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.

智力优势：本提案的目的是调查高温海底喷发产生的热液通量可能对上覆海洋的地球化学产生的影响。 一个特别的焦点是铁的命运，它是强烈富集的（约。一百万倍），在喷口流体相比，开放的海洋水域。 先前的研究估计，从排气释放的溶解铁定量沉淀接近海底排气口网站，并表明，多金属硫化物和铁羟基氧化物颗粒形成的过程有可能显着修改总热液流体通量。 有人认为，在极限情况下，热液颗粒的吸收甚至可能是一些溶解化学物质预算的重大下沉。 为了调查这一点，我们提出了一个分析研究的沉降热液羽颗粒收集在沉积物陷阱部署直接相邻的两个已知的喷口网站在东太平洋海隆在950 'N。 我们将分析的样本来自该地点最近一次火山爆发（2005-06年冬季）之前和之后。 虽然人们知道，这种喷发事件”可以触发迅速演变的物理、化学和生物热液反应，但仍然不知道的是，这些短暂的影响对任何特定系统的时间平均热液流量有多大意义。 通过比较最近一次EPR 9-10 N喷发后几个月内每周收集的样本与喷发前一年收集的样本，我们将能够很好地回答这个问题。 我们将调查沉积物捕集器内收集的多金属硫化物和铁羟基氧化物颗粒的矿物学和化学成分，以及相关的生物物质。 我们将在分析中使用元素和同位素技术，包括使用Fe同位素来潜在地识别”热液来源的Fe和U系列放射性核素，作为从海水中摄取的明确示踪剂。 作为我们跨学科研究的一个组成部分，我们将通过对相同样品的平行微生物调查来补充我们的地球化学工作。 我们的微生物研究将特别集中在铁氧化细菌在控制深海热液来源铁的地球化学命运中的作用。更广泛的影响：本研究是一项多学科的跨机构合作，支持三名教师，两名研究生和2-3名本科生的研究。 我们的研究提供了额外的机会，以支持另外两名早期职业博士后研究人员（一名女性），他们正在开发与深海矿物相分析相关的最先进的分析技术。 在对更广泛的科学界的影响方面，该项目将直接解决NSF Ridge 2000方案中关于热液生物圈的限制和热液通量对海洋化学、物理学和生物学的影响的七个关键问题中的两个。 通过我们的铁同位素研究测试目前的一个假设是，热液来源的铁不仅占主导地位的溶解铁预算在深海中，但通过上升流，也有助于显着作为一个重要的微量营养素的表面海洋生产力。 因此，该项目有可能有助于在大洋中脊的固体地球过程与对全球海洋碳循环和气候具有重要意义的过程之间建立直接联系。