Simulation of hydrochemical patterns in regional groundwater flow

The chemical state of a regional groundwater system in which several different processes are acting is described by a partial equilibrium simulation model that incorporates mass transfer rates and reaction kinetics. Quantitative analysis with the model indicates that mineral dissolution, saturation constraints on dissolution, the degree of saturation, partial pressures of CO 2 gas, and reaction kinetics in relation to the residence time of the groundwater flow play different roles in determining the spatial distribution of ionic constituents. Simultaneous evaluation of several geochemical processes permits the study of interdependent phenomena such as shifts in equilibrium concentrations resulting from the addition of common ions by cation exchange or sulfate reduction processes. The utility of the model is demonstrated by applying it to the groundwater reservoir in the Upper Kettle Creek, Ontario, Canada, where a favorable comparison is achieved between the real and the theoretical hydrochemical patterns.