Molecular-isotopic studies of microbial processes and organic matter in the subseafloor coalbed biosphere of Shimokita (IODP Exp. 337)

本提案寻求继续支持与IODP远征337（2012年7月26日至9月30日）相关的巡航后研究，其中Kai-Uwe Hinrichs教授（支持者）和他的同事dr。Verena Heuer、Yu-Shih Lin和Marshall Bowles分别担任联合首席科学家和船上科学家。IODP Exp. 337是第一个使用隔水管钻井技术对海底碳氢化合物系统进行岩心和取样的科学海洋钻井项目。C0020A孔钻探水深1180 m，总沉积深度2466 m。这是目前科学海洋钻探所钻的最深的洞。此次考察旨在探索与日本海底以下约2公里深埋煤层相关的微生物生态系统和微生物过程，以及通过科学钻探探测和检查迄今为止最深处微生物群落的特征。我们建议研究下基塔半岛外烃系统中微生物与有机质之间的多种关系。特别是，我们打算解决以下问题：煤层是否作为地球生物反应器，在大埋藏深度维持微生物的生命？煤衍生化合物的转化和运移是否影响深层和上覆浅层的碳流和生物量？深层生物圈延伸到海底有多深，生命的限制因素是什么？我们打算使用有机地球化学方法，包括对气体、溶解有机物和代表活微生物生物量的极性膜脂进行定性、定量和分子同位素分析。我们将在以栽培为基础的实验室实验中检验我们关于煤层作为深层生物圈能源和碳源的作用的假设。为了阐明代谢途径，我们将使用碳和氢的稳定同位素和碳的放射性同位素作为示踪剂。这些技术将有助于深入了解沉积环境中有机物的生物降解、原核生物生物量的数量以及微生物群落的碳代谢和活动。

This proposal seeks continued support for post-cruise research related to IODP Expedition 337 (July 26 to September 30, 2012), in which Prof. Dr. Kai-Uwe Hinrichs (proponent) and his co-workers Drs. Verena Heuer, Yu-Shih Lin, and Marshall Bowles participated as co-chief scientist and shipboard scientists, respectively. IODP Exp. 337 was the first scientific ocean drilling initiative to core and sample a subseafloor hydrocarbon system using riser-drilling technology. Hole C0020A was drilled at a water depth of 1180 m and reached a total sediment depth of 2466 m. It is currently the deepest hole that was drilled by scientific ocean drilling. The expedition seeks to explore the microbial ecosystem and microbial processes associated with a deeply buried coalbed situated ~2 km below the seafloor off Japan as well as to detect and examine the signatures of the deepest microbial communities ever accessed by scientific drilling. We propose to investigate the diverse relationships between microorganisms and organic matter in the hydrocarbon system off the Shimokita peninsula. In particular, we intend to address the following questions: Does the coalbed act as geobiological reactor that sustains microbial life at great burial depth? Do the conversion and transport of coal-derived compounds influence carbon flow and biomass at depth and in the overlying shallower strata? How deep does the deep biosphere extend into the seafloor and what are the limiting factors for life? We intend to use organic geochemical approaches including qualitative, quantitative, and molecular-isotopic analyses of gases, dissolved organic matter, and polar membrane lipids representative of live microbial biomass. We will test our hypothesis on the role of coalbeds as energy and carbon sources for the deep biosphere in cultivation-based laboratory experiments. In order to elucidate metabolic pathways we will use stable isotopes of carbon and hydrogen and the radioisotope of carbon as tracers. These techniques will provide insights into biodegradation of organic matter, quantities of prokaryotic biomass, and carbon metabolism and activities of microbial communities in sedimentary environments.