Sedimentary and geochemical characteristics of two small permafrost-dominated Arctic river deltas in northern Alaska.
Sedimentary and geochemical characteristics of two small permafrost-dominated Arctic river deltas in northern Alaska.
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DOI：
10.1007/s41063-018-0056-9
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Walker DA
中科院分区：
文献类型：
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作者：
Fuchs M;Grosse G;Jones BM;Strauss J;Baughman CA;Walker DA
北极河流三角洲是北部环极地永久冻土地区高度动态的环境，受到河流、沿海和永久冻土融化过程的影响。它们的特点是厚厚的沉积物含有大量但约束较差的冷冻有机碳和氮。这项研究提供了关于土壤有机碳和氮存储以及伊克皮克普克河和鱼溪河三角洲积累率的新数据，这两个三角洲位于阿拉斯加北部北极沿海平原，是两个以永久冻土为主的小型北极河流三角洲。 Ikpikpuk 和 Fish Creek 河三角洲前 2 m 土壤的土壤有机碳储量分别为 42.4±±1.6 和 37.9±3.5 kg C m− 2，土壤氮储量分别为 2.1± 0.1 和 2.0± 0.2 kg N m− 2。虽然上层土壤含有 3.57 Tg C，但两个三角洲的第二米土壤（100–200 cm）内也储存了大量的碳（3.09 Tg C 或 46%）。碳随深度的增加和不均匀分布表明土壤有机碳储存的主导作用是三角洲沉积过程，而不是土壤形成过程。很大程度上，我们的核心中的全新世中晚期放射性碳测年表明，过去 2000 年这两个三角洲的碳积累率不同。 Ikpikpuk 河三角洲的速率高达 28 g C m− 2 年− 1，大约是 Fish Creek 河三角洲的两倍。通过这项研究，我们强调了将这些高度动态的永久冻土环境纳入未来永久冻土碳估算的重要性。本文的在线版本 (10.1007/s41063-018-0056-9) 包含补充材料，可供授权用户使用。
Arctic river deltas are highly dynamic environments in the northern circumpolar permafrost region that are affected by fluvial, coastal, and permafrost-thaw processes. They are characterized by thick sediment deposits containing large but poorly constrained amounts of frozen organic carbon and nitrogen. 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. 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. 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. 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. Largely, mid- to late Holocene radiocarbon dates in our cores suggest different carbon accumulation rates for the two deltas for the last 2000 years. 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. With this study, we highlight the importance of including these highly dynamic permafrost environments in future permafrost carbon estimations. The online version of this article (10.1007/s41063-018-0056-9) contains supplementary material, which is available to authorized users.