Pollutant Transport in Geomedia Using X-ray Computed Tomography

Computed tomography (CT) measurement systems have been introduced as a method to measure fluid transport at the macropore-scale to estimate transport parameters. The objective of this study was to use x-ray CT methods to measure transport of iodophenol solution in geomedia columns and estimate spatial distributions of chemical retardation. An initial CT-measured breakthrough curve experiment was conducted with potassium iodide to spatially estimate pore-water velocity and dispersivity in the geomedia core, with a subsequent transport experiment with iodophenol to estimate the spatial distribution of chemical retardation. A geomedia core was removed from the surface horizon of Sarpy loamy sand (Typic Udispamment). Spatial distributions followed a fractal pattern with dimension values similar among pore-water velocity, dispersivity and retardation coefficient parameters. The retardation coefficient estimated using CT methods was similar compared to the dynamic fluid experiment indicating this new method may be appropriate for pollutant transport analysis. This study illustrates that the CT method is useful for evaluating solute transport on a macropore-scale for porous materials