Relationships between greenhouse gas production and landscape position during short-term permafrost thaw under anaerobic conditions in the Lena Delta

• Published in: Biogeosciences
• Main Authors: Laurent, M., Fuchs, M., Herbst, T., Runge, A., Liebner, S., Treat, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: lena delta; permafrost
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5018479; https://gfzpublic.gfz-potsdam.de/pubman/item/item_5018479_1/component/file_5018776/5018479.pdf

Soils in the permafrost region have acted as carbon sinks for thousands of years. As a result of global warming, permafrost soils are thawing and will potentially release greenhouse gases (GHGs) such as methane (CH4) and carbon dioxide (CO2). However, small-scale spatial heterogeneities of GHG production have been neglected in previous incubation studies. Here, we used an anaerobic incubation experiment to simulate permafrost thaw along a transect from upland Yedoma to the floodplain on Kurungnakh Island. Potential CO2 and CH4 production was measured during incubation of the active layer and permafrost soils at 4 and 20 ∘C, first for 60 d (approximate length of the growing season) and then continuing for 1 year. An assessment of methanogen abundance was performed in parallel for the first 60 d. Yedoma samples from upland and slope cores remained in a lag phase during the growing season simulation, while those located in the floodplain showed high production of CH4 (6.5×103 µg CH4-C g−1 C) and CO2 (6.9×103 µg CO2-C g−1 C) at 20 ∘C. The Yedoma samples from the permafrost layer started producing CH4 after 6 months of incubation. We conclude that landscape position is a key factor triggering CH4 production during the growing season time on Kurungnakh Island.