Assessment Of The Concentration Of Chemical Elements And Water Quality Index Of Shallow Groundwater In Parts Of Mangu Area, North Central Nigeria

Abstract

The study area Mangu and environs in Central Plateau State, is defined by latitudes 9^O.28¹ to 9^O.36¹ and longitudes 8^O.51¹ to 8^O.57¹. The inhabitants of the area depend mostly on groundwater from hand dug wells and boreholes (hand pumps) for most domestic and small-scale irrigation activities. These groundwater sources are located close to pollution point sources which may serve as threat to their quality. The aim of the study was to determine concentration and water quality indices of groundwater sources in the area. Twenty groundwater samples were collected in the dry season from shallow sources used for drinking and other uses. Physical parameters – pH, TDS, conductivity, and temperature) – were determined in the field with the HACH KITS. Major and trace elements were determined with the use of Inductively Coupled Plasma Optical Emission Spectrophotometer and anions (HCO₃, Cl and NO₃) by titration methods, while SO₄ was determined using double UV-visible spectrophotometer (Hitachi model 2000). Concentration of physical parameters and major elements vary for the different sources but are higher for most of the shallow groundwater sources within the Mangu Central Area, where the population is dense and human activities are high. The trace elements are, however, generally low for all sources. Gibbs plot indicates the source of elements in the water to be dominantly from rock weathering dominance.  Factor analysis and water types suggest sources of elements to be from both rock-water interaction and anthropogenic activities. The contribution of anthropogenic activities is confirmed by the high concentration of chloride, nitrate, and sulphate. Effluent discharges from the Mangu Abattoir, septic tanks and pit latrines and indiscriminate disposal of solid wastes, could be responsible for the high concentrations. The Water Quality Index ranged from 7.36 - 66.55 and classified the water as 30% excellent, 50% good, 15% poor and 5% unsuitable for drinking. The waters are generally hard and not suitable for laundry purpose but may be beneficial for optimal function of the heart. This work recommends the determination of bacteriological content of the waters, owing to the high content of nitrate, chloride, and sulphate in some of the sources.