Analysis of the chemical quality of underground waters in the municipality of Dassa-zoumè

Abstract

In some parts of Benin, like in many African countries, the fluorine rates contained in waters are higher than the rate recommended by the World Health Organization (WHO) (0.7-1.5 mg- /- L). Fluorine is useful against dental caries and makes the tooth enamel stronger. Nevertheless, at a higher concentration, it stains on teeth, weakens bones or causes focal points that may eventually lead to deforming joint arthritis: fluorosis. The aim of this study was to contribute to the assessment of the quality of borehole water in the municipality of Dassa-Zoumè where fluorine contaminations had been proven. The multiparameter tool was used for the in-situ measurement of the physical and chemical parameters of the waters which were sampled. The concentrations of Ca²⁺, NH⁴⁺, NO₃^-, NO₂^- and F^- were determined by an ionic liquid chromatography and a spectrophotometer in the National Hydraulics Laboratory in Benin. The water quality was assessed according to the standards prescribed by WHO in 2002 and enacted in the Republic of Benin. Statistical analyses for p <0.05 have not shown any correlation between F^- and the four elements (Ca²⁺, NO₃^-, NH⁴⁺ , NO₂^- ). But correlation appears with an increase in pH ranging from 6.4 to 7.08 for an average of 6.83. Generally, only waters of the Akofodjoulé district are all contents below the WHO standard for consumable water. The calcium content is also below standard.
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Keywords: Drinking water, fluorine, Bénin