Hydrochemistry and assessment of heavy metals groundwater contamination in an industrialized city of sub-Saharan Africa (Douala, Cameroon). Implication on human health

Douala is one of the largest cities in sub-Saharan Africa where 80% of the population relies on groundwater without any control of their quality. In this context, this study evaluates the groundwater quality and the implications for human health. Water samples, including hand dugs wells, spring waters and borehole were collected. pH values are out of the WHO limit, with too much acidity for human consumption. Three water types are identified: Na–Cl (76.2%), Ca–Cl (14.3%) and Ca-Mg-Cl (9.5%) indicating significant anthropogenic fingerprint. Water Quality Index shows that 90.5% of the samples have “poor” to “unsuitable” quality for drinking purposes. Heavy metal Pollution Index and Heavy Metal Evaluation Index highlight that the groundwater are “lightly” to “moderately” polluted. Human Health Risk tool shows that heavy metal poses a non-carcinogenic risk by ingestion of water for child. These results highlight the necessity of groundwater monitoring to ensure a sustainable water supply.