Heavy Metals and Hydrocarbon Assessment in Soil; Implication as Source of Contaminants in Okerenkoko Community Warri South-West, Delta State, Nigeria.

Abstract

Heavy metal and hydrocarbon proportion in Okerenkoko Community, Delta State is alarming. Five (5) soil samples were collected randomly from the community, the collected samples were investigated to determine the effects of these substances in the soil to living things at large using Atomic Absorption Spectrometer (AAS) and Gas Chromatography respectively. The Heavy metal concentration investigated result show a range of: Fe (386.6 - 665.6 with mean value 502.3) mg/kg, Cu (11.3 - 29.8 with mean value 21.1) mg/kg, Pb (0.388 - 0.523 with mean value 0.46) mg/kg, Cr (6.53 - 8.24 with mean value 7.23) mg/kg, Zn (37.5 - 63.3 with mean value 50.1) mg/kg, the average proportion of the heavy metals occurred in order of Fe>Zn>Cu>Cr>Pb. From the study, it showed that the concentration of most of the heavy metals in the soil falls below the level, meanwhile Zn has high concentration level when compared with the standard of World Health Organization (WHO) permissible limit. This implies that Okerenkoko Community is still contamination free with respect some specific heavy metals and notwithstanding, caution has to be taken to prevent potential future contamination and Zn with high concentration of about 50 mg/kg should call for immediate remediation. Furthermore, the concentration of hydrocarbon (TOC and THC) ranges from: TOC (18.28 - 31.53 with mean value 24.52) %, THC (250.53 - 874.74 with mean value 566.74) g/kg, the investigation of Total Organic Carbon (TOC) and Total Hydrocarbon Content (THC) showed the community has an carbonate soil as the Total Organic Carbon level goes beyond 12 - 18% in concentration which is considerably high in concentration. However, under different conditions, this TOC level can be considered both beneficial and the soil in Okerenkoko Community is Highly Contaminated and this contamination is believed to be associated with petroleum spills from oil tankers, local means of production and transportation of petroleum products.