Evaluation of the impact of crude oil spillage on soil and cassava plant (Manihot esculenta) in Uzere, Isoko south LGA of Delta State Nigeria.

Abstract

An evaluation of the impact of crude oil spillage on soil, cassava tubers and leaves in Uzere (contaminated site) and Ekrejeta (control site) communities of Delta State were carried out. Three representative soil samples, cassava tubers and leaves were collected from three different points within each study site and determined in triplicates. Physicochemical parameters, heavy metal content, polycyclic aromatic hydrocarbons (PAHs) and total hydrocarbon contents (THC) of soil, heavy metal content and PAHs in cassava tubers and leaves were determined using standard analytical methods. Parameters determined include pH, conductivity, nitrate, sulphate, PAHs and THC as well as concentration of some heavy metals (Cd, Cr, Ni, Pb, Zn, Fe) in both soil and cassava samples. Concentrations of heavy metals were determined using Atomic absorption spectrophotometry. The average heavy metals detected in the soil include iron (Fe) 989.11mg/kg, cadmium (Cd) 1.50mg/kg, chromium (Cr) 8.26mg/kg, nickel (Ni) 3.92mg/kg, zinc (Zn) 10.04mg/kg, lead (Pb) 7.08mg/kg while average heavy metal detected in cassava tubers and leaf samples include lead (Pb) 3.13 and 3.22mg/kg, iron (Fe) 69.23 and 62.45mg/kg, cadmium (Cd) 0.00 and 0.22mg/kg, nickel (Ni) 2.73 and 6.38mg/kg, zinc (Zn) 14.04 and 32.72mg/kg respectively. The average pH of soil samples from the test site (Uzere) was 5.5, conductivity 58.67µs/cm. The average PAHs content of the soil was 0.17mg/kg. THC of 151.83mg/kg was detected in the soil. These findings suggest that the study site is heavily impacted by the crude oil spillage.

Keywords: Soil, cassava tubers, cassava leaves, physicochemical parameters, heavy metals