Collaborative Research: Hydrothermal Estuaries: What Sets the Hydrothermal Flux of Fe and Mn to the Oceans?

合作研究：热液河口：是什么决定了铁和锰进入海洋的热液通量？

• 批准号: 1851007
• 负责人: Chris German
• 金额: $ 38.22万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1851007&HistoricalAwards=false
• 关键词: Collaborative; Research; Hydrothermal; Estuaries; What

Like volcanoes on land, the mid-ocean ridges that cross the ocean floor are not continuously erupting; however, the magmatic heat present just beneath the surface can continue to drive hot springs, just like the ones found within the crater of the "super volcano" at Yellowstone. In our recent work, we have shown that the chemicals released into the oceans from seafloor hot-springs can be dispersed all across the oceans. Now our interest has focused in on one element in particular, iron. This is one of the most abundant elements in every planetary body in the Universe yet it is vanishingly rare in Earth's oceans today. Set against that, it is essential to just about every form of life on Earth from the simplest and most ancient strains of microbes to the most complex animals including humans. In Earth's oceans, the lack of this "essential micro-nutrient" has been found to limit how much life can flourish near both the south and north poles in the Pacific Ocean in the sunlit surface ocean even though the supply of sunlight and other major nutrients (phosphorous, nitrogen) should be more than adequate. Our newest research suggests that iron released from hydrothermal plumes (where the concentrations coming from vents are more than 1 million times higher than normal ocean water) could play a major role. Despite undergoing massive dilution as hydrothermal solutions leave the vents and traverse thousands of kilometers through the oceans, we believe that at least some of the iron released from deep sea hot springs can survive this journey and make a significant impact on how much live exists in Earth's polar oceans and how much CO2 it draws down from the atmosphere. To investigate that idea, this project will study the fate of iron released from a hydrothermal vent over a length scale that hasn't been studied before - from the first 1km through the ocean out to 100km away from the vent-site. This will fill a gap in our knowledge between what happens right at a vent-site (as studied by research submarines) and what happens to ocean chemistry all across Earth's entire ocean basins (as studied by a huge international research project called GEOTRACES). Our work will use a 3D computational model to predict where the plume of material from a vent in the Northeast Pacific Ocean should escape to after it is erupted from some vents at a volcanic system called the Juan de Fuca Ridge. We will then use an advanced autonomous free-swimming robot to search out in the predicted plume area, first to test the accuracy of our predicted model and, second, to collect samples from the hydrothermal plume from where it first forms to as far out as we can follow it. The samples we collect will include both filtered seawater and the particulate material (whether mineralogical or microbiological) that we can extract from the filters. Together, this will allow us to track the fate of the iron and other key physical and geochemical tracers down-plume away from the vents, to work out where it ends up (in the water and in the sediments) and also how fast those processes happen. The work we do will also help plan how to conduct similar robotics-based exploration on future space missions