Phytoremediation of Cu and Cd-contaminated roadside soils by using stem cuttings of Portulaca oleracea L

This study investigates the phytoremediation efficiency of stem cuttings of Portulaca oleracea L. grown in Cu and Cdcontaminated soils collected from six major arterial roadsides in Coimbatore, India. The levels of Cu and Cd extractable by diethylene triamine penta acetic acid (DTPA) were tested in all soils. Furthermore, plant growth parameters and the accumulation of Cd and Cu were tested after stem cuttings were grown for 30 days in all soils. The DTPA-extractable levels of Cu (8.45 to 35.34 & mu;g/g) and Cd (0.18 to 3.10 & mu;g/g) showed wide ranges of variations between sites. Furthermore, levels of Cu were higher in all soils (3.46 to 135.92 times higher) than Cd. After 30 days of growth, significant variation was not found between the soils in the plants' number of leaves (39 & PLUSMN; 2.0 to 41 & PLUSMN; 1.5 leaves), length of roots (8.0 & PLUSMN; 0.7 to 8.7 & PLUSMN; 0.7 cm), and fresh weight (11.40 & PLUSMN; 0.59 to 11.73 & PLUSMN; 0.36 g). The accumulation of Cu was higher (by 2.45 to 5.92 times) than that of Cd in all plants. The calculated accumulation factor (transport of Cu and Cd from soil to plants) was higher for Cd (3.01 to 39.22) than Cu (1.24 to 4.59). There was no clear trend between the order of DTPA-extractable Cu and Cd in soil, Cu and Cd accumulation in plants, and the calculated accumulation factor. Considering the accumulation efficiency of P. oleracea for Cu and Cd, this plant could be explored further for the removal of metals from roadside soils.