Modeling solute segregation during freezing of peatland waters

Abstract

Freezing of the shallow water in a peatland causes the downward movement of solutes. Field and laboratory data demonstrate that a considerable portion of the solutes are driven into the top soil from the overlying water by freezing. Such solute redistribution phenomena in peatlands are of interest for establishing the geochronology of deposits and determining the nature of pollutant burial. A mathematical model has been developed to describe the solute segregation processes at the freezing front in both overlying water and interstitial water in the porous peat and solute transport in the unfrozen water. An algorithm has been developed to solve this nonlinear moving interface problem. The solute concentrations in ice and water phases are reproduced by the model. Computer simulation results provide good predictions of independent experimental data.