美国印第安纳大学Zhu Chen的研究团队耦合了溶解和沉淀反应动力学的多同位素示踪，来辅助研究实验设计的地球化学模型。2023年12月21日，国际知名学术期刊《地球化学学报》发表了这一成果。

研究人员展示了一个地球化学建模辅助实验设计的例子，该实验设计使用多种同位素示踪剂耦合了闪光拉长石溶解和方解石及粘土矿物沉淀。在这项研究中，之所以选择闪光拉长石（斜长岩）作为反应物，是因为它既是玄武岩中的主要成分，也是最具反应性的矿物之一。根据过去十年我们对单一矿物的同位素掺杂研究，模拟中的初始溶液掺杂了多种同位素(例如，钙和硅)。

地球化学模拟结果表明，同位素示踪剂的使用比基于浓度的常规方法具有更高的灵敏度，并能够在近平衡条件下分离溶解和沉淀反应。模拟结果表明，精确的单向溶解速率可以告诉我们斜长石的溶解遵循何种速率规律。方解石沉淀发生在近平衡状态，多同位素示踪实验将提供近平衡沉淀速率，这对于传统的基于浓度的实验是一个挑战。此外，该研究还将揭示粘土相的沉淀是否是某些多矿物体系中的限速步骤。总体而言，多矿物反应动力学的模拟结果将提高对多矿物系统中溶解-沉淀耦合的理解，并提高地球化学模拟预测玄武岩系统中CO₂去除和储存效能的质量。

据介绍，在多矿物系统中，对矿物溶解和沉淀的耦合研究进行全面而有效的实验设计是一个挑战，因为很难推测最佳实验持续时间、最佳采样计划、不同实验条件的影响以及如何在实际实验之前最大化实验输出。地球化学建模是通过虚拟运行所研究系统的所有感兴趣的场景，并预测实验结果来辅助实验设计的高效且有效的工具。

附：英文原文

Title: Geochemical modeling to aid experimental design for multiple isotope tracer studies of coupled dissolution and precipitation reaction kinetics

Author: Chen, Mingkun, Lu, Peng, Song, Yongchen, Zhu, Chen

Issue&Volume: 2023-12-21

Abstract: It is a challenge to make thorough but efficient experimental designs for the coupled mineral dissolution and precipitation studies in a multi-mineral system, because it is difficult to speculate the best experimental duration, optimal sampling schedule, effects of different experimental conditions, and how to maximize the experimental outputs prior to the actual experiments. Geochemical modeling is an efficient and effective tool to assist the experimental design by virtually running all scenarios of interest for the studied system and predicting the experimental outcomes. Here we demonstrated an example of geochemical modeling assisted experimental design of coupled labradorite dissolution and calcite and clayey mineral precipitation using multiple isotope tracers. In this study, labradorite (plagioclase) was chosen as the reactant because it is both a major component and one of the most reactive minerals in basalt. Following our isotope doping studies of single minerals in the last ten years, initial solutions in the simulations were doped with multiple isotopes (e.g., Ca and Si). Geochemical modeling results show that the use of isotope tracers gives us orders of magnitude more sensitivity than the conventional method based on concentrations and allows us to decouple dissolution and precipitation reactions at near-equilibrium condition. The simulations suggest that the precise unidirectional dissolution rates can inform us which rate laws plagioclase dissolution has followed. Calcite precipitation occurred at near-equilibrium and the multiple isotope tracer experiments would provide near-equilibrium precipitation rates, which was a challenge for the conventional concentration-based experiments. In addition, whether the precipitation of clayey phases is the rate-limiting step in some multi-mineral systems will be revealed. Overall, the modeling results of multi-mineral reaction kinetics will improve the understanding of the coupled dissolution–precipitation in the multi-mineral systems and the quality of geochemical modeling prediction of CO₂ removal and storage efficacy in the basalt systems.

DOI: 10.1007/s11631-023-00654-2

Source: https://link.springer.com/article/10.1007/s11631-023-00654-2