Physico-chemical and Coliform Bacteria characterization of Selected Shallow wells in Awe, South-western Nigeria

Abstract

Due to lack of town-water supply in Awe area within South-western Nigeria, residents rely on shallow groundwater for household utilization. The aim of the present work is to study the water quality from selected hand-dug wells in Awe communities. The study involved analyses of major ions and trace elements which included iron, lead, zinc, copper and cadmium; and assessment of coliform bacteria counts in thirty (30) shallow hand-dug wells. Spectrophotometric method was used for chemical analyses while multiple-tube technique was employed for the bacterial enumeration in water. From the results, the pH was between 5.9 and 7.4 mg/l, Electrical Conductivity (EC) ranged from 20 to 1000 μS/cm while total dissolved solids (TDS) ranged between 30 and 500 mg/L. Concentration of major ions in mg/L were; calcium, 9.63- 76.8, magnesium, 4.58- 32.03, sodium, 2.12 – 27.85 and potassium, 1.68- 20.29 while for anions bicarbonate, 46- 260, nitrate, 0.1- 0.42; sulphate 4- 26 and chloride-7.81- 103.6. Trace elements occurred below detection limits ranging from < 0.01 to < 0.05 mg/L. From the Piper plot, the dominant hydrogeochemical facies was Ca-HC03 type. The concentrations of the major ions are within the acceptable limits. However, there is presence of coliform bacteria in most wells and the growth were too numerous to count in some wells. This indicated anthropogenic inputs from infiltration of contaminated water most likely from poorly maintained human waste storage facilities such as toilet facilities and poor maintenance culture of the sampled hand-dug wells.