Seasonal Variation of Heavy Metals Concentration of Industrial Effluents and Receiving Rivers in Iguosa and Ikopba, Benin City, Edo State, Nigeria

Abstract

This study was carried out to investigate the impact of pollution on the receiving waters (Iguosa and Ikopba rivers) in Benin City. Effluents and water samples were analysed quantitatively for the presence of lead (Pb), Copper (Cu), Chromium (Cr), Manganese (Mn), Iron (Fe), Zinc (Zn) and Nickel (Ni) for both wet and dry season were determined using Atomic Absorption Spectrometer (AAS). Heavy metals analysis results for 7-Up Bottling Company showed that Pb (0.06mg/L – 0.97mg/L), Cu (0.12mg/L – 2.84mg/L), Cr (0.5mg/L – 8.16mg/L), Mn (0.88mg/L – 4.36mg/L), Fe (0.55mg/L – 7.55mg/L), Zn (0.38mg/L – 3.97mg/L), Ni (0.27mg/L – 1.66mg/L) and Cd (0.03mg/L – 0.74mg/L) while results for Guinness Nigeria Plc showed that Pb (0.06mg/L – 0.95mg/L), Cu (0.07mg/L – 2.62mg/L), Cr (0.14mg/L – 2.96mg/L), Mn (0.16mg/L – 6.63mg/L), Fe (0.31mg/L – 4.96mg/L), Zn (0.14mg/L – 7.98mg/L), Ni (0.12mg/L – 1.69mg/L) and Cd (0.03mg/L – 0.56mg/L) for both wet and dry season. This showed that the concentrations of the metals were higher during wet season than the dry season except that of lead and cadmium. However, the presence of metals at various concentrations revealed that the effluents from these industries contaminated the stream.