CAREER: Balancing the global alkalinity cycle by improving models of river chemistry

职业：通过改进河流化学模型平衡全球碱度循环

• 批准号: 2338139
• 负责人: Mark Torres
• 金额: $ 61.29万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2025
• 资助国家: 美国
• 起止时间: 2025-01-01 至 2029-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2338139&HistoricalAwards=false
• 关键词: CAREER; Balancing; global; alkalinity; cycle

The water flowing in a river today is largely composed of rainwater that fell in the past and traveled underground before arriving at the river channel. The amount of time this transit takes is also the amount of time available for chemical reaction to occur. At the same time, the exact path that rain takes through watersheds - whether through shallow soils or deep, fractured bedrock - influences which reactions occur and at what rates. Consequently, observations of river water chemistry can be described equally well by models that attribute all variation to changes in either flow paths or flow rates. This ambiguity is problematic as the predicted effects of climate change on water resources are different depending upon the exact processes governing flow and reaction. To provide new insights into the controls on river water chemistry, this project will develop new approaches for analyzing variations in chemistry over time to separate the effects of flow paths from flow rates. The project will engage undergraduate students through an engineering design course, internships, and public outreach on local water quality issues.This work will leverage the information content of time-series data to constrain the coupled timescales of subsurface water transit and solute acquisition. To avoid some of the assumptions embedded in past work, non-parametric approaches will be used to infer geochemical kinetics and solute generation mechanisms. After being validated against 2-D numerical and analog experiments, the analysis approach will be used to elucidate the role of Critical Zone structure in the climate-weathering feedback as well as account for the non-linear behavior of trace element and isotopic proxies to improve mixing models. The results of these applications will be used to inform a new global analysis of weathering processes and their implications for planetary habitability with a timescale-agnostic framework for comparing terrestrial and marine systems. To lower barriers to collecting time-series data, undergraduate engineering design teams will develop a design-for-purpose autosampler. To help engage more undergraduate students in geoscience research, the project will develop a new, outreach-based course on local water quality issues.This project is co-funded by the Hydrologic Sciences and Geobiology & 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.

今天河流中流动的水主要由过去落下的雨水组成，在到达河道之前经过地下。此传输所需的时间也是发生化学反应的时间。与此同时，雨水穿过流域的确切路径——无论是穿过浅层土壤还是深层、破碎的基岩——都会影响发生的反应以及发生的速度。因此，河水化学的观察结果可以通过模型同样很好地描述，该模型将所有变化归因于流路或流速的变化。这种模糊性是有问题的，因为气候变化对水资源的预测影响是不同的，具体取决于控制流量和反应的确切过程。为了提供对河水化学控制的新见解，该项目将开发新方法来分析化学随时间的变化，以将流路的影响与流速分开。该项目将通过工程设计课程、实习和对当地水质问题的公众宣传来吸引本科生。这项工作将利用时间序列数据的信息内容来限制地下水传输和溶质采集的耦合时间尺度。为了避免过去工作中嵌入的一些假设，将使用非参数方法来推断地球化学动力学和溶质生成机制。经过二维数值和模拟实验验证后，该分析方法将用于阐明关键带结构在气候风化反馈中的作用，并解释微量元素和同位素代理的非线性行为，以改进混合模型。这些应用的结果将用于为风化过程及其对行星宜居性的影响进行新的全球分析，并采用与时间尺度无关的框架来比较陆地和海洋系统。为了降低收集时间序列数据的障碍，本科生工程设计团队将开发一种专用自动进样器。为了帮助更多本科生参与地球科学研究，该项目将开发一门关于当地水质问题的新的外展课程。该项目由水文科学和地球生物学与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。