Radiocarbon as a Tool for Studying Organic Matter Diagenesis in Rapidly Accumulating, Continental Margin Sediments: Linking Bulk Organic Matter and Molecular Level Studies

摘要沉积物中有机质的氧化作用在广泛的地球化学循环中起着核心作用。 尽管有机地球化学和孔隙水取样和模拟的最新进展使我们对这一过程的理解有所提高，但海洋地球化学家尚未对沉积成岩作用的定量模型取得令人满意的描述。伍兹霍尔海洋研究所的研究人员将通过以下途径进行研究，以提高我们对大陆边缘沉积物中有机物氧化的定量认识：将溶质和固体成分测量与溶解相和固相C的碳同位素组成（稳定碳和放射性碳）测定相结合。 该项目将与T博士合作进行。 埃格林顿说，他目前正在进行一个项目，研究大陆边缘沉积物中特定有机化合物的浓度和放射性碳年龄。 通过他们的共同努力，研究人员计划以其他不可能的方式研究有机地球化学工作中产生的假设。 他们将把工作重点放在三个领域：（1）使用放射性碳作为示踪剂调查边缘沉积物中有机物的氧化，（2）检验放射性碳定年的难降解有机化合物的分布可用于推断沉积物沉积后迁移的假设，（3）在埃格林顿小组对特定有机化合物的底层剖面进行测量的基础上，增加了对生物扰动混合速率和机制的测量，以计算一套反应性。 由此产生的无机和有机的综合观点将提供一个实质性的步骤，超越了在海底地球化学中一直是规范的单独的有机和无机研究。 他们还将在以下两个地点进行详细的溶质和固相测量：W站，这是监测物理海洋学参数和颗粒浓度的系泊设施所在地，以及一套系泊沉积物收集器，位于马萨诸塞州以南3 000米深处;与哈特拉斯角外的大西洋中部海湾沉积中心形成鲜明对比。就更广泛的影响而言，开发模型来研究海洋地球化学循环在全球碳和养分收支中的作用，是解释过去气候变化和预测未来变化的努力的一个关键部分。 该项目将通过收集新数据和研究解释数据的新方法，促进模型的开发。 它还将为研究生和本科生提供研究机会。 此外，PI将在他们教授的研究生水平沉积物地球化学课程中使用该项目的结果。

ABSTRACTOCE-0526389Organic matter oxidation in sediments plays a central role in a wide range of geochemical cycles. Although recent advances in organic geochemistry and pore water sampling and modeling have led to improvements of our understanding of the process, marine geochemists have not yet achieved a satisfactory description for quantitative models of sedimentary diagenesis.In this project, researchers at the Woods Hole Oceanographic Institution will conduct studies to advance our quantitative understanding of organic matter oxidation in continental margin sediments through the combination of solute and solid composition measurements with determinations of the carbon isotopic composition (stable C and radiocarbon) of dissolved and solid phase C. The project will be carried out in collaboration with Dr. T. Eglinton who is currently undertaking a project to study the concentration and radiocarbon age of specific organic compounds in continental margin sediments. Through their combined efforts, the researchers plan to examine hypotheses arising from the organic geochemical work in ways that would not otherwise be possible. They will focus the effort in 3 areas: (1) The use of radiocarbon as a tracer for investigating organic matter oxidation in margin sediments, (2) Examination of the hypothesis that distributions of radiocarbon-dated, refractory organic compounds can be used to infer post-depositional transport of sediments, (3) Adding measurements of bioturbation mixing rates and mechanisms to the Eglinton group's measurements of downcore profiles of specific organic compounds to calculate a suite of reactivities. The resulting combined inorganic and organic perspective will provide a substantial step beyond the separate organic and inorganic studies that have been the norm in benthic geochemistry. They will also carry out work with detailed solute and solid phase measurements at two locations: Station W, the location of moorings for monitoring physical oceanographic parameters and particle concentrations as well as a set of moored sediment traps, which is located at a depth of 3000m, south of Massachusetts; and a contrasting site at the Mid-Atlantic Bight depocenter off Cape Hatteras.In terms of broader impacts, the development of models to examine the role of marine geochemical cycles in global carbon and nutrient budgets is a key part of efforts to explain past climate changes and forecast future changes. This project will contribute to model development through both the collection of new data and the examination of new ways to interpret the data. It will also provide research opportunities for graduate and undergraduate students. In addition, the PIs will use results from this project in the graduate level Sediment Geochemistry course that they teach.