Polychlorinated Biphenyls in Soils and Earthworms near Electric Power Sub-Stations in Benin City: Contamination Levels and Distribution Patterns

Authors: Asemota OC, Enuneku AA, Tongo I, Ezemonye LIN

DOI Info: N/A

ABSTRACT

Soil and earthworms from Benin City, Southern Nigeria were examined to determine the levels and distribution of polychlorinated biphenyls (PCBs) congeners near electric power substations (EPS). Two power substations (EPS Sapele Road and EPS Ugbowo) were sampled. A rural area (Okhun Village) was sampled as control station. PCBs analysis for 19 congeners were carried out using a Gas Chromatograph, HPGC 5890 series II fitted with an electron capture detector (ECD). Cluster analysis (CA) congregated PCBs congeners into three groups with PCBs 7 and 18 forming a cluster. One cluster was formed by PCB 60 alone while other PCBs analyzed formed the last cluster. The major contributor to the total dioxin-like PCBs was PCB 105, which accounted for 53% in EPS Sapele Road, 47% in EPS Ugbowo and 33% in Okhun Village. Commercial PCBs mixtures are known to contain a high proportion of PCB 105. The mean levels of PCBs in soil in all studied areas ranged from 0.001?g/kg to 0.022 ?g/kg while the mean levels of the PCBs in earthworm samples ranged from 0µg/kg to 0.003 ?g/kg. These levels were significantly lower than the levels in soil (p<0.05). It was observed that a significant positive correlation (p<0.05, R = 0.829) occured between PCB levels in soil and earthworm samples. In this study, levels of PCBs in soil samples were generally below the ecological benchmark of 0.3 mg/kg. Nonetheless, the occurrence of these toxic compounds in the environment raises serious worries owing to their persistence and toxic potentials.

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