中文摘要：

高温高压下水流体的pH值是影响矿物-水流体相互作用平衡和动力学过程的一个重要参数。确定高温高压流体pH的方法主要包括电位势测量、化学分析与热力学计算及电导率方法。电位势测量在化学领域应用广泛，也被用来测量了洋中脊的热液流体的pH值。人们尝试了各种形式的电极，如氢电极、钯氢化物电极、金属-金属氧化物电极和钇稳定的氧化锆（YSZ）电极。玻璃电极只取得了有限的成果，通常用来测量常温及低温下的流体的pH值。对金属-金属氧化物电极在较宽的温度范围内进行了研究，但它需要利用合适的参比溶液来校正，与玻璃电极一样都表现出较大的偏移和误差以及不可回测性。陶瓷薄膜电极，如钇稳定的氧化锆（YSZ）电极，为测量相对较高温度下的pH值提供了一个可靠的方法。利用高温淬火水的化学分析和常温下的pH的测量，通过求解络合反应质量平衡与所有组分质量平衡的联立方程，来计算指定温度压力下pH值和水溶液种类的分布，是获得高温pH值的另一个重要而常用的方法，但热力学数据中的数值误差和不确定性以及分析误差能够影响计算出的高温溶液的pH值的精度。对高温高压超临界水流体的电导测量已经取得很大的成就，它被用来作为确定溶液内部离子反应平衡常数的一种最常用的方法，通过获得的这些反应的平衡常数，就可以得到在高温高压下流体的就位物质组成，这个方法可以测量更高温度压力下流体的pH值。

英文摘要：

The pH of fluids play an important role in the dynamics and equilibrium between minerals and fluids at high temperature and pressure. This article reviews various methods of pH determination of aqueous fluids at elevated p-T conditions. These methods include potential measurement and electrical conductivity measurement of electrochemical cell and calculation of pH from fluid compositions. Over the past few decades considerable progress has been made in developing practical potentiometers for measuring pH in high temperature aqueous solutions. Platinum-hydrogen electrodes are very precise for pH measurement of various solutions at relative low temperatures. Potentiometer based on ceramic membrane such as yttria-stabilized zirconia（YSZ）membrane sensor is one of the most significant achievements in high temperature potentiometer. Using chemical analyses and 25 ℃ pH measurements, the pH and distribution of aqueous species at high temperature can be calculated by solving simultaneous mass action equations for complexes equilibria and mass balance equations. Numerical errors and uncertainties in thermodynamic data and analytical errors can effect these computed values. Electrical conductance measurements of aqueous solutions at high temperatures and pressures provide unique information concerning the extent of ionic interaction of ions in solutions. From the results of electrical conductance measurements of aqueous solution we can obtain pH values at relative high temperature and pressures.