Biogenic processes of methane production and oxidation along thermokarst lake to lagoon transitions ...

• Main Authors: Liebner, Susanne, Anthony, Sara E, Christian, Knoblauch, Jens, Kallmeyer, Jens, Strauss, Sizhong, Yang
• Format: Text
• Language: English
• Published: Deutsche Geologische Gesellschaft - Geologische Vereinigung e.V. (DGGV) 2023
• Subjects: Arctic; arctic methane; polar fox; Thermokarst; Siberia
• Online Access: https://dx.doi.org/10.48380/r7yy-1a48; https://www.dggv.de/e-publikationen/biogenic-processes-of-methane-production-and-oxidation-along-thermokarst-lake-to-lagoon-transitions

Thermokarst lagoons form at the terrestrial-marine interface when thermokarst lakes, hotspots for Arctic methane emissions, erode onto the Arctic shelf. Thermokarst lagoons are dynamic environments with seasonal ice build-up and potential alternations between freshwater and marine discharge. Aiming to understand how microbial methane cycling changes along thermokarst lake to lagoon transitions we have investigated the sediment geochemistry and microbiota of the Polar Fox lagoon, a thermokarst lagoon in north-eastern Siberia, relative to that of two adjacent thermokarst lakes. In-situ methane concentrations, methane-carbon isotopic signatures, analysis of amplicon sequencing variants (ASVs), metagenomics, and pore-water geochemistry point towards efficient communities of anaerobic methane oxidizers (AOM) in a sulfate-methane transition zone 2-3 meters below the sediment surface of the lagoon. The lagoon’s in-situ methane concentration in the sulfate zone was only 0.4 – 5% that of the deeper sediment and of ...