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Assessment of quality and acquisition of groundwater mineralization in the Mbour Fatick area, central-western Senegal
* 1 , 2 , 3 , 4
1  Laboratoire Eau-Energie-Environnement-Procédés industriels (LE3PI), Ecole Supérieure Polytechnique, Université Cheikh Anta DIOP, Dakar, Sénégal
2  Département de Géologie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal
3  Bordeaux Imaging Center, Université de Bordeaux, Bordeaux, France
4  Univ. Lille, Univ. Artois, IMT Lille Douai, JUNIA, ULR 4515 – LGCgE, Laboratoire de Génie Civil et Géo-Environnement, F-59000 Lille, France
Academic Editor: Nicolò Colombani

Abstract:

Abstract: Water resource management is one of the major global challenges today, both in terms of agricultural and industrial activities and direct consumption by the population. Access to drinking water is a major priority in the Mbour-Fatick area (Central West, Senegal), where groundwater resources, the only ones available, are subject to severe climatic and anthropogenic pressures. Several aquifers contain significant groundwater quantities, but the quality does not meet consumption standards due to deterioration caused by natural and/or anthropogenic processes. This work aims to update knowledge on the chemical quality of groundwater. Its main objective is to assess changes in groundwater chemistry, identify the processes responsible for mineralization, and determine the suitability of the water for consumption. The study was based on the results of physicochemical analyses of 42 samples collected during two campaigns conducted in September 2019 (22 wells and 20 boreholes) and May-June 2023 (20 wells and 15 boreholes), as well as data from SARR's work in 1982. Methodological approach used to achieve these objectives incorporates both hydrogeochemistry and multivariate statistical analysis. The results obtained showed that pH values range from 6.89 to 8.2, indicating that the waters are neutral to basic. Geochemical analysis has shown that water-rock interaction (dissolution and alteration of carbonate and silicate minerals), ions exchange, and evaporation are the main processes regulates water chemistry. A comparative study of fluoride and chloride ion concentrations between different data sets shows significant spatial and temporal variation. Hierarchical cluster analyses (HCA) revealed the presence of two water groups: highly mineralised waters and moderately mineralised alkaline waters with dominant facies of the mixed Cl-type and mixed HCO3-type, respectively. Calculation of Total Health Index (THI) for fluoride indicates that the health risk is very high, especially in children, with a high probability of diseases such as dental and bone fluorosis.

Keywords: Groundwater; processes; mineralization; spatio-temporal variation; multivariate statistical; fluoride; Mbour-Fatick
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