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

浅层海相碳酸盐沉积物碳酸盐溶解再循环通量的大小：孔隙流体和沉积物地球化学评价

• 批准号: 8811058
• 负责人: Lynn Walter
• 金额: $ 9.1万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-01-01 至 1989-11-08
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8811058&HistoricalAwards=false
• 关键词: Magnitude; Carbonate; Dissolution; Recycling; Flux

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.

本项目将研究佛罗里达湾浅海碳酸盐沉积物的孔隙流体和沉积物地球化学，以评估其作为碳酸钙和有机质回收点的意义。一项初步研究的结果表明，与先前的假设相反，沉积物孔隙流体中发生了显著的碳酸盐溶解，这是由硫酸盐还原过程中有机物氧化释放的碳酸驱动的。扩大的调查将在更大的环境和水深范围内评估这一过程，而不是在试点研究中。孔隙流体化学（重点是Ca/Cl、硫酸盐还原度和碳酸体系参数）将被确定，硫酸盐还原率将被实验测量。沉积物有机碳含量和孔隙流体碳同位素组成的测定将更好地约束硫酸盐还原的控制和后果。研究结果将对浅层碳酸盐陆架沉积在碳酸钙和有机质的海洋循环中所起的作用提供严格的评估。长期以来，人们一直认为碳酸钙的溶解发生在深水中。然而，试验项目的结果证明，大部分溶解发生在浅水中。该项目将收集佛罗里达湾的沉积岩心，并在收集后立即开始对沉积物进行地球化学分析。这项研究将把这一重要的地球化学过程的知识扩展到一个更深入的新环境，以研究其他环境参数在这一过程中的作用。