The dissolution rates of natural glasses as a function of their composition at pH 4 and 10.6, and temperatures from 25 to 74°C
The dissolution rates of natural glasses as a function of their composition at pH 4 and 10.6, and temperatures from 25 to 74°C
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DOI：
10.1016/j.gca.2004.05.027
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发表时间：
2004-12
影响因子：
5
通讯作者：
D. Wolff-Boenisch;S. Gíslason;E. Oelkers;C. Putnis
中科院分区：
文献类型：
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作者：
D. Wolff-Boenisch;S. Gíslason;E. Oelkers;C. Putnis
在pH值为4和10.6、温度为25至74℃的混合流动反应器中，测量了一组从玄武岩到流纹岩的火山玻璃的远平衡溶解速率。在相似成分的玻璃上进行的实验表明，溶解速率与几何表面积比BET表面积更接近成正比。在25°C时测量的几何表面积归一化溶解速率（r+,geo）随玻璃的二氧化硅含量呈指数变化。对于pH值为4的溶液，其关系式为：；对于pH值为10.6±0.2的溶液，其关系式为：这些方程可用于估计天然玻璃在远离平衡状态下的寿命和金属释放通量。在pH值4和25°C条件下，1毫米玄武岩玻璃球的寿命计算为500年，而1毫米流纹岩玻璃球的寿命计算为4500年。估计天然玻璃的营养物质释放率随着二氧化硅含量的增加呈指数下降。
Far-from-equilibrium dissolution rates of a suite of volcanic glasses that range from basaltic to rhyolitic in composition were measured in mixed flow reactors at pH 4 and 10.6, and temperatures from 25 to 74°C. Experiments performed on glasses of similar composition suggest that dissolution rates are more closely proportional to geometric surface areas than their BET surface areas. Measured geometric surface area normalized dissolution rates (r+,geo) at 25°C were found to vary exponentially with the silica content of the glasses. For pH 4 solutions this relation is given by: and at pH 10.6 ± 0.2 this relation is given by: These equations can be used to estimate lifetimes and metal release fluxes of natural glasses at far-from-equilibrium conditions. The lifetime at pH 4 and 25°C of a 1 mm basaltic glass sphere is calculated to be 500 yr, whereas that of a 1 mm rhyolitic glass sphere is 4500 yr. Estimated nutrient release rates from natural glasses decrease exponentially with increasing silica content.