Coupling bioaccumulation and phytotoxicity to predict copper removal by switchgrass grown hydroponically

Abstract

A major challenge in phytoextraction is to increase plants' removal rates of metals from contaminated soils. In this study, we developed a phytoextraction model, by coupling a saturable Michaelis-Menten type accumulation model and an energy-based toxicity model, to predict copper (Cu) removal by switchgrass (Panicum virgatum L.) grown hydroponically under various exposure concentrations. Results of the present study indicated that the phytotoxicity of Cu to switchgrass is relatively low, whereas a certain accumulation capacity exists in the plant for Cu. In addition, the simulation results suggested that, under a lower dissolved concentration, Cu removal is increased more efficiently as the exposure duration increases. Although it is difficult to extrapolate the results from greenhouse-based hydroponic experiments to field conditions, we believe that the current methodology can offer a first approximation in predicting the phytoextraction duration needed for plant species to remove a specific metal from contaminated sites, which is crucial in evaluating the economic costs for remediation purposes.

Copper phytoextraction with willow (Salix viminalis L.) under various Ca/Mg ratios. Part 1. Copper accumulation and plant morphology changes

“…The results for physiological 4:1 Ca/Mg ratio did not confirm the results presented by Juang et al (2011). This observation is a sign of the significant role of Ca/Mg ratio for willow growth.…”

“…No significant differences in shoot growth between particular copper doses and significant differences between them and a medium without copper addition (0) confirm the high immunity of the tested willow taxon. In addition, the studies described by Juang et al (2011) indicate significant inhibition of the plant growth rate with metal concentration increase in the nutrient solution. The same results were also observed in our experiment but with use of a higher copper concentration in Knop solution.…”

Phytoextraction of Metals: Modeling Root Metal Uptake and Associated Processes

“…Uptake of metals at the biosurface by the root and root hairs is assumed to follow a nonlinear Michaelis-Menten rate equation ( energy-based toxicity model aims to enhance the ability to assess the feasibility of phytoextraction (Juang et al 2011). The bioaccumulation and phytotoxicity parameters of Cu in switchgrass (Panicum virgatum L.) were adapted by fitting the models to the data obtained from hydroponic experiments under various exposure concentrations (Juang et al 2011).…”

“…Uptake of metals at the biosurface by the root and root hairs is assumed to follow a nonlinear Michaelis-Menten rate equation ( energy-based toxicity model aims to enhance the ability to assess the feasibility of phytoextraction (Juang et al 2011). The bioaccumulation and phytotoxicity parameters of Cu in switchgrass (Panicum virgatum L.) were adapted by fitting the models to the data obtained from hydroponic experiments under various exposure concentrations (Juang et al 2011). Lehto et al (2006) presented a "dynamic plant uptake model" which describes plant Zn uptake using MichaelisMenten kinetics but includes consideration of the labile metal K D value, advective replenishment of metal at the soilroot interface, and the short-term kinetics of desorption from soil solids.…”

“…Metal uptake, via the transporters, from the root surface into the root symplast is concentration dependent and can be fitted to a MichaelisMenten saturation kinetics (Nissen 1996). So, the metal removal by a plant can be calculated using a saturable Michaelis-Menten-type absorption model, and from that the removal rate can be expressed as a time-dependent parameter (e.g., Juang et al 2011). The root absorption power can be determined from the uptake rate of each metal on a fresh weight basis.…”