The Effect of Two Biodegradable Chelates on Phytoremediation Potential of Vetiver (Chyrsopogon zizanioides) in Copper Contaminated Soils

One of the remediation methods for soil contaminated with heavy metals is to use hyperaccumolator plants which is known as phytoremediation. The use of a new generation of biodegradable chelate agents is increasing the efficiency of phytoremediation and preventing environmental pollution. Vetiver is a good option for using the new generation of chelators. The aim of this study was to investigate the effect of different levels of biodegradable chelates EDDS and MGDA at four levels (0, 1, 2 and 4 mmol per kg of soil) on increasing copper extraction at three levels of copper pollution (100, 200 and 400 mg kg-1 of soil) which was carried out by Vetiver grass (Chyrsopogon zizanioides L.). The amount of copper uptake by vetiver in the presence of 4 mmol EDDS treatments at 100, 200 and 400 ppm levels of copper contamination were respectively 8281, 10125 and 10423 µg plant-1 after 120 days, which were 51, 84 and 89 percent more than the one in control treatment (absence of chelate). The amount of copper uptake in 4 mmol MGDA treatment at the aformentioed levels were 5679, 7688 and 8831 µg plant-1, respectively, which they were increased 19, 61 and 85 percent compared to the control treatment. Application of EDDS chelate increased the level of extractable copper with DTPA. The maximum amount of extractable copper at 4 mmol EDDS and MGDA and 400 ppm-copper treatment was 27.5 and 16.7% more than the one in control treatment, respectively. The mean values of bioconcentration factor (BCF) in 4 mmol of EDDS and MGDA were 0.51 and 0.37 respectively, and the mean value of translocation factor (TF) was 0.19. The results of this study showed that vetiver has a special ability to remediate copper-contaminated soils and 4 mmol EDDS per kg of soil treatment intensifies the uptake of copper in the roots. Consequently, vetiver grass could be considered as a candidate species for phytostabilization of Cu pollution, which not only protect the soil but also reduces the risk of food chain pollution and EDDS is introduced as a suitable biodegradable chelate that enhances phytorermediation of copper by vetiver.