Movement of Chloride in a Soil with Variable Charge Properties: I. Chloride Systems1
- K. Y. Chan,
- H. R. Geering and
- B. G. Davey2
The movement of synthetic chloride solutions, simulating a treated sanitary landfill leachate, through columns filled with the subsoil of a xanthic ferralsol were studied in the laboratory. The chloride movement did not follow the miscible displacement equation or more sophisticated models, because the amount of positive charge carried by the soil depended on both pH and the ionic strength of the solution moving through it. During movement of the alkaline synthetic leachate into the column, the amount of positive charge increased due to the higher ionic strength of the leachate relative to the soil solution. A further temporary increase in positive charge also took place due to the decrease in pH induced by cation exchange caused by the leachate front. Later, the desorption of Cl took place as the alkaline leachate titrated the soil to pH > 9.0 and the positive charge was neutralized by OH adsorption. These results show that variation in the positive charge of the soil, induced by the solution moving through it, causes the Cl outflow curve to deviate from theory. Before more advanced theories of miscible displacement can be applied to this type of situation, it will be necessary to develop adequate kinetic theories to describe the changes in the soil's charge properties induced by the solution moving through it.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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