Icy landscapes from the Brooks Range to the Beaufort Sea: Quantifying the mobilization, transport and deposition of sediment and carbon in Arctic Alaska

由于持续变暖，北极景观正在迅速变化。这种变暖的一个影响是永久冻土，即即使在夏天也保持冻结的地面，现在正在融化。永久冻土解冻使以前冻结的有机土壤物质暴露于分解，这一过程将二氧化碳释放到世界大气中，并可能导致温室效应。解冻还将新的土壤和碳物质带入北极河流，然后沉积在洪泛区和海岸。这些土壤和碳通过河流走廊的运输，以及这些物质在海岸的掩埋，是如何影响碳分解的，目前还不清楚。该项目收集的数据将监测阿拉斯加州坎宁河的水和碳化学变化。这些对陆地表面、河漫滩和河岸的测量，将使我们能够发展出关于碳循环的新理论。这些新发现将用于开发预测未来景观变化和碳释放的计算机模型。该项目将通过培训四名学生和一名综合数据收集和计算机建模的博士后，帮助建立未来的劳动力。我们将透过短片与公众分享我们的见解。我们还将通过与美国地质调查局、鱼类和野生动物管理局以及国家公园管理局的密切合作，与地区决策者合作。对季节性冰冻景观中沉积物产生的机制，对河流走廊中沉积物和碳的运输、储存和转化以及海岸沉积的机制的了解有限，使我们无法预测北极未来的碳循环。该项目解决了地貌运输系统及其与有机碳释放和封存的联系。该研究通过阿拉斯加北坡坎宁河的输送系统追踪沉积物和碳的地球化学特征，从布鲁克斯山脉的冰川源头到波弗特海的三角洲。我们将发展新的理论和定量数值模型。实地工作包括在坎宁河沿岸建立延时相机，使用无人机和新的北极数字高程模型进行高分辨率形态变化测绘，部署温度和沉积物运输传感器，以及收集水、沉积物和碳样本，将揭示从陆地域到北冰洋沿岸的沉积物和碳通量的大小。这些测量将提供一个基线数据集，用以评估未来的变化。该研究将研究由溶蚀作用引起的山坡沉积物运输、由融化控制的河流沉积物运输、由霜裂引起的沉积物粉碎、热河岸侵蚀以及在海冰覆盖的海洋中的三角洲沉积。该项目开发的数值方案将改进现有的开源模型框架，用于模拟高纬度、水文、生物地球化学和形态动力学。该项目将在野外、实验室和数值模拟方法的综合背景下，培养北极系统科学、地貌学和沉积过程方面的研究生和本科生。该奖项由北极自然科学项目和地貌学和土地利用动力学项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Arctic landscapes are rapidly changing because of ongoing warming. One effect of this warming is that permafrost, which is ground that remains frozen even in summer, is now thawing. Permafrost thaw exposes previously frozen organic soil material to decomposition, a process that releases carbon dioxide to the world’s atmosphere and can contribute to the greenhouse effect. Thaw also brings new amounts of soil and carbon material into Arctic rivers, which then gets deposited in floodplains and coasts. How the transport of this soil and carbon through river corridors and the burial of this material on the coasts, affect carbon decomposition is unclear. This project collects data that will monitor changes in water and carbon chemistry for the Canning River in Alaska. These measurements from the land surface, floodplain and river banks, will allow us to develop new theories about the carbon cycle. These new insights will be used to develop computer models that predict future landscape change and carbon release. The project will help build the future workforce through training of four students and a postdoctoral fellow in integrated data collection and computer modeling. We will share our insights with the public through a short film. We will also work with regional decision makers through close collaboration with the US Geological Survey, Fish and Wildlife Service, and at the National Park Service.Limited understanding of the mechanisms of sediment production in seasonally frozen landscapes, of transport, storage, and transformation of sediment and carbon along river corridors, and deposition at the coasts, prevents us from predicting Arctic carbon cycles into the future. This project addresses the geomorphic transport system and its connection to organic carbon liberation and sequestration. The study tracks sediment and carbon geochemical characteristics through the conveyor system of the Canning River on Alaska’s North Slope, from its glacial headwaters in the Brooks Range to its delta in the Beaufort Sea. We will develop new theory and quantitative numerical models. Field efforts, which include the establishment of time-lapse cameras along the Canning River, high resolution morphological change mapping using drones and the new Arctic Digital Elevation Model, deployment of temperature and sediment transport sensors, and the collection of water, sediment and carbon samples, will shed light on the magnitudes of sediment and carbon fluxes from the terrestrial domain to the coastal Arctic Ocean. These measurements will provide a baseline data set against which future change can be assessed. The study will address hillslope sediment transport by solifluction, thaw-controlled fluvial sediment transport, sediment comminution by frost cracking, thermal riverbank erosion, and deltaic deposition in a sea-ice-covered ocean. The numerical schemes developed in this project will improve existing open-source model frameworks for simulating high latitude, hydrology, biogeochemistry, and morpho-dynamics. This project will train graduate and undergraduate students in Arctic system science, geomorphology, and sedimentary processes, within the integrated context of field, laboratory, numerical modeling methods.This award is co-funded by the Arctic Natural Sciences Program and the Geomorphology and Land-use Dynamics Program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.