Heavy Metals and PAHs Levels in Aquatic Organisms (Crab, Fish and Crayfish) from Crude Oil Polluted Rivers (Ekpan and Ogunu Rivers), Warri, Delta State, Nigeria

Abstract

The purpose of this work was to determine level of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in aquatic organisms from crude oil polluted rivers in Warri, Delta State (Ekpan and Ogunu communities) and non-oil exploration site (Agbarho). The aquatic animals (crabs, fish, and crayfish) collected were washed, oven dried separately and homogenized in a blender and stored for analysis. Three replicates of each sample collected were used for analysis. PAHs were determined by Gas Chromatography (GC) with Flame Ionization Detector (FID) while heavy metal contents were determined by Atomic Absorption Spectrophotometer. The results revealed that the aquatic organisms from Ogunu and Ekpan had high levels of heavy metals and PAHs. The heavy metal contents such as Cadmium, Zinc, Chromium, Mercury, Copper, and Lead of the samples from Ogunu were found to be higher  compared to those of Agbarho and Ekpan at p<0.05. The highest levels of PAHs in crabs were found in samples from Agbarho and Ekpan with little significant difference. In fish sample, the highest levels of PAHs were found in samples from Ogunu (0.0244 mg/kg) while the least was found in fish samples from Agbarho (0.014 mg/kg). PAHs levels in crayfish samples was higher in samples from Ogunu. The study generally suggests that samples from Ekpan and Ogunu communities are polluted compared to those from Agbarho with some certain exceptions. The order of pollution was found to be in the following order Ogunu>Ekpan>Agbarho.