Determination of the physicochemical properties and selected heavy metal concentrations in soil around a Kolo Creek oil well head in Bayelsa State, Nigeria

Abstract

Environmental impact of crude oil exploration and exploitation has become worrisome leading to the discharge of toxic elements into the environment. Soil samples obtained from Kolo Creek oil well head 22T in Bayelsa State, Nigeria were analysed for their physico-chemical properties using standard analytical methods while the heavy metals (Co, Cr, Ni, Pb, Fe and Cu) were analysed using Atomic Absorption Spectrophotometer (AAS). The results obtained for the physico-chemical properties such as pH, electrical conductivity and total organic carbon ranged from 7.70±0.06 to 8.20±0,06, 24.00±0.58 to 37.00±0.58𝜇S/cm and 0.28±0.01 to 0.39±0.01% respectively, while the selected heavy metal levels (in mg/kg) ranged from BDL to 9.67 0.33 (Co), 12.33±0.33 to 38.66±0.88 (Cr), 11.33±0.33 to 15.66±0.33 (Ni), 31.33±0.33 to 173.66±0.33 (Pb), 15123.67±0.33 to 24211.33±0.33 (Fe) and 11.33±0.88 to 21.33±088 (Cu). These results showed that iron had the highest concentration while cobalt had the lowest. The levels of these heavy metals in this study area were below the DPR maximum allowable limits for these heavy metals in Nigeria soils. However, the amounts of lead in the top and middle soil were higher than the Department of Petroleum Resources (DPR) target value but lower than the intervention value. Hence, there is need for regular monitoring of the crude oil exploration activities in Bayelsa State to prevent direct discharge of untreated effluents containing heavy metals into the environment. Furthermore, constant maintenance of the oil pipelines and well heads to prevent corrosion is recommended to avert this environmental menace.