Organic Carbon Content in the Subsurface Sediments of Floodplains Across the Yukon River Basin, Alaska, 2022

The carbon stored in permafrost deposits represents the single largest soil carbon reservoir on Earth. Concerns about the instability and dynamics of this carbon reservoir during permafrost thaw associated with polar amplification of climate warming contribute a large part of the uncertainty in forecasting future climate. We have been studying the carbon dynamics of permafrost deposits contained in the floodplains of large Arctic rivers. Across Arctic floodplains, accelerating bank erosion can liberate permafrost organic carbon (OC) as carbon dioxide (CO2) or methane (CH4), and/or redeposit it in fluvial units. These different fates have very different implications for climate feedback. Determining OC stocks and their dynamics in Arctic floodplain cutbanks and point bars, as well as the OC load in fluvial transport, is essential to better understand the recycling and export of permafrost carbon. As part of a National Science Foundation (NSF) funded project to better understand the effects of erosion in the Yukon River Basin, floodplain sediments were collected between June and September 2022 at two locations underlain by discontinuous permafrost within the Yukon River Basin in Alaska: Beaver (65.700° North (N), 156.387° West (W)) and Huslia (66.362° N, 147.398° W). This dataset mainly reports OC contents for collected subsurface sediments in floodplains measured by elemental analyzer. The coupled mercury content can be found in Isabel et al., 2024 (https://doi.org/10.18739/A2RF5KH5J).永久冻土沉积物中储存的碳是地球上单一最大的土壤碳库。气候变暖的极地放大效应引发永久冻土融化，在此过程中该碳库的不稳定性与动态变化，是造成未来气候预测不确定性的重要来源。我们长期致力于研究大型北极河流泛滥平原内永久冻土沉积物的碳动态。北极泛滥平原的岸坡侵蚀加剧，可将永久冻土有机碳（organic carbon, OC）以二氧化碳（carbon dioxide, CO₂）或甲烷（methane, CH₄）形式释放，或使其重新沉积于河流沉积单元中。这两种不同的归宿对气候反馈的影响差异极大。要更深入理解永久冻土碳的循环与输出过程，必须明确北极泛滥平原岸坡与点沙坝中的有机碳储量及其动态变化，同时厘清河流输运中的有机碳负荷。作为美国国家科学基金会（National Science Foundation, NSF）资助的育空河流域侵蚀效应研究项目的一部分，我们于2022年6月至9月间，在阿拉斯加育空河流域两处分布有不连续永久冻土的点位采集了泛滥平原沉积物：一处为比弗（Beaver，65.700° N，156.387° W），另一处为赫斯利亚（Huslia，66.362° N，147.398° W）。本数据集主要报告了通过元素分析仪测定的采集到的泛滥平原地下沉积物的有机碳含量。配套的汞含量数据可参考Isabel等人2024年的研究（https://doi.org/10.18739/A2RF5KH5J）。