Evaluation of pollution status of groundwater resources of parts of Owerri metropolis and environs, Southeastern Nigeria, using health risk and contamination models

Abstract

Some groundwater resources within Owerri Metropolis and environs, Southeastern Nigeria were evaluated to ascertain the level of groundwater contamination as well as the intrinsic health risk that may result from the oral ingestion of the groundwater from the study area. Groundwater samples from 27 boreholes were taken and analysed using standard procedures. The results revealed pH levels (6.04 ± 0.09 to 6.47 ± 0.06) which were lower than the World Health Organisation (WHO) permissible limit. Elevated levels of lead (0.01 ± 0.01 to 0.08 ± 0.02 mg/L) concentration above the WHO standard for safe drinking water were observed in some samples. Though the pollution load index for the area was low, however, the contamination factor revealed lead (Pb) contamination of the samples with positive correlations existing between the metallic pollutants. Electrical conductivity and dissolved solids showed a very strong correlation with r = 1. However, the result of the water quality index revealed that the groundwater samples were within good to excellent water quality. The principal component analysis of the samples grouped the metallic pollutants into three different components, suggesting similarity in the source of occurrence with only one coherent cluster established by the hierarchical component analysis indicating their association in terms of occurrence. The individual hazard quotient and hazard index of the metallic pollutants for adults and children were < 1, which implies slight or no negative health hazard from the intake of the water samples, though the presence of Pb in some samples may pose some health risk. Similarly, low chronic daily intake values were recorded. Though low PLI and CDI were recorded across the area in addition to HQ and HI values < 1, appropriate treatment is recommended for the studied groundwater samples before consumption to prevent an impending health challenge due to possible bioaccumulation of metallic contaminants which may take place over time.