Collaborative Research: Hydrogen Isotope Biogeochemistry of Anoxic Environments - Field and Laboratory Studies

Valentine/Sessions摘要该项目正在开发化合物特定氢同位素分析，作为缺氧环境过程导向生物地球化学研究的工具。 研究的重点是硫酸盐还原菌（SRB），因为它们对海洋环境中碳循环的重要性。 对黑海和阿拉伯海沉积物捕集器中脂肪酸的初步测量表明，dD值低至-350。 该项目正在测试一种假设，即厌氧原核生物消耗分子氢（H2）导致脂质中的氘（D）强烈耗尽，因为H2本身相对于水是同位素耗尽的（通常为~ 600或更多）。 实地研究的重点是从黑海和圣莫尼卡盆地收集的悬浮颗粒物和沉积物中提取的生物标志物脂质中的dD。 这项工作的结果将代表化合物的具体dD值在缺氧环境中的第一次实质性的调查，并应提供一个指示的生物区系负责的大同位素分馏。实验室实验的重点是脂氢的来源（即，H2与水）和氢同位素分馏通过操纵SRB培养。正在研究代谢率，H2浓度，物种和底物的影响。

Valentine/Sessions AbstractThis project is developing compound-specific hydrogen isotope analyses as a tool for process-oriented biogeochemical studies of anoxic environments. Research is focusing on sulfate-reducing bacteria (SRB) due to their quantitative importance for carbon cycling in marine settings. Preliminary measurements of fatty acids from sediment traps in the Black and Arabian Seas indicate dD values as low as -350. This project is testing the hypothesis that consumption of molecular hydrogen (H2) by anaerobic prokaryotes leads to lipids strongly depleted in deuterium (D), because H2 itself is isotopically depleted (typically -600 or more) relative to water. Field studies is focusing on dD in biomarker lipids extracted from suspended particulate matter and sediments collected in the Black Sea and Santa Monica Basin. The results of this work will represent the first substantial survey of compound-specific dD values in anoxic environments, and should provide an indication of the biota responsible for the large isotopic fractionations. Laboratory experiments are focusing on the sources of lipid hydrogen (i.e., H2 versus water) and hydrogen-isotopic fractionations through manipulation of SRB cultures. Effects of metabolic rate, H2 concentration, species, and substrate are being examined.