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Simulating fluoride evolution in groundwater using a reactive multicomponent transient transport model: Application to a crystalline aquifer of Southern India

Abstract : Overexploitation of crystalline aquifers in a semi-arid climate leads to a degradation of water quality, with the main processes responsible for the observed salt loads probably being irrigation return flow (IRF) and a high evaporation rate. The present study has focused on modelling the F- accumulation caused by IRF below rice paddy fields in the small endorheic Maheshwaram watershed (Andhra Pradesh, Southern India). The transient simulation was performed with a 1D reactive transport PHREEQC column and took into account IRF evaporation, kinetically controlled mineral dissolution/precipitation, ion adsorption on Fe hydroxides, and mixing with fresh groundwater. The results revealed the role of cationic exchange capacity (CEC) in Ca/Na exchange and calcite precipitation, both favouring a decrease of the Ca2+ activity that prevents fluorite precipitation. Iron hydroxide precipitation offers a not inconsiderable adsorption capacity for F- immobilization. The principal sources of F- are fluorapatite dissolution and, to a lesser extent, allanite and biotite dissolution. Anthropogenic sources of F-, such as fertilizers, are probably very limited. After simulating an entire dry-season irrigation cycle (120 days), the results are in good agreement with the observed overall increase of Cl- in the Maheshwaram groundwater. The model enables one to decipher the processes responsible for water-resource degradation through progressive salinization. It shows that F- enrichment of the groundwater is likely to continue in the future if groundwater overexploitation is not controlled.
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Contributeur : Anne-Marie Pouget <>
Soumis le : lundi 21 juillet 2014 - 15:38:03
Dernière modification le : samedi 22 août 2020 - 13:48:01

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Marie Pettenati, Jérôme Perrin, Hélène Pauwels, Shakeel Ahmed. Simulating fluoride evolution in groundwater using a reactive multicomponent transient transport model: Application to a crystalline aquifer of Southern India. Applied Geochemistry, Elsevier, 2013, 29, pp.102-116. ⟨10.1016/j.apgeochem.2012.11.001⟩. ⟨hal-01026410⟩

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