Experimental and Theoretical Studies of Potential New Atmospheric Sources and Sinks of Nitrous Oxide

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9526510 Wine This project addresses the subject of sources and sinks of atmospheric nitrous oxide. This species is the dominant source of ozone-destroying nitric oxide radicals in the stratosphere. Furthermore, it is a greenhouse gas, and its concentration has been increasing. The current belief is that nitrous oxide has no natural sources other than microbiological activity in the ground and oceans, and its destruction is solely by photodissociation and reaction with excited atomic oxygen in the upper atmosphere. However, current estimates of sources and sinks suggest the existence of a currently unrecognized source. Furthermore, recent measurements of the isotopic composition of atmospheric nitrous oxide cannot be explained by accepted sources. Laboratory experiments will be performed in this project to investigate the potential formation of nitrous oxide from the reactions of electronically excited nitrogen dioxide and hydroxyl radicals with molecular nitrogen in the presence of oxygen. Chemical kinetics modeling studies will investigate why nitrous oxide is efficiently formed upon UV illumination of a nitrogen/oxygen mixture without ozone added, but not in a mixture of all three. These calculations will provide guidance for future experimental investigation of the issue of nitrous oxide production and destruction. ***