WWRC 93-04
Geochemical Speciation as Related to the Mobility of F, Mo and Se in Soil Leachates
Abstract
Chemical speciation of soil leachates is necessary for evaluating a number of processes
including solid phase controls, leaching potentials and toxicity problems. The objectives of this study were
to examine chemical composition of soil leachates, potential solid phase controls of F, Mo and Se and
evaluate their mobility in a calcareous soil. A typical calcareous soil was sampled at 10-cm increments
from the surface to a depth of 70-cm. Soil leachates were extracted with distilled deionized H2O and
subjected to speciation studies. As depth of the soil increased, concentrations of F and Mo increased from
0.77 to 6.74 mg/l and 0.06 to 0.15 mg/l. respectively. Selenium concentration increased slightly (0.002-
0.005 mg/l) but showed highest levels at intermediate soil depths. Chemical speciation indicated soil
leachates were dominated by F , MgMoO°4 and MgSeO°3 species. The F and Mo concentrations, at lower
depths, indicated a close approach to saturation with respect to fluorite (CaF2) and powellite (PbMoO4),
respectively. Results obtained in this study suggest that as soil depth increases, the mobility of F, Mo and
Se is increased due to the chemical form in which these elements are present in the soil leachates,
Water Resources Publications List
Water Resources Data System Library |
Water Resources Data System Homepage
