Effect of Oil Spill on Physicochemical Properties of Soil Spilled Sites in Kokori, Ethiope East Local Government Area, Delta State, Nigeria

Abstract

Oil pollution might affect soil physicochemical properties. Pore spaces might be clogged, which could reduce soil aeration, water infiltration and increase bulk density, subsequently affecting plant growth. This study investigated the effect of oil spill sites at Kokori, Delta State, Nigeria, analyzing physicochemical properties, total petroleum hydrocarbon, polyaromatic hydrocarbon, benzene, anions and selected heavy metal concentrations using standard methods. Data obtained revealed that the physicochemical properties of the assessed soils were insignificantly altered when compared with their respective DPR intervention values. PH values were in the range of 4.80-5.60 which is considered to be strongly acidic. The electrical conductivity ranged from 122µS/cm to 185µS/cm indicating that the soil is saline. Chloride ion values were between 32.50mg/kg to 82.10mg/kg. Nitrate ranged from 0.85mg/kg to 1.04mg/kg, while phosphate was between 0.34mg/kg and 0.96mg/kg. Total petroleum hydrocarbon varied from 7.12-45.66mg/kg for topsoil and 7.12-37.82mg/kg for bottom soil. It is lowest at 7.12mg/kg, mean at 18.1mg/kg. These values were within the DPR permissible limits. Benzene and Polyaromatic Hydrocarbon (PAH) had a constant value of 0.001mg/kg in all locations.  Iron, arsenic, lead, mercury, cadmium, nickel and copper were the heavy metals detected. Their concentrations at spill sites were moderate and generally did not exceed their respective target limits. However, level of lead was as high as 11.6mg/kg in location 3. The soil should be monitored so that it does not exceed the threshold values of the studied parameters.