EXPLORING CONTROLS ON ANOMALOUS SOLUTE TRANSPORT IN COLUMN EXPERIMENTS

The advection-dispersion equation (ADE) fails to describe solute transport processes when applied to a multitude of natural systems. Here, we explore the relationship between mobile and less-mobile pore space and its effect on solute transport in a series of controlled column experiments. The objective of this research is to quantify phenomena controlling solute transport in three different grain packings, including homogeneously and heterogeneously packed Accusand, which contains no internal pore space, and zeolite, which contains an intragranular pore space. The tests include injection of either potassium bromide (KBr) or lithium bromide (LiBr) tracers at volumetric flow rates ranging from 1.1 mL/min to 2.5 mL/min with tracer injection times ranging from 24 to 80 hours dependent on column length and packing configuration. Results indicate that heterogeneous systems experience tailing, a transport phenomena described by highly asymmetrical BTCs. Homogeneous, single porosity systems fit the ADE, as expected. The numerical model STAMMT-L is used to estimate the parameters controlling transport; we simulate homogeneous Accusand systems with BTCs similar to the ADE where heterogeneous systems do not. The differences in results from both systems present the need for exploration into quantifying the relationship between mobile and immobile pore space and its effect on solute transport.