Phytoextraction Modeling of Heavy Metal (Lead) Contaminated Site Using Maize (<i>Zea Mays</i>)

Abstract

Phytoextraction is an ecofriendly technology through which plants are used for removing heavy metal contaminant from polluted sites. The effective implementation of this cost effective emerging technology requires a conceptual insight of soil and plant processes that control the uptake of targeted contaminant from the problematic area. Most of the current research deals with the plants grown in heavy metal contaminated soils and analyzed experimentally to determine their capacity to remove them from the soil. However, the prediction of the metal uptake by plants through mathematical modeling has received very little attention so far due to the complexity of the soil-plant-atmosphere continuum. In this study, a mathematical model is developed to investigate the removal of a heavy metal, lead (Pb), by maize at different growth stages of the plant. The model comprised of two parts: (1) moisture flow prediction and (2) contaminant uptake simulation. The first part predicts the actual water uptake by plant and computes the hydraulic regime of the soil profile for different moisture conditions. Through the second part of the model, the lead extraction kinetics is simulated using the water uptake data and plant root biomass accumulation. The model yields a set of partial differential equations which are solved numerically by the finite difference technique for varying boundary conditions. The moisture flow simulation is validated using the literature of field data for maize and the metal extraction simulation is performed based on this prediction for a characteristic example to remediate a lead contaminated site.