Mathematical estimation of heavy metal accumulations in Helianthus annuus L. with a sigmoid heavy metal uptake model

Abstract

It is a core issue in the application of phytoremediation technology to describe and predict the movement of contaminants from soil to plants. For this purpose, a mathematical model to describe the heavy metal accumulations in the entire soil-sunflower biomass system was developed, and validated using a sigmoid function and bioaccumulation factor. Both pot and field experiments were performed using sunflowers and target heavy metals (i.e., Cd, Ni, Pb, and Zn) with various concentrations to monitor the changes in both biomass of sunflower and heavy metal accumulations during the different phases of growth. No statistical difference in the biomass production was found between sunflowers in contaminated soils with target heavy metals and those in control soils (p > 0.05), indicating that the heavy metals in soils with various concentrations evaluated in this study have not significantly affected both growth and biomass production of sunflowers. The biomass, bioaccumulation factor, and heavy metal concentration in soil are the most important parameters to the uptake of heavy metals from the soil and have been identified through sensitivity analysis. The heavy metal uptake by sunflowers was successfully estimated using a sigmoid heavy metal uptake model for field under validation test. Even though this study is based on limited data, it provides a direction and potential for predicting the mass of heavy metal accumulation in plant. This model may have potential application in identifying the green plant to removal the heavy metal. (C) 2019 Elsevier Ltd. All rights reserved.