Geocheminar spring-2015

Methane is an important greenhouse gas with a significant impact on the chemistry of the troposphere and stratosphere. Methane in the atmosphere reacts with Cl•, OH•, and other reactive molecules, to produce the methyl radical (CH3•). The rates and isotopic signatures of these reactions are of interest for understanding the budgets of methane, water vapor, CO and other reactive gases in air. In this study we estimated kinetic isotope effects (KIE) for the doubly substituted isotopologues of methane, CH2D2 and 13CH3D, reacting with OH• and Cl•, using electronic structure modeling and transition state theory. Then, doubly substituted isotopologues of methane were used to predict the different atmospheric methane sources’ isotopic signature in the air. We are developing a model to track methane in atmosphere based on its chemical behavior using CH2D2 and 13CH3D.