Sediment pollution of the Benin – Ethiope fluvial system around Sapele (Nigeria) from industrial and urban wastes

 

Abstract

Sediments of rivers receiving industrial and urban effluents are often polluted, and this  has prompted investigation. Sediment samples were collected twice every season for two years from the Benin river-Ethiope River System around Sapele, Nigeria. Trace heavy metals were determined by flame atomic absorption spectrophotometric method. Total petroleum hydrocarbons (TPH) and other physicochemical parameters were determined too. Important results were: pH (5.8±1.0), total organic extract (3780±2600 mg/kg), TPH (2800±1900 mg/kg), Cu (12±16 mg/kg), Pb (38±35 mg/kg), Ni (12±15 mg/kg), Cd (7.10±20 mg/kg), Zn (63±42 mg/kg), Cr (25±56 mg/kg), and Mn (67±39 mg/kg). The average concentrations of some of the pollutant parameters exceeded sediment quality guideline values. The enrichment ratio values of some of the trace metals showed that most of the sampling stations suffered much enrichment with the metals. The contamination/pollution index calculations of each metal also showed that all sampling stations are polluted with one or more trace metal.

Keywords: effluents, trace metals, total petroleum hydrocarbons, sediment guideline values,enrichment ratio