Are strong ligands and dissolved iron tightly coupled in hydrothermal systems?

强配体和溶解的铁在热液系统中紧密耦合吗？

• 批准号: 2122928
• 负责人: Randelle Bundy
• 金额: $ 31.73万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2122928&HistoricalAwards=false
• 关键词: strong; ligands; dissolved; iron; tightly

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Iron is one of the most abundant elements in the Earth’s crust, but it is extremely diluted in the ocean. Iron-poor surface waters limit the growth of microscopic marine life, called phytoplankton, and their ability to remove carbon from the atmosphere and surface ocean. However, over the last few decades, our understanding of how iron enters the ocean has evolved. Recent data has shown that deep-sea hot springs, also known as hydrothermal vents, impact global iron budgets and are important for surface iron supply. Hydrothermal vents are found globally along volcanic spreading centers where new seafloor is created through tectonic activity. The new porous seafloor allows seawater to circulate through the hot, chemically reactive rocks to create hydrothermal fluids. These fluids are less dense (hotter, 300-400°C) than deep ocean waters (2°C), so the water exiting the vents rises while mixing with ambient seawater, eventually forming hydrothermal plumes. These nutrient-rich plumes can extend for 10-1000s of kilometers into the ocean interior. To account for the long-range transport of hydrothermal iron into the ocean interior, models have shown that stabilizing agents (i.e. organic ligands) are needed to prevent iron from precipitating and settling to the seafloor. However, we still do not know the sources and identities of these organic ligands, as well as how common they are in various hydrothermal systems across the global ocean. Investigating these mechanism(s) for hydrothermal iron stabilization across different vent systems will provide insight into both local and long-range iron utilization by deep-sea marine microorganisms and phytoplankton in the surface ocean. In this project, the sources, concentration, and identities of iron-binding organic ligands in hydrothermal plumes from four different volcanic spreading centers will be examined to understand their impact on iron stabilization and transport into the ocean interior. The major aim of this research is to test whether (1) the concentrations of strong organic ligands tightly control the distal transport of hydrothermally derived dissolved iron in neutrally buoyant plumes across a variety of hydrothermal vent systems and (2) investigate if microbes from hydrothermal systems are responsible for production of these strong organic ligands (i.e. siderophores). This work will use a combination of existing samples and samples of opportunity that will be collected during an upcoming field expedition, each from distinct spreading centers. These findings would significantly enhance our understanding of hydrothermal iron transport and aid in future modeling efforts on the fate of hydrothermal iron in the global iron cycle. This project will support the training of two early career scientists, an undergraduate intern, and STEM workshop kits for middle school programs about deep-sea environments, which will be developed in collaboration and made freely available through the NOAA Pacific Marine Environmental Education and Outreach webpage.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.

该奖项的全部或部分资金来源于《2021 年美国救援计划法案》（公法 117-2）。铁是地壳中最丰富的元素之一，但在海洋中却极度贫乏。地表水限制了浮游植物等微观海洋生物的生长，以及它们从大气和表层海洋中去除碳的能力。然而，在过去的几十年里，我们对铁如何进入海洋的理解已经发生了变化。最近的数据表明，深海热泉（也称为热液喷口）影响全球铁预算，并且对地表铁供应非常重要。全球各地的火山扩张中心都发现了热液喷口，这些热液喷口通过构造活动形成了新的海底。海底允许海水通过热的化学反应性岩石产生热液，这些流体的密度低于深海水域（温度更高，为 300-400°C）。 (2°C)，因此离开喷口的水在与周围海水混合的同时上升，最终形成这些营养丰富的热液羽流，可以延伸到海洋内部 10-1000 公里，以解释长距离运输。当热液铁进入海洋内部时，模型表明需要稳定剂（即有机配体）来防止铁沉淀并沉降到海底。然而，我们仍然不知道铁的来源和情况。这些有机配体的特性，以及它们在全球海洋各种热液系统中的常见程度，研究这些跨不同喷口系统的热液铁稳定机制将有助于深入了解深部的局部和远程铁利用。 -海洋表层海洋微生物和浮游植物在该项目中，将检查来自四个不同火山扩散中心的热液羽流中铁结合有机配体的来源、浓度和特性，以了解它们。本研究的主要目的是测试（1）强有机配体的浓度是否严格控制热液衍生的溶解铁在穿过各种热液喷口的中性浮力羽流中的远端运输。系统和（2）研究来自热液系统的微生物是否负责产生这些强有机配体（即铁载体）。这项工作将使用现有样本和将在过程中收集的机会样本的组合。即将进行的实地考察，每个都来自不同的传播中心。这些发现将极大地增强我们对热液铁运输的理解，并有助于未来对热液铁在全球铁循环中的命运的建模工作。该项目将支持对两名早期职业生涯的培训。科学家、本科生实习生以及有关深海环境的中学项目的 STEM 研讨会套件，这些套件将共同开发，并通过 NOAA 太平洋海洋环境教育和外展网页免费提供。该奖项反映了 NSF 的法定使命，并已认为值得支持通过使用基金会的智力优点和更广泛的影响审查标准进行评估。