Hydrologic constraints on global carbon dioxide emissions from inland waters

内陆水域、溪流、河流、湖泊和水库是全球碳循环的重要组成部分，特别是它们作为二氧化碳（CO2）向大气的来源。尽管我们对内陆水域碳循环的概念最近取得了进展，但这些水域的全球二氧化碳排放量仍然高度不确定。本研究将结合水流、地表水形态和碳运输与转化模型，开发基于过程的全球溪流、河流、湖泊和水库二氧化碳通量计算模型。这些模型将提供关于全球CO2通量和内陆水体CO2源分布的新见解，以及这些通量和源如何响应河流流量的变化。研究人员将培训一名博士生，并指导一名博士后研究员，并通过“尤里卡！与女孩公司和马萨诸塞大学阿姆赫斯特分校合作的项目。该项目的主要目标是对包括河流、溪流、湖泊和水库在内的内陆水域的全球二氧化碳通量提供可靠的、有物理约束的估计。这将通过假设驱动的研究目标来实现：(1)将全球最先进的水力和水文路径系统与最近开发的二氧化碳流网络模型结合起来，包括物质运输的物理表示、输入（地下水流入、与富含二氧化碳的孔隙水的潜流交换、水柱呼吸）和输出（初级生产力、大气交换）；(2)利用现有的全球地表水和地下水地球化学观测数据集对CO2水文和流网络耦合模型进行验证，并将基于物理的模型与现有的统计升级技术进行比较；(3)将该模型应用于不同流量条件下CO2排放的平均时空变化特征，并探讨流量变化对河流CO2排放的影响。该奖项将由水文科学、地球生物学和低温地球化学项目共同资助。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。

Inland waters, streams, rivers, lakes, and reservoirs, act as an important component of the global carbon cycle, particularly in their role as sources of carbon dioxide (CO2) to the atmosphere. Despite recent advances in our conceptions of inland water carbon cycling, global CO2 emissions from these waters remain highly uncertain. This research will develop process-based computational models of global CO2 fluxes from streams, rivers, lakes, and reservoirs by combining models of water flow, surface water morphology, and carbon transport and transformation. The models will provide new insights into global CO2 fluxes and the distribution of inland water CO2 sources, and how these fluxes and sources respond to changes in streamflow. The researchers will train a PhD student and mentor a postdoctoral researcher, and enhance STEM education in the Holyoke and Springfield, MA area, by creating educational activities for high school girls through the Eureka! Program in collaboration with Girls, Inc. and the University of Massachusetts Amherst. The primary goal of this project is to provide robust, physically constrained estimates of global CO2 fluxes from inland waters including rivers, streams, lakes, and reservoirs. This will be accomplished through hypothesis-driven research objectives to: (1) couple global state-of-the-art hydraulic and hydrologic routing systems with a recently developed stream network model of CO2 including physical representations of mass transport, inputs (groundwater inflows, hyporheic exchange with CO2-rich pore waters, water column respiration), and outputs (primary productivity, atmospheric exchange); (2) validate the coupled hydrology and stream network model of CO2 against existing datasets of global surface and groundwater geochemical observations, and compare our physics-based model with existing statistical upscaling techniques; and (3) apply the model across a range of flow conditions to characterize average and spatiotemporal variability in CO2 emissions, and explore how changes in streamflow impact stream CO2 emissions.The award will be co-funded by the Hydrologic Sciences and the Geobiology and Low-Temperature Geochemistry programs.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.