HYDRO-CHEMICAL ASSESSMENT OF GROUNDWATER QUALITY WITHIN ILORIN NW SHEET 223, SOUTH-WESTERN NIGERIA

Abstract

The assessment of groundwater quality within Ilorin NW, Sheet 223 using physico–chemical indices has been carried out. The study assesses quality of groundwater in the area for domestic and agricultural purposes by insitu measurement of its physical parameters; laboratory analysis of its chemical parameters and assessment of levels of some hazard parameters for irrigation quality. The physical parameters which include colour, turbidity, pH, temperature and electrical conductivity were measured by insitu method using HANA Model HI83200 Multimeter while the chemical parameters which are (Ca2+), (Na+ ), (K+ ), (Mg2+) ,(Cu2+), (Fe2+), (Mn+ ), (Zn+ ),( Pb2+),(Cd+ ),(SO4 - ),(PO4 - ) (Cl- ) , (HCO3 - ) , (CO3 - ) , and (NO3 - ) were analysed by rock chemical composition determination methods at the University of Ilorin Central Research Laboratory. The parameters assessed for irrigation purpose include Residual Sodium Carbonate (RSC), Sodium Adsorption Ratio (SAR), Salinity Hazard, Toxic Elements Hazard and Kelley‘s Index (K.I) using specified chemical equations. The result of the physical parameters measured shows average concentrations of 5 (TCU), 182.3 (NTU), 5.8, 31.290C and 359.14 (µS/cm) respectively, the laboratory analysis of chemical parameters indicates average concentrations of 0.85, 1.23, 0.35, 0.56, 0.03, 0.1, 0.02, 0.03, 0.05, 0.02, 0.11, 1.43, 65, 157, 123 and 0.47 (all in mg/l) respectively and the parameters calculated for irrigation quality revealed unsuitable (RSC), Excellent (SAR), medium salinity hazard, low toxic elements and suitable K.I. The major water types based on piper trilinear plot are Sodium–potassium bicarbonate and Calcium bicarbonate. Conclusively, the result of the physico–chemical assessment of groundwater samples in the area shows values that fall below the maximum desirable and permissible limits of World Health Organization (WHO) standard; suggesting that the groundwater is good for human consumption. It was also observed that the suitability of groundwater in the area for irrigation purpose is of excellent to good quality based on irrigation quality assessed parameters