SOME HEAVY METALS IN SURFACE WATER, SEDIMENT AND FISH (Clarias gariepinus) FROM IKPOBA RIVER BENIN-CITY, EDO-STATE, NIGERIA

Abstract

Fumes from high vehicular traffic dense areas combined with mixed effluent sources, and run-off waters from some industrial areas channelled into water bodies are possible sources of metal pollutions. Specimens of Clarias gariepinus, surface water samples and sediments from Ikpoba River were collected from two stations, on monthly basis for six months: They were analyzed for concentrations of some heavy metals, using Atomic Absorption Spectrophotometer (AAS). Metal absorption in all three samples revealed a decreasing order of concentration as follows: fish>sediments>surface water. Total mean concentration of metals in samples also showed a decreasing order Zinc>Lead > Copper>Cadmium>Chromiun. ANOVA results revealed that all metals except Chromium and Copper, were higher in fish  harvested from station 1 than those from station 2. Samples of fish, water or sediment harvested in station 1, contained higher concentration of metals than those isolated from station 2. For instance,  Zinc (45.03mg/l) had the highest total mean concentration from fish in stations 1. Surface water in station 1 (0.111mg/l) had higher concentration of lead than station 2 (0.106mg/l) whereas station 2 (0.154mg/l) recorded higher concentration of Copper than station 1 (0.137mg/l). All metals analyzed in sediment samples were higher in station 1 than in station 2 except for Chromium where the value in station 2 (0.29mg/l) exceeded that in station 1 (0.15mg/l). Lead and Zinc concentrations from sediments were highest at station 1 (28.71mg/l) and (24.11mg/l) respectively. The observed concentrations of Lead and Cadmium in fish samples exceeded the WHO maximum permissible limits for aquatic lives, while other metals did not. The results suggest that Ikpoba River is polluted and Clarias gariepinus fish from the river may not be fit for human consumption.