Landscape position and soil profile heterogeneity affects on solute transport

Hydraulic and morphologic heterogeneity in the soil environment contribute to the complexity of characterizing water and solute transport. The objective of this laboratory study was to investigate the effect of soil physical and hydraulic properties on the spatial variability of solute transport. Undisturbed blocks of Cecil soil (Clayey, kaolinitic, thermic Typic Kanhapludults) were collected from a interfluve, linear slope, and footslope. Soil blocks were placed on a grid lysimeter plate for water and solute collection. A single application of 400 mL of 1000 mg bromide (Br) L-1 was uniformly sprayed onto the soil surface. Soil water content and soil water pressure were measured once during each experiment outflow at predetermined intervals over a 24-h period. Flow was dominated by preferential flow during the first 3 h and matrix flow during the last 21 h of the experiment. Bromide mass increased as volume collected per cell increased for all landscape positions suggesting Br transport dominated by preferential flow pathways.