The effect of edta-application to heavy metals phytoremediation by vetiver

Abstract

Contaminated soil with heavy metals includes Pb, Zn, and Cd were remediated by phytoremediation with vetiver to solved the problem in Thailand. This study compared the ability of two species of vetiver (i.e., Songkhla 3 and Prachuap Khiri Khan) in absorbing Pb, Zn, and Cd in contaminated soils and study the effect of EDTA application. After the experiment, Toxicity Characteristic Leaching Procedure (TCLP) test, Allium test, and seed germination were used to determined the toxicity of remediated soil. In this study, 5 mmol of ethylenediaminetetraacetic acid (EDTA) was used to improve the solubility of heavy metals in soil which leads to an increase in translocation factor and bioaccumulation factor.

According to microwave digestion method, the concentration of heavy metals includes Pb, Zn, and Cd was lower in soil and higher in both shoot and root parts of two ecotypes of vetiver in period of studied. While the EDTA application significantly increased the bioaccumulation of Zn in shoot and root part of Songkhla3, it did not significantly increase the total uptake of Zn in root parts of Prachuap Khiri Khan. TCLP results showed that the concentration of heavy metals was lower than regulatory level after 3 months of remediation,but concentration increased after EDTA application in fourth month. To confirm the ability of vetiver in phytoremediation, Allium test showed no effect of heavy metals in chromosomal aberration and high percentage of seed germination was observed in aliquot extracted from remediated soil by Songkhla3. The results from experiment confirmed that two ecotypes of vetiver grass have ability to reduce heavy metal concentration in contaminated soil and accumulated the in their shoot and root.