EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Thawing permafrost in retrogressive thaw slumps leads to higher N availability

Claudia Fiencke1,2, Maija E. Marushchak3, Rica Wegner4, and Christian Beer1,2
Claudia Fiencke et al.
  • 1Institute of Soil Science, Department of Earth System Sciences, Faculty of Mathematics, Informatics and Natural Sciences (MIN), Universität Hamburg, Allende-Platz 2, 20146 Hamburg, Germany
  • 2Center for Earth System Research and Sustainability, Universität Hamburg, Allende-Platz 2, 20146 Hamburg, Germany
  • 3Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 1627, 70211 Kuopio, Finland
  • 4Stockholm University, Department for Environmental Science (ACES), 10691 Stockholm; Sweden

Currently, 20% of the Northern Hemisphere is affected by thermokarst, with an increase expected in future. In particular, ice-rich Yedoma sediments are susceptible to abrupt thaw, which leads to the formation of retrogressive thaw slumps (RTS). These erosion processes result in loss of vegetation, expose long-term frozen permafrost sediments at the surface, and makes soil organic matter (SOM) available for mineralization. Permafrost-affected soils of RTS exhibited higher N availability, as indicated by higher δ15N content of bulk soil, higher nitrate content and higher microbial N turnover (N mineralization especially net nitrification and denitrification) associated with high abundance of functional N genes compared to undisturbed soils. This elevated N availability results in significant emission of the greenhouse gas N2O, especially from exposed permafrost. Based on measured N2O emissions, N2O loss could be as high as 54.8 mg N2O-N per year, which is 0.14% of the initial inorganic N content of exposed Yedoma. The higher N availability of eroded permafrost-affected soils might affect C mineralization because eroded soils had lower aerobic CO2 production than undisturbed soils and CH4 production was detectable in laboratory incubations only in the absence of N2O production.

How to cite: Fiencke, C., Marushchak, M. E., Wegner, R., and Beer, C.: Thawing permafrost in retrogressive thaw slumps leads to higher N availability, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15903,, 2023.