Organic matter characteristics: From Pleistocene permafrost to Lena river water

Climate change will enhance the release of organic and inorganic compounds such as carbon (C) and nitrogen (N) via increased permafrost thawing and river runoff in the Arctic. However, the amount of C and N as well as its composition during runoff is largely unknown. Our study aims to characterize and define the source and fate of riverine C and N and its effect on primary productivity in Arctic coastal waters. In order to assess the alteration of the erosion signal from land to sea, we analyzed a fastly degrading permafrost cliff in the Lena River delta (Sobo Sise Island). Furthermore, we collected Lena river water samples from 13 locations (CACOON on Ice Expedition, spring 2019) between the Sobo Sise Cliff and the coast. 28 permafrost samples were analyzed for terrestrial parameters (grain size, total organic carbon, stable isotopes and lipid biomarkers. In order to analyze the thaw impact on Lena river water, we used a hydrochemical approach to determine DON, TDN and respective isotope analysis of the water samples. Describing organic matter fluxes and characteristics will lead to a better understanding of the nutrient load associated with permafrost thaw, and thus warming climate in Arctic environments