PHYSICO-CHEMICAL QUALITY OF SHALLOW WELL-WATERS IN GBOKO,BENUE STATE, NIGERIA

Abstract

Water quality and the problem of contamination in shallow wells have been assessed in Gboko. Ten wells were sampled and the water analysed for quality parameters and trace metals. Various standard methods were used for anions while trace metals were analysed using atomic absorption spectrophotometer. Results obtained in three seasons showed no significant variabilities (p > 0.05); an indication that the wells are fairly protected and do not receive considerable seepage. The water showed lower pH (5.7–7.8) in comparison to the WHO recommended range (6.5–8.5), with moderate permanent hardness (86.3–380.7) mg/L CaCO 3 . Concentrations of most trace metals and anions were below the WHO standards for drinking water and other purposes. However, iron (0.29–1.79) mg/L and copper (1.39–1.44) mg/L were considered slightly elevated in comparison to the WHO maximum permissible levels of 1.0 and 2.0 mg/L, respectively. Chromium and lead were found in four wells situated in densely populated and in the vicinity of metal workshops, heavy motor traffic/commercial/motor station areas, and are indicative of localized anthropogenic contamination. Apart from these limitations, all the other chemical evidences show that the water is good and potable. The determined data are considered to be baseline. KEY WORDS : Shallow wells, Water quality, Low pH, Localized contamination, Baseline data, Nigeria Bull. Chem. Soc. Ethiop. 2009 , 23(1), 123-128.