Collaborative Research: Hydrothermal Fluxes and their Impact on Ocean Biogeochemistry: An Integrated pre-and post-eruption Study at the EPR, 9-10 degrees N

合作研究：热液通量及其对海洋生物地球化学的影响：EPR 喷发前和喷发后综合研究，北纬 9-10 度

• 批准号: 0648287
• 负责人: Katrina Edwards
• 金额: $ 13.29万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0648287&HistoricalAwards=false
• 关键词: Collaborative; Research; Hydrothermal; Fluxes; their

Intellectual Merit: The objective of this proposal is to investigate the impact that hydrothermal fluxes from high-temperature seafloor venting may have on the biogeochemistry of the overlying ocean. One particular focus is the fate of iron, which is strongly enriched (ca. one million-fold) in vent-fluids when compared to open-ocean waters. Prior studies estimated that dissolved Fe released from venting is quantitatively precipitated close to seafloor vent-sites and demonstrated that the process of polymetallic sulfide and Fe-oxyhydroxide particle formation had the potential to significantly modify gross hydrothermal fluid fluxes. In the limit, it has been argued, uptake onto hydrothermal particles could even represent a significant sink for some dissolved chemical budgets. To investigate this, we have proposed an analytical study of settling hydrothermal plume particles collected in sediment-traps deployed directly adjacent to two known vent-sites on the East Pacific Rise at 9 50'N. The samples we will analyze date from both before and after a recent volcanic eruption at this site (Winter 2005-06). While it is known that such eruption events" can trigger rapidly evolving physical, chemical and biological hydrothermal responses, what remains unknown is how significant these transient effects might be to the time-averaged hydrothermal flux from any given system. By comparing samples collected at weekly intervals during the months immediately following the latest EPR 9-10 N eruptions with those collected during the year leading up to the eruption we will be uniquely well positioned to answer that question. We will investigate the mineralogy and chemical composition of polymetallic sulfide and Fe-oxyhydroxide particles collected within the sediment traps, as well as associated biogenic material. We will use elemental and isotopic techniques in our analyses including use of Fe isotopes to potentially fingerprint" hydrothermally-sourced Fe and U-series radionuclides as unambiguous tracers of uptake from seawater. As an integral part of our interdisciplinary study, we will complement our geochemical work with parallel microbial investigations of the same samples. Our microbial studies will, in particular, concentrate upon the role of Fe-oxidizing bacteria in controlling the biogeochemical fate of deep-ocean, hydrothermally-sourced iron. Broader Impacts: This research is a multi-disciplinary inter-institutional collaboration, which supports the research of three faculty, two graduate students, and 2-3 undergraduates. Our research offers additional opportunities in support of two other early-career postdoctoral researchers (one female) who are developing state-of-the-art analytical techniques pertinent to the analyses of deep-ocean mineral phases. In terms of impact on the broader science community, this project will directly address two of seven key questions from the NSF Ridge 2000 program concerning the limits of the hydrothermal biosphere and the impact of hydrothermal fluxes on ocean chemistry, physics and biology. One current hypothesis to be tested through our Fe-isotopic studies is that hydrothermally-sourced Fe not only dominates dissolved Fe budgets in the deep ocean but, through upwelling, also contributes significantly as an essential micro-nutrient for surface-ocean productivity. Thus, the potential exists that this project will help to establish a direct connection between solid-earth processes at Mid-Ocean Ridges and processes that are significant to global ocean carbon cycles and climate.

知识分子的优点：该提议的目的是研究高温海底排气的水热通量可能对上覆海的生物地球化学有所产生的影响。 一个特别的重点是铁的命运，与开放海洋相比，它在通风流体中强烈富集（大约100万倍）。 先前的研究估计，从通风中释放的溶解的Fe被定量沉淀到海底排气线附近，并证明了硫化物和氧羟基氧化物颗粒的形成的过程有可能显着改变总水热液体。 在极限上，有人认为，对某些溶解的化学预算的吸收甚至可能代表了一个重要的水槽。 为了研究这一点，我们提出了一项分析研究，该研究是针对直接与东太平洋上升的两个已知通风孔相邻的沉积物陷阱中收集的水热羽流颗粒的分析研究。 我们将分析该地点最近发生的火山喷发前后的样品（2005-06冬季）。 虽然众所周知，此类喷发事件“可以触发迅速发展的物理，化学和生物学水热反应，但仍然未知的是，这些瞬时影响可能与任何给定系统的时间平均水热磁通的重要性。问题。海水。 作为我们跨学科研究的组成部分，我们将通过对同一样品的平行微生物研究来补充地球化学工作。 特别是我们的微生物研究将集中于富氧化细菌在控制深海角，水热铁的生物地球化学命运中的作用。更广泛的影响：这项研究是一项多学科的机构间合作，它支持三名教职员工，两名研究生和2-3名本科生的研究。 我们的研究提供了更多的机会，以支持其他两位早期的博士后研究人员（一名女性），他们正在开发与深度海矿物相分析有关的最先进的分析技术。 就对更广泛的科学界的影响而言，该项目将直接解决NSF Ridge 2000计划中关于水热生物圈限制以及水热通量对海洋化学，物理和生物学的影响的七个关键问题。 当前通过我们的FE-异位研究进行检验的一个假设是，水热的FE不仅主导着深海中溶解的Fe预算，而且通过上升流，也可以显着贡献，这是表面 - 海洋生产率的必不可少的微生体。 因此，潜在的潜力是，该项目将有助于建立对全球海洋碳周期和气候重要意义的海脊和过程的固体地球过程之间的直接联系。