The Effect of Application of EDTA on the Phytoextraction of Heavy Metals by Vetivera zizanioides, Cymbopogon citrates and Helianthus annuls

Abstract

This study investigates the effect of the application of EDTA (ethylenediamine-tetraacetic acid) on the phytoextraction of Cd, Co, Cu, Ni, Pb, and Zn by Vetivera zizanioides, Cymbopogon citrates and Helianthus annuls harvested from experimental site (with EDTA) and a control area (without EDTA) in Zaria-Nigeria. The concentrations of Cd, Co, Cu, Ni, Pb, and Zn in different parts of each of the plant species collected from the experimental and control soils were determined using atomic absorption spectrophotometry. Application of 5 mmol/kg EDTA in soil did not affect plant growth but significantly increased Cd, Co, Cu, Ni, Pb, and Zn concentrations in shoots and roots of the plants. The concentrations of heavy metals measured in the tissues of plants collected from the experimental site were higher (P ≤ 0.05) than in the control. The percentage increase in the metal concentration for each plant specie were:- for Vetivera zizanioides, Cd – 75%, Co – 205%, Cu – 190%, Ni – 645%, Pb – 5% and Zn – 29%; for Cymbopogon citrates, Cd – 100%, Co – 109%, Cu – 551%, Ni – 907%, Pb – 39% and Zn – 50%; for Helianthus annuls, Cd – 21%, Co – 235%, Cu – 44%, Ni – 507%, Pb – 70% and Zn – 02%. The heavy metal concentrations were higher in leaves (P ≤ 0.05) than in roots of the plants. The translocation factor (TF) for all the metals studied were greater than 1.The results of this study demonstrated that EDTA is an efficient soil amendment in enhancing desorption of Cd, Co, Cu, Ni, Pb, and Zn from soil and in increasing their accumulation in plants. As for plant species tested, the effectiveness in the uptake of the metals studied was Helianthus annuls < Vetivera zizanioides < Cymbopogon citrates.