ASSESSMENT OF HEAVY METAL CONTAMINATION AND POLLUTION INDICES IN WATER, SEDIMENTS, AND FISH ORGANS OF OSE RIVER, ONDO STATE, NIGERIA

Abstract

Six heavy metals; iron (Fe), lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and zinc (Zn) were assessed in water, sediments, and organs of Coptodon zilli, Sarotherodon galilieus and Oreochromis niloticus from Ose River, Nigeria using atomic absorption spectrophotometer (AAS). Heavy metal assessment of water showed that the concentrations of Cd (0.010-0.030mg/kg) and As (0.010-0.05mg/kg) were higher than the stipulated limits of 0.01mg/kg respectively. The mean concentrations of Fe (20.30-29.47mg/kg), Zn (1.13-2.140mg/kg) and Cd (0.13- 0.216mg/kg) in the sediments were found to be greater than the permissible limits of 5mg/kg, ≤1mg/kg and 0.1mg/kg respectively. However, Fe concentration in the gill (151mg/kg) of C. zilli was above the WHO limit of 123.5mg/L. Lead concentration was high in the heart (3.200mg/kg), gill (1.810mg/kg), liver (1.900mg/kg) and muscle (4.42 mg/kg) of C. zilli, heart (1.167mg/kg), gill (1.483mg/kg), and muscle (0.930mg/kg) of O. niloticus and in gill (1.040mg/L), liver (1.220mg/kg) and kidney (1.820mg/kg) of S. galilieus. Furthermore, Cr concentrations ranged from 0.273- 1.87mg/kg in all organs and muscles of the three species and all concentrations were higher than the WHO limit. This study concluded that the river was polluted with heavy metals and constant monitoring of the river was therefore recommended.