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: 2308547
• 负责人: Laura Rademacher
• 金额: $ 26.79万
• 依托单位: University of the Pacific
• 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=2308547&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，它塑造和记录景观记忆，产生维持生态系统的水质和营养物质，并在较长时间内吸收大气中的二氧化碳。在流域中，水通过雨和雪注入景观。它沿着地下的各种路径开始旅程，水与矿物质相遇并交换，吸收从固体中释放的化学物质，并在称为风化的过程中将其转化为其他形式。传统观点认为，水与周围地下接触的时间越长，其化学演化程度就越高，在流域内观察到的风化程度应该是密不可分的。从历史上看，这种关系很难完全评估，该项目将使用现代地球化学工具与先进的建模方法来加深我们对山区流域地下水年龄和风化通量之间关系的理解。 Sagehen Creek盆地位于加利福尼亚州内华达山脉中部，这项合作研究工作将为两名早期职业科学家、一名博士生和一名现场技术人员提供支持，并为本科生研究提供机会，研究人员将与知名的地球科学教育工作者合作开展这项研究。一系列教育产品和举措，让更广泛的公众、高中生和教师参与水文学和水质主题。这项研究旨在通过结合水文和水质更好地描述流域范围内地下水年龄和硅酸盐风化率之间的关系。地球化学方法。由于反应动力学缓慢，硅酸盐风化反应与流域水文学有着独特的联系；因此，溶质的生成本质上取决于流体接触矿物质的时间，该项目将开发和利用新的综合水时代（CFC、SF6 和 35S）。 ）和风化（δ30Si、δ44Ca 和 Ge/Si）示踪数据集，以告知耦合的二维物理输运水文和同位素启用的多组分反应输运该研究将在 Sagehen Creek 盆地进行，Sagehen 是一个对气候敏感的融雪火成山流域，之前的几项研究表明了测量的风化引起的溶质通量与地下水停留时间之间的相关性。混合水文和地球化学方法将为流体传输时间和硅酸盐风化之间的协同关系提供前所未有的见解，研究人员计划生成动态的、不断变化的水传输时间分布，以响应这两者。季节性和事件强迫，并通过纳入“快”/浅层和“慢”/深层地下水成分，这项研究进一步提供了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的机会，以及量化反应程度如何充当“反应时钟”。这项研究由地球科学部和地球生物学部共同资助。低温地球化学计划和水文科学计划。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和更广泛的影响审查标准进行评估，被认为值得支持。