Magnitude of the Carbonate Dissolution Recycling Flux from Shallow Marine Carbonate Sediments: Evaluation from Pore Fluid and Sediment Geochemistry

本项目将研究孔隙流体和沉积物 佛罗里达浅海碳酸盐沉积物的地球化学 湾，以评估其重要性，作为回收网站 碳酸钙和有机物。 试点结果 研究表明，与先前假设相反， 碳酸盐溶解发生在沉积物孔隙流体中， 有机物氧化过程中释放的碳酸 硫酸盐还原 扩大调查将评估 这一过程跨越了更广泛的环境和水 深度超过了试点研究中可达到的深度。 孔隙流体 化学（强调Ca/Cl，硫酸盐还原程度， 碳酸系统参数）将被确定， 实验测量的还原率。 沉积物有机 孔隙流体的碳含量和碳同位素组成 将决心更好地约束控制， 硫酸盐还原的后果。 结果将提供 严格评估浅层碳酸盐陆架 沉积物在碳酸钙的海洋循环中起作用， 有机物 %%% 长期以来，人们一直认为碳酸钙的溶解 发生在深水中。 试点项目的结果， 然而，证明了大量溶解发生在浅水中。 该项目将收集佛罗里达湾的沉积岩芯 并立即开始对沉积物进行地球化学分析 收集后。 这项研究将扩大知识 这一重要的地球化学过程的新环境， 更深入地研究其他环境 过程中的参数。

This project will investigate pore fluid and sediment geochemistry of shallow marine carbonate sediments from Florida Bay in order to assess their significance as recycling sites for calcium carbonate and organic matter. Results of a pilot study suggest that, contrary to prior assumptions, significant carbonate dissolution occurs in sediment pore fluids, driven by carbonic acid liberated from organic matter oxidation during sulfate reduction. The expanded investigation will evaluate this process across a wider range of environments and water depths than were accessible in the pilot study. The pore fluid chemistry (emphasis on Ca/Cl, degree of sulfate reduction, and carbonic acid system parameters) will be determined and sulfate reduction rates measured experimentally. Sediment organic carbon contents and carbon isotopic compositions of pore fluids will be determined to better constrain controls and consequences of sulfate reduction. Results will provide a rigorous assessment of the role shallow carbonate shelf deposits play in the oceanic cycles of calcium carbonate and organic matter. %%% The dissolution of calcium carbonate has long been thought to occur in deep water. The results of the pilot project, however, prove that much dissolution occurs in shallow water. This project will collect sedimentary cores from Florida Bay and begin geochemical analyses of the sediments immediately after their collection. This study will expand the knowledge of this important geochemical process to a new environment at greater depth to examine the role of other environmental parameters on the process.