Understanding paleo-climate tools: Effects of carbonic anhydrase and Mg on oxygen isotopes in dissolved and solid carbonate

“这项奖励是根据2009年美国复苏和再投资法案（公法111-5）资助的。”在生物成因碳酸钙壳中使用稳定同位素是古气候研究的标准工具。然而，在充分利用这一工具之前，仍有一些突出的问题需要解决。夏威夷大学的研究人员将研究(1)碳酸酐酶（CA）对溶解无机碳（DIC）与水之间氧(O)同位素平衡速率的影响，以及(2)镁离子对溶解无机碳（DIC）与水之间O同位素平衡速率的影响。这些过程的影响将通过定量（快速）和慢速无机碳酸盐沉淀实验来确定。本项目将研究对氧同位素的两种潜在影响，因为它们代表了海洋环境中基本的生物或化学过程或事件，因此必须加以辨别。碳酸酐酶的可能影响是重要的，因为它在多种基本过程中起着重要作用，而镁离子的影响是表征海水化学及其对化学平衡影响的重要参数。更广泛的影响：这项研究将有助于提高对古气候学中常用的工具-碳酸盐微化石中的氧同位素的理解。预期的结果将是将过去的气候信号与不受欢迎的偏差更好地分离开来。这种分离将有效地帮助我们更好地了解地球的气候历史。该项目的另一个目标是促进不同层次学生的教育。这项研究是由一名研究生设计的，他也协助准备了项目提案。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."The use of stable isotopes in biogenic calcium carbonate shells is a standard tool in paleoclimate studies. However, there are still outstanding issues that need to be addressed before this tool can be utilized to its full potential. Researchers at the University of Hawaii will study (1) the effects of carbonic anhydrase (CA) on the rate of oxygen (O) isotope equilibration between the dissolved inorganic carbon (DIC) species and water and (2) the effects of magnesium ions on the O isotope equilibrium between DIC-species and water. The effects of these processes will be determined using quantitative (rapid) and slow inorganic carbonate precipitation experiments. The two potential effects on oxygen isotopes that will be studied in this project are important to discern because they represent fundamental biological or chemical processes or occurrences within the marine setting. The possible influence of carbonic anhydrase is important because it plays an important role in a variety of essential processes whereas the influence of magnesium ions represents an important parameter in characterizing ocean water chemistry and its influence on chemical equilibrium.Broader Impacts: This study will contribute to the improved understanding of a tool commonly employed in paleo-climatology - oxygen isotopes in carbonate microfossils. The anticipated outcome will be an improved separation of past climate signals from undesirable biases. This separation would effectively lead to a better understanding of Earth's climate history. An additional goal of the project is to foster education of students at different levels. This study was designed in part by a graduate student who also assisted in the preparation of the project proposal.