CAREER: A Hydrologic Thermostat for the Global Carbon Cycle?

职业：全球碳循环的水文恒温器？

• 批准号: 1254156
• 负责人: Katharine Maher
• 金额: $ 45万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1254156&HistoricalAwards=false
• 关键词: CAREER; Hydrologic; Thermostat; Global; Carbon

The chemical weathering of minerals moderates the concentration of carbon dioxide in the atmosphere, the supply of key nutrients to terrestrial and aquatic ecosystems and the release of naturally occurring contaminants. As such, chemical weathering is a critical component of the Earth system. The movement of water through soils and hillslopes is an important control on overall chemical weathering rates, and the resulting connection between the movement of water and chemical reactions in the subsurface is thus critical for understanding not only Earth's history, but also how Earth's systems will respond to future climatic and anthropogenic changes. However, current models cannot predict the observed export of dissolved solutes from landscapes. To address this problem, this project will use a combination of field studies and reactive transport modeling approaches to determine (1) how the competition between the rates of chemical reactions and solute transport dictates concentration-discharge relationships in rivers and the resulting chemical fluxes, (2) the consequences of weathering reactions and fluid mixing on the stable and radiogenic isotopic composition of waters, and (3) the operation of a 'hydrologic thermostat' that governs global scale chemical weathering rates, and by extension atmospheric carbon dioxide levels, over geologic timescales. Evaluation of the latter is an overarching goal of this project that has the potential to provide new information about the mechanism underlying one of the most profound features of Earth's history: its long-term temperature stability. Students from diverse backgrounds and across different levels will benefit from the exposure to field measurement, data synthesis and numerical modeling during the course of the project. The reactive transport approach is powerful tool for understanding the chemical evolution of Earth's environments. Nevertheless, there are very few opportunities for professional training in this area at or beyond the graduate school level, although reactive transport approaches are widely used in both industry and research. A major educational goal of this project is to build a solid conceptual understanding of reactive transport approaches and models by offering a yearly short-course on reactive transport at Stanford University for graduate students, postdoctoral fellows and faculty from a broad spectrum of U.S. institutions. The course will serve as an introduction to key reactive transport concepts and their application to biogeochemical systems, and will thus provide an entry point into the field and access to a growing community of people that use and develop these models. Each year the course will include several instructors and provide an opportunity for participants to discuss their research and receive feedback and recommendations. The research proposed here will also be featured as examples, and the graduate students from my research group will play key roles in continuing to develop and improve the course, gaining experience as instructors that will carry over into their future careers.

矿物的化学风化作用缓和了大气中二氧化碳的浓度、陆地和水生生态系统关键营养物质的供应以及自然产生的污染物的释放。因此，化学风化是地球系统的重要组成部分。水通过土壤和山坡的运动是对整体化学风化速率的重要控制，因此，水的运动和地下化学反应之间的联系不仅对了解地球的历史，而且对了解地球系统如何应对未来的气候和人为变化至关重要。然而，目前的模式无法预测已观测到的溶质从景观中排出的情况。为了解决这一问题，本项目将结合实地研究和反应输运建模方法，以确定(1)化学反应速率和溶质输运速率之间的竞争如何决定河流中的浓度-排放关系以及由此产生的化学通量；(2)风化反应和流体混合对水的稳定和放射性同位素组成的影响；(3)“水文恒温器”的运作，它控制着全球尺度的化学风化速率，进而控制着地质时间尺度上大气中的二氧化碳水平。对后者的评估是这个项目的首要目标，它有可能提供关于地球历史上最深刻特征之一的机制的新信息：它的长期温度稳定性。来自不同背景和不同水平的学生将受益于项目过程中的现场测量，数据合成和数值建模。反应输运方法是理解地球环境化学演化的有力工具。然而，在研究生院或研究生院以外，在这一领域进行专业培训的机会很少，尽管反应输送方法在工业和研究中广泛使用。该项目的一个主要教育目标是通过在斯坦福大学为来自美国各大机构的研究生、博士后和教职员工提供每年一次的短期反应输运课程，建立对反应输运方法和模型的坚实概念性理解。本课程将介绍关键的反应输运概念及其在生物地球化学系统中的应用，从而为进入该领域提供一个切入点，并为使用和开发这些模型的越来越多的人提供机会。每年的课程将包括几位讲师，并为参与者提供讨论他们的研究并获得反馈和建议的机会。这里提出的研究也将作为例子，我的研究小组的研究生将在继续发展和改进课程中发挥关键作用，获得作为讲师的经验，这些经验将延续到他们未来的职业生涯中。