Water Quality Assessment of Osse River, Gele-gele: A Tributary of Benin River, Southern Nigeria

The physical/chemical characteristics and some heavy metals of Osse River, Gele-gele, Southern Nigeria was assessed during the dry and wet seasons. Four stations were studied from upstream to downstream with an average distance of 500meters between each station. A total of twenty-one (21) physical/chemical parameters were studied. pH ranged from 6.2-7.5, Suspended Solid 4-48mg/l, Turbidity 0-39NTU, Electrical Conductivity 20-110μS/cm, Alkalinity 8-48mg/l, Chloride 7.1-17.7mg/l, Hardness 8-56mg/l, Phosphate 0.01-0.53mg/l, Sulphate 5-33mg/l, Nitrate 1.2-9.3mg/l, Dissolved Oxygen 2.0-8.4mg/l, Biochemical Oxygen Demand 0.6-5.8mg/l. Heavy metals level generally ranged from 0.1 to 1.8mg/l for Iron, Zinc 0.0 to 0.93mg/l, Chromium 0.0 to 0.65mg/l, Cadmium 0.0 to 0.041mg/l, Lead 0.0 to 0.26mg/l, Manganese 0.0 to 0.082mg/l, Copper 0.0 to 0.059mg/l, Nickel 0.0 to 0.49mg/l. The mean concentration of metallic ions in Station 3 was significantly higher across the four sampled, with manganese, iron, cadmium, and copper responsible for this difference. Water Quality Index showed that all four stations had a range of 8.03-9.07. The concentration of the metals in the Osse river are within background concentration level, the mean Dissolved Oxygen and Biological Oxygen Demand obtained indicate the water is rated between fairly clean and clean, and the Water Quality Index indicates excellent water quality. Thus, the water is presently suitable for domestic use, but its quality may deteriorate with time if the current rate of anthropogenic activities around the water body is not curtailed.