Methanogenesis in wetland soils: It may not always be as deep as we all thought
EMSL Project ID
50229
Abstract
This proposal focuses on understanding the constraints on methane metabolism in freshwater temperate wetland soils, as these systems currently represent the largest source of natural methane emissions to the atmosphere. The overarching goal of our research is to understand the complex network of chemical, physical, and biological regulatory controls acting on the microbial methane cycling community, at a level that allows better emission predictions at an ecosystem scale. In this EMSL proposal we target critical knowledge gaps on the types, distributions, and responses of methanogens to various geochemical conditions. Specifically, we hypothesize, that input carbon is the master controller, enabling methane production in bulk soils with unfavorable redox, or hindering methanogenesis in soils with favorable redox. To assess methanogen substrate availability across highly resolved time and space gradients, in aim 1 we pair methanogen and methanotroph substrate metabolite profiles to soil porewater greenhouse gas measurements, metatranscriptomic data, and modelled methane production and consumption profiles. Together this integrated data will provide high resolution visualization of the dynamics of methane cycling microorganisms across cm depth scales, monthly temporal cycles, and with lateral and ecological land coverage changes in the wetland. In aim 2, we incorporate dissolved organic matter profiles, hypothesizing that soils with high levels of methanogenesis will have more favorable (positive) nominal oxidation states of carbon and high inferred levels of carbon degradation from glycoside hydrolase transcript profiles. We will also, evaluate the soil physical structure as a component that could constrain methanogenesis in deeper anoxic sediments. Data from aim 1 and aim 2 will be collected from the same samples, and integrated with metatranscript data allowing for a complete reconstruction of the microbial contribution to carbon and nitrogen cycling in these soils. In the last aim, we leverage laboratory cultivated strains that are nearly identical to dominant wetland strains, to better evaluate the physiological properties of field relevant organisms under various redox (e.g. oxygenated conditions). This lab observed phenomena can then be linked back to the field using predictive ecosystem models, to identify processes that may be relevant at the wetland scale. In conclusion, this EMSL support will enable an ecologically-contextualized dataset of soil chemical diversity, insight that can be linked to organismal abundances and activity, as well as in situ greenhouse gas production and emissions, to help establish paradigms for soil methane cycling. Project Details
Project type
Large-Scale EMSL Research
Start Date
2018-10-01
End Date
2021-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members