Heavy metals scavenging of soils and sludges by ornamental plants

Abstract: The recent developments to identify or evolve high biomass crop plants having capabilities to accumulate heavy metals suggest that phytoremediation of metal contaminated soil can be a viable alternative to most conventional clean up technology. Comparative study of heavy metals concentration in the roots, shoots and leaves of different woody plants species e.g. Bougainvillea glabra, Croton spp, Quisqualis indica, Ficus benjamina Variegata, Toona ciliata, and Siris (Albizia lebbeck) indicated their high heavy metals scavenging capacity. For studying the heavy metal content of sewage sludge and plant species, solid sludge and plants were collected from seven Sewage Treatment Plants (STPs) viz., Howrah, Garulia, Bhatpara, Nabadwip, Srirampur, Kona, Chandannager, and from the Periurban areas viz., Nadia/Chakdaha/Ektapur (N/C/E), Pumlia (N/C/P), Sikarpur (N/C/S), Tatla (N/C/T). Sludge samples were taken from heaps at various places in the pile of each plant, using an auger. Around 6-10 individual samples were mixed together and pooled sample were used for analysis. The concentration of Cd, Pb, Cr, and Ni in the roots of plants at STP ranged from 0.805 to 1.03, 9.24 to 32.6, 10.62 to 15.56, and <0.05 mg kg^-1, respectively. Whereas, Cd, Pb, Cr, and Ni content in the shoots of plants at STPs ranged from 1.55 to 1.7, 9.27 to 22.6, 5.35 to 11.03, and <0.05 mg kg^-1, respectively. In the leaves, Cd, Pb, Cr, and Ni content ranged from 1.76 to 3.58, 9.1 to 22.76, 8.76 to12.02, and <0.05 mg kg^-1, respectively. Therefore, above mentioned plant species can be selected for scavenging heavy metals from soils and sludges.