Title Acetaldehyde in the Alaskan subarctic snowpack
Author Domine, F.; Houdier, S.; Taillandier, A.S.; Simpson, W.R.
Author Affil Domine, F., CNRS-Institut National des Sciences de l'Univers, Laboratoire de Glaciologie et Géophysique de l'Environnement, Saint-Martin d'Heres, France. Other: Université Joseph Fourier- Grenoble I, France; University of Alaska
Source Atmospheric Chemistry and Physics, 10(3), p.919-929, . Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680- 7316
Publication Date 2010
Notes In English. Published in Atmospheric Chemistry and Physics Discussions: 23 September 2009, http://www.atmos-chem-phys- discuss.net/9/19683/2009/acpd-9-19683-2009.ht ml; accessed in May, 2011. 70 refs. GeoRef Acc. No: 310106
Index Terms adsorption; aerosols; crystals; density (mass/volume); experimentation; hydrocarbons; ice; ice crystals; melting; snow; temperature; thermodynamic properties; United States--Alaska--Fairbanks; acetaldehyde; Alaska; atmosphere; catalysis; density; ethers; experimental studies; Fairbanks Alaska; formaldehyde; hydrolysis; kinetics; laboratory studies; organic compounds; oxidation; photochemistry; snowpack; solution; United States
Abstract Acetaldehyde is a reactive intermediate in hydrocarbon oxidation. It is both emitted and taken up by snowpacks and photochemical and physical processes are probably involved. Understanding the reactivity of acetaldehyde in snow and its processes of physical and chemical exchanges requires the knowledge of its incorporation mechanism in snow crystals. We have performed a season-long study of the evolution of acetaldehyde concentrations in the subarctic snowpack near Fairbanks (65°N), central Alaska, which is subjected to a vigorous metamorphism due to persistent elevated temperature gradients in the snowpack, between 20 and 200°C m-1. The snowpack therefore almost entirely transforms into depth hoar. We have also analyzed acetaldehyde in a manipulated snowpack where temperature gradients were suppressed. Snow crystals there transformed much more slowly and their original shapes remained recognizable for months. The specific surface area of snow layers in both types of snowpacks was also measured. We deduce that acetaldehyde is not adsorbed onto the surface of snow crystals and that most of the acetaldehyde is probably not dissolved in the ice lattice of the snow crystals. We propose that most of the acetaldehyde measured is either trapped or dissolved within organic aerosol particles trapped in snow, or that acetaldehyde is formed by the hydrolysis of organic precursors contained in organic aerosols trapped in the snow, when the snow is melted for analysis. These precursors are probably aldehyde polymers formed within the aerosol particles by acid catalysis, but might also be biological molecules. In a laboratory experiment, acetaldehyde-di-n- hexyl acetal, representing a potential acetaldehyde precursor, was subjected to our analytical procedure and reacted to form acetaldehyde. This confirms our suggestion that acetaldehyde detected in snow could be produced during the melting of snow for analysis.
URL http://www.atmos-chem-phys.net/10/919/2010/acp-10-919-2010.pdf
Publication Type journal article
Record ID 65006747