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.

这项建议的目的是研究在雨水渗透迅速的地方，即在地下水流动和天气模式方面，使用稳定的惰性气体作为示踪剂，在断裂的岩石系统中。水中的稀有气体浓度与温度有关，几十年来，稀有气体温度计一直用于沉积系统的古气候重建。最近在加拉帕戈斯群岛进行的研究表明，裂隙地下水系统中的补给水反映了渗透精确时间的地表温度，而不是通常认为的年均气温值。如果这一点得到证实，断裂岩石地区的惰性气体将记录季节性，因此，应提供有关补给时间和地点的信息。许多加拉帕戈斯样本中的稀有气体也表明，水有时与表面的大气不平衡。最近在密歇根州进行的一项雨水试点研究不仅表明，雨水在陆地表面确实与大气不平衡，而且雨水中的惰性气体成分与天气模式之间存在直接联系。雨水和加拉帕戈斯的泉水都表明，雾可能会改变空气饱和水的惰性气体成分。拟议工作的主要目标将主要在毛伊岛东部进行，那里的降水和雾非常多，泉水和地下水威尔斯井丰富，主要目的是测试这些假设，并评估惰性气体是否可用于追踪快速雨水渗透系统中的地下水流和天气模式。 这项工作的更广泛的意义和重要性将在多个层面上感受到，既有知识性，也有社会性。在知识层面上，这项研究将导致深入了解知之甚少和受限制的地表和近地表过程，这些过程能够影响大气惰性气体浓度，从而影响惰性气体温度计在世界许多地区的使用。在社会层面上，这项工作是相关的，因为它有助于更好的水资源管理计划在断裂，水资源紧张的地区，无论是在美国和世界各地。毛伊岛本身面临着不断增长的人口，预计到2030年，水需求将增加40%，再加上气候变化导致的降雨量减少。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，并通过为本科生参与PI创造新的机会，为吸引越来越多的本科非理科专业学生进入科学职业做出贡献。research.