V. Palm, A MODEL FOR SORPTION, FLUX AND PLANT UPTAKE OF CADMIUM IN A SOIL-PROFILE - MODEL STRUCTURE AND SENSITIVITY ANALYSIS, Water, air and soil pollution, 77(1-2), 1994, pp. 169-190
Fluxes of cadmium in a soil profile are simulated by coupling a model
for linear and nonlinear equilibrium sorption to an existing hydrologi
cal model. The aim is to develop a model for Cd transport in soil syst
ems. A separate flow model is used to calculate the water fluxes, whic
h are then used in an equilibrium sorption model, allowing different F
reundlich isotherms to be chosen. The model is tested and a sensitivit
y analysis is made. The variation of soil compartment sizes gave small
changes in the results, which is interpreted as a measure of the solu
tion stability. The factor influencing Cd transport most, according to
these simulations, is the sorption isotherm. The degree to which Cd s
orbs to soil decides how much will be available in the soil water for
plant uptake or transport through the soil to the ground water. Other
studied factors such as root distribution and hydrological properties
influence the result only to a limited degree. With an application of
10 mg Cd/m2 in the given range of Freundlich isotherms, the simulation
s gave a plant uptake of between 0 and 30% of the applied Cd in two ye
ars. At the concentration mainly used in this study (with 10 mg Cd/m2
applied), the nonlinear isotherms found in the literature gave Cd lowe
r mobility than the linear isotherms used for comparison. For high Cd
concentrations the situation would be the reverse.