Ride Integrated Studies at 9degN East Pacific Rise: Establishing a Role for Fe and S Microbial Metabolism in Ocean Crust Weathering

这项综合实地和实验室研究正在调查化学合成微生物群落在深海海洋地壳变化和生物质生产中的作用。这些研究是基于对海底浅层海洋地壳风化和流体-岩石相互作用早期阶段的初步研究。本项目所验证的主要假设是自养铁和硫氧化原核生物的活动在海洋地壳的初始定殖和风化过程中起重要作用。这一过程导致：1)与表面地壳岩石（海底暴露表面或海底暴露于沿裂缝循环流体的表面）相关的急剧氧化还原梯度的发展，以及2)新鲜有机碳（Corg）向脊侧的流动，可能被内生异养（包括铁和s还原）原核生物群落用于呼吸。这些群落可能在富含还原铁和S矿物相（黄铁矿、磁铁矿）的次生蚀变带的发育中起作用，但它们在促进地壳风化中的作用尚不清楚，本项目正在对其进行研究。本研究有四个主要组成部分：1。利用依赖培养和不依赖培养的方法，研究了与海洋地壳风化早期阶段相关的内生铁和硫微生物的系统发育和生理多样性（基于野外）。2. 利用地球化学技术（元素和同位素），研究了海洋地壳沿风化带的渐进风化过程；将发现与(1)（基于字段）关联起来。3. 使用一套预表征的天然地壳材料（玄武岩玻璃、玄武岩、不同成分）进行6个月至1年的实地孵化研究。根据(1)和(2)分析。利用现有的和预期的新的铁和硫微生物菌株进行实验室实验，探索地壳蚀变与生物量生产之间的动力学关系，并确定可归因于生物学的元素分配和物种形成效应。实地考察是基于两个巡航：一个巡航到EPR计划在2003年春季(OCE-9819261，博士。福纳里，蒂维和斯考顿，PI。S)，第二次巡航将于6-12点后返回同一地区。第一次巡航开始了实地孵化实验，并在9degreeN的玄武岩流上收集了一些初步样本，年龄从~0-20,000年不等。后续巡航的目的是收集现场孵化样本，并以受控的方式收集新鲜环境样本，以确保材料的生物完整性。

This integrated field and laboratory studies is investigating the role of chemosynthetic microbial communities in ocean crust alteration and biomass production in the deep-sea. The studies are based on preliminary studies concerning the early stages of ocean crust weathering and fluid-rock interactions in the shallow sub-seafloor. The principal hypothesis tested in this project is that the activities of autotrophic Fe- and S-oxidizing prokaryotes play important roles in the initial colonization and weathering of ocean crust. This process results in: 1) the development of sharp redox gradients associated with the surface crustal rock (seafloor-exposed surfaces, or subseafloor surfaces exposed to circulating fluids along fractures), and 2) a flux of fresh organic C (Corg) to ridge flanks that may be used for respiration by endolithic heterotrophic (including Fe- and S-reducing) prokaryote communities. These communities likely play a role in the development of secondary alteration zones rich in reduced Fe and S mineral phases (pyrite, magnetite), but their role in promoting crustal weathering is not yet known, and is being investigated in this project. The research has four principal components: 1. Using culture-dependent and culture-independent methods, examining the phylogenetic and physiologic diversity of endolithic Fe and S microorganisms associated with the early stages of ocean crust weathering (field-based). 2. Using geochemical techniques (elemental and isotopic), examining the progressive weathering of ocean crust along weathering rinds; correlate finding with (1) (field-based). 3. Conducting field-incubation studies for 6 mo. to 1 yr. using a suite of pre-characterized natural crust material (basaltic glass, basalt, varying compositions). Analyze according to (1) and (2). 4. Conducting laboratory experiments using existing and anticipated new strains of Fe and S microorganisms exploring the kinetic relationships between crust alteration and biomass production, and to determine elemental portioning and speciation effects attributable to biology. The fieldwork is based on two cruises: one cruise to EPR scheduled for Spring 03 (OCE-9819261, Drs. Fornari, Tivey, and Schouten, PI.s), and a second cruise to return to the same region 6-12 mo. later. The first cruise initiated field incubation experiments and collected some preliminary samples along transects at 9degreeN on basalt flows, of ages from ~0-20,000 yrs. The purpose of the follow-up cruise is to collect the field incubation samples and to collect fresh environment samples in a controlled manner that insures biological integrity of the material.