Studies of Organic Nitrate Concentration, Composition, and Variation in the Troposphere

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This research project is concerned with the study of alkyl nitrates and other organic nitrate species in the troposphere. Alkyl nitrates are products of hydroxyl radical initiated hydrocarbon oxidation in the presence of the oxides of nitrogen. Other organic nitrates are formed from alkenes, carbonyls, and biogenic hydrocarbons when they are oxidized in the presence of nitrogen oxides. Because of their potential contribution to the reactive nitrogen budget, and because of their significance to tropospheric ozone chemistry, detailed information is required to understand the sources, composition, concentration, and transport of organic nitrates in the global troposphere. This research program includes laboratory and field investigations of selected organic nitrates compounds. Laboratory studies will improve analytical methodology and examine reactions of hydrocarbons in test systems. The field program is designed to accurately measure a suite of organic nitrates at remote sites subject to episodic inputs of air masses containing primary and secondary organic emissions. The sites include a station in the Arctic, in the North Atlantic, and in the continental US. Since these sites have active atmospheric chemistry studies already underway, the measurements can be related to a broad scope of atmospheric chemical processes. Measurements of the concentration and composition of nitrates (and other species) will be compared to existing models of organic nitrate formation, sources, and transport. These studies should help to refine understanding of nitrogen/carbon transformations and fate of reactive nitrogen in the global atmosphere.