Oxygenated Polycyclic Aromatic Hydrocarbons in Surface Water of Four Major Rivers in the Niger Delta of Nigeria

Abstract

The aim of this study was to determine the occurrence and distribution pattern of oxygenated polycyclic aromatic hydrocarbons (OPAHs) in surface water of four major rivers in the Niger Delta of Nigeria. A total of 20 surface waters were collected from the Warri, Forcados, Benin and Escravos rivers. Samples were extracted with a mixture of dichloromethane and hexane. The cleaned extracts were analyzed for eleven OPAHs using a gas chromatograph equipped with mass spectrometry (GC-MS). Total OPAH concentrations ranged from 46–186 µg/L in the Benin River, 290–716 µg/L in the Escravos River, 338–492 µg/L in the Forcados River, and 308–640 µg/L in the Warri River. The concentrations of OPAHs in the rivers were in the order of Escravos River > Warri River > Forcados River > Benin River, while the occurrence pattern of PAHs was in the order 3-ring > 1-ring > 2-ring > 4-ring. Result from Pearson’s correlation analysis indicated that the OPAHs in the surface water of these rivers were from similar sources and have similar fate in the aquatic environment.