Ground-truthing lithium paleo-proxies: Experimental study on the Li incorporation and isotope fractionation during inorganic calcite and aragonite precipitation

真实的锂古代理：无机方解石和霰石沉淀过程中锂的掺入和同位素分馏的实验研究

• 批准号: 2001927
• 负责人: Joji Uchikawa
• 金额: $ 39.24万
• 依托单位: University of Hawaii
• 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: 2020-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2001927&HistoricalAwards=false
• 关键词: Ground; truthing; lithium; paleo; proxies

Chemical break down of continental silicate rocks (referred to as “weathering”) consumes atmospheric CO2. During this process, lithium (Li) contained in silicate rocks is released and eventually delivered into the ocean by rivers. Intensity of weathering is known to influence the amount and isotopic composition (δ7Li) of Li delivered into the ocean. Thus, changes in the concentration of Li in seawater and its δ7Li can provide valuable information on the history and evolution of silicate weathering and its roles in regulating global carbon cycle and the Earth’s climate. Calcium carbonate (CaCO3) minerals produced by certain groups of marine organisms are known to incorporate trace amounts of Li from seawater, and thus they can be used as a recorder for those changes. However, our current understanding on how Li is incorporated into CaCO3 and what controls the process is extremely limited. In this study, researchers from the University of Hawaii (UH) will perform a series of laboratory experiments to better understand the mechanism of Li incorporation into CaCO3. This work will pave the road for further development in the use of marine CaCO3 minerals as the tracer for past changes in seawater Li and hence continental silicate weathering. The project will enhance education and career development in the geosciences for graduate and undergraduate students at the University of Hawaii. This team will also talk about their findings in the annual open house events such as “Mad About Science” and “Science Alive” at the Bishop MuseumWeathering of continental silicate rocks while releasing and eventually delivering Li into the ocean by rivers. Changes in seawater Li concentration and δ7Li can provide valuable information on the history and evolution of silicate weathering and its roles in regulating global carbon cycle and the Earth’s climate. CaCO3 minerals that incorporate Li can be used as a recorder for those changes. This study will be based on well-established inorganic CaCO3 precipitation experiments, where an array of solution physicochemical parameters will be systematically varied from the same control condition for straightforward comparisons of their impacts on δ7Li and Li concentrations in CaCO3. Furthermore, with the use of seeds, both calcite and aragonite samples will be synthesized under identical experimental conditions to examine the polymorphic controls on Li incorporation. This project is expected to provide by far the most complete experimental datasets, which will be combined with the use of surface kinetic modelling to establish a firm inorganic (kinetic and equilibrium) baseline for the elemental and isotopic partitioning of Li between solution and CaCO3 minerals. The project enhances education and career development in the geosciences for graduate and undergraduate students at the University of Hawaii, where the student population has diverse and often underrepresented ethnic background. This team will also talk about their findings in the annual open house events such as “Mad About Science” and “Science Alive” at the Bishop MuseumThis 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.

连续硅酸盐岩石（称为“风化”）的化学分解会消耗大气二氧化碳。在此过程中，有机硅岩石中包含的锂（Li）被释放，并最终被河流传递到海洋中。众所周知，风化的强度会影响传递到海洋的LI的量和同位素组成（Δ7Li）。这是LI在海水及其Δ7LI中的浓度的变化，可以提供有关硅酸盐风化的历史和演变及其在调节全球碳循环和地球气候中的作用的宝贵信息。已知某些海洋生物产生的碳酸钙（CACO3）矿物质已知从海水中掺入痕量的LI，因此可以用作这些变化的记录仪。但是，我们目前对LI如何纳入CACO3的理解以及哪些控制过程非常有限。在这项研究中，夏威夷大学（UH）的研究人员将进行一系列实验室实验，以更好地了解Li行业的CACO3机制。这项工作将铺平道路，以进一步开发使用海洋CACO3矿物作为过去变化的示踪剂，从而使海水li和不断的有机硅风化。该项目将在夏威夷大学的研究生和本科生的地球科学中增强教育和职业发展。该团队还将在一年一度的开放日活动中谈论他们的发现，例如“关于科学的疯狂”和“科学活着”，在主教博物馆的连续硅酸盐岩石上，同时释放并最终通过河流将Li运送到海洋中。海水LI浓度和Δ7LI的变化可以提供有关硅胶风化的历史和演变及其在调节全球碳循环和地球气候中的作用的宝贵信息。掺入LI的CACO3 Minarals可以用作这些更改的记录器。这项研究将基于建立良好的无机CACO3沉淀实验，其中一系列溶液的物理参数将与同一控制条件系统变化，以直接比较其对CACO3中Δ7LI和LI浓度的影响。此外，使用种子的使用，钙和芳香族样品都将在相同的实验条件下合成，以检查LI行业的多态性对照。预计该项目将提供迄今为止最完整的实验数据集，该数据集将结合使用表面动力学建模来建立牢固的无机（动力学和平衡）基线，以在溶液和CACO3矿物质之间进行LI的元素和同位素分配。该项目增强了夏威夷大学研究生和本科生的地球科学的教育和职业发展，那里的学生人口具有潜水员，并且通常不足的种族背景。该团队还将在年度开放日活动中谈论他们的发现，例如“关于科学的疯狂”和“科学活着”奖，这反映了NSF的法定任务，并使用基金会的知识分子和更广泛的影响评估标准，被视为通过评估来获得珍贵的支持。