CHEMICAL COMPOSITION OF BOREHOLE WATER IN TWO LOCAL GOVERNMENT AREAS OF ONDO STATE WITH SPECIAL REFERENCE TO POTENTIAL TOXIC METALS

 ABSTRACT

Many households are used to the construction of shallow wells, but the wells hardly provide adequate water supply in term of volume and quality throughout the year. As a result, government adopted the construction of boreholes as an alternative to pipe-borne water supply and as an immediate solution to water supply and quality problem. Groundwater (borehole water) samples were collected randomly from two (2) Local Government Areas: Akure south (Oda, Ijoka, Sebi, Kajola, Ijapo housing, Alagbaka area and Akure metropolis) and Akure north (Oba-ile, Ugele, Odudu, ltaogbolu, and !ju) of Ondo-state. The water samples were subjected to physicochemical analysis with special reference to toxic metals that included Cd, Zn, As and others. The result shows that colour, odour, turbidity, pH, chloride, nitrate, total dissolved solids, total hardness, electrical conductivity and trace element like manganese were within WHO permissible limit in the two Local Government Areas, while calcium, magnesium, total alkalinity and some potentially toxic metals, particularly zinc, iron and cadmium, were above WHO permissible limit in six samples from Akure South Local Government Area and three samples from in Akure North Local Government Areas. This study, thus, concluded that since the concentration of total alkalinity, calcium, magnesium, iron, zinc, and cadmium were above WHO limits in some of the water samples, they are considered unfit for human consumption.