Geochemical speciation as related to the mobility of F, Mo and Se in soil leachates

The chemical composition of soil leachates was studied to evaluate potential solid-phase controls on fluorine, molybdenum and selenium and assess their mobility in a calcareous soil. Leachates extracted from successive 10 cm depth intervals in a typical calcareous soil were subjected to speciation studies. Concentrations of all 3 elements in leachates increased with depth. There was a close approach to saturation with respect to calcium fluorite and powellite in the case of fluorine and molybdenum, respectively. Mobility increased with depth due to the chemical form in which the 3 elements were present.