Mobilization of Ancient Carbon from Thawing Permafrost to Laptev Sea (Arctic Ocean) Sediments During the Last Deglaciation

Summary The aim of this study is to provide evidence of the mobilization of ancient carbon from thawing permafrost to the Laptev Sea sediments during the last deglaciation. The Lena is one of the largest Siberian Rivers that drain extensive permafrost areas into the Laptev Sea. In this study, we use a marine sediment core from off the Lena River outflow located on the Laptev Sea continental slope to reconstruct deglacial permafrost thaw events by analyzing terrigenous biomarkers (high-molecular weight n-alkanoic acids (fatty acids); branched glycerol dialkyl glycerol tetraethers (brGDGTs)) and carbon isotopes (Δ14C and 𝛿13C). The sediment core covers the period between ∼16,500 and 9,300 cal years BP and therefore covers most of the deglaciation. By combining the records of mass accumulation rates at the core location and age at deposition of terrigenous biomarkers extracted from sediment samples, we can determine the occurrence of past massive permafrost degradation and mobilization. The results from this study will further contribute to and extend the limited data sets on the age of deglacial permafrost carbon from the Laptev Sea and provide additional insights on the fate of permafrost-derived soil organic carbon in a warming climate.