OCE-PRF: Towards Quantifying Calcium Carbonate Sediment Dissolution During Marine Diagenesis

OCE-PRF：量化海洋成岩过程中碳酸钙沉积物溶解

• 批准号: 2205984
• 负责人: Mohammed Hashim
• 金额: $ 37.65万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2205984&HistoricalAwards=false
• 关键词: OCE; PRF; Towards; Quantifying; Calcium

OCE-PRF Towards Quantifying Calcium Carbonate Sediment Dissolution During Marine DiagenesisThe goal of the project is to investigate dissolution of calcium carbonate (CaCO3) in sediments below the seafloor and determine its importance to the chemistry of seawater. This project uses sediment samples and chemical data collected from different parts of the ocean during the past five decades by scientific ocean drilling programs. Sediment dissolution of carbonate can lessen the impact of ocean acidification, the process that causes the pH of the ocean to decrease due to the uptake of carbon dioxide (CO2) from the atmosphere. Ocean acidification threatens the survival of marine organisms, such as oysters, clams, and coral reefs, which could alter marine food chains and food supply to humans. By improving understanding of carbonate dissolution in the ocean, results from this project will enable better predictions of the effects of ocean acidification on marine organisms. This will advance the progress of science and contribute to the knowledge that can inform public policy. In addition, understanding carbonate sediment dissolution serves other important purposes. For example, dissolution can create small spaces between sediments that may get filled with groundwater once sediments convert to rocks over millions of years. Thus, understanding the occurrence and spatial distribution of spaces within rocks may help determine the volume and movement of groundwater in subsurface aquifers. This project provides support for a postdoctoral research fellow and research training opportunities for students through the Summer Student Fellowship and Woods Hole-wide Partnership Education Programs at the Woods Hole Oceanographic Institution. Carbonate mineral dissolution is an integral part of the alkalinity and carbon cycles in the ocean and is expected to play an increasingly significant role in mediating changes in ocean chemistry as atmospheric CO2 continues to rise. The goal of this project is to provide thermodynamic constraints necessary for quantifying carbonate sediment dissolution in marine diagenetic environments. Specifically, the CaCO3 saturation state of pore fluids will be calculated in 365 globally distributed sites from previous scientific ocean drilling expeditions using a specially developed Pitzer ion activity model which is particularly useful for calculating activity coefficients in high ionic strength solutions such as those that characterize most diagenetic environments. These calculations will be substantiated with geochemical and textural analyses of sediment samples from four representative sites to identify the specific diagenetic processes (e.g., dissolution, precipitation, and recrystallization) and document the conditions responsible for their occurrence and prevalence. The immediate advantage of calculating the saturation state of pore fluids is that such data can be used to estimate carbonate sediment dissolution below the seafloor and quantify its contribution to the alkalinity and carbon cycles, which will lead to more accurate predictions of the consequences of ocean acidification. Another benefit of the global saturation state dataset is that it will improve our understanding of authigenic carbonate precipitation and its link to the carbon cycle over Earth history, which has been proposed as a significant sink for carbon. Furthermore, by complementing the thermodynamic calculations with textural and geochemical analyses, this project will parse out various diagenetic processes and identify the sedimentological and geochemical conditions responsible for their occurrence. Such knowledge is crucial for evaluating the impact of diagenesis on the carbonate-hosted paleoenvironmental proxies. Collectively, this project will pave the way towards a mechanistic understanding of carbonate diagenesis. This will provide important constraints on the oceanic alkalinity cycle, carbon burial rates, and geochemical proxies, which ultimately help us better understand the future of our ocean system in the context of climate change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

OCE-PRF用于量化海洋成岩作业期间碳酸钙沉积物溶解的目标是研究碳酸钙（CACO3）在海底以下的沉积物中溶解（CACO3），并确定其对海水化学的重要性。该项目使用科学海洋钻井程序在过去的五十年中，使用从海洋不同地区收集的沉积物样品和化学数据。碳酸盐的沉积物溶解可以减少海洋酸化的影响，海洋酸化的影响会导致海洋pH值减少，这是由于大气中二氧化碳（CO2）的吸收而减少的。海洋酸化威胁着海洋生物的生存，例如牡蛎，蛤and和珊瑚礁，这可能会改变海洋食品链和对人类的粮食供应。通过提高对海洋中碳酸盐溶解的理解，该项目的结果将更好地预测海洋酸化对海洋生物的影响。这将提高科学的进步，并为可以为公共政策提供信息的知识做出贡献。此外，了解碳酸盐沉积物溶解还可以解决其他重要目的。例如，溶解可以在沉积物之间产生较小的空间，一旦沉积物转变为数百万年的岩石，可能会填充地下水。因此，了解岩石内空间的发生和空间分布可能有助于确定地下含水层中地下水的体积和运动。该项目为通过夏季学生奖学金和伍兹霍尔孔海洋学机构的伍兹霍尔·伙伴关系教育计划提供了博士后研究员和研究培训机会的支持。碳酸盐矿物质溶解是海洋中碱度和碳周期不可或缺的一部分，随着大气CO2的持续增长，预计在介导海洋化学变化中起着越来越重要的作用。该项目的目的是提供用于量化海洋成岩环境中碳酸盐沉积物溶解所需的热力学约束。具体而言，使用特殊开发的Pitzer离子活性模型，将在365个全球分布的位点中计算孔隙流体的CACO3饱和状态，该模型在高离子强度解决方案中特别有用，例如在高离子强度解决方案中，例如表征大多数基质环境的那些。这些计算将通过来自四个代表性地点的沉积物样品的地球化学和纹理分析来证实，以识别特定的成岩过程（例如溶解，降水和重结晶），并记录负责其发生和普遍性的条件。计算孔隙流体饱和态的直接优势在于，该数据可用于估计海底下方的碳酸盐沉积物溶解，并量化其对碱度和碳循环的贡献，这将导致更准确地预测海洋酸化后果。全球饱和状态数据集的另一个好处是，它将提高我们对地球历史上碳酸盐降水及其与碳循环的联系，这已被认为是碳的重要水槽。此外，通过通过质地和地球化学分析来补充热力学计算，该项目将解析各种成岩过程，并确定负责其发生的沉积和地球化学条件。这种知识对于评估成岩作用对碳酸盐托管的古环境代理至关重要。总体而言，该项目将为对碳酸盐成岩作用的机械理解铺平道路。这将为海洋碱度周期，碳埋葬率和地球化学代理提供重要的限制，最终帮助我们更好地了解气候变化的环境中的海洋系统的未来。该奖项反映了NSF的法定任务，并通过评估该基金会的智力功能和广泛的影响来审查CRITERIA。