Nitrogen Pollution and Fecal Contamination of Well Water in Divo, Southwest Ivory Coast: Characterization and Health Implications

Abstract

Access to quality drinking water is a major public health issue, particularly in urban and peri-urban areas of developing countries. Its use for food or hygiene purposes requires excellent physicochemical and microbiological quality.  Thus, to assess the quality of well water in the city of Divo in western Côte d'Ivoire, an evaluation of the physico-chemical and bacteriological quality was carried out and focused on 18 wells in this locality. The methodology adopted is based on a sampling campaign of several wells in the city of Divo, followed by laboratory analyses. The physicochemical parameters measured include temperature, pH, conductivity, nitrogen ions (NH₄⁺, NO₂⁻, NO₃⁻), chlorides and orthophosphates. The bacteriological analysis targeted mesophilic aerobic germs (MAGs), Escherichia coli, faecal streptococci, Salmonella and Shigella. A fecal contamination index (FCI) was calculated. The results reveal significant nitrogen pollution, marked by high levels of ammonium (55.1 ± 13.2 mg/L), nitrites (7.7 ± 5.1 mg/L) and nitrates (34.1 ± 22.6 mg/L). The average pH is acidic (5.3 ± 0.6), the mineralization low (average conductivity of 6.2 ± 4.4 μS/cm), and the high temperatures (31.2 ± 0.2 °C), reflecting the vulnerability of shallow aquifers. Microbiologically, 98% of the samples contained GAM, 26.31% E. coli, and all were positive for Salmonella and Shigella. The average TFR above 150 confirms a high level of faecal contamination. These results indicate that the majority of well water in Divo is unfit for consumption without treatment. Measures to protect wells, water treatment and community awareness are essential to safeguard public health.