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.

河床可以将潜在的温室气体（一氧化二氮）发射到大气中，该气体会捕获外向的太阳辐射，并导致气候变暖。由于缺乏有利于其生产的条件的了解，因此很难估算从河流发出的一氧化二氮量。一氧化二氮是在没有氧气的丰富区域中产生的。但是，这些“微区”的大小使它们难以定位和测量。该项目将在模仿河流沉积物的受控条件下研究低氧微区的形成。实验和数值模拟将用于确定沉积物中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，以估算河流一氧化二氮排放率更高的确定性。这项研究不仅将揭示导致河床的一氧化二氮排放的过程，并告知可以减少温室气体排放的策略的设计，而且还将改善对低氧微区调节污染物转化和地下水中营养循环的了解。研究团队将通过在博士后，研究生和本科生的潜水员背景的心理列车中培训未来的环境工程师。此外，该团队将领导活动，以增强公众对浅水的影响如何影响河流中的水质，包括地下水基础茎务夏季计划和针对K-12学生和公众在河流修复地点的现场演示。该项目的目的是确定如何与河水中的氧化氧化微氮酮形成的动力学联系起来。项目团队将执行沉积物柱实验，以量化宏观上的一氧化二氮的产生，进行微流体实验，以表征孔隙尺度上缺氧微区的空间和临时发生，并使用基于过程的数值模拟将两个量表链接起来。通过这些努力，研究人员将检验一个新的假设，即流体流量和微生物生物膜生长之间的耦合决定了缺氧微分辨率的空间动力学，以及赋予反应物的递送，从而促进了微区内一氧化二氮的产生。研究成果将对微观过程和生物活动如何影响多孔媒体的宏观行为有根本性的理解，对固体运输，污染物命运和温室气体通量产生影响。该奖项反映了NSF的法定任务，并通过使用该基金会的知识分子优点和广泛的影响来评估NSF的法定任务。