Assessment of water quality of Ogun River in southwestern Nigeria

Abstract

The present study assessed the water quality of Ogun river in southwestern Nigeria. Forty water samples were collected from twenty monitoring stations along Ogun River Basin between April 2013 and January 2014. Water samples were analyzed for important physical and chemical parameters such as temperature, pH, turbidity, total suspended solids (TSS), total dissolved solids (TDS), total solids (TS), electrical conductivity EC, dissolved - - 3- - oxygen (DO), silica, anions (F , Cl , PO , NO ), hardness, alkalinity and metals (Fe, Pb, Cd, Na, K) using the 4 3 standard procedures. Data collected were subjected to simple descriptive (mean and standard deviation) and inferential statistics (Duncan Multiple Range Test, DMRT and Principal Component Analysis, PCA) using the Statistical Package for Social Sciences (SPSS, Windows' version 16.0). Results showed higher mean concentrations of turbidity (49.7±13.0 NTU) and total suspended solids (1205.2±4.7 mg/L) than the permissible limits of the World Health Organization (WHO) in drinking water. The values of phosphate (1.14±1.3 mg/L), Cd (0.02±0.01 mg/L) and Pb (0.33±0.05 mg/L) were also observed at higher concentrations than the permissible standards of the WHO. The sources of pollution to Ogun River Basin identified by varimax rotated PCA were industrial effluents, runoff, fertilizer and dissolved salts.