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EAR-PF: Source or Sink? Hyporheic zone controls on the biogeochemical processing of arsenic in rivers impacted by acid mine drainage

EAR-PF：源还是汇？

基本信息

批准号：
1806718
负责人：
Nell Hoagland
金额：
$ 17.4万
依托单位：
Hoagland Nell E
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-01-01 至 2020-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1806718&HistoricalAwards=false
关键词：
EAR PF Source Sink Hyporheic

项目摘要

The process and conditions by which arsenic (As) goes from being in sediment loads, in solids, and into the drinking water may effect public safety and environmental health. Dr. Nell Hoagland has been awarded a postdoctoral fellowship to work at the Colorado School of Mines to determine the conditions driving the sequestration or release of arsenic (As) from the hyporheic zone in rivers impacted by acid mine drainage. Using a combination of microbial and hydrological methods, the researcher will investigate the spatial and temporal scaling of the hyporheic zone, where groundwater-surface water interactions modulate the timing, magnitude, and speciation of solutes. This work will build upon previous U.S. Geological Survey (USGS) investigations of the hyporheic zone in the Animas River of Colorado, where an accidental breach of mine pond wastewaters in August 2015 led to the release of 11 million liters of tailings directly into the river. By constraining the location and timing of total As and As(III) fluxes to the stream channel, this study will provide the geochemical and hydrological context needed to develop engineering solutions for river recovery in mine-impacted catchments. New insights related to the timing of As release to the Animas River will be shared in a publically accessible technical report with public health officials and municipal water authorities in the affected region. This project will engage undergraduate and graduate students at Colorado School of Mines and local community colleges by offering a summer short-course, where students will learn about the field of environmental hydrology and the impacts of acid mine drainage. The biogeochemical processing of metalloids such as arsenic is unpredictable in redox transition zones. Redox conditions in the hyporheic zone will change on seasonal and storm-event scales, impacting net As release or storage. The working hypotheses for this study include: (a) the export of total As and the ratio of As(III)/As(V) from the hyporheic zone in an acid mine drainage stream increases over the course of a storm event in response to increasingly reduced sediment conditions, and (b) the hyporheic zone acts as a source of As to the stream channel during the summer (e.g. wet, high discharge) and a sink of As in the winter. The proposed work will evaluate the hyporheic zone at high temporal and spatial resolution in order to provide new information on microbial and mineralogical mechanisms controlling As speciation across redox gradients. Deliverables will include a conceptual model that relates climatic controls on hyporheic zone area and exchange rates to the mobilization of contaminants from hyporheic sediments at the reach-scale. The conceptual framework in combination with reactive-transport modeling will guide interpretations of contaminant transport at the watershed-scale.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

砷（As）从沉积物负荷、固体中进入饮用水的过程和条件可能影响公共安全和环境健康。内尔·霍格兰博士已被授予博士后研究金，在科罗拉多矿业学院工作，以确定驱动砷（As）从受酸性矿井排水影响的河流的潜流区中封存或释放的条件。使用微生物和水文方法的组合，研究人员将调查的潜流区，地下水-地表水的相互作用调节的时间，幅度和溶质的物种的空间和时间尺度。这项工作将建立在美国地质调查局（USGS）之前对科罗拉多阿尼马斯河（Animas River）潜流区的调查基础上，2015年8月，该矿池废水意外泄漏，导致1100万升尾矿直接排入河流。通过限制的位置和时间的总As和As（III）的流通道的通量，本研究将提供所需的地球化学和水文背景下开发工程解决方案，在矿山影响的流域河流恢复。有关砷释放到阿尼马斯河的时间的新见解将在一份可供查阅的技术报告中与受影响地区的公共卫生官员和市政水务局分享。该项目将通过提供夏季短期课程吸引科罗拉多矿业学院和当地社区学院的本科生和研究生，学生将了解环境水文学领域和酸性矿井排水的影响。在氧化还原过渡带中，砷等类金属的地球化学过程是不可预测的。氧化还原条件在潜流区将改变季节性和风暴事件的规模，影响净作为释放或存储。本研究的工作假设包括：（a）酸性矿山排水流中来自潜流区的总As输出和As（III）/As（V）的比率在风暴事件过程中响应于沉积物条件的日益减少而增加，以及（B）在夏季，潜流区充当As到河道的源（例如潮湿，高排放）和冬季的As汇。拟议中的工作将在高的时间和空间分辨率，以提供新的信息，微生物和矿物学机制控制作为物种跨越氧化还原梯度的潜流带。可评估项目将包括一个概念模型，该模型将对潜流区面积和交换率的气候控制与河段尺度上潜流沉积物中污染物的移动联系起来。概念框架结合反应传输模型将指导在流域尺度上对污染物传输的解释。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。