Collaborative Research: Chemical Hydrogeologic Investigations of Tungsten: Field, Laboratory, and Modeling Studies of an Emerging Environmental Contaminant

例如，内华达州法伦的儿童白血病聚集症被初步认为与靠近含钨(W)的矿藏和矿石加工作业有关。由于法伦居民的身体系统中有很高的W负荷量，因此有人认为W可能是儿童白血病高发病率的原因。自那以后的研究表明，钨可能有毒，并可能致癌。了解环境中的钨的必要性也很重要，因为它越来越多地被用作弹药和渔具中铅的替代品。在这里，W的使用最初被认为是一种无毒的、低环境流动性的惰性金属，因此它是一种限制有毒铅添加到环境中的方式。然而，W在氧化后很容易在环境中被活化，实际上人们对其在环境中的生物地球化学，特别是它在真实地下水流动系统中的迁移和运输知之甚少。本项目将研究W在环境中的反应和传输的生物地球化学。具体地说，该项目将评估W浓度如何随着地下水、含水层矿物、有机物和原位微生物群落之间的生物地球化学反应而沿地下水流动路径演变，改变地下水溶液的组成和氧化还原条件。为了进行这项研究，该项目将：1)测量特征良好的含水层中沿流动路径的W浓度以及氧化还原敏感参数[例如，Fe物种，S(-II)]和其他地球化学成分，以确定溶液组成和氧化还原条件的变化如何影响含水层中的W；2)检查含水层沉积物中固相W的形态(例如，XANES、EXAFS、顺序提取)；3)测量硫代钨酸盐络合物在硫酸盐水溶液中的稳定常数，以开发溶液络合模型，从而能够预测好氧和厌氧地下水中的W形态；4)建立了一个概念性的生物地球化学模型，该模型结合了硫代钨酸盐络合物的稳定常数和目前可用的钨酸根氧阴离子的热力学数据，以探索W沿地下水流动路径的生物地球化学行为。该项目的重点是原始含水层，这是重要的饮用水水源，以调查含水层中钨的自然地球化学循环。由此得到的“基线”数据和概念模型将为其他研究人员研究人为来源的W在环境中的影响提供重要资源。

Childhood leukemia clusters in e.g. Fallon, NV have been tentatively linked to the proximity to tungsten (W)-bearing ore deposits and ore-processing operations. Because residents of Fallon were shown to have high body-burdens of W in their systems, it has been suggested that W may be responsible for the high incidence of childhood leukemia. Studies have since shown that W can be toxic and may be carcinogenic. The need to understand W in the environment is also important due to its increasing use as a replacement for lead in ammunition and in fishing weights. Here, the use of W was originally thought to be a non-toxic, inert metal of low environmental mobility, it was thus a manner in which to limit the addition of toxic Pb to the environment. However, W is readily mobilized in the environment following oxidation and very little is actually known about its biogeochemistry in the environment, and in particular, its mobility and transport in real groundwater flow systems. This project will investigate the biogeochemistry of W reaction and transport in the environment. Specifically, the project will evaluate how W concentrations evolve along groundwater flow paths as biogeochemical reactions between groundwaters, aquifer minerals, organic matter, and in situ microbial communities, modify the groundwater solution composition and redox conditions. To conduct the study, the project will: 1) measure W concentrations along flow paths in well characterized aquifers along with redox sensitive parameters [e.g., Fe species, S(-II)], and other geochemical constituents to determine how changing solution composition and redox conditions affect W in aquifers; 2) examine solid-phase W speciation in aquifer sediments (e.g., XANES, EXAFS, sequential extractions); 3) measure stability constants for thiotungstate complexes in sulfidic aqueous solutions to develop a solution complexation model that will allow prediction of W speciation in aerobic and anaerobic groundwaters; and 4) assemble a conceptual, biogeochemical model that incorporates the stability constants for thiotungstate complexes along with the currently available thermodynamic data for the tungstate oxyanion to probe the biogeochemical behavior of W along groundwater flow paths. The project focus on pristine aquifers that are important drinking water sources to investigate the natural geochemical cycling of W in aquifers. The resulting 'baseline' data and conceptual model will provide an important resource for other investigators studying the effects of anthropogenic sourced W in the environment.