The interplay between methanotrophy, methanogenesis, and soil geochemistry and its impact on net methane flux to the atmosphere from Arctic soils

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Abstract(1) Technical descriptionMicrobial communities recycle carbon and nitrogen in the terrestrial environment and are central to the flux of soil gases, including methane (CH4), a potent greenhouse gas. Unfortunately, patterns of CH4 release from soils, especially in the Arctic are changing, and there is an urgent need to better understand the basis of in situ CH4 production by methanogens and oxidation rates and patterns by methanotrophs; the main biological mechanism for CH4 consumption. Laboratory work by the PI has established that mineral-bound nutrients are accessible to methanotrophs and enhance their activity. Preliminary fieldwork in soil environments near Ny Ålesund, Svalbard suggests that soil macronutrients, such as P, and perhaps trace metals like Cu and Ni may limit methanotroph activity and therefore methane oxidation rates. There is little known, however, how these geochemical and nutrient conditions vary through the biological active zone (BAZ) and impact methanogenesis. In collaboration with two researchers from Newcastle University in the UK, who will perform all microbiological, metagenomic and gas flux analyses, the PI proposes to perform geochemical, mineralogical, and isotopic analyses on soils collected through the BAZ from more than 13 sites in the vicinity of Ny Ålesund, Svalbard. EAGER funds are requested to: 1. Field-test these laboratory relationships in a complex natural Arctic permafrost soil environment, in which success is not guaranteed. 2. Test the innovative hypothesis that soil geochemistry is a fundamental control on methane flux, a hypothesis that has not been field-tested previously, nor with the rigor of our proposed sampling plan that includes variation in altitude, hydrology, geomorphology, and bedrock lithology. 3. Develop a geochemical tool for predicting methane flux in Arctic environments, which utilizes existing geochemical data or new data, acquired at relatively low cost. (2) Broader significance and importanceMethane fluxes from Arctic soils are an important input into the global climate system; this project, if successful, can strengthen our ability to predict and model global climate change. Understanding the link between soil geochemistry and methanotroph/methanogen activity has broad applicability for many natural systems outside of the Arctic. This project strengthens international collaboration (with UK researchers). One B.S. student will be trained through this grant. The PI has also partnered with a biology high school teacher to provide research opportunities for high school students.