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

作　　者：Mingkun Chen Peng Lu Yongchen Song Chen Zhu 

机构地区：[1]Department of Earth and Atmospheric Sciences,Indiana University,Bloomington,IN 47405,USA [2]School of Energy and Power Engineering,Dalian University of Technology,Dalian 116024,China [3]EXPEC Advanced Research Center,Saudi Aramco,31311 Dhahran,Saudi Arabia

出　　处：《Acta Geochimica》2024年第1期1-15,共15页地球化学学报（英文）

基　　金：partially supported by U.S. National Science Foundation grants EAR-2221907;partly sponsored by agencies of the United States Government。

摘　　要：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 withmultiple 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 multimineral reaction kinetics will improve the understanding of the coupled dissolution–precipitation in the multi-mineral systems and the quality of geochem

关 键 词：Kinetics FELDSPAR Isotope doping Near-equilibrium CO_(2)sequestration BASALT 

分 类 号：P595[天文地球—地球化学] P588.145[天文地球—地质学]