Collaborative Research: Understanding substrate limitation and Lithium and Silicon isotope fractionation during secondary clay formation in marine systems

合作研究：了解海洋系统次生粘土形成过程中的底物限制以及锂和硅同位素分馏

• 批准号: 1923802
• 负责人: Yuanzhi Tang
• 金额: $ 33.89万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-01-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1923802&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; substrate; limitation; Collaborative; Research; Understanding; substrate; limitation

A long-standing topic of investigation in the field of chemical oceanography is understanding the processes that deliver elements to, and remove them from, seawater. There has long been a "missing sink" in the global marine silicon (Si) budget in that removal to sediments did not appear to balance the inputs from rivers. Several decades ago, it was postulated that "reverse weathering" in marine sediments could be this missing sink. In this process, the weathering process that takes place on land, whereby silicon is removed from minerals and dissolved in water, would be reversed and these minerals would be reconstituted in marine sediments through the formation of clays. Evidence for this process was very difficult to obtain, and only recently have studies using advanced measurement techniques shown that the global magnitude of marine reverse weathering could account for all the missing sink term in the global Si budget. If validated, this means reverse weathering would represent the largest individual sink for marine Si identified to date, with most of this burial occurring in a relatively small area of the ocean, the land-sea interface. Moreover, the continued upward revision of the marine reverse weathering rate has implications for the sequestration of other elements (e.g. iron, aluminum) and for other coastal processes (e.g. ocean acidification, as carbon dioxide is a byproduct of the reverse weathering process). This project aims to understand the most important factors affecting how fast reverse weathering occurs, and developing new approaches to evaluate this process in the field environment. Beyond the scientific pursuits, this project will support an early career researcher, a postdoctoral investigator, a graduate student, and undergraduate interns. It will also support high school outreach through science fair participation and annual scholarships for students wishing to pursue Marine Science education. This project will develop a community outreach activity to be used annually during the Atlanta Science Festival, Georgia's biggest science fair that showcases science and technology to the public. Finally, it will build capacity for silicon isotope measurements in the U.S.In this project, the investigators propose to understand the driving factors of marine secondary clay formation and facilitate the determination of reaction degree in the field using a novel dual silicon and lithium stable isotope approach. The overarching goals are: 1) to better constrain the geochemical factors, kinetics, and mechanisms involved in secondary clay formation from diatom-produced silica (bSiO2); this will be done by conducting controlled laboratory experiments using pure mineral phases, diatom bSiO2, and artificial seawater; 2) to test the validity of the isolated geochemical factors by conducting mesocosm incubation experiments using field sediment materials, diatom bSiO2, and seawater; and 3) to experimentally determine whether laboratory-derived Li and Si isotope fractionations are valid during secondary clay formation under marine sediment conditions. This work addresses one of the eight Ocean Sciences Priorities identified in The National Research Council's 2015-2025 Decadal Survey of Ocean Sciences, specifically "How have ocean biogeochemical and physical processes contributed to today's climate and its variability, and how will this system change over the next century?" These results have fundamental importance to understanding the factors regulating marine elemental sequestration (e.g. Si, C, Fe, Al, Mg, K) and those driving global climate through oceanic CO2 evolution, a byproduct of the reverse weathering reaction, in marine sediments.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.

化学海洋学领域的一个长期调查主题是了解将元素传递给海水并将其删除的过程。在全球海洋硅（SI）预算中，长期以来一直存在“缺失”，因为将其拆除到沉积物中似乎并没有平衡河流的投入。几十年前，据推测，海洋沉积物中的“反向风化”可能是缺失的水槽。在此过程中，将在陆地上进行的风化过程，从而将硅从矿物质中取出并溶解在水中，将被逆转，这些矿物将通过粘土的形成在海洋沉积物中重构。这一过程的证据很难获得，直到最近才使用高级测量技术进行了研究，表明全球逆向风化的全球幅度可以解释全球SI预算中所有缺失的下沉术语。如果经过验证，这意味着反向风化将代表迄今为止确定的海洋SI最大的单个水槽，大部分埋葬发生在海洋相对较小的土地界面。此外，海洋反向风化速率的持续向上修订对其他元素（例如铁，铝）和其他沿海过程（例如海洋酸化，因为二氧化碳是二氧化碳是反向面对面过程的副产品）的影响。该项目旨在了解影响风化速度发生速度的最重要因素，并开发新的方法来评估该过程在现场环境中。 除了科学追求之外，该项目还将支持早​​期职业研究员，博士后研究员，研究生和本科实习生。它还将通过科学博览会参与和希望接受海洋科学教育的学生的年度奖学金来支持高中宣传。该项目将开发一项社区外展活动，每年在佐治亚州最大的科学博览会上每年使用，向公众展示科学和技术。最后，它将在美国该项目中建立硅同位素测量的能力，研究人员建议了解海洋次级粘土形成的驱动因子，并促进使用新型的双硅和锂稳定的同位素方法来确定田间反应程度。总体目标是：1）更好地限制从硅藻生产的二氧化硅（BSIO2）中涉及的二级粘土形成的地球化学因素，动力学和机制（BSIO2）；这将通过使用纯矿物相，硅藻BSIO2和人造海水进行受控实验室实验来完成。 2）通过使用野战沉积物材料，硅藻BSIO2和海水进行中cosm孵育实验来测试分离的地球化学因子的有效性； 3）实验确定实验室衍生的LI和SI同位素分馏在海洋沉积物条件下在二次粘土形成期间是否有效。 这项工作介绍了国家研究委员会2015 - 2025年对海洋科学的十年级调查中确定的八项海洋科学重点之一，特别是“海洋生物地球化学和物理过程如何有助于当今的气候及其变化，以及该系统在下一世纪将如何变化？”这些结果对于理解调节海洋元素隔离的因素（例如Si，C，Fe，Al，Mg，K）以及那些通过Oceanic CO2 Evolution（反向风化反应的副产品）在Marine Sediments中的副产品，这是NSF奖励的范围，这反映了NSF的法定任务和宽广的支持，这反映了NSF的法规及其范围的支持，这是基本的重要性。 标准。