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: 2308548
• 负责人: Adrian Harpold
• 金额: $ 2.54万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 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=2308548&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一个基本过程，它塑造和记录了景观的记忆，产生水质和营养物质以维持生态系统，并在较长的时间尺度上减少大气中的二氧化碳。在流域，水通过雨和雪进入景观，在那里它开始沿着地下的各种路径沿着旅行。沿着这条路，水与矿物质相遇并交换，结合从固体中释放出来的化学物质，并在称为风化的过程中将它们转化为其他形式。最终，带有独特化学特征的水从系统中被冲入附近的河流和地下水泉。传统观点认为，水与周围的地下水接触的时间越长，它的化学演变就越多。在这一框架下，在一个集水区观察到的风化程度应该与地下水年龄有着不可分割的联系。从历史上看，这种关系很难全面评估。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，以促进我们对位于加州中部塞拉内华达州山脉的山地流域Sagehen Creek盆地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，并为本科研究提供机会。研究人员将与地球科学教育工作者合作，推出一套教育产品和举措，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和地球化学相结合的方法，更好地描述地下水年龄和硅酸盐风化率之间的关系，在流域尺度。硅酸盐风化反应是唯一耦合到集水水文由于缓慢的反应动力学，因此，溶质的产生本质上取决于时间的流体暴露于矿物。该项目将开发和利用一个新的综合水龄（CFC、SF6和35 S）和风化（δ 30 Si、δ 44 Ca和Ge/Si）示踪数据集，为耦合的二维物理传输水文和同位素支持的多组分反应传输模型提供信息。该研究将在Sagehen Creek盆地进行，这是一个受融雪驱动的火成岩山地流域，对气候敏感。Sagehen是一个广泛研究的网站与几个先前的研究表明测得的风化衍生的溶质通量和地下水停留时间之间的相关性。这种混合水文和地球化学方法将提供前所未有的洞察流体过境时间和硅酸盐风化之间的协同关系。研究人员计划生成动态的，不断变化的水过境时间分布，以响应季节和事件强迫，并通过纳入“快”/浅和“慢”/深的地下水成分。这项研究进一步提供了一个机会，以评估效用的稳定同位素和微量元素示踪剂，是敏感的不同的反应途径，并量化的反应程度可以作为“反应时钟”。研究结果将提供洞察关键区科学相关的流域水文地球化学响应气候变化的持久性问题。该研究由地球科学部地球生物学和低温地球化学计划以及水文科学计划共同资助。该奖项反映了NSF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。