beyond Earth where it has been hypothesized that seafloor events also exist (e.g. Saturn's moon Enceladus) and where, if we are really lucky, we may find that life is hosted based on the energy from seafloor volcanoes, just as happens here on Earth. We have a resident artist embedded in our program who has already begun experimenting with the use of air-flow and sound in her sculptures to help communicate the complex nature of these plumes. She will join our cruise, and work with our team post-cruise to design and hopefully build a sculpture that that could potentially result in a large and long-term outdoor installation. The international GEOTRACES program has revealed that iron (Fe) is released ubiquitously from submarine ridges to the deep ocean. Results from US GEOTRACES section GP16 showed that both dissolved and particulate (colloidal) Fe may persist so far as to be able to influence primary productivity in High-Nutrient/Low-Chlorophyll (HNLC) regions of the Southern Ocean. As a complement to these sectional studies, we propose a detailed process study to elucidate the mechanisms by which hydrothermally sourced Fe can persist across the oceans at the scale that GEOTRACES has revealed. Specifically, while the "persistent" Fe in a hydrothermal plume appears to behave quasi-conservatively from 100km to 4000km across the SE Pacific Ocean, it is also known that the majority of the Fe present at the Southern EPR on that US GEOTRACES GP16 cruise did not persist over the 100km separation between that station and the next deep ocean station beyond the ridge crest. To fill that gap, this project will conduct a coupled modelling and field study to investigate the fate of hydrothermally sourced Fe at ranges of 0-1, 1-10 and 10-100km down-plume away from a well established vent-source. To begin, we will use the detailed micro-bathymetry and the long-term current meter data available from the Main Endeavour Segment of the Juan de Fuca Ridge to implement a recently developed 3D theoretical plume dispersion model that can predict both the detailed 3D dispersion trajectory and the rate of flow within the hydrothermal plume away from two long-studied and well characterized Main Endeavour Field (MEF) vents. At sea, we will use that predictive model to guide Sentry autonomous underwater vehicle (AUV) surveys that will follow the plume "down-wind" and "across-plume" to compile a 3D survey using in-situ sensors [optical, redox, conductivity, temperature, depth (CTD)] that will allow us to (1) confirm (and better constrain) the predictive model, and to (2) map out the shape and trajectory of the plume to provide context for discrete water column samples that we will collect - both from the AUV and from a trace metal clean CTD-rosette. Sampling from the AUV will use the latest generation of SUPR samplers designed for the CLIO trace-metal-clean water sampler. This will suffice for samples of dissolved, colloidal and particulate trace metals and collection of filtered material for grain-by-grain mineralogical and biogeochemical analyses. That sampling program will be backed up by larger volume sampling down-plume using a CTD-rosette to augment our AUV-based program with helium isotope analyses (to track extents of physical plume dilution at increasing distances downwind and across plume) and for complementary ligand and organic compound analyses to investigate the role that organic complexation might play in protecting reduced species of Fe [and manganese (Mn), too] against oxidative precipitation and removal from the oceanic water column. Post cruise, our combination of biogeochemical measurements and improved 3D physical modelling will not only be able to provide new insights into the processes that control the fluxes of Fe and Mn to the oceans from hydrothermal venting but also the length scales over which those processes take effect. Finally, because our 3D theoretical model includes velocities, we also anticipate being able to deduce the rates at which these processes occur.