SGER: Clay Microfabric Signatures Driving Organic Matter Preservation in Marine Sediment: Micro- to Nano-scale Properties and Processes

摘要：细粒沉积物中微纳米级屏障的观察、识别、定量测量和化学物理实验的能力，不仅有可能彻底改变我们对海洋沉积物中有机质（OM）保存的认识，而且有可能改变我们对细粒沉积物结构及其对沉积物物理性质（如孔隙度、渗透率和水力导电性）的影响的认识。该项目旨在开发透射电子显微镜（TEM）和组织化学染色技术，这些技术将允许对细颗粒沉积物的未受干扰的微结构和矿物基质中特定有机化合物的分布进行成像和分析。技术开发将首先在已知成分的人工制造的模型沉积物上进行，然后应用于天然海洋沉积物聚集体。初步研究的天然聚集体将包括多毛类蠕虫粪便颗粒。之所以选择这些，是因为它们易于生产，并且易于在实验室中通过生物力学手段（即沉积物通过蠕虫的肠道）进行复制。它们还包含两个重要的端元粘土微织物特征：(1)沿颗粒边界排列的面向面对面的粘土薄片（结构域和“瓦”）和(2)由颗粒内部边缘面向的织物（“纸牌屋”或随机排列的结构域）主导的开放式有机粘土网络。一旦这些技术可以可靠地应用于自然样品，将进行两个试点实验，旨在研究粘土微织物对海洋沉积物中OM保存的影响，以证明该技术在解决海洋科学界重要问题方面的效用。更广泛的影响包括为其他TEM相关的技术方法提供基础，以研究细粒度海洋沉积物中OM的保存和储存，并在此基础上建立其他创新的TEM和样品制备技术；为模型的发展提供现实世界的基础，这些模型描述了有机粘土聚集体中被捕获的OM的行为，以及OM在不同的化学、物理和环境条件下随时间的降解速度；支持国家科学基金会在教育、培训、性别和种族多样性方面的目标。

Abstract: Proposal # - 0438079 The ability to observe, identify, quantitatively measure, and perform chemical and physical experiments with micro- and nanoscale barriers in fine-grained sediments has the potential to revolutionize our understanding not only of organic matter (OM) preservation in marine sediments, but also of fine-grained sediment structure and its effects on sediment physical properties such as porosity, permeability, and hydraulic conductivity. This project seeks to develop transmission electron microscope (TEM) and histochemical staining techniques that will allow imaging and analysis of both the undisturbed microfabric of fine-grained sediments and the distribution of specific organic compounds within the mineral matrix. Technique development will be initially carried out on artificially created model sediments of known composition and then applied to natural marine sediment aggregates. Natural aggregates for the pilot study will consist of polychaete worm fecal pellets. These were chosen because they are easy to produce and are easily reproducible in the laboratory by biomechanical means (i.e., passage of sediment through the worm's gut). They also contain two important end member clay microfabric signatures: (1) aligned face-to-face-oriented clay platelets (domain and "shingle") along the border of the pellets and (2) open organo-clay networks dominated by an edge-to-face fabric ("house of cards", or random arrangement of domains) in the pellet interior. Once the techniques can be reliably applied to natural samples, two pilot experiments designed to study the impact of clay microfabric on the preservation of OM in marine sediments will be performed to demonstrate the utility of the technique for addressing questions of importance to the marine science community. Broader impacts include providing a basis for other TEM-related technical approaches for studying OM preservation and storage in fine-grained marine sediments upon which other innovative TEM and sample preparations techniques can be built; providing a real-world basis for the development of models describing the behavior of OM trapped in organo-clay aggregates and the rates at which OM degrades with time and under different chemical, physical, and environmental conditions; and support of NSF goals in education, training, and gender and ethnic diversity.