EAR-PF: Quantifying methane reactivity and turnover in the subterranean estuary: combined in-situ and ex-situ isotope tracer approaches

EAR-PF：量化地下河口的甲烷反应性和周转：原位和异位同位素示踪方法相结合

• 批准号: 2204584
• 负责人: Stephanie Wilson
• 金额: $ 18万
• 依托单位: Wilson, Stephanie J
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2204584&HistoricalAwards=false
• 关键词: EAR; PF; Quantifying; methane; reactivity

At the interface of land and sea, subterranean estuaries (STEs) serve as subsurface transition zones. STEs can support a variety of biogeochemical reactions that influence concentrations and transport of nutrients and carbon. High concentrations of methane (CH4), an important greenhouse gas and major player in the global carbon cycle, has been observed in the coastal subsurface. However, the way that this CH4 pool is transformed and transported within STEs remains unconstrained. This study will provide a novel understanding of how CH4 is cycled in the subsurface, specifically its turnover time and the transformations controlling concentration and fate, just prior to release to surface waters. These research products represent fundamental constraints, which are critical to determining fluxes of CH4 from the subsurface and the role of STEs in the global carbon cycle. Dr. Stephanie Wilson will build upon previous work conducted by multiple research groups along the east coast, to further scientific understanding of CH4 cycling and exchanges between the subsurface and the overlying water or atmosphere. The results of this study will be directly applicable to ongoing research and modeling efforts, providing fundamental information about CH4 to inform calculations of fluxes and emissions from the subsurface, with implications beyond the fields of groundwater hydrology and geochemistry. Moreover, the project is designed to optimize the reach of its findings and develop human capital. Results will be disseminated at conferences, departmental seminars, and published in scientific journals. Dr. Wilson will incorporate undergraduate students in both field and lab research efforts with the goal of creating an inclusive environment that promotes personal growth and scientific learning. Research findings will be made available to the public via several avenues designed to engage K-12 students, educators, the local community, and the larger public via a variety of engagement activities.Subterranean estuaries (STEs) are important transition zones within the subsurface that host a variety of biogeochemical reactions. They are dynamic systems influenced by both watershed and tidal drivers. Within the STE, biogeochemical reactions control the speciation and concentration of subsurface nutrients and carbon, therefore, they determine the fate of these analytes when they are released to the overlying water and/or the atmosphere. There is a growing body of literature reporting high concentrations of methane (CH4) in the subsurface along coastal margins; however, the mechanisms of transformation and transport of this pool remain unknown. There is, therefore, a limited understanding of how this subsurface CH4 pool exchanges with the overlying water and/or atmosphere. The STE may act as a passive interface whereby CH4 generated within the aquifer moves through the STE conservatively, or CH4 inventories may be modified via consumption or production within the STE on timescales faster than net transport. The lack of context and defined constraints controlling the STE CH4 pool represents a knowledge gap essential to determining fluxes of CH4 from the subsurface and the role STEs play in the global carbon cycle. The project includes examination of the transformations and transport of CH4 in STEs using a three-pronged approach that combines in situ and ex situ stable isotope labeled tracer experiments with the characterization of subsurface geochemical gradients. The work addresses rates and mechanisms. Tracer experiments will be conducted in several STEs along the east coast of the US parsed into the two dominant coastal STE types, wetland and sandy, and spanning a spectrum of hydrologic forcings. Results from this study will provide a novel understanding of how CH4 is cycled in the subsurface, specifically its turnover time and the transformations controlling concentration and fate, just prior to release to surface waters. Specifically, this work will provide information regarding the CH4 pool rate of turnover, transformation, and transport. These products represent fundamental constraints, which are critical to determining fluxes of CH4 from the subsurface and the role of STEs in the global carbon cycle. This novel information will be directly applicable to ongoing research determining the role of transition zones in greenhouse gas dynamics and global climate change. Research products will provide fundamental information, which will reach beyond the fields of groundwater hydrology and geochemistry. Results will provide fundamental constraints on modeling atmospheric fluxes of CH4 meditated by the STE and the project is designed to optimize the reach of its findings and develop human capital.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.

在海陆交界面，地下河口是地下过渡带。ste可以支持各种影响营养物和碳的浓度和运输的生物地球化学反应。高浓度的甲烷（CH4）是一种重要的温室气体，也是全球碳循环的主要参与者，已在沿海地下观测到。然而，这种CH4池在STEs内转化和运输的方式仍然不受限制。本研究将对CH4如何在地下循环提供新的认识，特别是在释放到地表水之前，它的周转时间和控制浓度和命运的转化。这些研究成果代表了基本的约束条件，这些约束条件对于确定地下CH4的通量和STEs在全球碳循环中的作用至关重要。斯蒂芬妮·威尔逊博士将在东海岸多个研究小组先前开展的工作的基础上，进一步科学地了解甲烷的循环和地下与上覆水或大气之间的交换。这项研究的结果将直接适用于正在进行的研究和建模工作，提供有关CH4的基本信息，为地下通量和排放的计算提供信息，其影响超出了地下水水文和地球化学领域。此外，该项目旨在优化其调查结果的影响范围并发展人力资本。结果将在会议、部门研讨会上传播，并在科学期刊上发表。威尔逊博士将整合本科生的实地和实验室研究工作，目标是创造一个包容性的环境，促进个人成长和科学学习。研究结果将通过多种途径向公众公布，旨在通过各种参与活动吸引K-12学生、教育工作者、当地社区和更大的公众。地下河口（STEs）是地下重要的过渡带，承载着各种生物地球化学反应。它们是受流域和潮汐驱动因素共同影响的动态系统。在STE中，生物地球化学反应控制着地下营养物质和碳的形态和浓度，因此，它们决定了这些分析物释放到上面的水和/或大气中时的命运。越来越多的文献报道沿海岸边缘的地下存在高浓度的甲烷（CH4）；然而，这一池的转化和转运机制尚不清楚。因此，对地下CH4库如何与上覆水和/或大气交换的理解有限。STE可以作为一个被动界面，使含水层内产生的CH4保守地通过STE移动，或者通过STE内的消耗或生产在时间尺度上比净运输更快地修改CH4库存。缺乏控制东南沿海地区CH4库的背景和明确的约束，这对确定地下CH4通量和东南沿海地区在全球碳循环中发挥的作用至关重要。该项目包括使用三管齐下的方法，将原位和非原位稳定同位素标记示踪实验与地下地球化学梯度表征相结合，检查STEs中CH4的转化和运输。这项工作涉及比率和机制。示踪实验将在美国东海岸的几个STE中进行，将其解析为两种主要的沿海STE类型，湿地和沙质，并跨越水文强迫的频谱。本研究的结果将为CH4在地表下的循环提供一个新的认识，特别是在释放到地表水之前，它的周转时间和控制浓度和命运的转化。具体来说，这项工作将提供有关CH4池的周转、转化和运输速率的信息。这些产品代表了基本的限制条件，这对于确定地下CH4的通量和STEs在全球碳循环中的作用至关重要。这一新的信息将直接适用于正在进行的研究，以确定过渡带在温室气体动力学和全球气候变化中的作用。研究产品将提供基本信息，这些信息将超越地下水水文学和地球化学领域。研究结果将为STE模拟大气CH4通量提供基本约束条件，该项目旨在优化其研究结果的覆盖范围并开发人力资本。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。