Petroleum Hydrocarbon Pollution of Sediments of the Benin-Ethiope Fluvial System Around the Oghara Industrial Area, Delta State, Nigeria

Abstract

Activities in the petroleum industry downstream sector have been known to pollute the environment. It is necessary to ascertain the effect of these activities on the sediments of the Benin-Ethiope Fluvial System where much of such activities take place. Sediment samples were collected from five sampling stations in the study area and two control (upstream) sampling stations twice in a season for two years. Sediment samples were analyzed for trace metals by method of flame atomic absorption spectrophotometry after wet digestion with 2M HNO₃. Analysis for sediment geochemical parameters including total petroleum hydrocarbons (TPH) were carried out by standard methods. Results obtained are, pH (5.17±0.86), total organic carbon (TOC) (6.20±0.13 %), total organic extracts (TOE)+ (4090±1704 mgkg⁻¹), TPH (31802±30.40 mgkg⁻¹), Cu (7.4±2.9 mgkg⁻¹), Pb (0.83±1.1 mgkg⁻¹), Zn (22±26 mgkg⁻¹), Cd (0.15±2.3 mgkg⁻¹), Ni (4.4±1 mgkg⁻¹). The concentrations of the two oil parameters (i.e. TPH and TOE) in the study area are found to be very much higher than their concentrations in the control area. The average concentration of TPH in the study area very much exceeded guideline value. The sediments of the area is polluted with petroleum hydrocarbons in addition to the sediments having high acidity. The sediments of the study area are therefore of low quality.