Erosion of ice-rich permafrost coasts and the release of dissolved organic carbon into the Arctic Ocean

• Main Authors: Tanski, George, Couture, N. J., Lantuit, Hugues, Eulenburg, Antje, Fritz, Michael
• Format: Conference Object
• Language: unknown
• Published: 2016
• Subjects: Arctic; Arctic Ocean; Yukon; Ice; permafrost
• Online Access: https://epic.awi.de/id/eprint/41252/; https://epic.awi.de/id/eprint/41252/1/GTanski_Poster_ICOP.pdf; https://hdl.handle.net/10013/epic.48177; https://hdl.handle.net/10013/epic.48177.d001

Ice-rich permafrost coasts in the Arctic are highly sensitive to climate warming and erode at a pace that exceeds the global average. Permafrost coasts deliver vast amounts of organic carbon into the nearshore zone of the Arctic Ocean. Numbers on flux exist for particulate and total soil organic carbon (POC and TOC). However, they do not exist for dissolved organic carbon (DOC), which is known to be highly labile. This study aims to estimate DOC stocks in coastal permafrost as well as the annual flux into the ocean. DOC concentrations in ground ice were analyzed along the ice-rich Yukon coast (YC) in the western Canadian Arctic. The annual DOC flux was estimated using available numbers for coast length, cliff height, annual erosion rate, and volumetric ice content in different stratigraphic horizons. Our results showed that DOC concentrations in ground ice range between 0.3 and 347.0 mg L-1 with an estimated stock of 13.55 g m-3 along the YC. An annual DOC flux of 54.9 Mg yr-1 was computed. These DOC fluxes are low compared to POC fluxes from coastal erosion or POC and DOC fluxes from Arctic rivers. We conclude that DOC fluxes from permafrost coasts play a minor role in the Arctic carbon budget. However, this DOC is assumed to be highly labile. We hypothesize that DOC from coastal erosion is important for ecosystems in the Arctic nearshore zones, particularly in summer when river discharge is low, and in areas where rivers are absent.