Development of Noble Gases as Tracers of Groundwater Circulation in Fractured and Karstic Systems

开发稀有气体作为裂缝和岩溶系统地下水循环示踪剂

• 批准号: 1344357
• 负责人: M. Clara Castro
• 金额: $ 49.95万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-02-01 至 2018-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1344357&HistoricalAwards=false
• 关键词: Development; Noble; Gases; Tracers; Groundwater

This proposal is intended to investigate the use of stable noble gases as both tracers of groundwater flow and weather patterns in places where rainwater infiltration is rapid, i.e., in fractured rock systems. Noble gas concentrations in water are temperature dependent and the noble gas thermometer has been used for decades in paleoclimate reconstructions in sedimentary systems. Recent work in the Galapagos Islands suggests that recharge water in fractured groundwater systems reflect the temperature of the ground surface at the precise time of infiltration rather than the mean annual air temperature value, as is commonly assumed. If this is confirmed, noble gases in fractured rock areas will be recording seasonality, and thus, should provide information about timing and location of recharge. Noble gases in many Galapagos samples also suggest that water sometimes is not in equilibrium with the atmosphere at the surface. A recent pilot study of rainwater in Michigan not only suggests that rainwater is indeed not in equilibrium with the atmosphere at land surface but that there is a direct link between the noble gas composition in rain and weather patterns. Both rain and Galapagos spring water suggest that fog might modify the noble gas composition of air saturated water. The main goal of the proposed work, which will be carried out mostly in East Maui where the presence of precipitation and fog is prominent, and where there is an abundance of springs and groundwater wells, is to test these hypotheses and to assess whether or not noble gases can be used to trace both groundwater flow and weather patterns in rapid rainwater infiltration systems. The broader significance and importance of this work will be felt at multiple levels, with both an intellectual and societal nature. On an intellectual level, this study will lead to an in-depth understanding of poorly understood and constrained surface and near-surface processes capable of impacting atmospheric noble gas concentrations and thus, the use of the noble gas thermometer in many regions around the world. On a societal level, this work is relevant because it contributes to better water resource management plans in fractured, water stressed areas, both in the US and throughout the world. Maui itself faces a growing population and a forecasted increase in water demand of 40% until 2030, combined with decreasing rainfall due to climate change. This work will also foster collaborations between the University of Michigan, US Geological Survey, and the University of Hawaii. This project will support a PhD student and contribute to drawing increasing numbers of undergraduate non-science majors into scientific careers by creating new opportunities for undergraduate students to participate in the PIs? research.

该提案旨在调查稳定的贵重气体的使用，因为地下水流量的示踪剂和天气模式在雨水渗透迅速的地方，即在破裂的岩石系统中。水中的贵重气体浓度是温度依赖性的，并且在沉积系统中古气候重建中使用了数十年的贵重气体温度计。加拉帕戈斯群岛的最新工作表明，断裂的地下水系统中的补给水反映了在精确渗透时间而不是平均年度空气温度值的情况下，反映了地面的温度，如通常所假定的。如果确认这一点，则碎石区域中的贵重气体将记录季节性，因此应提供有关充电时间和位置的信息。许多加拉帕戈斯样品中的贵重气体还表明，水有时与表面大气的平衡不处于平衡状态。密歇根州雨水的最新试点研究不仅表明，雨水确实与陆地表面的大气没有平衡，而且在雨中的贵重气体成分与天气模式之间存在直接联系。雨水和加拉帕戈斯春水都表明，雾可能会改变空气饱和水的贵重气体成分。拟议工作的主要目标（主要是在东毛伊岛）进行的，那里的降水量和雾的存在是突出的，并且有大量的弹簧和地下水井是为了测试这些假设，并评估是否可以使用降低的气体来追踪雨水流入快速的地下水流动和天气模式。 这项工作的更广泛的意义和重要性将在智力和社会性质上都在多个层面上感受到。在智力上，这项研究将导致对能够影响大气贵族气体浓度的表面和近地表过程的深入了解，因此，在世界许多地区使用贵族气体温度计。在社会层面上，这项工作很重要，因为它在美国和全世界都有助于更好的水资源管理计划。毛伊岛本身面临的人口不断增长，预计水需求增加了40％，直到2030年，由于气候变化导致降雨量的减少。这项工作还将促进密歇根大学，美国地质调查局和夏威夷大学之间的合作。该项目将支持一名博士生，并通过为本科生参加PIS的新机会来促进越来越多的本科非科学专业的专业。研究。