Collaborative Research: Inventories of Primary Productivity by In-situ Mass Spectrometry in the Upper Ocean

合作研究：通过原位质谱法对上层海洋初级生产力进行盘点

• 批准号: 1429940
• 负责人: Brice Loose
• 金额: $ 25.68万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1429940&HistoricalAwards=false
• 关键词: Collaborative; Research; Inventories; Primary; Productivity

Production of organic matter from carbon dioxide (specifically by photosynthetic organisms) and respiration of organic matter back to carbon dioxide (by a wide variety of organisms, including photosynthesizers) are very nearly in balance over much of the ocean -- but not quite. In some regions remote from land, more carbon is produced through photosynthesis than is respired back to carbon dioxide; in others, just the opposite is true. Figuring out which is exceedingly important because in regions where photosynthesis exceeds respiration, there is a net production of food for marine life as well as a net removal of carbon dioxide (a powerful greenhouse gas) from the atmosphere. Conversely, oceanic regions where respiration exceeds photosynthesis are zones of net food consumption and release of carbon dioxide to the atmosphere. In practice, the problem is that the differences, one way or the other, are so small that it is difficult to distinguish between the measurements themselves and noise (that is, scatter) in the data. Resolution of this problem requires new technology that can make the necessary measurements with very high precision in the ocean itself rather than in a bottle of sampled seawater. In this project, the investigators will attempt to do just that using a sophisticated instrument normally found only in an analytical laboratory -- a mass spectrometer, a device capable of making ultra-high-precision measurements of changes in the amount of dissolved oxygen, carbon dioxide, and other substances associated with photosynthesis and respiration in the marine water column. The investigators will support graduate students to participate as integral members of the research team. There will also be public educational outreach to secondary school students offering them the opportunity to engage with the project to gain first-hand experience seeing how the basic sciences can be used to solve oceanographic problems.In this project, a team of investigators will evaluate one facet of these methodological concerns using in-situ mass spectrometry to better constrain net community production (NCP). The UMIMS is a fast-response Underwater Membrane Inlet Mass Spectrometer that can be deployed in autonomous and remotely-operated vehicles. In this application, UMIMS will be deployed aboard a SeaSoar tow vehicle to make high resolution vertical sections of the excess dissolved oxygen (O2) over argon (Ar) budget, a promising measure of NCP in the surface ocean. Profiles with the UMIMS can provide the capacity to resolve processes throughout the mixed-layer and euphotic zone that affect the NCP budget. In the near term, the team will utilize the capabilities of the UMIMS to make accurate and simultaneous mixed layer profiles of O2 and Ar and compare measurements of NCP from the UMIMS with measurements from the conventional shipboard O2/Ar budget from underway seawater. These comparisons will be used to determine the limitations of both methods and the degree to which they can resolve the ambient physical processes leading to non-stationary exchange. In the long term, the researchers expect to make the technological and methodological advances necessary to deploy the UMIMS on Lagrangian floats and sea gliders. As such, this project is expected to make a significant step toward measuring near-continuous time and space series observations of the oceanic metabolic balance and the biological pump, similar to the way Argo floats measure temperature and salinity today.

在大部分海洋中，从二氧化碳（特别是通过光合生物）生产有机物和将有机物呼吸回二氧化碳（通过多种生物，包括光合作用生物）几乎处于平衡状态，但又不完全平衡。在一些远离陆地的地区，通过光合作用产生的碳多于呼吸返回的二氧化碳；在其他情况下，情况恰恰相反。 弄清楚哪一个非常重要，因为在光合作用超过呼吸作用的地区，海洋生物的食物净生产量以及大气中二氧化碳（一种强大的温室气体）的净去除量。 相反，呼吸作用超过光合作用的海洋区域是净食物消耗和向大气释放二氧化碳的区域。 实际上，问题在于，无论哪种方式，差异都很小，以至于很难区分测量本身和数据中的噪声（即分散）。 解决这个问题需要新技术，能够在海洋本身而不是在一瓶海水样本中以非常高的精度进行必要的测量。 在这个项目中，研究人员将尝试使用通常只在分析实验室中才能找到的精密仪器来做到这一点——质谱仪，一种能够对溶解氧、碳含量变化进行超高精度测量的设备。二氧化碳以及海水中与光合作用和呼吸有关的其他物质。 研究人员将支持研究生作为研究团队的重要成员参与其中。 还将向中学生进行公共教育宣传，为他们提供参与该项目的机会，以获得第一手经验，了解如何利用基础科学来解决海洋学问题。在该项目中，一组研究人员将评估一项这些方法论问题的一个方面是使用原位质谱来更好地限制净群落生产（NCP）。 UMIMS 是一款快速响应的水下膜入口质谱仪，可部署在自动驾驶和远程操作的车辆中。在此应用中，UMIMS 将部署在 SeaSoar 拖车上，以对超出氩 (Ar) 预算的过量溶解氧 (O2) 进行高分辨率垂直剖面，这是一种很有前景的表层 NCP 测量方法。 UMIMS 的配置文件可以提供解决整个混合层和透光区影响 NCP 预算的流程的能力。在短期内，该团队将利用 UMIMS 的功能来准确、同步地制作 O2 和 Ar 的混合层剖面，并将 UMIMS 的 NCP 测量值与来自航行海水的传统船载 O2/Ar 预算的测量值进行比较。这些比较将用于确定两种方法的局限性以及它们可以在多大程度上解决导致非平稳交换的环境物理过程。从长远来看，研究人员希望取得在拉格朗日浮体和海上滑翔机上部署 UMIMS 所需的技术和方法上的进步。因此，该项目预计将在测量海洋代谢平衡和生物泵的近连续时间和空间序列观测方面迈出重要一步，类似于今天Argo浮标测量温度和盐度的方式。