Evaluation of physicochemical properties and heavy metal speciation of groundwater in Ifetedo and Garage Olode, Osun State, Nigeria

To a large extent, public health can be prevented from being compromised by having access to potable water whose physicochemical fingerprints conform to the WHO Guidelines for drinking water. This study was carried out to assess the physicochemical properties and heavy metals speciation of groundwater in Nigeria. Water samples from thirteen sites were collected for three months and analysed for levels of pH, conductivity, nitrate, sulphate, phosphate, and heavy metals using standard methods. The results of the analysis revealed that the respective mean temperature, conductivity, pH, total dissolved solids, and oxygen reduction potential of Ifetedo sites were 27.57 ± 0.66 °C, 318.93 ± 108.58 µS/cm, 5.29 ± 0.20, 207.40 ± 73.58 mg/L, and 265.17 ± 11.29 mV, while those of Garage Olode were 28.53 °C, 275.04 ± 133.75 µS/cm, 5.23 ± 0.04, 177.66 ± 89.37 mg/L, and 270.43 ± 37.75 mV. Total mean levels (µg/mL) of heavy metals ranged from 0.04 ± 0.01 Cd to 26.21 ± 3.63 Mn at Ifetedo, while at Garage Olode, the range was between 0.02 ± 0.00 Cd and 14.49 ± 5.70 Mn. The respective ranges of mean values (µg/mL) of exchangeable metals were 0.01 ± 0.00 Cd to 10.64 ± 1.20 Mn and 0.01 ± 0.00 to 7.53 ± 2.57 Mn at Ifetedo and Garage Olode. Going by WHO provision for drinking water, the study concluded that the levels of heavy metals in the potable water samples could constitute serious health hazards over prolonged usage unless some water treatment protocols are adopted.