UNDER FIELD CONDITIONS, a single application of a tracer pulse often produces a wide spectrum of differently shaped BTCs. Observed BTCs can be interpre-.
DIVISION S-l-SOIL PHYSICS Heterogeneous Flow and Solute Transport in an Unsaturated Stony Soil Monolith B. Buchter,* C. Hinz, M. Flury, and H. Fluhler Most transport studies in soil columns have been done under steady-state and saturated conditions. Furthermore, column experiments have commonly been done with sieved, dried, and repacked soil materials. The soil structure is destroyed through such a pretreatment. This shortcoming can be overcome by using undisturbed soil columns or by carrying out field experiments. The latter provide an excellent view into water transport processes (Jardine et al., 1988) but often suffer from the impossibility of precisely quantifying a mass balance for the control volume. Furthermore, much of the available experimental data on solute transport under field conditions is limited to the saturated zone. Even though the vadose zone controls the flux of contaminants to the groundwater, field experiments under Unsaturated conditions are still rare (Gelhar et al., 1992). Recently, efforts to investigate solute transport under unsaturated conditions have increased (Schulin et al., 1987b; Bond and Phillips, 1990; Alemi et al., 1991). The latter two studies, as many others before, used soil columns of lateral dimension
