Diagenesis and CaCO3 Dissolution on the Ceara Rise, Equatorial Atlantic

本课题研究的是过饱和底水覆盖的沉积物中有机物的氧降解导致的CaCO3溶解。这项工作的重点是确定在一定深度和饱和度范围内发生的溶解量。采样分析方案旨在研究含氧有机物降解/CaCO3溶解的化学计量学，通过分析和建模来约束溶解速率常数，并评估沉积CaCO3溶解的平衡常数。该油田位于西阿拉隆起，从西阿拉隆起的顶部到相邻底板的样带将是有机碳氧化和CaCO3溶解过程中产生或消耗的化学物质孔隙水剖面的来源。样品将通过现场全芯挤压机进行取样。这项工作正在与雷默斯的一个单独项目进行协调，该项目利用微电极分析器技术在现场研究孔隙水化学，而另一个项目则由扬克利用底栖生物通量室测量相同参数的底栖生物通量。

This research project is a study of the dissolution of CaCO3 that results from the oxic degradation of organic matter in sediments overlain by supersaturated bottom waters. The work centers on determining the amounts of dissolution occurring over a range of depths and saturation states. The sampling and analysis scheme is designed to permit study of the stoichiometry of oxic organic matter degradation/CaCO3 dissolution, to constrain the rate constant of dissolution through analysis and modelling, and to evaluate the equilibrium constant for dissolution of sedimentary CaCO3. The field site is the Ceara Rise, and a transect from the crest of the Rise to the adjacent floor will be the source of pore water profiles of chemical species produced or consumed during organic carbon oxidation and CaCO3 dissolution. The samples will be taken by means of an in situ Whole Core Squeezer. This work is being coordinated with a separate project by Reimers to study pore water chemistry at the site with a microelectrode profiler technique, and another by Jahnke to measure benthic fluxes of the same parameters with a benthic flux chamber.