Phytoextraction of heavy metals from coal fly ash for restoration of fly ash dumpsites

This study reports the efficiency of Saccharum spontaneum and Saccharum munja for phytoextraction and phytostabilization of metal-contaminated coal fly ash (FA) dumpsites. Pot experiments with FA and garden soil (GS) as control were conducted for a period of one year. Heavy metals in FA and their relative translocation to root and shoot tissues were analyzed. The accumulation of heavy metals in the roots was higher than the shoots. A considerable amount of heavy metals was sequestered and accumulated by the roots but the amount of contaminants was not translocated to the shoot system. This could be supported by the translocation factor (TF) values. Values of bioaccumulation factor (BAF) greater than unity indicated that Saccharum is a potential heavy metal accumulator. The BAF values for roots in S. spontaneum plants grown on FA were higher (8.01, 1.40, 3.02, 0.92, 1.66 and 1.47 for Zn, Pb, Cu, Ni, Cd and As, respectively) than those of S. munja (Zn - 8.54, Pb - 1.66, Cu - 3.24, Ni - 0.76, Cd - 1.63 and As - 1.41). The BAF of the metals was less than unity in shoots. This is congruent with the results on DNA damage that increased significantly in the root cells and remained unaffected in the shoot. Results suggest that the plants are suitable for extracting Zn, Cu, Cd, Pb and As from FA and stabilize them in the underground plant parts. Therefore, for long-term management and restoration of FA, use of Saccharum plants for phytoremediation will be an effective strategy.