Total suspended matter, particulate organic carbon and its isotopic composition in the Lena River and its Delta

Total Suspended Matter (TSM), Particulate Organic Carbon (POC) and its isotopic composition were measured in water samples from the Lena River and its Delta (Sardakhskaya branch). Samples were taken in summer 2019 during the CACOON expedition (Fuchs et al., 2021a, b and 2022) along ~ 1600 km transect from Yakutsk downstream to the Lena Delta disembogue into the Laptev Sea. 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 TSM content (difference in weights between dried filters with TSM and pre-weighed empty filters), POC concentration and δ13C-POC (Sercon 20-20 isotope ratio mass spectrometer coupled to an Automated Nitrogen Carbon Analyzer), ∆14C-POC analysis (accelerator mass spectrometer achieved on a Mini Carbon Dating System) and relative OC content in TSM (calculated by dividing the sample POC content by the TSM content). Our aim was to characterize POC along the Lena River over a transect from upper reaches of the Lena River north to the Lena delta in order to decipher the distribution, main sources, and transformation of POC on its way from the permafrost catchment to the Arctic Ocean.