OPP-PRF: Linking the Physical and Chemical Drivers of Carbon Cycling in Arctic Source-to-sink Systems

全球碳循环调节着地球的气候和宜居性。北极的景观，尤其是永久冻土（冻土），储存了大量的碳——几乎是大气的两倍。随着北极气温的升高，永久冻土融化，富含碳的有机物就会被释放出来。一旦被释放，这些碳就会转化为二氧化碳和甲烷——温室气体。永久冻土释放的碳也可能被输送到海洋中，在那里它可以被埋藏多年，使其远离大气。这项研究的主要目标是在北极地区找到永久冻土融化的热点，并了解从永久冻土中释放出来的碳会发生什么。该项目支持一名博士后学者，并提供资金分析从阿拉斯加北极地区一条河流采集的样本。这项工作将产生一个数学模型来模拟碳在北极地区的流动。该项目还将创建一个教育工具，向学生传授碳-气候反馈。该项目旨在建立对北极景观中物理侵蚀、氧化风化和有机碳（OC）转化之间反馈的机制理解。本项目采用“源到汇”的方法，在景观尺度上研究多年冻土融化的物理和化学效应，并评估OC在动员和下游运输过程中的转化。该项目以阿拉斯加北部的坎宁河为重点，将比较现代河流OC通量与由宇宙形成放射性核素地球化学得出的长期流域平均OC输出量。为了确定永久冻土来源的OC在穿越北极景观的过程中是否被氧化成二氧化碳，该项目采用了新的地球化学方法，包括斜坡热解氧化- 14c和溶解铼分析。这些结果将限制永久冻土融化中OC的分解速率，这在很大程度上是未知的，但需要预测北极未来的二氧化碳排放。利用该项目产生的数据，PI将构建北极河流集水区耦合侵蚀、风化和碳循环的模型。该耦合模型的进一步应用将揭示气候、侵蚀、沉积物路径和OC循环之间的反馈，这将促进我们对北极景观对未来气候变化响应的理解。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。

The global carbon cycle regulates the climate and habitability of our planet. The Arctic landscape, particularly permafrost (frozen ground), stores a massive amount of carbon – nearly twice as much as the atmosphere. As air temperatures in the Arctic increase, the permafrost thaws and carbon-rich organic matter can be released. Once released, this carbon can be transformed into carbon dioxide and methane – greenhouse gases. The carbon released from permafrost may also be transported to the ocean where it can be buried for many years, keeping it out of the atmosphere. The primary goals of this research are to find hotspots of permafrost thaw in the Arctic landscape and to understand what happens to carbon after it is released from the permafrost. This project supports one postdoctoral scholar and provides funding to analyze samples collected from a river in Arctic Alaska. This work will result in a mathematical model that simulates the flow of carbon across the Arctic landscape. The PI will also create an educational tool to teach students about carbon-climate feedbacks.This project aims to develop a mechanistic understanding of the feedbacks between physical erosion, oxidative weathering, and organic carbon (OC) transformation in Arctic landscapes. This project uses a “source-to-sink” approach to study the physical and chemical effects of permafrost thaw at the landscape-scale and assess the transformation of OC upon mobilization and downstream transport. Focusing on the Canning River in northern Alaska, the PI will compare modern river OC fluxes with long-term catchment-average OC export derived from cosmogenic radionuclide geochemistry. To determine whether permafrost-derived OC is oxidized to CO2 during transport across the Arctic landscape, this project applies novel geochemical methods, including ramped pyrolysis oxidation-14C and dissolved rhenium analyses. The results will constrain decomposition rates of OC mobilized from thawing permafrost, which are largely unknown but needed to predict future CO2 emissions from the Arctic. Using data generated from this project, the PI will construct a model of coupled erosion, weathering, and carbon cycling in Arctic river catchments. Further application of this coupled model will reveal the feedbacks among climate, erosion, sediment routing, and OC cycling that will advance our understanding of Arctic landscape response to future climate change.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.