Radium and barium sorption and precipitation on crystalline rock; experimental results and modeling development

Abstract

The sorption and precipitation of Ra and Ba on crystalline rock was studied with batch sorption and precipitation experiments, and geochemical modeling. Following the precipitation experiments, (Ba,Ra)SO₄ experimental partition coefficient (λ) and RaSO₄(s) solubility constant values were obtained. It was observed that especially in groundwaters of low overall salinity, and/or of high SO₄ and Ba content, Ra is strongly removed from the solution to both coprecipitation and sorption. A new geochemical model was developed which successfully interprets the experimental results. The precipitates of BaSO₄(s) were directly observed with the rock minerals with a SEM/EDX analysis.