Polychlorinated biphenyls (PCBs) levels and distribution in Ethiope and Benin Rivers of the Niger Delta, Nigeria: surface water and sediments

Abstract

Concentrations of polychlorinated biphenyls (PCBs) were determined in surface water and sediment samples from the Ethiope and Benin Rivers of the western Niger Delta. Specific individual congener analysis of PCBs was undertaken using a HPGC, series 6890. Mean levels of ΣPCBs (sum of eight congeners) in surface water samples from river stations ranged from 1.50–1.5 µg l^−l (Ethiope River) and 0.03–2.93 µg l^−l (Benin River). Levels in sediment samples were higher with mean concentration of PCBs ranging from 0.73–6.7 ng g^−l (Ethiope River) and 0.35–15.15 ng g^−l (Benin River). The null hypothesis of normality was rejected at P > 0.05 indicating a significant difference between the matrices. The principal component analysis (PCA) showed that patterns of distribution of individual congeners differed between the stations and matrices. Although low levels of PCBs were observed in the water samples, some stations, had values exceeding the USEPA PCBs limits in surface waters (0.0005 mgl^−l) and water quality criterion for chronic exposure (79 pgl) through drinking water and fish ingestion. This observation makes PCBs, contaminants of concern in western Niger Delta aquatic ecosystem.

Keywords:

• PCBs
• Concentrations
• Distribution
• Water
• Sediment
• Niger Delta
• Nigeria