Diagenesis and CaCO3 Dissolution in Sediments of the EasternEquatorial Atlantic Ocean and Continental Margin Off Cape Hatteras

赤道东部大西洋和哈特拉斯角大陆边缘沉积物中的成岩作用和 CaCO3 溶解

• 批准号: 9617430
• 负责人: William Martin
• 金额: $ 45.33万
• 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: 1998-06-01 至 2001-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9617430&HistoricalAwards=false
• 关键词: Diagenesis; CaCO3; Dissolution; Sediments; EasternEquatorial

9617430 Martin Dissolution of CACO3 will be measured in marine sediments of the eastern tropical Atlantic Ocean and western north Atlantic continental rise. The study areas have key characteristics for extending understanding of CaCO3 dissolution: (1) the range in saturation of bottom waters with respect to calcite, from CO32-=28 to =40, includes both substantial undersaturation -- ideal for constraining parameters in dissolution models -- and supersaturation, which is essential for the direct measurement of dissolution rates in sediments above the calcite lysocline; (2) the values of the important, dissolution-controlling Corg : CACO3 ratio in the material raining to the sea floor appear to be quite high, in some areas exceeding 2.5 mol/mol, in contrast to other above- saturation horizon regions that have been studied previously; (3) the area includes both a regions of high sediment O2 demand (the Cape Verde Plateau and western N. Atlantic margin) and one of lower demand, typical of non-upwelling, pelagic areas ( the Sierra Leone Rise); (4) the Sierra Leone Rise has been the site of extensive sedimentological and paleoceanographic investigation, resulting in a substantial set of ancillary data for the analysis of organic matter oxidation and CaCO3 dissolution, and allowing evaluation of the sedimentological indicators to above-saturation horizon dissolution; and (5) the study areas include high flux sites with low to moderate %CaCO3 (W.N. Atlantic margin) and with high %CaCO3 (Cape Verde Plateau, allowing evaluation of this factor as an explanation for discrepancies in dissolution rates measured by pore water and benthic chamber techniques. The examination of the variability in sedimentary oxidation and dissolution processes over the range of conditions on the sea floor is essential to accurate interpretations of the sedimentary record and to model-based predictions of the ultimate fate of anthropogenic CO2.

9617430将在热带大西洋东部和北大西洋大陆隆起西部的海洋沉积物中测量碳酸钙的马丁溶解。研究区域具有扩大对CaCO3溶解的理解的关键特征：(1)底层水相对于方解石的饱和度范围从CO32-=28到=40，既包括严重的欠饱和度--非常适合于在溶解模型中约束参数--也包括过饱和度，对于直接测量方解石溶跃层以上的沉积物的溶解速率是必不可少的；(2)在物质降雨到海底的物质中，控制溶解的重要的Corg：CaCO3比值似乎相当高，与以前研究的其他高于饱和层的区域相比，有些地区超过2.5mol/mol；(3)该地区既包括沉积物氧气需求量高的地区(佛得角高原和大西洋西部边缘)，也包括典型的非上升流、远洋区的低需求区(塞拉利昂隆起)：(4)塞拉利昂隆起进行了广泛的沉积学和古海洋学调查，为有机质氧化和CaCO3溶解分析提供了大量的辅助资料，并使沉积学指标能够评价到超过饱和层的溶解作用；(5)研究区域包括CaCO3含量低到中等的高通量场所(西北部大西洋边缘)和CaCO3含量高的场所(佛得角高原)，这使得评估这一因素可以解释用孔隙水和海底洞室技术测量的溶解速率的差异。研究各种海底条件下沉积氧化和溶解过程的可变性，对于准确解释沉积记录和以模型为基础预测人为二氧化碳的最终命运至关重要。