Kinetics of the dissolution of calcite and its applications to karstification
Kinetics of the dissolution of calcite and its applications to karstification
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DOI：
10.1016/0009-2541(80)90089-3
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发表时间：
1980
期刊：
影响因子：
3.9
通讯作者：
W. Dreybrodt
中科院分区：
文献类型：
--
作者：
W. Dreybrodt
利用Plummer等人的S关于CaCO_3在搅拌H2O--CO_2体系中溶解的速率方程，计算了纯H_2O--CO_2体系的初始状态和已溶解的Ca~(2+)浓度的函数的溶解速率。这适用于所有具有地质意义的情况，例如在恒定压力下向二氧化碳大气层开放的系统、最初与二氧化碳处于平衡状态然后关闭以进一步吸收二氧化碳的系统，以及两个饱和水混合的情况，即混合腐蚀。一个重要的结果是，溶解速度由溶液与固体CaCO3表面的体积之比控制。对于较大的比例，速率是表面控制的，而对于较小的值，二氧化碳的水合作用决定了速率。这些结果适用于在平坦或圆形石灰岩管道中流动的不饱和水，并通过溶液将其加宽。由此得到的值与文献中报道的观察结果吻合得很好。最后，考虑了两根导水扁平管道交叉处的混合腐蚀问题。在交叉处形成圆管，并计算其直径随时间的变化关系。使用扁平管道宽度的真实数据，即接头和分缝，我们发现洞穴在几百万年内发展到1米的通道直径是可能的。这对洞穴起源的理论有了新的认识，对地下排水的发展和洞穴的形成有了全面的认识。
Using Plummer et al.'s rate equations on dissolution of CaCO3in stirred H2OCO2systems, dissolution rates are calculated as functions of the initial state of the pure H2OCO2system and the Ca2+concentration already dissolved. This is done for all cases of geological interest, such as systems open to a CO2atmosphere at constant pressure, systems in equilibrium with CO2initially and then closed to further CO2absorption and for the case of mixing of two saturated waters, i.e. mixing corrosion. An important result is, that the solution rates are controlled by the ratio of the volume of the solution to the surface of the solid CaCO3. For large ratios the rate is surface controlled and for small values hydration of CO2determines the rates.These results are applied to undersaturated water flowing in flat or circular conduits of limestone and widening them by solution. The values thus obtained agree well with observations reported in the literature. Finally, the solution at a crossing between two water-leading flat conduits by mixing—corrosion is considered. At the crossing a circular tube develops and the time dependence of its diameter is calculated. Using realistic data for the width of the flat conduits, i.e. joints and partings, we find that cave development to passage diameters of 1 m is possible in a few million years. This sheds a new light on the theory of the origin of caves and gives a comprehensive picture of the development of underground drainage and the formation of caves.