Organic matter mineralization and trace element post-depositional redistribution in Western Siberia thermokarst lake sediments

Abstract. This study reports the very first results on high-resolution sampling of sediments and their porewaters from three thermokarst (thaw) lakes representing different stages of ecosystem development located within the Nadym-Pur in-terfluve of the Western Siberia plain. Up to present time, the lake sediments of this and other permafrost-affected re-gions remain unexplored regarding their biogeochemical be-havior. The aim of this study was to (i) document the early diagenesic processes in order to assess their impact on the organic carbon stored in the underlying permafrost, and (ii) characterize the post-depositional redistribution of trace el-ements and their impact on the water column. The esti-mated organic carbon (OC) stock in thermokarst lake sed-iments of 14 ± 2 kg m−2 is low compared to that reported for peat soils from the same region and denotes intense or