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

“该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。“在生物成因的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，在充分发挥这一工具的潜力之前，仍有一些悬而未决的问题需要解决。 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）物种和水之间氧（O）同位素平衡速率的影响，以及（2）镁离子对DIC物种和水之间O同位素平衡的影响。这些过程的影响将使用定量（快速）和缓慢的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，这两种影响很重要，因为它们代表了海洋环境中的基本生物或化学过程或事件。 碳酸酐酶的可能影响是重要的，因为它在各种重要的过程中发挥着重要作用，而镁离子的影响是一个重要的参数，在表征海洋水化学及其对化学平衡的影响。更广泛的影响：这项研究将有助于提高认识的一个工具，通常采用在古气候-碳酸盐微体化石中的氧同位素。预期的结果将是更好地将过去的气候信号与不受欢迎的偏差分开。这种分离将有效地导致更好地了解地球的气候历史。 该项目的另一个目标是促进对不同层次学生的教育。这项研究是由一名研究生设计的，他还协助编写了项目提案。

"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.