Distribution and causes of high fluoride groundwater in the western Bushveld area of South Africa
Dental fluorosis is endemic in the western Bushveld of South Africa. This study investigated the occurrence of fluoride (Fˉ) in groundwater in the area. It was hypothesised that fluoride in groundwater originated from the dissolution of fluorine-bearing minerals, principally fluorite, mica, amphibole and apatite, and that high F- groundwater would be hosted in rocks with a high fluorine (F) content. It was further hypothesised . that groundwater residence time, rare F-bearing minerals, ion exchange reactions and evaporation affected the Fˉ concentration of groundwater. These hypotheses were investigated by analysing data on Fˉ concentrations in groundwater, paired rock and soil samples, and selected minerals. Three hundred and thirty eight samples of groundwater from the field area were analysed for Fˉ by both Fluoride Ion Selective Electrode and High Pressure Ion Chromatography. The results were added to a database of three thousand water samples covering the western Bushveld and together provide the first complete picture of the distribution of high Fˉ groundwater in the area.
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