Nitrate health risk and geochemical characteristics of water in a semi-urban: implications from graphical plots and statistical computing

Abstract

ABSTRACT The aim of this study was to assess the nitrate health risks due to water consumption via oral and dermal contact routes and to evaluate the geochemical characteristics of waters in the Umunya area, Nigeria, as implied from ionic ratios, graphical plots, and multivariate statistics. This study is the first to assess the human health risks associated with nitrate contamination in the semi-urban. Standard methods were used to achieve the aim of the study. Water from commercial and household sources were sampled. Measured physicochemical properties showed that the water resources are slightly contaminated. Health hazard quotient (oral) ranged from 0–0.5072 for men, 0–0.5994 for women, and 0–0.6858 for children. On the other hand, the maximum hazard quotient (dermal) for men, women, and children were 0.0013, 0.0016, and 0.0042, respectively. The total hazard index for men, women, and children respectively varied from 0–0.509, 0–0.601 and 0–0.690. Overall, it was indicated that 46.67%, 53.33%, and 53.33% of the water samples expose men, women, and children to low chronic health risk of nitrate. However, the risk for water ingestion was higher than that for dermal absorption. Hydrogeochemical plots revealed that Ca2+-Mg2+-HCO3 − and Na+-HCO3 − water types, representing recharge and base ion exchange processes, respectively, are predominant. Principal component analysis and R-type hierarchical clustering revealed that the hydrogeochemical characteristics are mostly controlled by geogenic factors than human-related factors. The geology of the area and silicate weathering processes were implicated as the major influencers of the hydrogeochemistry. For sustainable development and improved water monitoring in the area, the insights provided in this paper are considered very beneficial.