Chemolytic Analysis of Macromolecular Organic Matter--A Proof of Concept

有机地球化学领域最具挑战性的问题之一是确定化石有机大分子的化学和物理结构-即源于活生物体但不再包含在其中的大分子。这些“地质聚合物”通常具有极高的分子量和高度交联，因此很难在实验室中使用。煤、泥炭和干酪根是重要的例子。虽然过去三十年来化学仪器的技术发展使我们能够穿透生物体中许多大分子的结构（例如，蛋白质、核酸），地质聚合物的难处理性质严重限制了相同技术对煤、泥炭、油母质和其它高分子量地质聚合物物质的研究的扩展。在这项研究中，主要研究人员将试图通过研究两种沉积物中的化石有机物质来解决这个问题：一种是来自秘鲁大陆边缘的相对年轻的海洋沉积物，另一种是来自蒙特雷组的中新世页岩。为了使这项艰巨的任务易于管理，他们的方法将主要集中在构成这些沉积物中有机基质的一类有机成分-脂质。使用一系列化学降解和溶剂提取步骤（化学分解），大分子结构将被分解，碎片，特别是脂质片段，将被识别和定量。通过以方法学的、逐步的方式进行化学溶解，研究人员希望能够推断出整个聚合物结构、其形成历史中所涉及的过程及其反应性。

One of the most challenging problems in the field of organic geochemistry is the determination of the chemical and physical structure of fossil organic macromolecules -- that is, macromolecules originating from living organisms but no longer contained in them. These 'geopolymers' are often of exceedingly high-molecular weight and so highly cross-linked that they are difficult to work with in the laboratory. Coal, peat, and kerogen are important examples. While technological developments in chemical instrumentation over past three decades have allowed us to penetrate the structures of a great many macromolecules in living organisms (e.g., proteins, nucleic acids), the intractable nature of geopolymers has severely limited extension of the same technology to the study of coal, peat, kerogen, and other high molecular weight geopolymeric substances. In this study, the principal investigators will attempt to make inroads into this problem by studying the fossil organic matter in two sediments: a relatively young marine sediment from the Peru continental margin, and a Miocene shale from the Monterey Formation. To keep this difficult task manageable, their approach will concentrate primarily on just one class of organic constituents that make up the organic matrix in these sediments - lipids. Using a series of chemical degradation and solvent extraction steps (chemolysis), the macromolecular structure will be broken apart and the pieces, especially lipid fragments, will be indentified and quantified. By carrying out the chemolysis in a methodological, stepwise fashion, the investigators hope to be able to draw inferences about the overall polymeric structure, the processes involved in its formative history, and its reactivity.