Organic Coatings on Sedimentary Mineral Grains

将验证A孔隙保护假说，为观察到的有机碳形态提供机理依据。有机质与矿物表面的关系将通过：(1)评估有机质在矿物颗粒上的覆盖程度来发展。有机碳是局限于小区域还是广泛分布？广泛的分散意味着主要组分一定存在于小孔隙中。这个问题将通过完成一种基于气体在矿物表面吸附的有前途的新方法的开发来检验。完井工作将侧重于裸露矿物表面的性质，确定由矿物学、微地形和源区域引起的变化；(2)通过仔细检查去除有机涂层对孔隙尺寸分布的影响，确定天然有机物是否优先存在于小的介孔中。该试验还将涉及在未涂覆的矿物颗粒上添加人工有机涂层的反向过程，从而深入了解有机物质吸附的定位和机制。(3)通过一系列的粒径排除和吸附实验，测试矿物颗粒上的这些小介孔是否确实可以排除水解酶。这些方法将在来自世界各地的各种沉积物上进行。除了测试孔隙假设外，该项目的结果将对碳循环、矿泉水相互作用和污染物循环产生重要影响。

9633230 Mayer A pore protection hypothesis will be tested, provide a mechanistic basis for the observed patterns of organic carbon. Relationships between organic matter and mineral surfaces will be developed by: (1) Assessing the extent of organic matter coverage on mineral grains. Is organic carbon localized in small areas or is it widely dispersed? Wide dispersal implies that major fraction must reside in small pores. This question will be tested by completing development of a promising new method based on the of gas adsorption onto mineral surfaces. Completion work will focus on the nature of naked mineral surfaces, identifying variations that derive from mineralogy, microtopography, and source area; (2) Determining if natural organic matter resides preferentially inside small mesopores, by careful examination of the effects of removal of organic coatings on the size distribution of pores. This test will also involve the reverse process of adding artificial organic coatings to uncoated mineral grains, providing insight into the localization and mechanism of organic matter sorption. (3) Testing if these small mesopores on mineral grains can indeed exclude hydrolytic enzymes, by performing a series of size- exclusion and adsorption experiments. These approaches will be carried out on a wide variety of sediments from around the world. In addition to testing the pore hypothesis, results from this project will have important implications for carbon cycling, mineral-water interactions, and pollutant cycling.