title: The biogeochemistry of methane isotopologues in marine and lacustrine sediments
abstract: Methane is a globally significant greenhouse gas, energy resource, and it is a product and reactant of microbial metabolisms. Multiple sources and sinks of methane can be challenging to distinguish from each other, thus complicating the understanding of methane budgets and the effects of microbes on mediating Earth’s carbon cycle. The relative abundances of methane isotopologues (e.g., 12CH4, 13CH4, 12CH3D, and 13CH3D) record process-based information about the formation conditions, transport, a