Strontium Attenuation in Basaltic Aquifers: Experimental Determination of Ca2+-Na+-Sr2+-K+ Exchange Between Heulandite and Aqueous Solutions

玄武岩含水层中的锶衰减：片沸石与水溶液之间 Ca2-Na-Sr2-K 交换的实验测定

• 批准号: 0001113
• 负责人: Dennis Bird
• 金额: $ 28.24万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0001113&HistoricalAwards=false
• 关键词: Strontium; Attenuation; Basaltic; Aquifers; Experimental

BirdEAR-0001113The proposed study is an experimental, theoretical, and geologic investigation of zeolite-solution interaction that aims to quantify ion exchange reactions between aqueous solutions and heulandite in geologic systems. Research is based on experimental evaluation of Ca2+, Na+, Sr2+, and K+ exchange reactions in natural heulandite, a common rock-forming zeolite, known to concentrate Sr2+ in its crystal structure via ion exchange. Our goal is to provide thermodynamic data required to model reactive mass transfer between heulandite and ground-waters in basaltic aquifers, with reference to attenuation of radioactive 90Sr derived from nuclear waste respositories. This study includes binary cation exchange experiments on heulandite to determine the thermodynamic properties of the exchange reactions and crystal-chemical investigation on the effects of ion exchange on the crystal structure of heulandite employing X-ray diffraction and nuclear magnetic resonance (NMR) techniques. Finally, the credibility of the laboratory experiments and thermodynamic analyses will be tested using measured fluid and mineral compositional relations in Icelandic geothermal/metamorphic systems. The work will be conducted at Stanford University, Lawrence Livermore National Laboratory, and the Stanford Synchrotron Radiation Laboratory. The specific objectives of this study are to determine: 1) Gibbs energies and enthalpies of ion exchange reactions, 2) quantitative description of cation sites and site occupancy in heulandite as a function of composition and 3) activity-composition models for binary solid solutions in the interchannel sites in heulandite. The results will facilitate geochemical modeling of alkali- and alkaline earth-metal mass-transfer in groundwater aquifers where zeolites occur. Our findings will provide essential data to help develop heuristic and quantitative models of groundwater-zeolite interaction and the fate of 90Sr in basaltic aquifers contaminated with nuclear waste such as those below the U. S. Department of Energy sites at the Hanford Nuclear Reservation, WA, and the Idaho National Engineering Laboratories, ID, as well as in more silicic volcanic rocks at Yucca Mountain, NV, where heulandite occurs.

Birdoff-0001113拟议的研究是沸石-溶液相互作用的实验、理论和地质调查，旨在量化地质系统中水溶液和片沸石之间的离子交换反应。 研究是基于天然片沸石中Ca 2+、Na+、Sr 2+和K+交换反应的实验评估，片沸石是一种常见的造岩沸石，已知通过离子交换将Sr 2+浓缩在其晶体结构中。我们的目标是提供所需的热力学数据来模拟片沸石和玄武质含水层的地下水之间的反应性传质，参考来自核废料respositories的放射性90锶的衰减。 本研究包括二元阳离子交换实验片沸石，以确定交换反应的热力学性质和晶体化学研究的影响，离子交换片沸石的晶体结构，采用X-射线衍射和核磁共振（NMR）技术。最后，实验室实验和热力学分析的可信度将测试在冰岛地热/变质系统中使用测得的流体和矿物成分的关系。 这项工作将在斯坦福大学、劳伦斯利弗莫尔国家实验室和斯坦福大学同步辐射实验室进行。本研究的具体目标是确定：1）吉布斯自由能和离子交换反应，2）定量描述的阳离子位点和网站占有率在片沸石作为一个功能的组成和3）活性组成模型的二元固溶体中的通道间网站片沸石。研究结果将有助于沸石发生的地下水含水层中碱金属和碱土金属质量转移的地球化学建模。我们的研究结果将提供必要的数据，以帮助开发启发式和定量模型的地下水沸石相互作用和命运的90锶在玄武岩含水层污染的核废料，如以下的美国。S.在华盛顿州汉福德核保护区的能源部和ID的爱达荷州国家工程实验室，以及在内华达州尤卡山的更多火山岩中，片沸石出现。