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规模最大的土壤碳储库。在与气候变暖极地放大效应相关的永久冻土解冻过程中，该碳储库的不稳定性与动态变化所引发的担忧，是未来气候预测不确定性的重要来源之一。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过程。在北极泛滥平原区域，加速的岸坡侵蚀可将永久冻土有机碳（organic carbon, OC）释放为二氧化碳（carbon dioxide, CO₂）或甲烷（methane, CH₄），或使其重新沉积于河流沉积单元中。这些不同的碳归宿对气候反馈的影响存在显著差异。明确北极泛滥平原陡岸与点坝中的有机碳储量及其动态变化，以及河流输运中的有机碳负荷，是深入理解永久冻土碳循环与输出过程的关键所在。作为美国国家科学基金会（National Science Foundation, NSF）资助的、旨在深入理解育空河流域侵蚀效应项目的一部分，我们于2022年6月至9月间，在阿拉斯加州育空河流域两处发育不连续永久冻土的点位采集了泛滥平原沉积物：比弗（Beaver，北纬65.700°，西经156.387°）与赫斯利亚（Huslia，北纬66.362°，西经147.398°）。本数据集主要记录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见Isabel等人2024年的研究（https://doi.org/10.18739/A2RF5KH5J）。