AUTHOR: OMEKE, OBIADERI JOEL
DEPARTMENT: SOIL SCIENCE TECHNOLOGY
AFFILIATION: FEDERAL UNIVERSITY OF TECHNOLOGY
A study of the chemistry and fertility status of arable soils around oil exploration sites in the Niger Delta region was conducted. A free survey approach was used in field sampling guided by morphological dissimilarities of the polluted and unpolluted sites. Results showed that soils were deep and sandy (72.8-98.2 % sand). Moisture content (MC) was lower in polluted soils (10.2-35 %) than in unpolluted pedons (21.6-49.6%) while the same trend was found in soil pH in polluted soils (pH=3.0-5.1) than unpolluted pedons (pH = 3.8-5.3). Organic matter (OM), total hydrocarbons (THC) and percent aluminium saturation (Al.sat.) were generally higher in polluted than unaffected pedons. Effective cation exchange capacity (ECEC) was lower in polluted soils (1.8-5.1 cmol/kg) when compared with unpolluted pedons (3.8-6.6 cmol/kg). Higher concentration of copper (Cu), manganese (Mn), iron (Fe), chlorine (Cl) and zinc (Zn) were recorded in polluted sites. Values of nitrate (NO3–) were higher in unpolluted soils than polluted site while the reverse was the case for phosphates. In polluted soils, values of Nickel (Ni) ranged from 0.2-2.1 mg/kg while 0.0-1.0 mg/kg was reported in unpolluted soils. Concentrations of mercury (0.0-0.1 mg/kg), cadmium (0.1-1.1 mg/kg), vanadium (0.1-2.0 mg/kg), chromium (0.0-1.8 mg/kg) and lead (0.1-5.3 mg/kg) were found in polluted soils when compared with 0.0-0.0, 0.0-0.5, 0.1-5, 0.0-0.4 and 0.1-1.2 mg/kg, respectively in unaffected soils. Results showed significant positive correlations (P <0.05) between heavy metals and total exchangeable acidity (TEA) while the reverse was the outcome when heavy metals were correlated with total exchangeable bases (TEB).
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