Dissolved and Particulate Organic Carbon and its isotopic composition in the Lena Delta in winter 2019 and in summer 2019, 2017 and 2016

Dissolved and particulate Organic Carbon (DOC and POC) and their isotopic composition were measured in water samples from the Lena Delta (Sardakhskaya branch). Samples were taken in winter (April) and summer (August) 2019 during the CACOON expedition (Fuchs et al., 2021a, b and 2022) and in the summer 2017 and 2016 during previous Lena Delta sampling campaigns. Water was filtered through pre-combusted (4.5 hours, 450 °C) and pre-weighed glass fiber filters (GF/F Whatman, 0.75 µm membrane, Ø 2.5 cm) for DOC analyses, filters with rest suspended matter on it were used to analyse POC. δ13C of DOC and POC was measured by Sercon 20-20 isotope ratio mass spectrometer coupled to an Automated Nitrogen Carbon Analyzer, ∆14C of DOC and POC by accelerator mass spectrometer achieved on a Mini Carbon Dating System. Our aim was to highlight the variability in quantity and composition between seasons and suggest that permafrost deposits are degrading year around, impacting the release of organic matter through the Lena Delta.