Collaborative Research: IODP Expedition 329 Objective Research on Supply of H2 by Water Radiolysis in Subseafloor Sediment of the South Pacific Gyre

合作研究：IODP Expedition 329 南太平洋环流海底沉积物中水辐射解供氢的客观研究

• 批准号: 1130531
• 负责人: Andrew Kurtz
• 金额: $ 16.42万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-15 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1130531&HistoricalAwards=false
• 关键词: Collaborative; Research; IODP; Expedition; 329

Intellectual MeritThe South Pacific Gyre (SPG) contains the lowest cell concentrations and lowest rates of microbial activity ever encountered in shallowly-buried marine sediment. However, the electron donors that sustain its subseafloor microbial ecosystem are not fully constrained. In recognition of the importance of this natural laboratory, the Integrated Ocean Drilling Program (IODP) selected the SPG as the target of its first riser-less expedition solely dedicated to study of subseafloor life (Expedition 329).This Expedition Objective Research (EOR) proposal has one fundamental objective: To quantify the extent to which subseafloor sedimentary communities of the SPG may be supplied with H2 by water radiolysis.In addressing this objective, the following testable hypotheses are posed:1) H2 is produced by water radiolysis at significant rates relative to other electron donorsin the organic-poor subseafloor sediment of the SPG.2) At some depth below seafloor, the production rate of H2 by water radiolysis exceedsthe availability of other electron donors (organic matter and reduced minerals).To test these hypotheses, this work will focus on four related activities:(1) Precise and accurate quantification of radioactive element concentrations and sedimentary grain size,(2) Quantification of alpha particle (4He) fluxes from the sediment to the interstitial water,(3) Refinement of H2 yield calculations by experimental radiation of representative SPGsediment samples, and(4) Quantification of the potential importance of radiolytic H2 to the subseafloor sedimentary communities by direct comparison of calculated H2 yields to shipboard H2 concentration data and rates of organic matter oxidation derived from shipboard data.This study will advance understanding of the subsurface world by (i) placing a clear boundary on the extent to which subseafloor sedimentary life may be energetically independent of the surface photosynthetic world and (ii) advancing understanding of the sources of microbial energy in sediment of Earth?s largest oceanic province. Because electron donor fluxes are so low in SPG sediment, this research may also help to constrain the limits to life.Broader Impacts, Education, and Data ManagementThis project will fully answer one of the primary objectives of IODP Expedition 329 by quantifying the production of H2 by water radiolysis in SPG sediment. It will address another of the expedition?s primary objectives by advancing understanding of the habitats and rates of metabolic activities in this very large low-energy environment. The project will heighten collaborations between URI (an EPSCoR institution), BU, and our Exp. 329 collaborators from throughout the U.S., Europe, Asia and Australia. The project will have strong training impacts. Graduate students will be integral project members. Undergraduates will be included as thesis advisees, work-study students, paid laboratory assistants, nationally competed NSF-sponsored GSO Summer Undergraduate Research Fellows, and through our courses. The URI Geobiology website will expand to include focus on this project. We will present our results to audiences via guest lectures and the Internet. Significant findings will be submitted for publication beginning in the second year of the project. To ensure accessibility to the scientific community and the public, data will be deposited into the SedDB database and samples will be catalogued through SESAR.

智力价值南太平洋环流（SPG）含有浅埋海洋沉积物中有史以来最低的细胞浓度和最低的微生物活动率。然而，维持海底微生物生态系统的电子供体并没有完全受到限制。认识到这个自然实验室的重要性，综合海洋钻探计划 (IODP) 选择 SPG 作为其首次专门研究海底生命的无立管探险队（第 329 号探险队）的目标。这项探险目标研究 (EOR) 提案有一个基本目标：量化 SPG 海底沉积群落可通过水辐射分解获得氢气的程度。 为了实现这一目标，提出了以下可检验的假设：1) 在 SPG 的有机贫乏的海底沉积物中，相对于其他电子供体，水辐射分解产生 H2 的速率显着。2) 在海底以下的某些深度，水辐射分解产生的 H2 的速率超过了其他电子供体（有机物质和还原矿物质）的可用性。为了检验这些假设，这项工作将重点关注四个相关的假设。 活动：(1) 精确、准确地量化放射性元素浓度和沉积颗粒尺寸，(2) 量化从沉积物到间隙水的 α 粒子 (4He) 通量，(3) 通过代表性 SPG 沉积物样品的实验辐射来细化 H2 产量计算，以及(4) 通过直接比较放射性分解 H2 对海底沉积物群落的潜在重要性进行量化 计算出的 H2 产量为船载 H2 浓度数据和源自船载数据的有机物氧化速率。这项研究将通过以下方式增进对地下世界的了解：(i) 对海底沉积生命在很大程度上独立于表面光合作用世界的程度设定明确的界限；(ii) 增进对地球最大海洋省份沉积物中微生物能量来源的了解。由于 SPG 沉积物中的电子供体通量如此之低，这项研究也可能有助于限制生命的极限。更广泛的影响、教育和数据管理该项目将通过量化 SPG 沉积物中水辐射分解产生的 H2 来充分回答 IODP 329 号探险的主要目标之一。它将通过增进对这个非常大的低能量环境中的栖息地和代谢活动速率的了解来实现探险队的另一个主要目标。该项目将加强 URI（EPSCoR 机构）、BU 和我们的 Exp 之间的合作。来自美国、欧洲、亚洲和澳大利亚的 329 名合作者。该项目将产生巨大的培训影响。研究生将成为不可或缺的项目成员。本科生将作为论文指导者、勤工俭学的学生、带薪实验室助理、全国性的 NSF 资助的 GSO 夏季本科生研究员以及我们的课程。 URI 地球生物学网站将扩展以包括对该项目的关注。我们将通过客座讲座和互联网向观众展示我们的成果。重要的研究结果将从项目的第二年开始提交出版。为了确保科学界和公众的可访问性，数据将存入 SedDB 数据库，样本将通过 SESAR 进行编目。