Study of Phytoremediation Potential of Fluted Pumpkin (Telfairia occidentalis) for Soil Contaminated with Heavy Metals

Aims: To investigate the phytoremediation potential of fluted pumpkin (Telfairia occidentalis) for some heavy metals (Cd, Cu, Pb, Cr and Co) in soil.
Study Design: The experimental design was based on the assumption of homogeneity of points where the experimental soils were collected.
Place and Duration of Study: Department of Chemistry, Nigerian Defence Academy (NDA) Kaduna, Nigeria, between January 2011 and April 2012.
Methodology: Surface soil (0 -20 cm) taken from various points of the department were used for the experiment. Pumpkin seeds were planted in polythene bags containing 1.5 kg of the soil which was contaminated with the metals of interest. The experiment consisted of six (6) contamination treatments and a control. These treatments were 5 mg kg-1, 20 mg kg-1, 75 mg kg-1, 100 mg kg-1, 200 mg kg-1 and 220 mg kg-1 of each metal. The soil and the pumpkin tissues (roots, stems and leaves) were analyzed for the metals, eight (8) weeks after planting, through atomic absorption spectroscopic (AAS) method. The physical and chemical characteristics of the soil were also determined.
Results: The plant’s shoot length, 8 weeks after planting, showed that Telfairia occidentalis grew better on uncontaminated (control) soil. Generally, the trend showed that the higher the metals level in the soil the shorter was the plant shoot length. The metals (Pb and Co) accumulated more in the shoot than in the roots (Translocation factor- TF > 1) and also than in the soil (Bioaccumlation factor- BF >1). Copper and chromium on the other hand accumulated more in the root and in the soil than in the shoot (both the TF and BF values are less than one).
Conclusion: The plant (pumpkin) can tolerate and survive high metals level in soil. It can be used as phytoremediator of soil contaminated with Pb and Co and to a lesser extent Cd.