Study of the physico-chemical quality of groundwater in the municipality of Bosso (Diffa, eastern Niger)

The objective of this study is to assess the potability of five boreholes in the municipality of Bosso. The analyses focused on physical parameters measured in situ (pH, electrical conductivity EC, and temperature) and chemical parameters measured by volumetry: ion content (HCO₃⁻, Cl⁻, Ca²⁺, Mg²⁺, and hydrometric titre) and, by spectrophotometry, ion content (SO₄²⁻, F⁻, NO₃⁻, NO₂⁻, Na⁺, K⁺, total iron). The results show an average temperature of 29.14°C and a pH that complies with potability standards in most cases (80% of samples). Electrical conductivity varies from 2500 µS/cm to 11140 µS/cm, with an average of 6207 µS/cm. The F⁻, NO₃⁻, NO₂⁻, total iron, Ca²⁺, and Mg²⁺ contents comply with WHO (2011) and MSP Niger (2021) guidelines. However, excessive concentrations were found for sulfate ions (2700 mg/L), chlorides (368 mg/L), and sodium (1500 mg/L). As a result, only one in five boreholes (20%) provides water suitable for human consumption. Interpretation of the data using the Piper diagram revealed two main hydrochemical facies: a chlorinated or sodium sulfate facies (60%) and a sodium bicarbonate facies (40%). Applying Richard's diagram for irrigation suitability classifies 80% of the water as poor and 20% as fair, due to the risk of soil salinization and alkalization.