Cadmium Release in Soil Solutions at Low Moisture Content
2008
Mensah, E. | Ponizovsky, A.A. | Allen, H.E. | Metzler, D.M.
Speciation of cadmium (Cd) was studied in four spiked agricultural soils at moisture content corresponding to 1.2 times field moisture capacity (FMC) and in the range from 1.2 FMC to soil-water 1:10. Cadmium desorption isotherms were nonlinear in all soils, resulting in the decrease in Cd partition coefficient with loading. The Windermere Humic Aqueous Model (WHAM VI) was applied to predict Cd concentration in the solutions, and predicted values were compared with the measured ones. Based on total Cd content in soils, with concentrations of dissolved organic carbon (DOC), calcium (Ca), magnesium (Mg), and sodium (Na) and soil solution pH as the input variables, WHAM VI predicted Cd concentration in soil solutions with the root-mean-square error (RMSE) of log[Cd] RMSE(log[Cd])=0.54 (n=37). Using total Cd content in soils, average concentrations of Ca and DOC in soil solutions, and soil pH instead of soil solution pH enabled prediction of Cd concentration in soil solution with RMSE(log[Cd])=0.56. Calculation of Cd concentration as a function of moisture content resulted in RMSE(log[Cd])=0.25 (n=20).
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