A Transfer Function Model of Solute Transport Through Soil: 2. Illustrative Applications

The results of field and laboratory studies of solute transport through undisturbed soils following narrow pulse or step‐change inputs of soluble salts or bacteria were analyzed using the transfer function equation developed in paper 1 ( Jury et al. , this issue) of this series. The travel time probability density function observed for Br and Cl during unsteady flow in an unsaturated, well structured clay suggested a two‐component mechanism comprising fast solute transport through large, interped voids and slow to negligible transport through small, intraped voids. The modal and median travel times varied with soil type, initial water content, and rate of water input. The fractional volume of water that participated in solute transport, θ st , was calculated from the rate of water input and the median solute travel time. Values of θ st , ranged from 14% to nearly 90% of the mean volumetric water contents ( ) of the soils.