Collaborative Research: Investigating Hyporheic Zone Reaction Enhancement by Bioclogging Across Scales

合作研究：研究跨尺度生物堵塞增强潜流区反应

• 批准号: 2345366
• 负责人: Veronica Morales
• 金额: $ 39.61万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-08-15 至 2027-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2345366&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Hyporheic; Zone

Riverbeds can emit a potent greenhouse gas, nitrous oxide, to the atmosphere, which traps outgoing solar radiation and leads to climate warming. The amount of nitrous oxide emitted from rivers is difficult to estimate due to a lack of knowledge of the conditions that favor its production. Nitrous oxide is produced in abundant but small zones where oxygen is not available. However, the size of these “microzones” makes them extremely difficult to locate and measure. This project will investigate the formation of low oxygen microzones in controlled conditions that mimic river sediments. Experiments and numerical simulations will be used to determine how bacteria growing in the sediments regulate the formation of these microzones. Knowledge of how bacteria control the size, location, and duration of low oxygen microzones will provide key information needed to estimate river nitrous oxide emissions with greater certainty. This research will not only reveal the processes responsible for nitrous oxide emissions from riverbeds and inform the design of strategies that can reduce greenhouse gas emissions, but it will also improve understanding of how low oxygen microzones regulate contaminant transformation and nutrient cycling in groundwater. The research team will train future environmental engineers by mentoring trainees from diverse backgrounds at the postdoctoral, graduate, and undergraduate levels. Further, the team will lead activities to enhance public understanding of how shallow groundwater influences water quality in rivers, including a Groundwater Basics STEM summer program and field demonstrations for K-12 students and the public at a river restoration site.The goal of this project is to determine how nitrous oxide production is linked to the dynamics of anoxic microzone formation in river sediments. The project team will perform sediment column experiments to quantify nitrous oxide production at the macroscale, perform microfluidic experiments to characterize the spatial and temporal occurrence of anoxic microzones at the pore scale, and use process-based numerical simulations to link the two scales. Through these efforts, the researchers will test the novel hypothesis that coupling between fluid flow and microbial biofilm growth determines the spatio-temporal dynamics of anoxic microzones, as well as the delivery of reactants that fuel the production of nitrous oxide within microzones. Research outcomes will provide a fundamental understanding of how microscale processes and biological activity influence macroscale behavior in porous media, with implications for solute transport, contaminant fate, and greenhouse gas fluxes.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.

河床可以向大气排放一种强效温室气体一氧化二氮，它会捕获太阳辐射并导致气候变暖。由于缺乏对其有利条件的了解，河流排放的一氧化二氮的量很难估计。一氧化二氮是在没有氧气的丰富但狭小的区域中产生的，然而，这些“微区”的大小使得它们极难定位和测量，该项目将研究受控的低氧微区的形成。模拟河流沉积物的条件将用于确定沉积物中生长的细菌如何调节这些微区的形成。了解细菌如何控制低氧微区的大小、位置和持续时间将提供所需的关键信息。更准确地估计河流一氧化二氮排放量 这项研究不仅将揭示河床一氧化二氮排放的过程，并为减少温室气体排放的策略设计提供信息，而且还将增进对低氧微区如何调节的了解。该研究团队将通过指导来自不同背景的博士后、研究生和本科生来培训未来的环境工程师。此外，该团队还将领导活动，以增强公众对浅层地下水如何影响水质的了解。河流修复项目，包括地下水基础知识 STEM 夏季项目以及在河流修复现场为 K-12 学生和公众进行的现场演示。该项目的目标是确定一氧化二氮的产生与缺氧动态之间的关系。项目团队将进行沉积物柱实验以量化宏观尺度的一氧化二氮产生，进行微流体实验以表征孔隙尺度上缺氧微区的空间和时间发生，并使用基于过程的数值模拟将其联系起来。通过这些努力，研究人员将测试新的假设，即流体流动和微生物生物膜生长之间的耦合决定了缺氧微区的时空动态以及缺氧微区的传递。研究成果将提供对微尺度过程和生物活动如何影响多孔介质中宏观行为的基本理解，以及对溶质迁移、污染物命运和温室气体通量的影响。该奖项反映了 NSF 的贡献。法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。