Assessment of heavy metals associated with bottom sediment of Asejire Reservoir, Southwest Nigeria

A study on the characteristic of sediment quality of Asejire Reservoir was conducted to evaluate the heavy metal content of the reservoir. Twenty stations were selected, samples and analyzed using standard methods. The result showed that the sediment was slightly acidic across the study stations, with low conductivity and organic matter content. The heavy metals order of dominance was: Fe>Pb>Cu>Zn>Mn>Al>Ba>Ni>Cr. The mean concentration levels of all the heavy metals were lower than mean background value except Fe, Cu and Pb. However, calculated Enrichment Factor (EF) values for all the heavy metals investigated showed that they were less than 1.5 (<1.5), suggesting that the heavy metals were all derived mainly from natural sources such as bedrock materials and weathering processes.