Analysis of acid-base equilibria in open atmospheric gas-liquid systems was performed. Usually acid-base equilibria are considered as a function of hydrogen ion concentration as an independent variable. In this work the analysis was performed including the dependence of hydrogen ion concentration on the composition of a system. Such an approach allowed us to find the important, from the point of view of atmospheric water acidification, dependence between system composition and the liquid phase hydrogen ion concentration.
In the first stage of the work a thermodynamic model of the studied systems was formulated and then it was used to determine the effect of acidic and alkaline atmospheric gaseous pollutants on the liquid phase pH and equilibrium composition. In the final stage of the work the obtained results were generalized to any open atmospheric gas-liquid systems of the type NH₃ – strong bases – strong acids – weak acids – CO₂ – H₂O. General equations for hydrogen ion concentration and criteria for neglecting the effect of acidic gaseous pollutants were derived. These equations and criteria are an effective and easy-to-use tool for examination and interpretation of equilibria in complex open gas-liquid atmospheric systems of the type NH₃ – strong bases – strong acids – weak acids – CO₂ – H₂O.