Collaborative research: Hydrogen isotopic studies of marine dissolved and particulate organic matter

合作研究：海洋溶解和颗粒有机物的氢同位素研究

• 批准号: 0550295
• 负责人: Arndt Schimmelmann
• 金额: $ 15.83万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0550295&HistoricalAwards=false
• 关键词: Collaborative; research; Hydrogen; isotopic; studies

Despite decades of research, the molecular compositions of marine particulate and dissolved organic matter (POM and DOM) remain uncertain. Detailed chromatographic analyses are able to identify up to 80% of the constituent molecules in POM from surface waters, but less than 20% of POM from particles after they have fallen into abyssal waters and sediments. Different analytical methods have also thus far produced disparate, and sometimes incompatible, results concerning factors affecting preservation or compositional changes during sinking. The composition of DOM is better constrained, but the primarily NMR-based studies have not been tested by independent methods. In this project, researchers from California Institute of Technology and from University of Illinois will apply existing methods for hydrogen-isotopic analysis to the study of marine POM and DOM in order to help constrain the biochemical composition of these materials. Hydrogen-isotopic analyses will place three new kinds of constraints on the molecular composition of these materials. The elemental ratio of hydrogen to carbon (H/C) in demineralized organic materials and selected biochemical fractions should allow distinction of fresh biomolecules (H/C 1.5) versus kerogen derived from sediments and black carbon (H/C 1.0). Second, the fraction of organic H that is susceptible to rapid isotopic exchange in water represents primarily O- and N-bound H, and is much higher in amino acids and carbohydrates (30-50%) than in lipids and hydrocarbons (5%). Third, the isotopic composition of non-exchangeable H ( 8 Dn) in biomolecules differs substantially between lipids (typically Dn -150% ), petroleum hydrocarbons (~-100%), and amino acids and carbohydrates (typically -50%). The hydrogen data will be complemented by a suite of ancillary analyses such as GCMS, pyrolysis-GCMS, SEM, and quantification of organic sulfur. Samples will be examined from a variety of locations such as the San Pedro Basin (coastal CA), Station M (eastern abyssal Pacific), and other locations around the world. Samples will be acquired during a 5-day research cruise, as well as via collaborations and piggy-backing on other cruises. This research will measure, for the first time, D/H fractionations between biochemical classes in both marine phytoplankton and heterotrophic bacteria, and will examine fractionations accompanying the degradation of algal biomass, both potentially useful for carbon-cycle studies. The PIs will explore the use of exchangeability profiles (i.e., the fraction of exchangeable H as a function of time or temperature) to characterize the compactness and cross-linking of tertiary structure in organic macromolecules, a property that should also be useful to biochemists or polymer chemists.Among the broader impacts is the transfer of H-isotopic analytical methods to marine applications. The researchers will also develop more automated and sensitive methods for measuring Dn using elemental analyzer technology, an achievement that will have important benefits for constructing high-resolution paleoclimate records based on organic D/H. The project will also provide a range of educational opportunities for undergraduate and graduate students at two major research universities. It will provide the basis for at least one Ph.D. dissertation and two undergraduate summer internships, and will provide an introduction to chemical oceanography for a high school volunteer.

尽管进行了数十年的研究，但海洋颗粒和溶解有机物（POM和DOM）的分子组成仍然不确定。详细的色谱分析能够鉴定出来自地表水的POM中多达80％的组成分子，但在颗粒中掉入深渊水域和沉积物后，颗粒中的POM不到20％。到目前为止，不同的分析方法也产生了不同的，有时是不兼容的，其结果涉及影响下沉过程中保存或组成变化的因素。 DOM的组成得到了更好的限制，但是主要基于NMR的研究尚未通过独立方法测试。在该项目中，来自加利福尼亚理工学院和伊利诺伊大学的研究人员将应用现有的氢 - 异位分析方法对海洋POM和DOM的研究，以帮助限制这些材料的生化组成。氢相关分析将对这些材料的分子组成施加三种新的约束。脱矿物化有机材料和选定的生化部分中氢与碳（H/C）的元素比应允许将新鲜生物分子（H/C 1.5）与源自沉积物和黑碳（H/C 1.0）的动干相比。其次，在水中易于快速同位素交换的有机h的比例主要代表O-和N结合H，并且在氨基酸和碳水化合物中（30-50％）中比脂质和碳氢化合物（5％）高得多。 。第三，生物分子中不可交换H（8 dn）的同位素组成在脂质（通常为DN -150％），石油烃（〜-100％），氨基酸和碳水化合物和碳水化合物（通常-50％）之间有很大不同。氢数据将通过一系列辅助分析（例如GCM，热解-GCM，SEM）和有机硫的定量来补充。将从各种地点检查样品，例如圣佩德罗盆地（CA），M（Easter Abyssal Pacific）和世界各地的其他地点。样品将在为期5天的研究巡游中，以及通过合作和其他巡游中的背包。这项研究将首次测量海洋浮游植物和异养细菌的生化类别之间的D/H分馏，并将检查伴随藻类生物量降解的分馏，这两者都可能对碳循环研究有用。 PI将探索使用交换性曲线（即，可交换h作为时间或温度的函数的比例）来表征有机大分子中三级结构的紧凑性和交联，该特性也应对生物化学家或生物化学家或生物化学家或聚合物化学家。更广泛的影响是将H-异位分析方法转移到海洋应用。 研究人员还将开发更多使用元素分析仪技术测量DN的自动化和敏感方法，这一成就将对基于有机D/H构建高分辨率古气候记录具有重要好处。该项目还将为两所主要研究的大学生和研究生提供一系列教育机会。它将提供至少一位博士学位的基础。论文和两个本科暑期实习，并将为高中志愿者提供化学海洋学的介绍。