Assessment of nitrate, trace elements and bacterial contamination of groundwater in ilora area of southwestern nigeria

Assessments of groundwater pollution parameters were carried out in samples collected from selected shallow hand-dug wells across Ilora township. The analysed nitrate, trace elements including, iron, cobalt, chromium, manganese, zinc, arsenic, cadmium and lead, bacteria count water; using spectrophotometric method, HM Metalyser 5000 multiple tube techniques respectively. pH the was between 6.4 7.6 TDS range 50 - 640 mg/l. concentration nitrate (NO3) water 12.8 274 For concentrations µg/l ; iron (Fe): 150 – 880, Cobalt (Co): 1 100, Manganese (Mn): 0.01 140, Chromium (Cr): 0.31, Zinc (Zn): 1.86 9.97, Arsenic (As): 3.11 20.80, Cadmium (Cd): 0.71 4.76, Lead (Pb): 1.00 6.82. Based on average order abundance Fe > Co Mn As Zn Pb Cd Cr. Total coliform (TCC) 18 370 cfu/100mL. From evaluation degree association parameters, a moderate to strong positive relationship occurred Fe/Mn (0.59), Fe/Cr (0.85), Fe/TC (0.56), NO3/Co NO3/Mn (0.48), NO3/Cd (0.51) Mn/Pb (0.85). Presence indicated fecal contamination surface environment. Comparing with guideline standards for drinking water, most are contaminated five either arsenic and/or cadmium, while some may have objectionable taste due high content. values harmful human health appropriate treatment is needed. contamination, deeper recommended, should be treated boiled prior consumption.