Potential of two invasive plant species, Lantana camara L. and Wedelia trilobata L., for selective heavy metal uptake.
This study examined the potential of the alien invasive species L. camara and W. trilobata to selectively remove ions of heavy metals, Cd, Cr, Cu, Co, Ni, Pb, Fe, Mn and Zn. The extent of removal of heavy metal ions by L. camara with reference to Albizia odoratissima was determined by using finely ground stems under static and dynamic conditions and by passing the metal ion solutions through fresh stems. The efficiency of heavy metal uptake by W. trilobata from polluted environments was investigated with reference to Ipomoea aquatica. Under static conditions, L. camara and A. odoratissima removed nearly 50% of Zn+2, Cd+2, Ni+2 and Mn+2. The removal of Cr+6, Co+2, Cu+2, Fe+2/Fe+3 and Pb+2 was less than 50%. The removal ability for each metal ion can be enhanced under dynamic conditions and when fresh stem segments were used. W. trilobata absorbed more than 1 mg dm-3 of Cu+2 Ni+2, Fe+2/Fe+3 after 72 h of treatment and Ni+2, Mn+2, Fe+2/Fe+3, Zn+2, Pb+2, Co+2, Cu+2, Cr+6 after 120 h of treatment. The high level of ion uptake ability by W. trilobata, A. odoratissima and L. camara can be attributed to the high amount of parenchyma in their tissues.