Release kinetics and concentration profile of dissolved silicon in compacted sediments

Abstract

The kinetics of release of dissolved silicon from river sediments under close to natural conditions have been studied on the basis of a semi-infinite diffusion model taking into account the dissolution of the support. A new theoretical framework suitable for the description and modelling of such processes has been developed and the numerical solution compared with the asymptotic behaviour at short times. The dynamics of the concentration profile of dissolved silicon in the sediment phase has been calculated, and by adjusting the model parameters to the experimental data on concentration profiles measured in a natural sediment and a fluvarium channel bed, reliable estimates for the diffusion coefficient and generation rate constant have been obtained.