Calculations of the metal sorption parameters by the example of strontium at high sodium nitrate concentrations

Summary

For the proper evaluation of underground water protection a comprehensive analysis of pollutant migration from the pollution source is required. The problem of solution salinity effect on the substance distribution between water and water-bearing material has been insufficiently covered in literature because of the low parametric support of the widely used geochemical models and also because of the imperfection of the applied thermodynamic data bases. In the process of geochemical modeling tabular values of interfacial distribution coefficient are often used. Another approach often used in practice is transferring laboratory measured Kd values to geochemical model. The use of tabular and experimental data on interfacial distribution coefficient without proper correction can result in falsified predictions since the available Kd tabular values for metals in the process of predicting sorption parameters, as a rule, provide for a recommended value only for a definite type of water-bearing material (sand, loam, clay) and (rarely) for one or two water types which is evidently insufficient for the correct choice of Kd coefficient. High solution mineralization reduces sorption of all the components because of the competition for the sorption sections and because of metal ion complexation with the solution components. In the article the difficulties in designing the geochemical model of 90S strontium sorption at high concentrations of dissolved sodium nitrate are considered. Strontium sorption by solid phases was considered in relation to ion exchange and surface complexation. The designed model was verified versus literature data. An algorithm of geochemical modeling of dissolved substances distribution between water and hard rock is recommended.

Key words

ground water , sorption , ion exchange , water-bearing material , geochemical modeling , interfacial distribution coefficient