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，北极的景观正在迅速变化。这种变暖的一个影响是，即使在夏天也保持冻结的永久冻土层现在正在融化。永久冻土融化使以前冻结的有机土壤物质分解，这一过程向世界大气中释放二氧化碳，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，然后沉积在洪泛平原和海岸。这种土壤和碳通过河流走廊的运输以及这种材料在海岸上的埋藏如何影响碳的分解尚不清楚。 该项目收集的数据将监测阿拉斯加坎宁河的水和碳化学变化。 这些从陆地表面、河漫滩和河岸进行的测量将使我们能够发展关于碳循环的新理论。这些新的见解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博士后研究员进行综合数据收集和计算机建模，帮助建立未来的劳动力队伍。我们将通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，与区域决策者合作。由于对季节性冰冻景观中沉积物产生机制、沉积物和碳沿着河流走廊的运输、储存和转化机制以及海岸沉积机制的了解有限，我们无法预测未来北极的碳循环。该项目涉及地貌运输系统及其与有机碳释放和固存的联系。这项研究通过阿拉斯加北坡坎宁河的输送系统跟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博福特海的三角洲。 我们将开发新的理论和定量数值模型。实地工作包括沿坎宁河沿着安装延时摄影机、使用无人驾驶飞机和新的北极数字高程模型绘制高分辨率形态变化图、部署温度和沉积物迁移传感器以及收集水、沉积物和碳样本，这些工作将有助于了解从陆地到北冰洋沿海的沉积物和碳通量的大小。 这些测量结果将提供一套基线数据，可据以评估今后的变化。该研究将解决山坡泥沙运输的soliflectin，解冻控制的河流泥沙运输，沉积物粉碎的冻裂，热河岸侵蚀，和三角洲沉积在海冰覆盖的海洋。该项目中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，地球化学和形态动力学。该项目将在野外、实验室、数值模拟方法。该奖项由北极自然科学计划和地貌学与陆地-该奖项反映了NSF的法定使命，并通过使用基金会的智力价值进行评估而被认为值得支持和更广泛的影响审查标准。

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.