Sources and behavior of carbonyl compounds in the Arctic atmosphere and snowpack
Abstract
Carbonyl compounds play an important role in tropospheric chemistry. Through photolysis, they can serve as an important source of HO x to the atmosphere, and their reaction with other radicals can serve as important sinks for those species. The chemistry of these types of compounds in polar regions has become of interest in recent years, as the measured gas phase concentration of these species in the troposphere is higher than predicted and recent field measurements indicate that irradiated snowpacks may serve as a source of a variety of chemical species to the lower troposphere, possibly including carbonyl compounds. Here, the interaction of these species with the polar snowpack is investigated. Measurements of acetaldehyde and acetone show that these species are emitted from the polar snowpack and that this emission is photochemical in nature. A laboratory experiment was designed to test possible production mechanisms under well-controlled environmental conditions. It was found that carbonyl compounds are photochemically produced in the condensed phase in snow samples obtained from Alert, Canada; Summit, Greenland; and South Pole, Antarctica. Organic material isolated from polar snow samples were analyzed using a variety of techniques in an effort to better characterize the organic material present in polar snowpacks. Mechanisms involving the OH induced oxidation of organic material in the snow have been proposed to account for the production of low molecular weight carbonyl compounds in the condensed phase in snow.
Degree
Ph.D.
Advisors
Shepson, Purdue University.
Subject Area
Analytical chemistry|Environmental science|Atmosphere
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