Evaluation of EDTA application method to reduce Pb leaching risk into ground waters using Hordeum bulbosum L.

This study was conducted to increase phytoextraction efficiency of Hordeum bulbosum L. in lead contaminate soil (Loamy Clay) in the EDTA-assisted, Ethylen ediamine tetra acetic acid (1.5, 5, 10 mmol kg−1), assessing optimum of treatment time and method of EDTA application to reduce Pb leaching risk into ground waters. Uncontaminated soil without EDTA (C) and contaminated soil without EDTA (W) used as the controls. The results revealed that the greatest Pb uptake (890.70 mgKg-1 in underground organs and 720.65 mgkg-1 in above ground organs) was observed in 5EDTA treatment. Therefore, 5mmolkg-1 was used in second step for assessing harvest time for 20(Vegetative stage), 80 (Flowering stage) and 140(Seed production) days. Results showed that the concentration of Pb in plant tissues was increased with passage of time, but between flowering stage and seed production there was no significant difference (p‹0/05) and the best harvest time in order to achieve maximum removal of the metal was flowering stage. In third step to reduce leaching risk of Pb-EDTA, 5 mmolkg-1 EDTA in three ways of single, double (two successive) and triple (three successive) were added to the soil. The results showed that under single dosage application, Pb content in the soil reached at its minimum concentration. The data indicated that the maximum Pb concentration in the plant organs was calculated at the single dosage while metal concentration in the plant organs did not vary considerably when double and triple dosage were added. Overall, optimum phytoextraction of H. bulbosum and Pb leaching risk reduction was observed when 5 mmol kg−1 EDTA was added in single dosage, 80 days after the plant cultivation.