Fossil Organic Matter in Arctic Permafrost

• Main Authors: Schirrmeister, Lutz, Strauss, Jens, Wetterich, Sebastian, Overduin, Paul
• Format: Conference Object
• Language: unknown
• Published: Alfred-Wegener-Institut Helmholtz-Zentrum für Polarund Meeresforschung 2013
• Subjects: Arctic; Global warming; Ice; permafrost; Polar Research; Thermokarst; Siberia
• Online Access: https://epic.awi.de/id/eprint/32707/; https://epic.awi.de/id/eprint/32707/1/Schirrmeister-Polartagung-2013.pdf; https://hdl.handle.net/10013/epic.41263; https://hdl.handle.net/10013/epic.41263.d001

Permafrost deposits constitute a large organic carbon pool vulnerable to degradation and potential carbon release due to global warming. Permafrost sections along coastal and river bank exposures and subsea cores in northeastern Siberia were studied for organic matter characteristics and ice content. Organic matter stored in permafrost grew, accumulated, froze, partly decomposed, and refroze under different periglacial environments, reflected in specific biogeochemical and cryolithological features. For the studied individual strata (Saalian ice‐rich deposits, Pre‐Eemian floodplain, Eemian lake deposits, early to middle Weichselian fluvial sands, middle and late Weichselian Yedoma , Taberites, Holocene cover, Holocene thermokarst and thermoerosional sediments, submerged lagoon and fluvial deposits) organic matter accumulation, preservation, and distribution are strongly linked to a broad variety of paleoenvironmental factors and specific surface and subsurface conditions. Permafrost deposits include twigs, leaves, peat lenses, grass roots, fine-distributed plant detritus, and particulate and dissolved organic matter. The vertical distribution of total organic carbon (TOC) in exposures varies from 0.1 wt % in fluvial deposits up to 45 wt % in Holocene peats. High TOC, high C/N, and low 13C values reflect less decomposed organic matter accumulated under wet, anaerobic conditions characteristic of relative temperate interglacial and interstadial periods. Glacial and stadial periods are characterized by less variable, low TOC, low C/N, and high 13C values indicating stable periglacial environments with reduced bioproductivity but stronger decomposition of organic matter under dryer, aerobic conditions. We present an in‐depth studies of organic matter distribution for the arctic permafrost zone, indicating the variability of organic matter distribution between different stratigraphical units, between the same stratigraphical unit at different study sites, and even within stratigraphic units at the same site that need to be taken into account in future inventories.