Carbon Isotope Constraints on Benthic Carbonate Dissolution in the Eastern Equatorial Atlantic and The North Carolina Continental Margin

碳同位素对东赤道大西洋和北卡罗来纳大陆边缘底栖碳酸盐溶解的限制

• 批准号: 9730932
• 负责人: Daniel McCorkle
• 金额: $ 25.03万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2002-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9730932&HistoricalAwards=false
• 关键词: Carbon; Isotope; Constraints; Benthic; Carbonate

Pore water and benthic flux chamber concentration (ECO2) and isotopic composition (o13C) measurements will be used to investigate the factors which control the rate of carbonate dissolution at the sea floor. The major goal of this work is to document the occurrence and impact of "metabolic" carbonate dissolution, dissolution driven by benthic decomposition reactions in sediments above the calcite saturation horizon, where the bottom waters are supersaturated with respect to calcite. Pore water samples will also determine the /\14C of dissolved inorganic carbon and dissolved organic carbon. The field work for this project will be carried out during two upcoming process studies of benthic carbonate dissolution. PIs. R. Jahnke, W. Martin, and F. Sayles have been funded to carry out coordinated dissolution studies in the eastern equatorial Atlantic Ocean (Cape Verde Plateau and Sierra Leone Rise) in 1998 and on the continental margin off North Carolina in 1999. Jahnke will carry out direct flux measurements (oxygen, nutrients, alkalinity, and calcium) using benthic flux chambers, and Martin and Silks will use in situ sampling techniques to measure pore water profiles of oxygen, nutrients, alkalinity, ECO2, calcium, iron, and manganese. Samples from Jahnke's benthic flux chambers and from Sayles and Martin's in situ pore water will be analyzed in this study using del C-13. These samples will provide independent estimates of the relative contributions of decomposition-derived CO2 (o13C = -20 o/oo) and dissolution- derived CO3 -2 (o13C = 0 o/oo) to the flux of ECO2 out of the sediments. It is particularly important to make these independent isotopic estimates because alkalinity and calcium flux estimates from Jahnke's benthic flux chamber and from Sayles' and Martin's in situ pore water sample yielded conflicting results in a previous dissolution study on the Ceara Rise (western equatorial Atlantic). In that Ceara Rise s tudy, both pore water and benthic flux chamber o13C results agreed with the pore water alkalinity and calcium data (and with microelectrode profiles of pore water pH and oxygen), indicating substantial metabolic dissolution at and above the saturation horizon.

孔隙水和海底通量室浓度（ECO 2）和同位素组成（o 13 C）的测量将用于调查控制海底碳酸盐溶解速率的因素。 这项工作的主要目标是记录“代谢”碳酸盐的发生和影响 溶解、溶解驱动 通过 高于方解石饱和度的沉积物中的底栖分解反应 地平线， 哪里 的 底部 沃茨 相对于方解石来说是过饱和的。 孔隙水样品还将测定溶解的无机碳和溶解的有机碳的14 C。 该项目的实地工作将在即将进行的两项海底碳酸盐溶解过程研究期间进行。 私家侦探R.扬克，W. Martin和F. 1998年和1999年，Sayles分别在赤道大西洋东部（佛得角高原和塞拉利昂海隆）和北卡罗来纳州外的大陆边缘获得资助，进行协调溶解研究。 Jahnke将使用底栖通量室进行直接通量测量（氧气、营养物质、碱度和钙），Martin和Silks将使用原位取样技术测量氧气、营养物质、碱度、ECO 2、钙、铁和锰的孔隙水剖面。 在这项研究中，将使用del C-13分析来自扬克的底栖通量室以及塞尔斯和马丁的原位孔隙水样品。 这些样品将提供分解产生的CO2（o 13 C = -20 o/oo）和溶解产生的CO 3 - 2（o 13 C = 0 o/oo）对沉积物中ECO 2通量的相对贡献的独立估计。 这是特别重要的，使这些独立的同位素估计，因为碱度和钙通量估计从扬克的海底通量室和塞尔斯和马丁的原位孔隙水样品产生了矛盾的结果，在以前的溶解研究塞阿拉上升（西赤道大西洋）。 在塞阿拉海隆的研究中，孔隙水和底栖通量室的13 C结果与孔隙水碱度和钙数据（以及孔隙水pH值和氧的微电极分布图）一致，表明在饱和层和饱和层以上存在大量代谢溶解。