Assessment of Spatial Variation of Surface Water Quality in Lagos, Using Multivariate Statistical Techniques

Surface water samples were collected from seven sel ected sites of the Anibire Stream, during four fiel d surveys, July and August 2011. Twenty five water quality parameters namely Temperature, pH, EC, DO, COD, oil and grease, turbidity, TA, SS, TDS, TH, Cl , PO 4 3, NO 3, SO 4 2, Fe, Zn, Cd, Mn, Ag, Cr, Ca, Na, K, Mg were analysed. The results showed that the observed pH (8.80) was slightly alkaline and within the natural background level (6.5-9.0). The river was moderately hard with overall ionic dominance pattern of Ca> K> Mg> Na and Cl - > HCO 3 - > SO 4 2- . The mean concentrations of trace metals followed the order Cr> Fe> Mn> Zn> Ag> Cd. Multivariate statistical techniques were used to identify t he spatial variation and pollution sources. The varifactors obtained fro m factor analysis indicate that the parameters resp onsible for the water quality variations are mainly trace metal, mineral, inorganic nutrient and organic pollution explainin g 81.83% of total variance. Therefore water quality monitoring and co ntrol of release of untreated anthropogenic wastes into the stream are strongly needed.