Comparative Chelate-assisted Phytoextraction ofHeavy Metals by Jatropha curcas, Jatropha gossypifolia and Jatropha multifida Cultivated onSoil Collected from Selected Dumpsites in Ekiti State, Nigeria

Abstract

Background: It is needful to design a process that will lead to the use of fast growing tropical plants for phytoextraction studies. Study Design: It is an analytical study. Place and Duration of Study: The study was conducted between October 2010 and June 2012 on selected dumpsites located in Ekiti State, Nigeria. Methodology: Bulk soil samples were collected from selected dumpsites on seven points at interval of 10 m, starting from top of the slope. Physicochemical and heavy metals content of soil were determined on bulk and fractional soil samples, using sequential extraction technique. The heavy metals were analyzed using atomic adsorption spectrophotometer, prior to plants’ cultivation. Heavy metal concentration of plant with and without 1g/kg EDTA was determined in different sections of plant by flame atomic absorption spectrophotometer, in other to determine their phytoextraction potentials. Results: The result revealed the mean value of pH (6.02±0.11-6.31±0.12), organic matter content (3.00±0.08-7.00±0.13%) and the CEC (59.20-62.40 mmol/kg) to be highest at Aba Egbira dumpsite. The result of sequential extraction revealed that heavy metal were distributed in fraction soil samples in the order 75>150>350>495>1000 µm, showing the effect of particulate site on the availability of heavy metals. Application of EDTA increased mobility of heavy metals from soil to shoot of plants with concentration of Cd in J. curcas, J. gossypifolia and J. multifida in the following range; (372.0-440.1; experiment, 150.2-186.6; control), (377.5-418.2; experiment, 142.2-202.4; control) and (455.0-530.6; experiment, 245.0-259.2; control) while Cu and Pb ranged from (921.0-118.0; experiment, 405.0-821.0; control), (818.0-962.0; experiment, 442.0-650.0; control) and (1079.0-1138.0; experiment, 644.0-686.0; control) and Pb (384.4-426.2; experiment, 242.2-283.0; control), (328.0-376.0; experiment, 159.0-186.2; control) and (417.0-436.0; experiment, 330.0-370.7; control) mg/kg respectively, in all dumpsites investigated. Bioaccumulation factor (BF), translocation factor (TF) and remediation ratio (RR) greater than one showed that they are effective in chelant-assisted phytoextraction. Conclusion: Therefore, the use the species of Jatopha are advocated for phytoextraction Cd, Pb and Cu.