CHEMICAL EQUILIBRIUM DIAGRAMS FOR GROUND-WATER SYSTEMS / Les graphiques de l'équilibre chimique pour les systèmes des eaux souterrainnes

Abstract

Chemical equilibrium in water in contact with calcite is expressed by means of a pH grid overlay on a log-log plot of activities of bicarbonate vs. calcium ions. Solubility of ferrous iron and the solid-phase minerals that would be stable in a solution containing activities of 10 ppm of sulfate and 100 ppm of bicarbonate or related species is expressed by means of a stability-field diagram with pH as abscissa and redox potential as ordinate. The diagrams can be used to tell whether water injected in recharge wells may form precipitates that may plug the aquifer and have other uses in studies of natural water chemistry.