Evaluation of the Validity and Statistical Variability of Lithium and Fluoride Distribution Coefficient Values in a Complex Geochemical System

摘要

Predictive modeling of solute transport requires accurate measurement or estimation of geochemical adsorption and ion exchange parameters for a given rock-fluid system. One such parameter is the distribution coefficient (Kd) used to predict the rate of movement of dissolved contaminant through soils and aquifers. The Kd describes the partitioning of a dissolved species between a solid phase and the aqueous solution in equilibrium with the solid phase. This research presents a statistical evaluation of the validity of the distribution coefficient to describe adsorption of lithium and fluoride in a complex, natural rock-fluid system. The general goal of the research was to generate Kd parameters appropriate for simulating contaminant migration from oil shale waste disposal sites planned for the Piceance Creek Basin of western Colorado. Specific objectives were to: (1) test the key assumptions that control valid application of the Kd in any rock-fluid system. Included among these are the assumptions that the slope of the partitioning function in constant linear that the choice of solid/solution ratio used in laboratory batch studies has no effect on the Kd determination and that the Kd value is independent of concentration. (2) Determine the statistical variability of Kd values for Li and F obtained in the laboratory and hence provide a confidence interval for Kd values for this rock-fluid system. 7 refs., 2 figs., 5 tabs. (ERA citation 11:025361)