Transport, Transformation, and Retention of Arsenic in a Headwater Stream: Hydrologic, Biological, and Geochemical Controls

源头河流中砷的迁移、转化和保留：水文、生物和地球化学控制

• 批准号: 0207784
• 负责人: Madeline Schreiber
• 金额: $ 22万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0207784&HistoricalAwards=false
• 关键词: Transport; Transformation; Retention; Arsenic; Headwater

0207784SchreiberIt is well-known that arsenic, a toxic and carcinogenic element, is readily transported in natural waters and that its forms, speciation, and concentrations are affected by biogeochemical reactions. In this proposal, we address the transport, transformation and retention of arsenic in a stream-aquifer system impacted by past mining activities. Given our current understanding of the structure of stream-aquifer system in close contact with the mine, we developed a number of questions regarding the role of hydrologic, geochemical and biological processes controlling the speciation and concentration of arsenic. The proposed research will center on addressing two central questions: (1) what factors control spatial and temporal variations in arsenic fluxes to the stream? (2) How do hyporheic processes influence retention of arsenic in the stream?To address these questions, we will utilize a combination of field, laboratory, and modeling techniques to evaluate the controls on arsenic mobility within the stream, with specific emphasis on characterizing the role of the hyporheic zone in acting as a source or a sink for arsenic. The proposed research elements include employing hydrologic and geochemical monitoring to characterize groundwater and surface water end-members as well as to describe biogeochemical conditions within the hyporheic zone. In addition, transient storage models will be used to evaluate the hydrologic characteristics of the hyporheic zone and, through incorporation of reactive uptake terms, to address the role of the hyporheic zone in retarding or promoting arsenic transport to the stream.Results of this proposed research will have implications for our general understanding of the biogeochemical cycling of redox-sensitive trace elements such as arsenic. The recent tightening of the arsenic drinking water standard from 50 to 10 ug/L will drive federal and state agencies to closely examine sources of both natural and human-introduced arsenic contamination. Improving the knowledge of the processes that control arsenic mobility will greatly aid these agencies in developing plans for protecting and treating drinking water supplies.

0207784Schreiber 众所周知，砷是一种有毒和致癌元素，很容易在天然水中迁移，其形态、形态和浓度受到生物地球化学反应的影响。 在本提案中，我们解决了受过去采矿活动影响的河流含水层系统中砷的运输、转化和保留问题。 鉴于我们目前对与矿山密切接触的河流-含水层系统结构的了解，我们提出了许多关于控制砷形态和浓度的水文、地球化学和生物过程的作用的问题。 拟议的研究将集中于解决两个核心问题：（1）哪些因素控制流中砷通量的空间和时间变化？ (2) 潜流过程如何影响砷在河流中的保留？为了解决这些问题，我们将结合现场、实验室和建模技术来评估对河流内砷迁移率的控制，特别强调表征潜流带作为砷源或汇的作用。 拟议的研究内容包括利用水文和地球化学监测来描述地下水和地表水终端成员的特征以及描述潜流区内的生物地球化学条件。 此外，瞬态储存模型将用于评估潜流带的水文特征，并通过结合反应性吸收项，来解决潜流带在延迟或促进砷向河流输送中的作用。这项研究的结果将对我们对氧化还原敏感的微量元素（例如砷）的生物地球化学循环的一般理解产生影响。 最近将砷饮用水标准从 50 微克/升收紧至 10 微克/升，这将促使联邦和州机构密切检查自然和人为砷污染的来源。 提高对控制砷迁移过程的了解将极大地帮助这些机构制定保护和处理饮用水供应的计划。