权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

CAREER: Unlocking the Isotopic Signatures of Weathering Recorded in Rivers Through Isotope-Enabled Reactive Transport

职业：通过同位素反应传输解锁河流中记录的风化的同位素特征

基本信息

批准号：
2047318
负责人：
Jennifer Druhan
金额：
$ 51.58万
依托单位：
University of Illinois at Urbana-Champaign
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-06-01 至 2026-05-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2047318&HistoricalAwards=false
关键词：
CAREER Unlocking Isotopic Signatures Weathering

项目摘要

The percolation of water through the shallowest layers of the solid Earth is vital to sustaining life on this planet. Moisture delivered to soil irrigates the crops we grow and sustains natural ecosystems. Water that reaches further into the subsurface recharges aquifers and supplies the baseflow to streams and rivers. This transit through the shallow Earth also introduces water as a reactive agent capable of weathering the minerals that compose the crust, allowing chemical transformations that convert rock to soil and set the chemical signature of water resources. Thus, water is an integrator of this “critical zone”, i.e., the surface of the Earth where we live and draw resources. Such vital transformations are largely hidden from direct study because they occur below our feet in the near surface. Thus, we rely upon models that describe the rates and pathways of fluid drainage through the critical zone, coupled to the chemical reactions that occur between water, minerals and life, to predict what takes place where we cannot make direct observations. These models are then checked against more accessible samples often using the chemistry of streams and rivers which drain watersheds. Using novel instrumentation and model development, this project will offer the first direct validation of these reactive transport models based on fluids and solids collected within the transition from soil to stream. The broader impacts of this study include the improvement of predictive models for the chemical signatures of water quality and critical zone functioning. The capability to develop and deploy such models is vital to the advancement of watershed management and critical zone science. In pursuit of this goal, the project will create an open access online training platform designed to educate the next generation of Earth scientists in the development of state-of-the-art reactive transport models. The teaching modules will be deployed as part of an NSF-RCN award and will feature ADA-compliant web design with both self-guided and classroom integration options. This resource will foster the expanded use and equitable availability of next generation quantitative models and promote international collaborations across the global critical zone community.Predictive models for the tight coupling between fluid transport and chemical reactivity in critical zone weathering profiles remain largely validated against easily accessible observations such as the fluids that emerge as spring water and baseflow to streams and rivers. These integrated signatures of fluid draining landscapes offer a vital means of testing forward models and an increasing emphasis is now being placed on the use of riverine stable isotope ratios (e.g., 7Li, 30Si, 27Mg, 44Ca) for their exquisite sensitivity to specific components of chemical weathering. Integration of these promising tools into reactive transport simulations could hold the key to high fidelity predictive models for the coupling of chemistry and fluid flow draining intact weathering profiles. This proposal will generate three major advancements towards this goal: (1) quantitative interpretation of solute isotope signatures as a function of fluid travel time; (2) validation of isotope signatures in the zone of weathering between infiltration and discharge; and (3) predictive models for the weathering processes recorded by the isotope ratios of rivers draining watersheds. This will be accomplished through leveraging of a series of laboratory column experiments designed to support model development and in turn application to a novel field-scale instrumentation capability which allows direct collection of fluid samples in the partially saturated section of the critical zone where fluid drains through regolith before emerging as the baseflow to streams. The results of this work will test a set of hypotheses that link theory to observations of isotope ratios in the solutes derived from chemical weathering.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.

水通过固体地球最浅的地层渗透对维持地球上的生命至关重要。输送到土壤的水分灌溉我们种植的作物，并维持自然生态系统。进一步进入地下的水补充了含水层，并为溪流和河流提供了基流。这种通过浅层地球的过境也引入了水作为一种反应剂，能够风化构成地壳的矿物质，允许化学转化，将岩石转化为土壤，并设定水资源的化学特征。因此，水是这一“关键区域”的整合者，即，我们生活和汲取资源的地球表面。这种重要的转变在很大程度上是隐藏在直接研究之外的，因为它们发生在我们脚下的近地表。因此，我们依赖于描述流体通过临界区排出的速率和路径的模型，再加上水，矿物质和生命之间发生的化学反应，来预测我们无法直接观察的地方发生了什么。然后，这些模型与更容易获得的样本进行比较，通常使用排水流域的溪流和河流的化学成分。使用新的仪器和模型开发，该项目将提供这些反应传输模型的基础上收集的流体和固体从土壤到流的过渡的第一个直接验证。这项研究的更广泛的影响包括改善水质和关键区功能的化学特征的预测模型。开发和部署此类模型的能力对于推进流域管理和关键区域科学至关重要。为实现这一目标，该项目将创建一个开放式在线培训平台，旨在教育下一代地球科学家开发最先进的反应性迁移模型。这些教学模块将作为NSF-RCN奖项的一部分进行部署，并将采用符合ADA的网页设计，同时提供自助和课堂整合选项。这一资源将促进下一代定量模型的扩大使用和公平可用性，并促进全球临界区社区的国际合作。临界区风化剖面中流体输运和化学反应性之间紧密耦合的预测模型在很大程度上仍然通过易于获得的观测结果进行验证，例如泉水和基流到溪流和河流中的流体。这些流体排泄景观的综合特征提供了测试正演模型的重要手段，现在越来越强调使用河流稳定同位素比（例如，7 Li、30 Si、27 Mg、44 Ca）对化学风化的特定组分具有极高的敏感性。这些有前途的工具集成到反应性输运模拟可能持有的关键，高保真度的预测模型耦合的化学和流体流排水完整的风化剖面。这一建议将产生三个主要的进展，实现这一目标：（1）定量解释溶质同位素签名作为流体旅行时间的函数;（2）验证同位素签名之间的风化带渗透和排放;和（3）预测模型的风化过程中记录的同位素比率的河流排水流域。这将通过利用一系列实验室柱实验来实现，这些实验室柱实验旨在支持模型开发，并进而应用于一种新的现场规模的仪器能力，该能力允许在临界区的部分饱和部分直接收集流体样品，在该临界区中，流体通过风化层排出，然后作为基流流入流。这项工作的结果将测试一系列假设，这些假设将理论与来自化学风化的溶质中同位素比率的观测联系起来。该奖项反映了NSF的法定使命，并被认为值得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来支持。