A simple model for predicting the pH values of acidic natural waters

This paper presents a simple computer model for predicting the pH values of acidic natural waters. Effects of various factors (such as, aluminum concentration, dissolved inorganic carbon (DIC), solubility product KSP of A1(OH)3 mineral phase and temperature) on the theoretical prediction of the pH values were discussed. Some valuable conclusions were obtained. This model has been applied to practical analysis of natural waters. The pH values calculated were found in accordance with the results measured. The uncertainties in calculation of the pH associated with the error from variations in thermodynamic constants and measured input data were evaluated by the Monte Carlo method.