Collaborative Research: Calibration of Raman Spectroscopy for Calcite Saturation State in Marine Biogenic Calcification

合作研究：海洋生物钙化中方解石饱和状态的拉曼光谱校准

• 批准号: 2323221
• 负责人: Joji Uchikawa
• 金额: $ 36.85万
• 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: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2323221&HistoricalAwards=false
• 关键词: Collaborative; Research; Calibration; Raman; Spectroscopy

Much of the anthropogenic CO2 released into the atmosphere has been absorbed by the ocean, which acts as a buffer against global warming and rapid climate change. But this makes seawater more acidic and corrosive to CaCO3 minerals (known as ocean acidification: OA), which is expected to harm marine organisms that build skeletons or shells from CaCO3 (marine calcifiers). Marine calcifiers typically grow their CaCO3 hard parts in a micro-scale “calcifying fluid (CF)” by modifying its chemistry from seawater to elevate the degrees of CaCO3 saturation (Ω). This process potentially enables calcifiers to cope with OA, at least to some extent. This research aims to establish the use of Raman Spectroscopy (RS) to constrain Ω of CF. Compared to other methods, this approach will be simple, rapid, and non-destructive to organisms and CaCO3 samples. This work will be a cornerstone for an important methodology that can advance knowledge on calcification mechanisms and resilience of marine calcifiers against OA. Rapid precipitation of CaCO3 at higher Ω levels leads to greater structural disorder in the mineral lattice due to increased defects and kinetically-driven uptake of minor/trace elements (e.g., Mg). Thus, the degree of lattice disorder determined from the positional shift in and width of Raman peaks should be a function of Ω. This concept has been validated for aragonites and RS has been extensively used to constrain Ω of CF in aragonitic calcifiers. But in calcites, Mg inclusion by substitution of Ca also contributes to structural disorder significantly. This necessitates a correction for Mg-driven lattice disorder for effective use of RS on calcitic organisms, which is currently lacking. This research will produce an extensive set of abiogenic calcite samples that vary significantly in Mg contents and solution Ω for precipitation based on laboratory experiments using artificial seawater. These samples will disentangle the overlapping effect of Mg inclusion and Ω on calcite structural disorder. This investigation will for the first time generate Raman calibrations for Mg contents and Ω that are applicable to marine biogenic calcites. This project is jointly funded by the Geobiology and Low-Temperature Geochemistry Program (GG), the Established Program to Stimulate Competitive Research (EPSCoR), and the Marine Geology and Geochemistry Program (MGG).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.

释放到大气中的大部分人为二氧化碳已被海洋吸收，海洋充当了全球变暖和气候快速变化的缓冲区。但这使得海水的酸性更强，对 CaCO3 矿物质具有更强的腐蚀性（称为海洋酸化：OA），预计这会损害利用 CaCO3（海洋钙化剂）构建骨骼或贝壳的海洋生物。海洋钙化剂通常通过改变海水的化学成分以提高 CaCO3 饱和度 (Ω)，在微型“钙化液 (CF)”中生长 CaCO3 硬质部分。这个过程有可能使钙化器至少在某种程度上能够应对骨关节炎。本研究旨在建立使用拉曼光谱 (RS) 来约束 CF 的 Ω。与其他方法相比，该方法简单、快速，且对生物体和 CaCO3 样品无破坏性。这项工作将成为一种重要方法的基石，该方法可以增进对钙化机制和海洋钙化物对 OA 的抵抗力的了解。由于缺陷增加和微量/微量元素（例如镁）的动力学驱动吸收，CaCO3 在较高 Ω 水平下快速沉淀会导致矿物晶格中更大的结构无序。因此，由拉曼峰的位置偏移和宽度确定的晶格无序程度应该是Ω的函数。这一概念已在文石中得到验证，并且 RS 已广泛用于约束文石钙化剂中 CF 的 Ω。但在方解石中，通过取代 Ca 来添加 Mg 也会显着导致结构紊乱。这就需要对镁驱动的晶格无序进行校正，以便在方解石生物上有效地使用 RS，但目前尚缺乏这种方法。这项研究将根据使用人工海水的实验室实验，生产出大量非生物方解石样品，这些样品的镁含量和沉淀溶液 Ω 变化很大。这些样品将解开 Mg 夹杂物和 Ω 对方解石结构无序的重叠影响。这项研究将首次生成适用于海洋生物方解石的 Mg 含量和 Ω 拉曼校准。该项目由地球生物学和低温地球化学计划 (GG)、刺激竞争研究既定计划 (EPSCoR) 以及海洋地质和地球化学计划 (MGG) 共同资助。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。