An assessment of seasonal variations in physico-chemical characteristics of underground water in a growing tropical city in Nigeria

Abstract

The quality of underground water is influenced by natural and anthropological factors which need to be constantly monitored in order to safeguard human health. This work investigated seasonal variations in well water in Iwo town, Osun State Nigeria. A total of 15 water samples were collected from hand-dug wells from each of the political wards. Samples were analysed for seven physico-chemical parameters namely pH, temperature, Electrical Conductivity, Phosphate, Sulphate, Nitrate and Total Hardness. The analysis was done according to standard method of water examination. The results of the analysis showed that the mean content of each of the parameters was higher during the dry season. These are respectively 8.10 ± 0.61, 28.55 o C ± 0.88, 185.60μᶴcm -1 ± 80.88, 0.04mg/L ± 0.02, 0.05mg/L ± 0.02, 0.02mg/L ± 0.01 and 315.47mg/L ± 92.34. These indicate that all water quality parameters analysed were within the WHO and NIS permissible limits. It implies that the well water in Iwo is generally safe for human consumption. However, efforts should be made for regular quality assessment, maintenance and prevention from surface wash into wells for better quality. Further investigation is suggested to examine the bacteriological contents of the underground water to ascertain that the water is free of bacteria to ensure its safety to human health. Keywords: Domestic uses, Osun State, Seasonal variation, Well water, Water quality