Phytoremediation Potential of Some Indigenous Herbaceous Plant Species Growing on Metalliferous Mining Site at Nahuta, Bauchi State, Nigeria

Abstract

Abstract

Heavy metals constitutes a serious threats because unlike most organic pollutants they are not easily degraded through natural process and therefore remain in the environment for a very long time. Soil contamination resulting from mining activities affects surrounding flora and fauna and presents a large clean-up challenge to the mining industry. One alternative biological approach to deal with this problem is phytoremediation – which involves the extraction or inactivation of these metals in soils by plants. Compared to other technologies, phytoremediation is less expensive and is particularly suitable for treatment of large volumes of soil in abandoned mining site. The extent of soil contamination by heavy metals (Zn, Cu, Pb and Cd) and potentials of herbaceous plant species to remediate the soil at Nahuta spoiled mining site in Bauchi State, Nigeria was assessed. Herbaceous plants and their associated soils were collected from three sites namely Jijigari, Jijidaba and Gamagari. There were generally higher concentrations of the heavy metals in plants than in soils which indicate the ability of the plants to tolerate and accumulate these metals. Considering the definition of a hyperaccumulator – plant that accumulate >1000mg kg−1 of Cu, Co, Cr, Ni or Pb, or >10,000mg kg−1 of Mn or Zn, none of the plants investigated attained the status of hyperaccumulator. However Chloris pilosa with BCF of 1.40 and TF of 1.04 is a potential phytoextractor of Cu. Cynadon dactylon with BCF of 2.74 and TF of 4.67 is also a good candidate for phytoextraction of Cd. It also means that all the herbaceous plants under consideration (except Eleusine indica and Pennisetum pedicellatum for Zn remediation) could be used as phytostabilizers of the various metals in the soil environment since they have BCF < 1and TF < 1.