Use of Festuca ovina L. in chelate assisted phytoextraction of copper contaminated soils

Abstract

Festuca ovina L. is a hyperaccumulating plant which has aroused considerable interest with respect to its possible use for phytoremediation of contaminated soils. This study has been conducted to evaluate the potentials of F. ovina L. to serve as a phytoremediation plant in the cleaning up of Cu in the polluted soils and to identify extraction efficiency of Ethylene Diamine Tetraacetic Acid (EDTA) for desorbing copper in relation to chelator dosage. Seeds have been sown in control and Cu contaminated pots (artificially contaminated with 150 mg kg-1 Cu). Results revealed that Cu negatively affected growth and tolerance indices of F. ovina and the root length was the most sensitive parameter among all measured parameters. The treatments used for assessing EDTA efficiency were 1.5, 3, 6, 15+1.5, 3+3 mmolkg-1, control (C: uncontaminated soil without EDTA) and W (contaminated soil without EDTA). Results showed that the application of 1.5 mmolkg-1 of EDTA did not significantly improve the phytoextraction of Cu and statistically, there was no significant difference in Cu uptake between single and split applications of 1.5 mmolkg-1 of EDTA. A sharp increase in root Cu concentration was observed when 3 mmolkg-1 of EDTA was applied. The highest amount of Cu extracted for the plant tissues was achieved at the doses of 6 mmolkg-1 and 3+3 mmolkg-1 EDTA, respectively. Higher Remediation Factors (RF) were obtained for the plants grown in contaminated soil and the highest RFs (0.08% and 0.07%) were recorded after the addition of 6 and 3+3 mmolkg-1, respectively. Application of EDTA showed a relatively decrease in TI (Tolerance Index) value and the lowest value of TI was recorded in 6 mmolkg-1 EDTA treatment. According to the experiment, EDTA has appeared to be an efficient amendment when Cu phyto-extraction with F. ovina was addressed. But further studies would be needed on investigating the reduction of percolation risk by the amount and process of chelate application.