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

这一综合实地和实验室研究正在调查化学合成微生物群落在海洋地壳变化和深海生物量生产中的作用。这些研究的基础是关于海洋地壳风化和浅海底下流体-岩石相互作用早期阶段的初步研究。 该项目检验的主要假设是，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中起着重要作用。 该过程导致：1）与表层地壳岩石（暴露于海底的表面，或暴露于沿着裂缝的循环流体的海底下表面）相关的急剧氧化还原梯度的发展，以及2）新鲜有机C（Corg）流向山脊侧翼，可用于石内异养（包括Fe-和S-还原）原核生物群落的呼吸。 这些社区可能发挥作用的次生蚀变带的发展，丰富的还原铁和硫矿物相（黄铁矿，磁铁矿），但他们的作用，促进地壳风化尚不清楚，并正在调查本项目。 本研究有四个主要组成部分：1。 使用文化依赖和文化独立的方法，研究与早期阶段的海洋地壳风化（现场）的石内铁和硫微生物的系统发育和生理多样性。2. 利用地球化学技术（元素和同位素），研究海洋地壳沿着风化带的渐进风化;将发现与（1）（基于实地）相关联。 3. 进行6个月的田间孵育研究。到1年。使用一套预先表征的天然地壳材料（玄武岩玻璃、玄武岩、不同成分）。 根据（1）和（2）进行分析。4. 利用现有的和预期的铁和硫微生物新菌株进行实验室实验，探索地壳变化和生物量生产之间的动力学关系，并确定生物学的元素分配和形态效应。 实地工作基于两次巡航：一次巡航到EPR，计划于2003年春季（OCE-9819261，Fornari博士，Tivey和Schouten，PI.s），第二次巡航返回同一地区6-12个月。后 第一次航行开始进行实地培养实验，并在玄武岩流上沿沿着9度的断面收集了一些初步样本，年龄从0年到20 000年。后续航行的目的是收集实地培养样本，并以确保材料生物完整性的控制方式收集新鲜环境样本。

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.