Geochemical modeling to aid experimental design for multiple isotope tracer studies of coupled dissolution and precipitation reaction kinetics
Geochemical modeling to aid experimental design for multiple isotope tracer studies of coupled dissolution and precipitation reaction kinetics
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DOI：
10.1007/s11631-023-00654-2
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发表时间：
2023-12
期刊：
影响因子：
1.6
通讯作者：
Mingkun Chen;Peng Lu;Yongchen Song;Chen Zhu
中科院分区：
文献类型：
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作者：
Mingkun Chen;Peng Lu;Yongchen Song;Chen Zhu
多矿物系统中矿物溶解与沉淀耦合研究的实验设计是一个挑战，因为在实际实验之前，很难推测出最佳的实验时间、最优的采样计划、不同实验条件的影响以及如何最大化实验输出。地球化学模拟是一种有效的辅助实验设计的工具，它可以模拟研究系统中所有感兴趣的场景并预测实验结果。在这里，我们展示了一个地球化学建模辅助实验设计的例子，利用多同位素示踪剂耦合labradorite溶解和方解石和粘土矿物沉淀。由于斜长石是玄武岩的主要成分，也是最具活性的矿物之一，本研究选择斜长石作为反应物。在我们过去十年对单一矿物的同位素掺杂研究之后，模拟中的初始溶液中掺杂了多种同位素（例如Ca和Si）。地球化学模拟结果表明，同位素示踪剂的使用使我们的灵敏度比基于浓度的传统方法高几个数量级，并使我们能够在接近平衡的条件下解耦溶解和沉淀反应。模拟表明，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。方解石沉淀发生在接近平衡状态，而多同位素示踪实验将提供接近平衡的沉淀速率，这对传统的基于浓度的实验是一个挑战。此外，还将揭示粘土相的析出是否是某些多矿物体系的限速步骤。综上所述，多矿物反应动力学建模结果将提高对多矿物体系溶蚀-沉淀耦合作用的认识，以及对玄武岩体系co2去除和封存效果的地球化学建模预测质量。
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 CO2removal and storage efficacy in the basalt systems.