Organic-Mineral Interactions in Coastal Margin Sediments

海洋沉积物中有机质（OM）有四种物理形式：无矿物组合、与生物矿物结合、与成岩矿物聚集形成聚集体、吸附在矿物表面。 有机质类型的比例随沉积状态和氧暴露时间（OET）而变化。 在亚氧沃茨（OET 1 y）下的沉积物中，OM的主要形式是不同的碎屑（占总OM的65%）。 沿着大陆边缘，大多数有机质储存在那里，OET较温和（数年至数世纪），有机质的主要形式是矿物聚集体（50%）。 沿着大陆隆起，沉积物暴露在氧气中的时间较长（数百年至数千年），存在的少量OM主要吸附到成岩矿物（60%）。 与生物矿物质相关的有机质在总有机质中的比例一直很小（10%），但生物保护有机质的比例上升，接近总有机质的20%。 在这个项目中，华盛顿大学的研究人员将进行实验室实验，以评估聚集和OET对早期成岩作用的短期影响。 这些实验将直接测试是否是氧气本身导致OET效应，或者动物群和混合是否是更重要的贡献者。 同样，在一个封闭的峡湾系统（Clayoquot Sound，不列颠哥伦比亚省）的沉积动力学的实地调查将解决这个问题。 观察聚集作用对成岩作用的长期影响（反之亦然），从华盛顿和温哥华边缘回收的一组沉积物多岩心将被分成不同的物理部分，并使用14 C和d13 C同位素分析的组合进行探测（确定年龄和来源），氨基酸分析（以确定降解状态）、元素分析和X射线光电子能谱（XPS;以确定OM和矿物质相互作用以及OM胶厚度）。 这种多方面的方法将允许定量估计的短期降解率的不同物理形式的OM（即使他们有类似的散装OM组合物）和长期的影响，物理改造和OET的聚集丰度和OM保存。 这项研究还将有助于探索的过程中，可能是负责陆地OM和海洋OM的替代品的损失，在岩石矿物的运输和buriing.Broader影响：有机物质的循环和存储的理解是重要的，在广泛的范围内，是经得起各种层次的细节和经验的评估。 该项目将为研究生提供关于碳循环和培训的量化速率和归宿信息。 此外，它将利用本科生指导计划，学徒学习计划，本科生研究人员由两名教员指导，并接受多学科研究培训

ABSTRACTOCE-0454698There are four physical forms of organic matter (OM) in marine sediments; free of mineral association, bound within biogenic minerals, clustered with lithogenic minerals forming aggregates, and sorbed to mineral surfaces. Proportions of the types of OM change with depositional regime and oxygen exposure time (OET). In sediments underlying suboxic waters (OET 1y), the predominant form of OM is as distinct debris (65% of the total OM). Along continental margins, where most OM is stored and where OET is more moderate (years to centuries), the predominant form of OM is within mineral aggregates (50%). Along the continental rise, where sediments are exposed to oxygen for longer periods (centuries to millennia), the little OM that is present is predominantly sorbed to lithogenic minerals (60%). OM in association with biogenic minerals is a consistently small (10%) component of total OM except for the rise, where biogenic- protected OM approaches 20% of total OM. In this project, researchers at the University of Washington will conduct laboratory experiments to evaluate the short-term effects of aggregation and OET on early diagenesis. These experiments will directly test whether it is oxygen itself that causes the OET effect, or whether fauna and mixing are more important contributors. Similarly, a field investigation of sediment dynamics in a closed fjord system (Clayoquot Sound, British Columbia) will address this question. To look at the longer-term effects of aggregation on diagenesis (and vice-versa), a set of sediment multicores recovered from the Washington and Vancouver margins will be split into different physical fractions and probed using a combination of .14C and d13C isotopic analyses (to determine age and source), amino acid analyses (to determine degradation state), elemental analyses, and X-ray photoelectron spectroscopy (XPS; to determine OM and mineral interactions and OM glue thicknesses). This multi-faceted approach will permit quantitatively estimation of both the short-term degradation rates of the different physical forms of OM (even if they have similar bulk OM compositions) and the longer-term influence of physical reworking and OET on aggregate abundance and OM preservation. This study will also help probe the processes that may be responsible for the loss of terrestrial OM and its replacement by marine OM during lithogenic mineral transport and burial.Broader Impacts: An understanding of organic matter cycling and storage is important on a broad scale and is amenable to evaluation at a variety of levels of detail and experience. This project will provide quantified rate and fate information on carbon cycling and training for graduate students. In addition, it will leverage an undergraduate mentoring program, the Apprenticeship Learning Program, where undergraduate researchers are mentored by two faculty members and receive multidisciplinary research training