Concentrations of heavy metals (Cu, Pb, Zn, Ni, Cd) in cassava grown on farmlands along highways in Owerri, was investigated. Cassava leaves and root samples were harvested from cassava farms along three major roads with high traffic density and another rural road that served as control location. Standard laboratory procedures to determine the concentration of these metals were adopted using Atomic Absorption Spectrophotometer. The metal concentrations in mg/kg in cassava root showed high levels of Cu (6.29±0.0346), Zn (8.49±2.243), Pb (0.5267±0.3156) and Cd (0.1167±0.0833). The concentrations of the heavy metals in the cassava leaves were of the order: Zn > Cu >Pb> Ni > Cd. Soil plant transfer factor values for all the metals in all the sites indicated medium accumulation. Heavy metal concentrations in soil showed significant correlation with concentrations in cassava root with no significant statistical differences in bioaccumulation of heavy metals in different parts of cassava. The overall results showed evidence of some heavy metal pollution on the soils and cassava plant.

The research was designed to ascertain the concentrations of heavy metals (Cu, Pb, Zn, Ni, Cd) in soil samples from farmlands along highways in parts of Owerri. Soil samples were collected from cassava farms along three major roads with high traffic density and a rural road that served as control location, for possible heavy metals contamination due to vehicular emission. Standard laboratory procedures were adopted to determine the concentration of heavy metals using Atomic Absorption Spectrophotometer (AAS). Contamination factor (CF) and Pollution Load Index were mathematically calculated. The results revealed that the mean concentrations of metals in soil samples in mg/kg ranged from 3.00-6.31 for Cu; Pb, 0.09-4.00; Zn, 3.97-8.59; Ni, 0.001-0.96; and Cd, 0.31-0.79. These metals showed decrease in concentrations with increase in distance away from the highway. The values of contamination factor (CF) were low except for Cd and Pollution Load Index (PLI) for all soil studied showed no sign of pollution. There was no correlation between traffic density and concentration of heavy metal in soil except for Cd (Rs= 0.800). The overall results showed evidence of some heavy metal pollution on the soils with possible cumulative effect over time.

Refinery wastewater was treated with activated carbon from rice husk (ARH) and corn cob (ACC) using batch method. Agrowastes were carbonized at 600oC and chemically activated, using phosphoric acid (H3PO4) and used as adsorbents. Titrimetric and spectrophotometeric methods were adopted for the determination of phenol, and some anions (Phosphate, Nitrate-Nitrogen, Sulphate and pH) of refinery wastewater. Readings after treatment with the adsorbents were also recorded and the efficiencies of the adsorbents compared, to ascertain the dose at which purification was best achieved. Initial phenol concentration of 315.9 mg/l was reduced to 159.0±48.0-276.5±46.0 mg/l (ARH), 154.7±50,0-260.2±53.0 mg/l (ACC) and 132.5±21.0-201.9±1.0 mg/l (ARH + ACC). The efficiencies of the activated carbon were of the order: Rice husk + corn cob > rice husk > corn cob, while the corresponding dose efficiencies was: 15g >10g > 5g. The highest adsorption efficiency observed for anions were COD (49.15% by corn cob), BOD, (49.4% by corn cob), phosphate, (68.18% by Rice husk + corn cob), nitrate (70.68% by rice husk) and sulphate (56.68% by corn cob). Efficiency removal was in this order: Rice husk + corn cob > corn cob > rice husk and 15g >10g > 5g for the dosage. There was significant difference (p≤0.05) between the untreated and the treated refinery wastewater samples and a significant difference also exists between the adsorbents. Findings herein showed that activated rice husks and corn cobs are effective in adsorbing phenol and selected anions in refinery wastewater.