Albite dissolution kinetics as a function of distance from equilibrium:: Implications for natural feldspar weathering
Albite dissolution kinetics as a function of distance from equilibrium:: Implications for natural feldspar weathering
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DOI：
10.1016/j.gca.2005.10.035
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发表时间：
2006-03-15
影响因子：
5
通讯作者：
Lüttge, A
中科院分区：
文献类型：
--
作者：
Beig, MS;Lüttge, A
确定涉及固体/流体相互作用的许多地质和工程过程的动力学需要对系统的吉布斯自由能依赖性有基本的了解。目前，为确定溶解速率与吉布斯自由能之间的关系而测量的动力学数据集之间似乎存在显着差异。为了确定这些差异的原因，我们结合了垂直扫描干涉测量、原子力显微镜和扫描电子显微镜技术，以确定钠长石单晶在吉布斯自由能范围内（-61.1 < Delta G < -10.2 kJ/mol）的溶解机制和定量溶解速率。在我们的实验中，先前溶解的具有蚀坑的钠长石表面和缺乏溶解特征的原始表面在热液流通式反应器中同时溶解。实验结果表明，经过不同预处理的表面之间的溶解速率差异高达 2 个数量级，这主要是由不同的溶解机制决定的。在一系列溶液饱和状态下持续存在的速率差异表明溶解机制遵循不同的吉布斯自由能依赖性。我们认为，这种速率差异是溶解机制动力学变化与平衡条件偏离的直接结果。这种动力学“开关”的存在表明，描述溶解速率和吉布斯自由能之间关系的单一连续函数可能是不够的。最后，我们讨论了我们的发现对钠长石风化速率的一些潜在影响，“特别关注样本的历史”。 (c) 2005 Elsevier Inc. 保留所有权利。
Determining the kinetics of many geologic and engineering processes involving solid/fluid interactions requires a fundamental understanding of the Gibbs free energy dependency of the system. Currently, significant discrepancies seem to exist between kinetic datasets measured to determine the relationship between dissolution rate and Gibbs free energy. To identify the causes of these discrepancies, we have combined vertical scanning interferometry, atomic force microscopy, and scanning electron microscopy techniques to identify dissolution mechanisms and quantity dissolution rates of albite single crystals over a range of Gibbs free energy (-61.1 < Delta G < -10.2 kJ/mol). During Our experiments, both a previously dissolved albite surface exhibiting etch pits and a pristine surface lacking dissolution features were dissolved simultaneously Within a hydrothermal, flow-through reactor. Experimental results document an up to 2 orders of magnitude difference in dissolution rate between the differently pretreated Surfaces, which are dominated by different dissolution mechanisms. The rate difference, which persists over a range of solution saturation state, indicates that the dissolution mechanisms obey different Gibbs free energy dependencies. We propose that this difference in rates is the direct consequence of a kinetic change in dissolution mechanism with deviation from equilibrium conditions. The existence of this kinetic "switch" indicates that a single, continuous function describing the relationship between dissolution rate and Gibbs free energy may be insufficient. Finally, We discuss some of the potential consequences of our findings on albite's weathering rates with a 'particular focus on the sample's history. (c) 2005 Elsevier Inc. All rights reserved.