On field-scale dispersion of strongly sorbing solutes in soils

Abstract

The practical application of parallel soil column (or stream tube) models is hindered by the difficulty to assess the probability density function of the pore water velocity, which at present requires extensive measurements. However, many environmentally relevant chemicals are strongly sorbed to the soil matrix. In this case, solute transport can be modeled to a good approximation on the basis of the pdf of infiltration and a constant water content. The exact value of the water content and its variability are not important. This follows from analysis of the travel time moments of a generalized multicompartment model and is shown to hold true for kinetic sorption to an arbitrary number of arbitrarily connected sorbent compartments with different equilibrium partitioning coefficients.