Evaluations of the Levels of Heavy Metals in River Water and Selected Species of Fish from Ogba River in Benin City, Nigeria

Abstract

Ogba River provides source of drinking water in Benin City metropolis and also serves as repository for urban drainage and agrochemical wastes which could potentially impact the water and biota such as fish. This study was therefore aimed at assessing the concentrations of copper, cadmium, chromium and lead in water and fish from Ogba River (Nigeria). The dominant fish species encountered in the study are Clarias gariepinus, Hemichromis fasciatus and Tilapia mariae with mean weight of 127.86g, 116.60 and 74.46g respectively. Water and whole fish tissues were acid digested and analyzed for metal concentrations using the atomic absorption spectrophotometer. The results showed that in water and fish species, copper concentrations of 0.211 mg/l and 0.760 mg/kg were highest in station one, while chromium concentrations of 0.002 mg/l and 0.040 mg/kg were lowest in station two. There was significant difference in the mean concentration of the heavy metals in the selected fish species (P<0.05). The need for enforcement of regulations inhibiting unwise use of aquatic resources and regular monitoring of environmental matrices (water, sediment, and fauna) is advocated given that fish from Ogba River is unfit for human consumption. 

Key words: Heavy metals, Ogba River, fish.