Assessment of potentially harmful elements in surface and groundwater from the granito-gneissic aquiferous formations in Bertoua city and environs, East Region, Cameroon, Central Africa: Effects on human health

This study of Bertoua city and its environs, in the East Region of Cameroon (4.46–4.6° N, 13.64–13.8° E) was to assess potentially harmful elements in surface and groundwater sources and their potential health risks, aligning with the Sustainable Development Goals (SDGs), particularly SDG 3, ensuring good health and SDG 6, ensuring clean water and sanitation. Thirty water samples were analysed for the presence of major ions: Na⁺, K⁺, Ca²⁺, Mg²⁺, SO₄²⁻, HCO₃⁻, N0₃^-, and Cl⁻ using ion chromatography (IC) during both the wet and dry seasons, and PHEs including Al, Si, Se, Fe, Cr, Co, and Cu using inductive coupled plasma mass spectrometry (ICP-MS) during the dry season. Results indicated high NO₃⁻ and Al above the permissible limits set by the World Health Organization. In groundwater, NO₃⁻ concentrations ranged from 0 to 643.5 mg/L in the wet season and 0–705.4 mg/L in the dry season, while Al concentrations ranged from 0.02 to 1.79 mg/L: both above the World Health Organization limit. In surface water, NO₃⁻ concentrations ranged from 152.71 to 188 mg/L in the wet season and 143.3–166.5 mg/L in the dry season, while Al concentrations ranged from 0.004 to 0.12 mg/L both above the same drinking water standard. The water types were Na⁺-K⁺-SO₄^2-, Ca²⁺-HCO₃^-, Ca²⁺-SO₄^2- and Ca²⁺-Cl^-, with simple dissolution and ion exchange responsible for them. Rock weathering was the dominant hydrogeochemical process controlling groundwater chemistry with minimal influence from atmospheric precipitation. Contamination inputs were from anthropogenic and geogenic sources. Calculated HQ_oral for males, females and children were greater than one (HQ_oral > 1) for NO₃⁻, Al, Se, and Fe with children having higher values compared to the other demographic age groups due to a larger body-size-to-volume ratio. The HQ_dermal values were low and below the safe limit of 1 for all demographic groups, indicating no health risks to the population from dermal exposure.