Interactions between Organic Matter and Minerals in Marine Sediment

摘要-0095287虽然海洋地球化学家已经知道沉积有机质主要以有机粘土聚集体的形式存在，但对这些聚集体的物理化学性质知之甚少。 在这个项目中，华盛顿大学的一个有机地球化学研究小组将对不同氧气暴露时间的海岸带沉积物进行系统调查，以检查有机颗粒的关联。 密度分级技术将用于量化有机粘土聚集体，并将确定密度级分的有机物组成。用于表征聚集体的分析技术将包括X射线光电子能谱（XPS）和基质辅助激光解吸电离飞行时间质谱（MALDI-TOF-MS），因为这些技术提供了关于有机物质量的独特观点，并且因为它们补充了传统测量（CHN，氨基酸水解等）。将进行实验室实验，以控制方式混合不同的矿物和有机材料，并监测有机粘土聚集体的形成和随后的微生物降解。从这两组研究中收集的信息将用于华盛顿海岸外的实地，在那里将对水柱和沉积物-水界面收集的新鲜材料进行有机-矿物相互作用评价。 特别强调将放在检查观察到的蛋白质，肽和氨基酸的降解模式，因为这些组件中观察到的沉积有机物的反应性和耐火性池。 XPS和MALDI-TOF-MS的沉积有机质成岩作用和有机-矿物相互作用的调查的应用将允许评估的表面相关的有机质的变化以及产生的蛋白质和肽在实验系统中的反应性的详细信息的散装特性。最终目标是量化矿物和有机物之间的功能关系，从而更好地确定如何利用这种关系来了解海洋环境中的有机碳循环。

ABSTRACTOCE-0095287Although marine geochemists have known for some time now that sedimentary organic matter is bound primarily as organic-clay aggregates, little is known about the physicochemical nature of these clusters. In this project an organic geochemistry research team at the University of Washington will conduct a systematic survey of coastal zone sediments with varying oxygen exposure times to examine the organic-particle association. Density fractionation techniques will be used to quantify organic-clay aggregates, and the organic matter composition of the density fractions will be determined. The analytical techniques used to characterize the aggregates will include X-ray Photoelectron Spectroscopy (XPS) and Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy (MALDI-TOF-MS) because these techniques offer unique views on organic matter quality and because they complement traditional measurements (CHN, amino acid hydrolysis, etc.). Laboratory experiments will be conducted in which different mineral and organic materials are mixed in a controlled fashion, and the formation and subsequent microbial degradation of organo-clay aggregates will be monitored. The information gathered from these two sets of studies will then be used in the field off the coast of Washington, where organic-mineral interactions will be evaluated for fresh materials collected in the water column and at the sediment-water interface. Special emphasis will be placed on examining the degradation patterns observed for proteins, peptides and amino acids because these components are observed in both the reactive and refractory pools of sedimentary organic matter. The application of XPS and MALDI-TOF-MS to the investigation of sedimentary organic matter diagenesis and organic-mineral interactions will allow appraisal of how both the bulk characteristics of surface-associated organic matter change as well as yield detailed information about the reactivity of proteins and peptides in the experimental systems. The ultimate goal is to quantify the functional relationship between mineral and organic matter and thus better determine how the relationship can be used to understand organic carbon cycling in the marine environment.