Establishing a Baseline for Kinetic and Thermodynamic Origins of Vital Effects: The Interplay of Factors that Control Mg and Sr Signatures in Calcite

建立生命效应的动力学和热力学起源的基线：控制方解石中镁和锶特征的因素的相互作用

• 批准号: 0526670
• 负责人: Patricia Dove
• 金额: $ 38万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0526670&HistoricalAwards=false
• 关键词: Establishing; Baseline; Kinetic; Thermodynamic; Origins

ABSTRACTOCE-0526670The ratios of Mg/Ca and Sr/Ca in carbonate biominerals have emerged as paleotemperature proxies due to their reduced susceptibility to changes in salinity and polar ice volume relative to isotopic indicators. The organisms that produce these biominerals employ complex controlled biomineralization strategies to create spatial and chemical microenvironments that directly influence the nucleation, growth, and shape of biominerals. The collective influences of these microenvironments can significantly mask external environmental signatures through what is called 'vital effects'. Many new studies report extensive vital effects for a variety of signatures and taxa; however, the interplay of factors that give observed signatures is poorly understood. This is an enormous obstacle to building reliable and calibrated paleoenvironmental proxy models. For this reason, a researcher at Virginia Polytechnic Institute and State University will establish the interplays between physical and microenvironmental factors in governing magnesium and strontium signatures in calcites. Using a mechanistic approach, rooted in thermodynamic and kinetic principles of mineralization, the researcher will examine the following: (1) how carbonate ion speciation affects magnesium and strontium content; (2) how coupled non-equilibrium interactions between these elements and other constituents in seawater affect signatures; and (3) how transport conditions affect signatures. By understanding compositional signatures rooted in a mechanism-based approach, paleoenvironmental proxy models will have a fundamental basis that can be reliably calibrated to the appropriate chemical and physical parameters. As regards broader impacts, the PI in collaboration with a Geosciences Outreach Coordinator will develop a hands-on activity (Biominerals-Earth to Life) that integrates minerals, organisms, results from this study, and other resources from the Virginia Tech Geosciences Museum. This activity is targeted for middle school students. Two graduate students and one undergraduate student will be trained as part of this project.

Abstractoce-0526670碳酸盐生物矿物质中Mg/Ca和Sr/Ca的比率已成为古过敏的代理，因为它们相对于同位素指标的盐度变化和极性冰的变化降低。 产生这些生物矿物质的生物体采用复杂的受控生物矿化策略来创建空间和化学微环境，从而直接影响生物矿物质的成核，生长和形状。 这些微环境的集体影响可以通过所谓的“重要效应”显着掩盖外部环境特征。 许多新研究报告了各种签名和分类单元的广泛重要影响。然而，对观察到的签名的因素的相互作用知之甚少。这是建立可靠和校准的古环境代理模型的巨大障碍。因此，弗吉尼亚理工学院和州立大学的研究人员将在计算物中的治理镁和锶标志中建立物理和微环境因素之间的相互作用。 使用机械方法，植根于矿化的热力学和动力学原理，研究人员将检查以下几点：（1）碳酸盐离子物种形成如何影响镁和锶含量； （2）这些元素与海水中其他成分之间的非平衡相互作用如何影响特征； （3）运输条件如何影响签名。 通过了解植根于基于机制方法的组成特征，古环境代理模型将具有基本的基础，可以可靠地校准适当的化学和物理参数。 关于广泛的影响，与地球科学外展协调员合作的PI将开发动手活动（生物矿工 - 地球），将矿物质，生物，本研究的结果以及弗吉尼亚理工大学地球科学博物馆的其他资源整合在一起。 这项活动针对中学生。 将在该项目的一部分中对两名研究生和一名本科生进行培训。