Characteristics and quality assessment of groundwater in parts of Akure, South-Western Nigeria

Groundwater samples were collected from different parts of Akure town and analysed for various physico-chemical parameters using conventional field and laboratory techniques. The essence of the study is to evaluate the characteristics and quality assessment of groundwater in the area. The pH values falls between 7.1 to 7.7, indicating that the ground water is neutral. The range of conductivity for the area is between 116 to 1000μS/cm with an average of 365μS/cm which met the WHO (2006) standard of 1000μS/cm for drinking water. The low levels of turbidity ranging from 1 to 2 NTU were obtained. The TDS concentrations range between 81 to 700 mg/l. The total hardness of water sampled range from 20.2 to 345.6mg/l. Sulphate ion concentration is between 2.5 to 23.2mg/l. Phosphate values ranges from 0.05 to 0.07mg/l in all locations, and average value of 0.12mg/l which are within the WHO (2006) standards for drinking water. Nitrate levels ranged from 1.13 to 2.91mg/l. The values of bicarbonates range from 28 to 88mg/l with a mean value of 43.9mg/l, as all locations are far below the W.H.O (2006) limit of 600mg/l. The concentration of calcium ranged from 12.3 to 92.2mg/l while the concentrations of magnesium ion ranged from 0.9 to 32.6mg/l with an average of 7.3gm/l and this is below the WHO limit for drinking water (150mg/l). The concentration of sodium ion (Na+) ranged from 1.067 to 8.696mg/l. The concentration of potassium also ranged from 7.537 to 51.881mg/l with a mean value of 19.098mg/l. Although there is no reference to WHO standards for the parameter, the relatively low values of potassium suggest the suitability of the analysed groundwater samples for drinking. The common form of iron in groundwater is the soluble ferrous ion Fe2+. The concentration of iron in the water samples ranged from <0.001 to 0.001mg/l showing a very low value of iron in all boreholes. Generally, results compare favourably with the WHO (2006) standards for drinking water, except chloride with low values (9.5 to 158mg/l) compared to W.H.O limit of 250m/l for drinking water. The low concentration is an indication of absence of salt water intrusion in the area. The study revealed that the water in the area is suitable for drinking and other domestic purposes. It is recommended that regular hydrogeochemical analysis of groundwater should be carried out, as this would be helpful in early detection of any future degradation. More importantly, hydrogeological study is very imperative to fully understand the hydrogeology of the area.