Laboratory experiments to study the transport of contaminants are sometimes conducted in cylindrical columns packed with unconsolidated natural porous media. Water is pumped through the columns, and the elution of contaminants can be measured over time. This is sort of like the river tracer tests we measured, except adsorption to the porous media can influence the movement of contaminants. $($To be discussed later.$)$

A cylindrical glass column is packed with soil and completely saturated with water. The following measurements were taken before and after saturation:

$\backslash$table$[[$column height:,$15cm$