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Fishing planet level 39 alaska2/22/2024 ![]() ![]() A unique aspect of Arctic river deltas is that large parts of the landscape are underlain by permafrost. Compared to low-latitude river deltas, harsh Arctic winters lead to pronounced seasonal runoff patterns with low or no discharge in winter, a peak discharge during the time of river ice break-up, and a declining discharge until freeze-up. They are characterized by typical fluvial and deltaic processes such as tides, periodic flooding, sediment deposition, channel migration, and shoreline erosion. With this study, we highlight the importance of including these highly dynamic permafrost environments in future permafrost carbon estimations.Īrctic river deltas are dynamic environments at the interface between land and sea. Rates up to 28 g C m − 2 year − 1 for the Ikpikpuk river delta are about twice as high as for the Fish Creek river delta. Largely, mid- to late Holocene radiocarbon dates in our cores suggest different carbon accumulation rates for the two deltas for the last 2000 years. An increasing and inhomogeneous distribution of C with depth is indicative of the dominance of deltaic depositional rather than soil forming processes for soil organic carbon storage. While the upper meter of soil contains 3.57 Tg C, substantial amounts of carbon (3.09 Tg C or 46%) are also stored within the second meter of soil (100–200 cm) in the two deltas. ![]() A soil organic carbon storage of 42.4 ± 1.6 and 37.9 ± 3.5 kg C m − 2 and soil nitrogen storage of 2.1 ± 0.1 and 2.0 ± 0.2 kg N m − 2 was found for the first 2 m of soil for the Ikpikpuk and Fish Creek river delta, respectively. This study presents new data on soil organic carbon and nitrogen storage as well as accumulation rates from the Ikpikpuk and Fish Creek river deltas, two small, permafrost-dominated Arctic river deltas on the Arctic Coastal Plain of northern Alaska. ![]() They are characterized by thick sediment deposits containing large but poorly constrained amounts of frozen organic carbon and nitrogen. Arctic river deltas are highly dynamic environments in the northern circumpolar permafrost region that are affected by fluvial, coastal, and permafrost-thaw processes. ![]()
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