USA.
*
To whom correspondence should be addressed. E-mail:
florent{at}lgge.obs.ujf-grenoble.fr, pshepson{at}purdue.edu
