Risk assessment of heavy metal and trace elements contamination in groundwater in some parts of Ogun state

The present study was carried out to investigate the risk of heavy metal contamination in groundwater in Ota, Ogun state. Water samples were taken from seven (7) major groundwater sources popularly consumed by the population in the study area. The samples were analyzed for heavy metals and trace elements, which include K, Mn, Cr, and Cu at the ACME laboratory in Canada using ICP-MS. The average concentrations obtained for each metal are as follows: 0.30, 7.30, 0.85, 25.34 mu g l(-1). This could be represented in this order, Cu > Mn > Cr > K. Furthermore, the average daily dose was determined for the heavy metal and Trace Elements in each sample, samples 1 and 7 reported higher results in Cu for adult male and female while samples 1, 2, 3 and 4 reported 3.878, 1.653, 1.980 and 4.467 mu g (kg.day)(-1) for Cu in children. The concentration of these elements detected in the water samples could be as a result of the geology of the area of study or due to human actions. Further study revealed the values of hazard quotient to be less than the recommended safe limit of 1 for all the samples. The average hazard quotient also reported values lower than 1 for all the age group, but Cu was noticed to be prominent across all the estimation. Therefore, regular monitoring must be considered for groundwater samples in the study area in order to avoid possible health risk that may occur as a result of the increase in the concentration of these heavy metals and Trace Elements over a long period if their sources are not eliminated.