Seasonal Variation in Physicochemical Properties of Water in Onitsha Metropolis, Southeastern, Nigeria

The study area is a metropolitan city with major markets and industries in the heart of Anambra State, Nigeria. A total of thirty (30) samples was collected over two seasons and were analysed for various physicochemical parameters. The result was used to evaluate the seasonal variation in the various water parameters. The results show that there were no significant seasonal variations in the concentration values of pH, EC, NO3, CO3, SO4, Pb and TDS. However, seasonal variations were observed in the concentrations of Mg, Ca, Cl, Mn, Hg, Na, Cd. Cu, Ni and Ag. The concentrations of the physical parameters, the major cations and anions and some of the heavy metals were within the permissible limit of the WHO standard. Furthermore, the concentrations for turbidity, mercury and cadmium in some of the water samples were above the permissible limits in both seasons. The water quality index (WQI) categorized the samples as good, poor, very poor and unfit for consumption while heavy metal pollution index (HPI) classified the water as poor to very poor. The WQI and HPI are season dependent and these ratings indicated that the water sources are heavily contaminated, and should be properly treated before drinking.