ECIMMEE Project: Molecular Fingerprinting of Microbial Surface Ocean Methane
Our group will perform an in-depth study of aquatic microbes that help regulate Earth’s carbon cycle. Each year microbes capture gigatons of carbon dioxide from the atmosphere, converting some to methane (CH4), a potent greenhouse gas. Precisely how much methane is released back into the atmosphere, and through what metabolic pathways, are outstanding questions that are a function of the environment in which microbes live and the local geochemical conditions in play. Answering these questions will advance our scientific understanding of Earth’s methane flux, as moderated by surface ocean and lake microbes. This research is timely and important because Earth’s methane flux is poorly understood and thus underrepresented in global climate models. These findings will help increase the fidelity of climate models going forward, as well as our understanding of carbon cycling in the geologic past. The recent discovery of three novel and independent microbial pathways to make methane in surface oceans means there are at least three currently untraceable and unquantified methane fluxes on Earth. Our group will cultivate the relevant microbes in the lab and determine the bulk and clumped isotope-based fingerprints of each mechanism to track and quantify methane from these formation pathways. In addition to targeting these novel pathways, we will also better characterize classical microbial methanogenesis pathways across physical and chemical environmental conditions. Concurrent to these lab-based efforts, our team will partner with field operations to capture, isotopically fingerprint and begin the inventory of these processes in natural systems, with the broader goal of developing regional and, ultimately, global inventories.
William (Wil) Leavitt is a geochemist and microbiologist. Leavitt’s group combines classical and novel experimental techniques from microbiology with high-precision tools from stable isotope geochemistry to address major knowledge gaps in the microbial cycling of life-critical elements (hydrogen, carbon, oxygen, nitrogen, sulfur, phosphorus). Leavitt and his lab members develop and employ long-term continuous cultivation approaches to quantify the environmental constraints on molecular records of past climate, as well as large-scale cultivation of ocean- and lake-dwelling microbes to determine the isotopic signatures they imprint on greenhouse gases. The overarching goal of all studies in the lab is to improve our understanding of how microbes have influenced elemental cycles in the past, how they dictate modern fluxes of matter and energy and how they may respond in future oceans.
Leavitt’s abiding interest in earth sciences was cultivated by his geologist parents, who guided his explorations of the high desert of Reno, Nevada, and his grandmother, who introduced him to tidepools in Monterey Bay, California. He received his B.A. in environmental microbiology and molecular evolution from Hampshire College in 2006, his M.A. in organismic and evolutionary biology in 2009, and his Ph.D. in earth and planetary sciences from Harvard University in 2014. He’s also an alum of Microbial Diversity at the Marine Biological Laboratory (2008). Before joining Dartmouth College, he was the Fossett Postdoctoral Fellow in the Department of Earth and Planetary Sciences at Washington University in St. Louis (2014-2016). Now he serves as an assistant professor in the Department of Earth Sciences at Dartmouth and adjunct assistant professor in the Department of Biological Sciences and the Department of Chemistry.