Cumulative Mass Approach for Column Testing

A cumulative mass approach for laboratory column testing using an analytical solution for miscible transport through soil is presented. The cumulative mass approach differs from the more traditional approach for column testing in that the analysis of the measured data is in terms of mass of solute instead of solute concentration. The potential advantages of the cumulative mass approach are: (1) The influence of increment in effluent sample volume on the measured concentrations is removed from consideration; (2) the effluent sampling procedure is less labor-intensive, and therefore potentially more cost-effective; and (3) the retardation factor and effective porosity can be evaluated directly from plots of the test results. A comparison of analyses of measured data based on the cumulative mass approach with the more traditional concentration-based approach indicates slight differences (less than 3%) in the regressed values of the dispersion coefficient and retardation factor. These differences are attributed to greater scatter in the data for the more traditional approach and to slight errors involved in the traditional approach due to plotting the average, incremental concentrations at the pore volumes of flow corresponding to the middle of the sampling interval.