Deterministic and stochastic modeling of reactive solute transport

Abstract

A sorption model for a solute (orthophosphate, denoted with P) subject to strong retardation is presented, and the parameter assessment is discussed. For validation, P transport in small columns is predicted and compared with breakthrough data with reasonable to good results. The validated sorption model is used for predictions of P transport in a column under field conditions. At relatively small flow velocities P tends to move through soil in a relatively sharp front. Due to spatial variability it is not justified to take displacement in a single column as the point of departure for the evaluation of transport in a field. To deal with spatial variability of sorption parameters and solute input we use a probabilistic approach. With an approximate analytical solution spatial variability is shown to have a large effect on transport in the case of continuous solute input. Monte Carlo simulations show that this is also the case for pulse-type input conditions.