Dissolution Rate of Gypsum in Flowing Water

Dissolution rates of gypsum were measured in water flowing through beds of gypsum fragments as affected by fragment size, solution velocity and initial concentrations of Ca 2+ , SO 4 2‐ and CO 3 2‐ in the flowing water. Equations were derived to describe the rates of dissolution, and a dissolution coefficient was defined which is a function of fragment size and solution velocity. Rates of dissolution are high enough to distribute quantities of gypsum, which are within economic reach of the farmer, on farm lands via the irrigation water. Sample calculations are made to show how these data may be used to design watercourse cross sections for applying given levels of gypsum to the flowing water.