Hydrogeochemical and Heavy Metals Characterization of River Niger at Lokoja, North Central Nigeria

Abstract

River Niger is the longest river in Nigeria and more likely to be contaminated by anthropogenic activities than groundwater, especially the section situated in urban cities. Surface water that is contaminated has its quality compromised. Consumption
of such water poses serious health challenge. The thrust of the paper is to assess the effect of urbanization on the quality and the suitability for irrigation of the water samples obtained from River Niger. The physiochemical analysis of water sampled collected was analyzed using Atomic Absorption Spectrometry (AAS) and Ion Chromatography. The results showed that 66.7% of water samples have pH that is within the World Health Organization (WHO) permissible limit. The alkalinity of water samples ranged from 8 to 15mg/l, hardness ranged from 10 to 19.4mg/l. Total dissolved solids, electrical conductivity and temperature of the water samples ranged from 25 to 42mg/1, 56 to 78μS/cm and 26 to 31.6℃, respectively. The concentrations of all representative cations and anions, except Mn2+ ion, are within the WHO permissible limit. 83.3% of the samples have Mn2+ concentration below the WHO permissible limit. Also, all the samples have concentration of Cd+ and Pb+ greater than the WHO permissible limit. 50% of samples have nickel concentration greater than the WHO permissible limit while Zn2+ has tolerable concentration in all
samples. Piper diagram plot classified the water samples into Ca-Mg-SO4 water type. The Sodium Absorption Ratio (SAR) ranged from 0.87 to 1.78, indicating low salinity hazard. This study concludes that although water samples indicate low salinity hazard and are thus good for irrigation, high concentrations of heavy metals observed in the water samples indicate that the surface water in the study area is unsafe for drinking