PHYSICO-CHEMICAL AND HEAVY METAL ASSESSMENT OF WATER, SEDIMENT AND FISH SAMPLES FROM ASA RIVER, ILORIN

Abstract

Water, sediments and fish (Clarias gariepinus) samples were taken at four different locations along the course of Asa River within Ilorin, Kwara state, covering both dry and wet seasons and were subjected to physicochemical and heavy metal analysis. The result of water temperature was found to range between 24.03 – 25.530C during both seasons. Turbidity, conductivity, pH, TSS, TDS, Acidity, Alkalinity of the water samples were found to be between 8.00-28.16 (NTU), 82.43-275.13 (μS/cm), 6.86-7.27, 16.13-152.30 (mg/l), 44.13-135.00 (mg/l), 26.33-50.23 (mg/l) and 188.46-405.06 (mg/l) respectively during the dry season, while during the wet season, 11.13-35.46 (NTU), 66.50-206.70 (μS/cm), 6.23-6.80, 12.73-244.00 (mg/l), 33.03-102.96 (mg/l), 28.80-55.40 (mg/l) and 86.23-302.33 (mg/l) were observed respectively. The lowest value of hardness, 47.20 mg/l CaCO3, was recorded at location 1 (control) during the wet season. DO, BOD, COD were found to range between 4.80-9.30 (mg/l), 2.20-6.70 (mg/l) and 29.60-228.50 (mg/l) covering both seasons. The anions, Cl-, NO3-, SO42- and PO43- had overall mean values of 60.91, 8.37, 67.96 and 0.36 mg/l respectively. The levels of metals in water were lower than their corresponding concentrations in sediment. With the exception of Cu and Zn, all the metal concentrations in water were above the WHO and FME stipulated values for drinking water. Fe, Mn, Cr and Zn were the most concentrated metals in the fish sample. These four metals were detected in the organs (liver, muscle, bone and gills) of this fish. The highest heavy metal concentrations were found in the liver and gills followed by the intestine and the least concentration was in the bone and flesh. The general trend of distribution of the metals in the organs was in the order, liver>gills>intestine>bone>flesh.