TY - JOUR A1 - Opel, Thomas A1 - Murton, Julian B. A1 - Wetterich, Sebastian A1 - Meyer, Hanno A1 - Ashastina, Kseniia A1 - Günther, Frank A1 - Grotheer, Hendrik A1 - Mollenhauer, Gesine A1 - Danilov, Petr P. A1 - Boeskorov, Vasily A1 - Savvinov, Grigoriy N. A1 - Schirrmeister, Lutz T1 - Past climate and continentality inferred from ice wedges at Batagay Highlands, interior Yakutia JF - Climate of the past : an interactive open access journal of the European Geosciences Union N2 - Ice wedges in the Yana Highlands of interior Yakutia - the most continental region of the Northern Hemisphere - were investigated to elucidate changes in winter climate and continentality that have taken place since the Middle Pleistocene. The Batagay megaslump exposes ice wedges and composite wedges that were sampled from three cryostratigraphic units: the lower ice complex of likely pre-Marine Isotope Stage (MIS) 6 age, the upper ice complex (Yedoma) and the upper sand unit (both MIS 3 to 2). A terrace of the nearby Adycha River provides a Late Holocene (MIS 1) ice wedge that serves as a modern reference for interpretation. The stable-isotope composition of ice wedges in the MIS 3 upper ice complex at Batagay is more depleted (mean delta O-18 about -35 parts per thousand) than those from 17 other ice-wedge study sites across coastal and central Yakutia. This observation points to lower winter temperatures and therefore higher continentality in the Yana Highlands during MIS 3. Likewise, more depleted isotope values are found in Holocene wedge ice (mean delta O-18 about -29 parts per thousand) compared to other sites in Yakutia. Ice-wedge isotopic signatures of the lower ice complex mean delta O-18 about -33 parts per thousand) and of the MIS 3-2 upper sand unit (mean delta O-18 from about -33 parts per thousand to -30 parts per thousand) are less distinctive regionally. The latter unit preserves traces of fast formation in rapidly accumulating sand sheets and of post-depositional isotopic fractionation. Y1 - 2019 U6 - https://doi.org/10.5194/cp-15-1443-2019 SN - 1814-9324 SN - 1814-9332 VL - 15 IS - 4 SP - 1443 EP - 1461 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Stolpmann, Lydia A1 - Mollenhauer, Gesine A1 - Morgenstern, Anne A1 - Hammes, Jens S. A1 - Boike, Julia A1 - Overduin, Pier Paul A1 - Grosse, Guido T1 - Origin and pathways of dissolved organic carbon in a small catchment in the Lena River Delta JF - Frontiers in Earth Science N2 - The Arctic is rich in aquatic systems and experiences rapid warming due to climate change. The accelerated warming causes permafrost thaw and the mobilization of organic carbon. When dissolved organic carbon is mobilized, this DOC can be transported to aquatic systems and degraded in the water bodies and further downstream. Here, we analyze the influence of different landscape components on DOC concentrations and export in a small (6.45 km(2)) stream catchment in the Lena River Delta. The catchment includes lakes and ponds, with the flow path from Pleistocene yedoma deposits across Holocene non-yedoma deposits to the river outlet. In addition to DOC concentrations, we use radiocarbon dating of DOC as well as stable oxygen and hydrogen isotopes (delta O-18 and delta D) to assess the origin of DOC. We find significantly higher DOC concentrations in the Pleistocene yedoma area of the catchment compared to the Holocene non-yedoma area with medians of 5 and 4.5 mg L-1 (p < 0.05), respectively. When yedoma thaw streams with high DOC concentration reach a large yedoma thermokarst lake, we observe an abrupt decrease in DOC concentration, which we attribute to dilution and lake processes such as mineralization. The DOC ages in the large thermokarst lake (between 3,428 and 3,637 C-14 y BP) can be attributed to a mixing of mobilized old yedoma and Holocene carbon. Further downstream after the large thermokarst lake, we find progressively younger DOC ages in the stream water to its mouth, paired with decreasing DOC concentrations. This process could result from dilution with leaching water from Holocene deposits and/or emission of ancient yedoma carbon to the atmosphere. Our study shows that thermokarst lakes and ponds may act as DOC filters, predominantly by diluting incoming waters of higher DOC concentrations or by re-mineralizing DOC to CO2 and CH4. Nevertheless, our results also confirm that the small catchment still contributes DOC on the order of 1.2 kg km(-2) per day from a permafrost landscape with ice-rich yedoma deposits to the Lena River. KW - Arctic lakes KW - ice complex KW - yedoma KW - thermokarst lakes KW - DOC KW - aquatic carbon cycle KW - permafrost KW - radiocarbon dating Y1 - 2022 U6 - https://doi.org/10.3389/feart.2021.759085 SN - 2296-6463 VL - 9 PB - Frontiers Media CY - Lausanne ER -