WATER QUALITY ASSESSMENT OF RIVER NIGER AT ASABA/ ONITSHA AXIS, NIGERIA

Abstract

The concentrations of heavy metals and selected water quality parameters of River Niger at Asaba/Onitsha axis were investigated during both dry and wet seasons in order to assess the water quality of the river. For the physicochemical properties of the water samples, the mean values ranged from 7.13 to 8.15 for pH, 227 to 749/cm for electrical conductivity, 132 to 430 mg/L for total dissolved solids and 12.3 to 13.9 mg/L for total suspended solids. The other physicochemical properties were in the ranges of (mg/L) 101 to 144, 0.06 to 0.20, 1.16 to 1.46, 6.79 to 8.48, 13.02 to 21.37 and 19.4 to 32.68 for chloride, nitrates suphate, dissolved oxygen, biochemical oxygen demand and chemical oxygen demand, respectively. The metal levels ranged from (mg/L) 6.15 to 7.69 for Fe, 0.73 to 1.15 for Zn, 0.12 to 0.22 for Cu, 0.15 to 0.02 for Mn, 0.16 to 0.22 for Ni, 0.04 to 0.06 for Cr, 0.17 to 0.26 for V, and 0.04 to 0.08 for Pb. The t-test analysis of the results revealed that there are significant variations in the values obtained for dry and wet seasons. The dry season values showed generally higher level of pollution loads. Some of the physicochemical parameters and almost all the metals investigated, showed values above Standard Organization of Nigeria (SON)  and world Health Organization (WHO) permissible standard values. The extremely high values obtained for water quality index computation confirms that the River Niger water at Asaba/Onitsha axis is very unsuitable for drinking purposes.