EVALUATION OF HEAVY METAL CONCENTRATION IN ELEPHANT GRASS (PENNISETUM PURPUREUM) FROM EXHAUST POLLUTION OF VEHICULAR MOVEMENT ALONG SAGAMU-ORE EXPRESSWAY.

This research was conducted to evaluate the heavy metals composition on plant (Pennisetum purpureum) and soil resulting from exhaust vehicular pollution from vehicular movement along Sagamu-Ore Expressway. Heavy metal composition were determined using Atomic Absorption Spectrophotometer (AAS). The results obtained with regards to the heavy metal composition in plant (Pennisetum purpureum) were of the range: Cr (between 0.00-3.10mg/kg) Pb (0.17-4.19 mg/kg) Cu (1.19-25.95 mg/kg) Zn (3.05-45.86 mg/kg) Fe (1794.31-5239.45 mg/kg), Mn (22.98-74.96 mg/kg) Ni (0.00-0.08 mg/kg) and Co (0.00-0.08 mg/kg) during dry season and Cr (1.01-3.89 mg/kg) Pb (0.00-3.12 mg/kg), Cu (0.43-21.73 mg/kg) Zn (1.96 - 42.63 mg/kg) Fe (1279.31-5106.38 mg/kg), Mn ( 15.81-70.51 mg/kg) Ni (0.00-0.08 mg/kg) and Co (0.00-0.06 mg/kg) during wet season. The values were found to be above the value recommended by FAO/WHO, FEPA and EU except for Zn, Ni and Co which are within the recommended limit in both seasons. Correlation coefficient indicates a general reduction in heavy metal concentration levels in the samples collected during rainy season when compared to samples collected during dry season and when moved inward (5 m, 15 m and 25 m). The difference in all the heavy metals in plant during dry and wet season is statistically significant (p≤0.05) with Cu and Pb levels being significantly higher during dry season. These findings revealed that Cr, Pb, Cu, Zn, Fe and Mn were the major contributors to pollution during dry and wet season along the study area, while Ni and Co were the least pollutants from the vehicular emissions. This study shows that Sagamu-Ore Expressway was generally polluted with heavy metals as revealed by their presence and concentrations in plant (Pennisetum purpureum).