Phytoremediation of Metals: A Numerical Analysis

Abstract

A finite element code was used for investigating the effect of some relevant characteristics of a phytoremediation project (crop type and density, presence of an irrigation system, soil capping and root depth). The evolution of the plume of contamination of Cd²⁺, Pb²⁺, and Zn²⁺ was simulated taking into account reactive transport and root processes. The plant contaminant uptake model was previously calibrated using data from greenhouse experiments. The simulations adopted pedological and climatological data representative of a sub-tropical environment. Although the results obtained were specific for the proposed scenario, it was observed that, for more mobile contaminants, poor water conditions favor stabilization but inhibit plant extraction. Otherwise an irrigation system that decreases crop water stress had an opposite effect. For less mobile contaminants, the remediation process did not have appreciable advantages. Despite its simplifying assumptions, particularly about contaminant sorption in the soil and plant system, the numerical analysis provided useful insight for the phytoextraction process important in view of field experiments.

Keywords:

• unsaturated soil
• phytoextraction
• phytostabilization
• immobilization

Acknowledgments

The first author thanks CAPES. The second author thanks CAPES, CNPQ, DAAD, and FAPERJ. The authors also thank Professor Martinus Van Genuchten for his contribution at the beginning of this research.