SURFACE REACTION RATE IN POROUS MEDIA: PERCOLATION THEORY APPLICATION

In this study, we apply a recently proposed approach based on the concepts of percolation theory for conservative solute transport extended to model reactive solute transport and surface reaction rate in porous media. We assume that at pore scale the equilibrium is reached. However, at larger scales solute transport velocity controls the equilibrium, meaning that the reaction rate becomes proportional to the solute transport rate. In order to evaluate our model specific tests are performed to compare results of the temporal and spatial dependences of the solute velocity with data for chemical weathering rates and with data for the temporal and spatial dependence of uranium dissolution in Hanford sediments as reported in the literature. Comparison with a wide range of experiments collected in either lab or field scale indicates that our theoretical description of solute transport predicts the time dependence of weathering rate over many orders of magnitude in accord with the measured data.