Nitrogen pools in permafrost deposits and soils of the Yedoma region

• Main Authors: Strauss, Jens, Schirrmeister, Lutz, Sanders, Tina
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Arctic; Ice; permafrost; Tundra; wedge*; Alaska; Siberia
• Online Access: https://epic.awi.de/id/eprint/38906/; https://hdl.handle.net/10013/epic.46158

The biogeochemical pools of fossil organic matter in permafrost, mainly the carbon pool, are subject in current research to estimate the quality, quantity and the potential release into the modern cycles maintained by permafrost thaw and accelerated by arctic warming. Organic matter freeze-locked in perennially frozen ground of the northern circumpolar region accumulated over tens of thousands of years during the last glacial and interglacial periods. A part of this permafrost region is composed of ice-rich silts penetrated by large ice wedges, resulting from sedimentation and syngenetic freezing accompanied by wedge-ice growth driven by certain climatic and environmental conditions during the late Pleistocene. These unique materials are called Yedoma deposits. This study focuses on the area of potential Yedoma deposit occurrence in Siberia and Alaska and on nitrogen which has mostly a subordinate role in current studies, but is also an important source of greenhouse gas N2O. Based on the most comprehensive data set of total nitrogen (TN) concentrations in permafrost, our study aims to estimate the present pool of nitrogen stored in the different stratigraphic units of the Yedoma region. Nitrogen stock calculations will be based on bootstrapping techniques using resampled observed values. The total mean pool size estimate will be derived afterward for every of the 10,000 bootstrapping runs, resulting in 1 mean calculated from 10,000 observation-based bootstrapping means. The conceptual formula for the nitrogen stock calculation is: TN budget [Gt] = (deposit thickness [m] × coverage [m²] × bulk density [g/cm³] × (100-WIV/100) × (TNwt%/100))/ 1,000,000,000; TN: total nitrogen; WIV: wedge-ice volume In conclusion, we expect a substantial amount of nitrogen sequestered in the Yedoma region, which is expected to be released after thaw, probably mitigating the current nitrogen limitation of Arctic tundra ecosystems.