Assessment of ground water pollution in the residential areas of Ewekoro and Shagamu due to cement production

Abstract

Chemical and physico–chemical parameters of ground water samples from wells were analyzed by multivariate statistical tools to provide the characterisation of the ground water distribution of the settlements around cement factories in Ewekoro and Shagamu, Ogun State in Nigeria. The 17 parameters determined include: pH, conductivity, dissolved oxygen (DO), total dissolved solids (TDS), biochemical oxygen demand (BOD), total hardness, acidity, and alkalinity; anions such as chlorides, sulphates, phosphates and nitrates as well as potentially toxic metals such as copper, lead, zinc, iron and cadmium. The analytical data were obtained from 6 wells in Ewekoro and 11 wells in Shagamu sampled during three different periods along a year covering both the wet, break and dry seasons of 2009. The concentrations of lead and cadmium are above the World Health Organisation (WHO) standard in all three seasons investigated with lead having as high as 1.05 mg/L and maximum of 0.068 mg/L for cadmium. It was also observed that the levels of sulphate was higher that the WHO standard during the dry season with a maximum concentration of 623 mg/L. All other physicochemical parameters fell within the permissible range as stipulated by the WHO. There was no seasonal difference in the concentrations of the potentially toxic metals analysed in the ground water from the two sites, while for the physicochemical properties, there was a seasonal variation in the results of the ground water quality in the two sites studied with DO having a p-value of 0.009, BOD with p-value of 0.04 and Alkalinity of 0.044 p-value. An approach for the characterisation of the groundwater system of the neighbourhood of the cement factories is proposed on the basis of its physico-chemical composition, in order to detect multivariate patterns for unpolluted waters as well as for eventual polluted zones.

Key words: Toxic metals, physico-chemical composition, multivariate, cement, ground water.