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.

就像陆地上的火山一样，穿过海底的中山山脊并没有不断爆发。但是，在表面下方存在的岩浆热可以继续驱动温泉，就像在黄石公园的“超级火山”的火山口中发现的那样。 在我们最近的工作中，我们表明，从海底热弹簧释放到海洋中的化学物质可以在整个海洋中分散。 现在，我们的兴趣特别关注了一个元素，铁。 这是宇宙中每个行星中最丰富的元素之一，但在当今的地球海洋中，它却消失了。 与此相反，从最简单，最古老的微生物到包括人类在内的最复杂的动物，几乎每种生活形式的生命都至关重要。 在地球的海洋中，已经发现缺乏这种“必需的微营养素”会限制在太平洋的南部和北极在阳光地面海洋中的南极和北极附近的生命，即使阳光和其他主要养分的供应（磷，氮）也应该多于足够的。 我们的最新研究表明，从水热羽毛释放的铁（来自通风孔的浓度比海水高的100万倍以上）可能发挥重要作用。 尽管水热溶液使通风孔和数千公里穿过海洋，但我们认为，至少有一些从深海温泉释放的铁可以生存在这一旅程中，并对地球极性海洋中存在多少生命以及它从大气中吸收多少二氧化碳。 为了研究这个想法，该项目将研究从没有研究的长度尺度上释放出的铁的命运 - 从第一个1公里到海洋，再到距离通风口的100公里。 这将填补我们在通风口站点（研究潜艇所研究的）与整个地球整个海洋盆地的海洋化学发生的事情之间的差距（正如一个名为Geotraces的庞大的国际研究项目所研究）。 我们的工作将使用3D计算模型来预测东北太平洋的通风口的羽毛羽流在从某些通风孔中爆发出来的火山系统，即Juan de Fuca Ridge的某些通风口。 然后，我们将使用先进的自主自由游泳机器人在预测的羽流区域中进行搜索，首先测试我们预测的模型的准确性，其次，从水热羽流中收集样品，从首先形成到我们可以遵循的情况下。 我们收集的样品将包括我们可以从过滤器中提取的过滤的海水和颗粒物（无论是矿物学还是微生物学）。 这将使我们能够跟踪铁和其他钥匙的物理和地球化学示踪剂的命运，从通风口向下倾斜，锻炼它的结尾（在水中和沉积物中）以及这些过程发生的速度。 我们所做的工作还将有助于计划如何对地球以外的未来太空任务进行类似的基于机器人的探索，在该地球以外的地球上，海底事件也存在（例如土星的月球土生土长），如果我们真的很幸运，我们可能会发现，我们可能会发现生活是基于Seafloor Volcanoes的能量，以及这里发生的。 我们有一位嵌入在计划中的常驻艺术家，他们已经开始尝试在她的雕塑中使用气流和声音，以帮助传达这些羽毛的复杂性。 她将加入我们的巡游，并与我们的团队裁判一起设计，并希望建造一个雕塑，该雕塑有可能导致大型且长期的户外装置。国际地理领域计划显示，铁（FE）从海底山脊到深海释放。 美国地理位置的结果GP16段表明，溶解和颗粒物（胶体）Fe均可持续存在，甚至能够影响南大洋高氮/低氯易感（HNLC）区域的一级生产力。 作为对这些分段研究的补充，我们提出了一项详细的过程研究，以阐明水热采购的Fe可以在Geotraces揭示的规模上遍布海洋的机制。 具体而言，虽然水热羽流中的“持久” fe在整个太平洋上的表现从100公里到4000公里，但也众所周知，在南部EPR上的大多数FE在美国GEOTRACES GP16巡航上都没有持续到该站的100公里分离，而在下一站和下一个深处的海洋之外，这并没有持久。 为了填补这一空白，该项目将进行耦合的建模和现场研究，以研究0-1、1-10和10-100公里的水热采购的Fe命运，距离已建立的通风源源。 To begin, we will use the detailed micro-bathymetry and the long-term current meter data available from the Main Endeavour Segment of the Juan de Fuca Ridge to implement a recently developed 3D theoretical plume dispersion model that can predict both the detailed 3D dispersion trajectory and the rate of flow within the hydrothermal plume away from two long-studied and well characterized Main Endeavour Field (MEF) vents. At sea, we will use that predictive model to guide Sentry autonomous underwater vehicle (AUV) surveys that will follow the plume "down-wind" and "across-plume" to compile a 3D survey using in-situ sensors [optical, redox, conductivity, temperature, depth (CTD)] that will allow us to (1) confirm (and better constrain) the predictive model, and to (2) map out the shape and trajectory of the plume to提供我们将收集的离散水柱样品的背景 - 从AUV和痕量金属清洁CTD -Rosette中。 来自AUV的采样将使用为Clio Trace-Metal-Clean水采样器设计的最新一代SUPR采样器。 对于溶解，胶体和颗粒物痕量金属的样品以及过滤材料收集的样品，以进行晶粒型矿物质和生物地球化学分析的收集。 该采样程序将通过使用CTD-Rosette进行更大的体积对下插头进行支持，以通过氦同位素分析来增强我们的基于AUV的程序（跟踪距离增加距离时的物理羽稀释度的范围），并在羽流和整个羽流中增加距离），并以互补的配体和有机化的作用，以使其具有互补的配体分析，以使其在较复杂的情况下进行保护，以使其在较复杂的情况下进行prove and Introve Introve Introve Intressive interive Intressive Introve Intressive Intressive Intressive Intress Intress Intressive Invortive confective confection（Man）的作用。从海洋水柱中氧化沉淀和去除。 巡航后，我们将生物地球化学测量和改进的3D物理建模的结合不仅能够提供对控制Fe和MN的过程的新见解，这些过程可以从热液排气中从水热通风中转化为海洋，而且还可以为这些过程带来的长度尺度。 最后，由于我们的3D理论模型包括速度，我们还希望能够推断出这些过程的速度。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的智力优点和更广泛影响的评估标准来通过评估来获得支持的。