HYDROCHEMICAL INVESTIGATION OF SURFACE AND SUBSURFACE WATERS ALONG IGBOKODA-AYETORO CREEK, SOUTHWESTERN NIGERIA

Abstract

Investigation into the hydrochemical characters of surface and subsurface waters along Igbokoda- Ayetoro Creek southwestern, Nigeria using physical and chemical parameters has been carried out.38 water samples were collected in the area for analyses. The physical parameters measured on the field are Temperature, pH, total dissolved solids, and electrical conductivity. The major dissolved ions analyzed are Na+, Ca2+, Mg2+, K+, CHO3, NO3, SO4, Cl and the trace metals are Fe, Pb, Cu, Cd, Co, Cr, Ni and Mn. Chloride ion was analyzed using silver nitrate titration, bicarbonate ion by acid-based titration while sulphate and nitrate ions were measured using UV Spectrometer. Dissolved major cat ions and trace metals were analyzed using Atomic Absorption Spectrophotometer. The data obtained were illustrated using descriptive plots like Stiff, bar, cone, pie and piper diagrams. The data were also subjected to factor and cluster analyses. For surface water mean values obtained for physicochemical parameters were 26.72oC for Temperature, 5.9 for pH, 154.06mg/lCaCO3 for total dissolved solids and 329.19μs/m for electrical conductivity. The mean physicochemical parameter values for rain water samples were 25.1oC for Temperature, 6.7 for pH, 25mg/lCaCO3 for total dissolved solids and 52μs/m for electrical conductivity. The groundwater samples had mean physicochemical parameter values of 26.855oC for Temperature, 6.7 for pH, 458.55mg/l CaCO3 for total dissolved solids and 915.15μs/m for electrical conductivity. The mean concentrations for major dissolved ions in surface waters are 13.376mg/l for Na+, 7.896mg/l for Ca2+, 7.039mg/l for Mg2+, 1.399mg/l for K+, 51.575mg/l for HCO3, 1.144mg/l for NO3, 6.728mg/l for SO4 and 19.360mg/l for Cl while the mean values in rain water are 5.682mg/l for Na+, 7.904mg/l for Ca2+, 0.287mg/l for Mg2+, 0.903mg/l for K+, 22.950mg/l for HCO3, 1.125mg/l for NO3, 2.576mg/l for SO4, 7.241mg/l for Cl and the mean values for groundwater are 13.156mg/l for Na+, 13.172mg/l for Ca2+, 7.925mg/l for Mg2+, 2.111mg/l for K+, 61.410mg/l for HCO3, 1.931mg/l for NO3, 15.480mg/l for SO4 and 19.861mg/l for Cl. The mean concentrations for trace metal dissolved ions in surface waters are 4.116mg/l for Fe, 0.799mg/l for Pb, 0.025mg/l for Cu, 0.057mg/l for Cd, 0.601mg/l for Co, 0.136mg/l for Cr, 0.314mg/l for Ni ,and 5.535mg/l for Mn, while the mean values in rain water are 1.274mg/l for Fe, 0.980mg/l for Pb, 0.049mg/l for Cu, 0.058mg/l for Cd, 0.404mg/l for Co, 0.053mg/l for Cr, 0.228mg/l for Ni, 1.351mg/l for Mn and the mean values for groundwater are 2.813mg/l for Fe, 1.405mg/l for Pb, 0.031mg/l for Cu, 0.062mg/l for Cd, 0.723mg/l for Co, 0.154mg/l for Cr, 0.371mg/l for Ni and 4.717mg/l for Mn. Comparison of calculated results with various established quality guidelines suggest that: waters in the study area are not suitable for drinking purpose based on pollution by trace metals. The Irrigation parameters indices (like EC, RSC, SAR, SSP etc) evaluated, indicated about 85.937% surface water and 91.2% of ground waters safe for irrigation purpose. For industrial purpose, all the surface water and about 70% of groundwater sampled are not suitable for industrial purpose. Piper diagram identified three water types for both surface and ground waters each. Factor analysis (FA) extracted five factors for surface water and six factors for ground water sampled. Cluster analysis (CA) through Dendrogram grouped sample locations (both surface and ground) into 2 major clusters each. It is concluded that, the quality of water bodies in the area not suitable for both industrial and drinking purposes when about 85.937% surface water and 91.2% of ground waters safe for irrigation purpose. Various Chemical processes were identified. It is recommended that potable water supply should be made available for people in this area.