Source Attribution of Methane Using Clumped Isotopologues

Abstract

Rising methane concentrations in the atmosphere have been studied using C2:C1 (ethane to methane ratios) and traditional stable isotopes. These tools are used to identify and attribute methane sources, but information about these tools is incomplete. Adding clumped isotopologues, methane molecules with more than one rare isotope substitution, can be used to reduce uncertainties and fill knowledge gaps of the other tools. Chapter 2 is a methane source identification study, where methane production in industrial steam is assessed, and clumped isotopologues reveal essential information about the methane production mechanism. Chapter 3 is a methane source attribution project, where methane sources are fingerprinted, and clumped isotopologues provide more refined information about methane sources and the processes that control fluxes. Both projects utilize clumped isotopologues as an additional tool to better understand and categorize methane sources, including both identifying new sources using compositions and attributing source signatures to known targets.