Gradient Exchange Mass Spectrometry (GEMS) for Quantifying a Suite of Dissolved Gas Fluxes

沿海生态系统是重要元素循环的高度活跃区域，但由于靠近人类种群，往往受到人为压力的显著影响。人类活动的压力，直接通过污染或间接通过温度和二氧化碳水平，在全世界造成了严重的水健康质量问题，包括营养物污染、低氧水平和海洋酸化。在这里，测量垂直水运和海水中溶解气体垂直分布的最新进展被结合在一个新的技术平台上，以测量这些重要的营养和元素循环的速率。这种梯度交换质谱（GEMS）系统利用水混合和输送的梯度或垂直分布的测量，以及溶解气体的质谱测量来测量自然条件下重要元素的交换。在两个沿海地点部署GEMS系统，一个受人类活动严重影响，另一个相对原始，将能够实时评估和比较自然和受污染的沿海生态系统。通过该提案开发的GEMS技术代表了一种变革性工具，用于精炼广泛的元素交换套件，在长期部署和应用于各种重要元素循环（例如氧、碳、硫和氮）方面具有无与伦比的潜力。这种对多个同步过程（如初级生产、呼吸、养分循环、硫循环、甲烷生成等）的综合视角有望对这些过程的动力学、驱动因素和相互作用产生新颖而重要的见解，这是任何其他技术或技术所无法比拟的。该项目的主要目标是培养青年科学家，其中包括两名早期职业科学家和本科生。本科生将通过包括伍兹霍尔海洋学研究所暑期学生奖学金和以多样性为重点的伍兹霍尔教育合作项目在内的项目获得技术发展和实地经验。当地的监测和外联组织，Buzzards Bay Coalition (BBC)，已经确定元素和营养循环是他们了解海湾健康和水质的主要知识差距。本研究将考察自然海草环境和退化系统的情况，并提供具体的指标、数据和结果，这些指标、数据和结果可用于BBC的教育和推广计划，以及他们与沿海管理者和地方政府的频繁互动和宣传。最后，集成在GEMS系统中的数据通信提供了一个独特的机会，可以通过网络界面实时分享我们的结果。这个网络界面将提供不断更新的GEMS数据的图形图，并在英国广播公司和伍兹霍尔海洋研究所的网站上托管，以吸引更广泛的受众。沉积物-水界面是一个具有较大物理、生物和化学梯度的区域，由沉积物和上覆水之间的关键元素的动态生物地球化学循环造成。测量底栖边界层中的这些物理和化学梯度可以确定溶质的交换速率；速率是确定全球生物地球化学循环的基础。本研究提出了一种创新技术，通过开发梯度交换质谱（GEMS）技术来量化一系列生物地球化学相关挥发物的汇率。通过有针对性地改进原型系统中使用的组件和第二代系统的组装，该项目将最终形成一个强大的、高耐久性的生物地球化学传感系统，允许对底栖生物通量动力学进行前所未有的检查。该系统结合了两种尖端技术，湍流边界层梯度交换和原位质谱的多重示踪能力，从而可以在不受干扰的情况下观察自然系统，同时量化氧、二氧化碳、甲烷、硫化氢和二氮的交换速率。拟议的GEMS的所有组成部分都已独立验证并在海洋系统中应用，尽管从未组合使用。pi在湍流边界层交换和原位质谱方面的集体经验使这种合作努力在海底-水界面交换过程的量化方面具有独特的变革性。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。

Coastal ecosystems are highly active regions of cycling of vital elements, but due to their proximity to human populations, are often significantly impacted by human-induced stresses. The pressure of human activities, directly through pollution or indirectly through temperature and carbon dioxide levels, has created severe water health quality issues worldwide, including nutrient pollution, low oxygen levels and ocean acidification. Here, recent advances in measuring vertical water transport and the vertical distribution of gases dissolved in seawater are combined in a new technological platform to measure the rates of these vital nutrient and element cycles. This Gradient Exchange Mass Spectrometry (GEMS) system uses measurements of the gradient, or vertical distribution, of water mixing and transport, with mass spectrometry measurements of dissolved gases to measure the exchange of vital elements under natural conditions. Deployment of the GEMS system in two coastal locations, one heavily impacted by human activity, and one relatively pristine, will allow real-time assessments of, and comparisons between, natural and polluted coastal ecosystems. The GEMS technology developed through this proposal represents a transformative tool for refining a wide suite of element exchanges that has an unparalleled potential in long-term deployment and application to a variety of important elemental cycles (for example Oxygen, Carbon, Sulfur and Nitrogen). This integrated perspective on multiple, simultaneous processes (e.g. primary production, respiration, nutrient cycling, sulfur cycling, methanogenesis, etc.) is expected to yield novel and significant insights on the dynamics, drivers and interactions of these processes that are unparalleled by any other technique or technology. A major goal of this project is the training of young scientists including two early career scientists and undergraduate students. Undergraduate students will gain technological development and field experience through programs including the Woods Hole Oceanographic Institution Summer Student Fellowship and the diversity-focused Woods Hole Partnership in Education Program. The local monitoring and outreach group, the Buzzards Bay Coalition (BBC), have identified element and nutrient cycles as a major knowledge gap in their understanding of the bay’s health and water quality. This research will examine natural seagrass environments with that of a degraded system and provide specific metrics, data, and results that can be used by the BBC in their education and outreach programs as well as their frequent interactions and advocacy with coastal managers and local governments. Finally, the data communication integrated in the GEMS system allows for a unique opportunity to share our results in real-time via a web interface. This web interface will provide graphical plots of the GEMS data, that continuously update, and be hosted on both the BBC and Woods Hole Oceanographic Institution websites to reach a wider audience.The sediment-water interface is a region of large physical, biological and chemical gradients, resulting from the dynamic biogeochemical cycling of critical elements between the sediment and the overlying water. Measuring these physical and chemical gradients in the benthic boundary layer allows for the determination of exchange rates of solutes; rates which are fundamental for determining global biogeochemical cycling. This research proposes an innovative technology for the quantification of exchange rates of a suite of biogeochemically relevant volatiles by developing the Gradient Exchange Mass Spectrometry (GEMS) technique. Through targeted improvement of components used in a prototype system and assembly of a second generation system, this project will culminate in a robust, high-endurance, biogeochemical sensing system allowing unprecedented examination of benthic flux dynamics. This system combines two cutting-edge techniques, turbulent boundary layer gradient exchange and the multiple-tracer capabilities of in situ mass spectrometry, thereby allowing undisturbed observation of natural systems while simultaneously quantifying exchange rates of oxygen, carbon dioxide, methane, hydrogen sulfide, and dinitrogen. All components of the proposed GEMS have been independently validated and applied in marine systems, though never in combination. The PIs’ collective experience with turbulent boundary layer exchange and in situ mass spectrometry uniquely poises this collaborative effort to be transformative in the quantification of exchange processes across the benthic-water interface.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.