Electronic Thesis and Dissertation Repository


Master of Science




Dr. Sheila Macfie


Metal contamination of soil can be reduced by adding chelators to improve the efficiency of metal uptake in phytoremediation, but optimal concentrations and types of chelators have not been determined. A geochemical model (Visual MINTEQ3.1) was used to estimate the effects of four chelators on the solubility of four metals in hydroponic solution. The model showed that no iron was soluble in the absence of a chelator, while the solubilities of cadmium, copper and zinc were high with or without chelators. Despite low iron uptake in all treatments, symptoms of iron-deficiency were not visible. High concentrations of exuded organic acids in solution had negligible effects on metal solubility because few metal-organic acid complexes formed. The amounts of metals taken up by radish (Raphanus sativus L.) varied with the type of chelator provided. EDTA and DTPA maximized cadmium and zinc uptake, respectively.