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

沿海生态系统是生命元素循环的高度活跃区域，但由于它们靠近人类群体，往往受到人类诱导的压力的显著影响。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，在世界范围内造成了严重的水健康质量问题，包括营养物质污染、低氧水平和海洋酸化。在这里，在测量垂直水运移和海水中溶解气体的垂直分布方面的最新进展被结合在一个新的技术平台中，以测量这些重要的营养和元素循环的速率。这种梯度交换质谱学(GEMS)系统使用水混合和传输的梯度或垂直分布的测量，以及溶解气体的质谱测量，以测量自然条件下重要元素的交换。在两个沿海地区部署GEMS系统，一个受人类活动的严重影响，另一个相对原始，这将使人们能够对自然和受污染的沿海生态系统进行实时评估和比较。通过这一提议开发的GEMS技术是一种变革性的工具，用于提炼一系列元素交换，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。这是对多个同步过程(例如初级生产、呼吸、营养循环、硫循环、产甲烷等)的综合观点。预计将在这些过程的动力学、驱动因素和相互作用方面产生新的和重要的见解，这是任何其他技术或技术都无法比拟的。该项目的一个主要目标是培养青年科学家，包括两名早期职业科学家和本科生。本科生将通过伍兹霍尔海洋研究所暑期学生奖学金和注重多样性的伍兹霍尔教育伙伴计划等项目获得技术开发和现场经验。当地监测和推广小组--秃鹰湾联盟(BBC)已确定，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。这项研究将考察退化系统的自然海草环境，并提供具体的指标、数据和结果，供BBC在其教育和外展计划以及与海岸管理者和地方政府的频繁互动和宣传中使用。最后，GEMS系统中集成的数据通信为通过网络界面实时分享我们的成果提供了独特的机会。这个网络界面将提供宝石数据的图形绘图，这些数据不断更新，并托管在BBC和伍兹霍尔海洋研究所的网站上，以接触到更广泛的受众。沉积物-水界面是一个具有大的物理、生物和化学梯度的区域，是沉积物和上覆水之间关键元素动态生物地球化学循环的结果。通过测量海底边界层中的这些物理和化学梯度，可以确定溶质的交换率；交换率是确定全球生物地球化学循环的基础。这项研究提出了一种创新的技术，通过发展梯度交换质谱学(GEMS)技术来量化一组生物地球化学相关挥发物的交换率。通过有针对性地改进原型系统中使用的组件并组装第二代系统，该项目将最终形成一个强大、高耐久性的生物地球化学传感系统，从而能够对海底通量动态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仪的多重示踪能力，从而可以不受干扰地观察自然系统，同时量化氧气、二氧化碳、甲烷、硫化氢和氮气的交换率。拟议中的宝石的所有组件都经过了独立的验证，并在海洋系统中应用，尽管从未组合在一起。PIS在湍流边界层交换和现场质谱学方面的集体经验使这一合作努力在海底-水界面的交换过程量化方面具有独一无二的优势。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.