A biophysically based framework for examining phytoremediation strategies: optimization of uptake, transport and storage of cadmium in alpine pennycress (Thlaspi caerulescnes)

Abstract

This work consists of constructing a model that combines an understanding of physical transport processes and the biological mechanisms involved in the uptake, transport and sequestration of contaminants by a hyperaccumulator, alpine pennycress (Thlaspi caerulesciens), a non-accumulator, field pennycress (Thlaspi arvense), and a maize. Specifically, the model uses a Michaelis-Menten formulation to describe uptake, and transpiration-driven translocation into aboveground biomass. Model simulations indicate that, despite its small biomass and slow growth, the hyperaccumulator alpine pennycress is a reasonable choice for phytoextraction due to the fast uptake rate as well as high metal tolerance, specifically in the aboveground biomass. In contrast, the field pennycress, which has a similar small biomass, but can only tolerate cadmium at much lower levels and does not translocate cadmium into aboveground biomass, is not an ideal candidate for phytoextraction. Although maize has a much larger biomass, phytoextraction using maize requires chemical treatment that mobilizes cadmium into the surrounding environment, and it has negative features similar to those of the field pennycress. Further studies that account for diurnal and seasonal variations in moisture and radiation may be required; however, the relative performance between those three species is not expected to change.