C.Muralidhar Rao*and G.Sudhakar**
*Officer on Special Duty, Environmental management cell
Atomic Minerals Directorate for Exploration & Research, Hyderabad
** Former Director, Environmental Protection Training and research Institute, Hyderabad.
Uranium mill tailings are the crushed rock residues of the uranium extraction process from Uranium Oxide ores. The tailings effluent and tailings solids from the mill are discharged as slurry to a waste retention pond, the tailing pond. Natural radionuclides and trace metals are present in mine tailing/soil in varying concentrations, some of these are found in elevated concentrations in uranium waste tailings. Radionuclide and metal pollution is a global environmental problem and the number of contaminants entering the environment has increased greatly in recent times and this is due to increased mining activities. A study was undertaken for three years to evaluate the potential of native plant species for the removal of residual heavy metals and radionuclides from tailing ponds of Uranium mines, Jaduguda, Jharkhand. Sampling stations: three at Jaduguda, one at Turamdih were selected. pH, Electrical conductivity (EC) 12 metals (- Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd, Pb) and 3 radionuclides – Co, Sr and U) of the tailings were analysed. From the analysis of sediment/soil / water/effluent of tailing ponds, 8-elements (Al,U, Mn, V, Fe, Ni, Cu and Zn) were found to be significantly in higher concentrations in tailing soils. U and Mn were found to be the predominant contaminants. 26 plant species were screened for their ability to accumulate and remediate the contaminated soils. Significant hyperaccumulants are [Sacchurum spontaneum(U 8ppm),Pteris vittata(U 4ppm), Cyprus compressus(U 2ppm), Lantana camara(U 4ppm) and Typha latifolia(U 3ppm)], S.spontaneum(Cr16ppm), Ricinus communis(Cr 19ppm) and Typha latifolia(Cr 18ppm)] and for Sr[Alstonia scholaris(98ppm), Buchanania lanzan(81ppm) and Cassia alata(77ppm). Considering various factors of suitability of the plant species for phytoremediation, 4 species viz;Sacchurum spontaneum, Typha latifolia, Pteris vittata and Cyprus compressus found to hold good potential as phytoaccumulants of heavy metals and radionuclides in tailings of uranium mines.
Keywords: Uranium; Tailing pond; Bioremediation; Phytoaccumulation, Phytoremediation; Nuclear wastes; Radionuclide; Trace metals
Volume -01, Issue -05 , December 2013.