Collaborative Research: Unraveling the link between water ages and silicate weathering rates at the catchment scale

合作研究：揭示流域尺度的水年龄和硅酸盐风化速率之间的联系

• 批准号: 2308546
• 负责人: Nicole Fernandez
• 金额: $ 65.64万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2308546&HistoricalAwards=false
• 关键词: Collaborative; Research; Unraveling; link; between

The interaction between water and minerals is a fundamental process that shapes and records memories of landscapes, generates water quality and nutrients to sustain ecosystems, and draws down atmospheric CO2 over longer timescales. In watersheds, water is fed into the landscape through rain and snow where it starts its journey along various paths in the subsurface. Along the path, water encounters and exchanges with minerals, incorporating chemicals liberated from the solids and transforming them into other forms in a process termed weathering. Eventually the water with its unique chemical signature is flushed from the system into nearby streams and groundwater springs. The conventional wisdom is that the longer water spends in contact with the surrounding subsurface, the more chemically evolved it becomes. Under this framework, the amount of weathering observed in a catchment should be inextricably linked with groundwater ages. Historically, this relationship has been difficult to fully evaluate. This project will use modern geochemical tools in tandem with advanced modeling approaches to advance our understanding of the relationship between groundwater ages and weathering fluxes in a montane catchment, Sagehen Creek Basin, located in the Central Sierra Nevada mountains in California. This collaborative research effort will support two early career scientists, one PhD student, a field technician, and provide opportunities for undergraduate research. Researchers will collaborate with established Earth Science educators to launch a suite of educational products and initiatives to engage the broader public, high school students and instructors on hydrology and water quality themes. This research aims to better characterize the relationship between groundwater ages and silicate weathering rates at the catchment-scale through a combined hydrologic and geochemical approach. Silicate weathering reactions are uniquely coupled to catchment hydrology due to slow reaction kinetics; thus, solute generation is inherently dependent on the time fluids spend exposed to minerals. The project will develop and leverage a new, comprehensive water age (CFC, SF6, and 35S) and weathering (δ30Si, δ44Ca, and Ge/Si) tracer dataset to inform a coupled 2D physical transport hydrologic and isotope-enabled, multicomponent reactive transport model. The study will be conducted at Sagehen Creek Basin, a snowmelt driven, igneous, montane watershed sensitive to climatic. Sagehen is a widely studied site with several prior studies demonstrating a correlation between measured weathering-derived solute fluxes and groundwater residence times. This hybrid hydrological and geochemical approach will provide unprecedented insight into the synergistic relationship between fluid transit time and silicate weathering. The researchers plan to generate dynamic, continually evolving transit time distributions for water in response to both seasonal and event forcing, and through the incorporation of “fast”/shallow and “slow”/deeper groundwater components. This research further provides an opportunity to evaluate the utility of stable isotopes and trace element tracers that are sensitive to distinct reaction pathways, and to quantify how the extent of reactions can serve as “reaction clocks”. Findings will provide insight into persistent questions in critical zone science related to watershed hydrogeochemical response to climate change. This research is co-funded by the Division of Earth Sciences Geobiology and Low-Temperature Geochemistry Program and Hydrologic Sciences 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.

水和矿物质之间的相互作用是形成和记录景观记忆的基本过程，产生水质和维持生态系统的营养物质，并在更长的时间尺度上吸收大气中的二氧化碳。在流域中，水通过雨雪进入景观，并沿着地下的各种路径开始其旅程。沿着路径，水与矿物质相遇和交换，结合从固体中释放的化学物质，并在风化过程中将其转化为其他形式。最终，具有独特化学特征的水从系统中被冲进附近的溪流和地下水泉中。传统观点认为，水与周围地下接触的时间越长，其化学进化程度就越高。在这一框架下，在集水区观测到的风化程度应与地下水年龄不可分割地联系在一起。从历史上看，这种关系一直难以全面评估。该项目将使用现代地球化学工具与先进的建模方法相结合，以加深我们对位于加利福尼亚州内华达山脉中部的Sagehen Creek盆地的山区集水区地下水年龄与风化通量之间关系的理解。这项合作研究工作将支持两名早期职业科学家，一名博士生，一名现场技术人员，并为本科生研究提供机会。研究人员将与现有的地球科学教育工作者合作，推出一套教育产品和倡议，让更广泛的公众、高中生和教师参与水文和水质主题。本研究旨在通过水文学和地球化学相结合的方法，更好地表征地下水年龄与流域尺度硅酸盐风化速率之间的关系。由于反应动力学缓慢，硅酸盐风化反应与流域水文具有独特的耦合关系；因此，溶质的生成本质上取决于流体暴露于矿物质的时间。该项目将开发和利用一个新的、综合的水年龄（CFC、SF6和35S）和风化（δ30Si、δ44Ca和Ge/Si）示踪数据集，为二维物理输运水文和同位素支持的多组分反应输运模型提供信息。这项研究将在Sagehen Creek盆地进行，这是一个由融雪驱动的火成岩山地分水岭，对气候很敏感。Sagehen是一个被广泛研究的地点，先前的几项研究表明，测量的风化产生的溶质通量与地下水停留时间之间存在相关性。这种混合水文和地球化学方法将为流体传递时间和硅酸盐风化之间的协同关系提供前所未有的见解。研究人员计划通过结合“快”/浅和“慢”/深地下水成分，根据季节和事件强迫，生成动态的、不断变化的水传输时间分布。这项研究进一步提供了一个机会来评估对不同反应途径敏感的稳定同位素和微量元素示踪剂的效用，并量化反应的程度如何作为“反应时钟”。研究结果将为与流域水文地球化学对气候变化的响应有关的关键带科学中持续存在的问题提供见解。本研究由地球科学部地球生物学和低温地球化学项目和水文科学项目共同资助。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。