Phytoremediation Potential of Ricinus communis L. (Castor Oil Plant) in Northern Nigeria

This research work is a field experiment carried out to evaluate the phytoremediation potential of Ricinus communis L (castor oil plant) in Zaria town of northern Nigeria. The sandy loam field (pH 6.78) used in the experiment was contaminated with Cd, Co, Ni and Pb from a metal dumpsite. A solution of 5 mmol/kg ethylenediamine-tetraacetic acid (EDTA) was applied on a portion of the field. The harvested plant and the soil collected from the experimental and control sites were analysed using atomic absorption spectrophotometer to determine the concentrations of Cd, Co, Ni and Pb in different parts of the plant and the soil treated and untreated with EDTA. The physicochemical parameters of the soils - pH, moisture content, particle size, cation exchange capacity (CEC) and organic matter (OM) were determined. The concentrations of the metals in the different parts of the plant harvested from the experimental site were higher than those from the control soil. The statistical analysis using One-way ANOVA Duncan grouping, showed that there is a significant difference (P < 0.05) between the concentrations of the studied metals in the soil and that of the plant tissues at the dumpsite. Also the metal levels in plant harvested from the soil treated with EDTA were higher than those from untreated soil and the increases for the studied metals in the entire plant were by the following factors: Cd – 1.9, Co – 1.8, Cu – 1.5, Ni – 8.8, Pb – 2.1 and Zn – 1.4. The Bioaccumulation factor (BF) and Translocation factor (TF) for the metals studied varied. Ricinus communis L (castor oil plant) was found to have good phytoremediation potential for soil contaminated with heavy metals.