Soil pollution assessment was carried out in seven oil producing areas in Rivers State, and also in Nnamdi Azikiwe University, Awka which served as the control area. Five composite soil samples from five different locations were randomly collected in each local government area (L.G.A.) with oil deposits, at a depth of 1 metre using soil auger. The samples were air-dried, ground, sieved and analyzed for pH, electrical conductivity, moisture content and heavy metals (cadmium, chromium, lead and nickel), using standard procedures. The data were subjected to statistical analysis using mean and bar graphs, and the results obtained were compared with those from the control area and DPR Standard. One way analysis of variance (ANOVA) was also done to establish the statistical difference between the study areas and the control area at 0.05 confidence level. The mean values of the parameters analyzed ranged as follows; pH: 4.25 - 6.48, electrical conductivity: 2.45 - 10.60 μS/cm, moisture: 0.60% - 0.90%, cadmium: 0.08 - 0.58 mg/kg, chromium: 2.86 - 7.91 mg/kg, lead: 0.22 - 9.79 mg/kg and nickel: 0.44 - 5.08 mg/kg. The control values were; pH: 6.04, electrical conductivity: 92.00 μS/cm, moisture: 0.80%, cadmium: 0.09 mg/kg, chromium: 8.72 mg/kg, lead: 1.04 mg/kg and nickel: 0.89 mg/kg. The results revealed that the pH levels of the soils were acidic and most of the values were within the DPR limit. Electrical conductivity and moisture contents of the soils were low and also below the control value and DPR standard. Heavy metal concentrations in the soils exceeded the control values but were below DPR limit. ANOVA results showed that there was a significant difference (p < 0.05) between chromium concentration in the assessed soils and the control soil. The results obtained revealed that the examined areas in Rivers State were not yet adversely polluted in terms of oil exploration and exploitation activities. Therefore, periodic monitoring of the project areas is strongly recommended to prevent the buildup of these contaminants beyond limits of maximum tolerance.
Cite this paper
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