Abstract

Application of WATEQ4F and SOLMINEQ.88 speciation-solubility codes to brines fmm La Playa in Los Monegros (Zaragoza) has been used to contrast different approaches in activity calculations and to determinate saturation indexo The evaporation process increases ionic force and activities of dissolved species but with notorious singularities; the salt precipitation is theoretically reached only with ionic forces greater than 3. Pitzer's formulation included in SOLMINEQ.88 options is the best one for approximation to natural observations, and WATEQ4F also shows good concordance with evolutive trend