常温高压下石膏在水中的溶解度突变现象及其意义

Abrupt solubility of gypsum in water at high pressure and ambient temperature and its implication

我们在26℃和0.1～900MPa压力下进行了纯水中石膏的溶解实验。实验结果发现在低于608MPa的压力下石膏一直保持稳定,而在高于该压力下石膏才开始发生溶解。在其后的八次加压过程中,尽管体积在缩小,但压力却并不线性上升,且石膏也不发生进一步的溶解。当加压使体系压力增加,且压力超过668MPa时石膏才突然全部溶解完。这种现象一方面表明压力对矿物在水中的溶解具有某种控制作用,另一方面,也可能说明水在高压下具有完全不同于常压下的性质。这意味着地壳内在约18km深度处可能存在着一种物理化学界面。该界面将对矿物、岩石及其地球物理性质产生重要影响。

Experimental study of solubility of gypsum was carried out at the pressure of 0.1 similar to 900MPa and ambient temperature. It shows that gypsum is stable at the pressure less than 608MPa, whereas at higher pressure it dissolves immediately. This phenomenon implies, on one hand, that the solubility of mineral is controlled by pressure, and on the other hand it probably indicates that water at high pressure has a quite different property.. It also implies that there would be a physical and chemical interface at the depth of similar to 18km and it would play an important role on the minerals/rocks and geophysical property.