Collaborative Research: Quantifying rare earth element transport in aquifers using field, laboratory, and numerical approaches

0126222约翰森地下水是美国饮用水的主要来源，占世界淡水供应的68%以上。因此，确保目前人口所需的地下水质量并保护其不受未来污染是一个重大关切。 地下水的消耗可以增加特定重金属的负载到我们的身体，地下水与掩埋的核废料的相互作用被认为是这些材料最有可能释放到环境的机制。了解含水层中重金属的地球化学特征对于建立精确的溶质运移模型至关重要，该模型可用于预测含水层中重金属在不同环境条件下随时间的去向和运移。我们试图量化稀土元素（REE）的浓度和行为沿着地下水流路径在真实的含水层，并开发一个耦合的地下水流和运输模型，这些重金属。稀土元素是感兴趣的，因为它们的潜在的地球化学示踪剂的水-岩石反应，因为它们的化学相似性超铀元素使他们有吸引力的天然类似物研究放射性污染物在含水层。我们的研究目标是：（1）阐明稀土元素沿沿着地下水流路径的地球化学行为，重点是它们的浓度、分馏模式和形态。(2)为稀土元素开发一个表面和溶液复合模型，该模型针对每个含水层，但也可广泛应用于其他系统。(3)组装并实现地下水系统中稀土元素的地下水流和反应迁移耦合模拟模型。 为了实现这些目标，我们将在三年内实施综合现场，实验室和数值模拟研究。我们将利用两个特征良好的含水层（即，卡里索沙，得克萨斯州;弗洛里丹含水层，佛罗里达）的外地组成部分的项目。 这两个含水层都是典型的饮用水含水层，代表共同的系统，尽管组成不同。 研究中产生的数据将对“校准”含水层中稀土元素的反应迁移模型至关重要，并将提高我们对反应溶质迁移的总体理解。

0126222Johannesson Groundwater is the principal source of drinking water in the United States, and represents over 68% of the world's fresh water supply. Therefore, assuring the quality of groundwater for current populations and protecting it from future contamination is of great concern. Groundwater consumption can increase the loading of specific heavy metals to our bodies, and interaction of groundwaters with buried nuclear wastes is considered the most likely release mechanism of these materials to the environment. Understanding the geochemistry of heavy metals in aquifers is critical to developing accurate solute transport models, which can be employed to predict the fate and transport of heavy metals in aquifers over time and under different environmental conditions. We seek to quantify rare earth elements (REE) concentrations and behavior along groundwater flow paths in real aquifers, and develop a coupled groundwater flow and transport model for these heavy metals. The REEs are of interest because of their potential as geochemical tracers of water-rock reactions, and because their chemical similarities to transuranics makes them attractive natural analogs for studying radioactive contaminants in aquifer. Our research objectives are: (1) To elucidate the geochemical behavior of REEs along groundwater flow paths in well characterized aquifers emphasizing their concentrations, fractionation patterns, and speciation.(2) To develop a combined surface and solution complexation model for the REEs that is specific to each aquifer, but can also be broadly applied to other systems. (3) To assemble and implement a coupled groundwater flow and reactive transport simulation model for REEs in groundwater systems. To accomplish these objectives, we will implement an integrated field, laboratory, and numerical modeling study over a period of three years. We will utilize two well characterized aquifers (i.e., Carrizo Sand, Texas; Floridan aquifer, Florida) for the field component of the project. Both are typical drinking water aquifers that represent common, albeit, compositionally different systems. The data generated in the study will be crucial for "calibrating" reactive transport models for REEs in aquifer, and will improve our general understanding of reactive solute transpor