Distribution of fluoride in surface and ground water: a case study of Langtang North, Plateau State, Nigeria

Abstract

The major ways in which humans get exposed to inorganic fluorides are through food and water. Therefore, this study focused on fluoride concentration in surface and ground water in Langtang North of Plateau State where dental fluorosis is more predominant. Twenty-six (26) samples from ground water and four (4) from surface water were collected from six localities of Langtang-North. These samples were analyzed using ion selective method to investigate the spatial distribution of fluoride concentration. Rock and soil samples were also collected for analysis. Hydrochemical results revealed the following concentrations; 1600 ppm – 2990 ppm for fluoride in rocks, and 100 ppm – 600 ppm for soil. Fluoride in water ranges from 1.1 – 6.0 mg/l, whereas, Na⁺, Mg²⁺, Ca²⁺, HCO₃^-, SO₄^2-, Cl^-, Al³⁺ and Fe²⁺ have average concentrations of 48.566 mg/l, 21.220 mg/l, 21.142 mg/l, 214.27 mg/l, 16.492 mg/l, 28.641 mg/l, 0.177 mg/l, and 0.261 mg/l respectively. Classification of the water using a Piper’s trillinear method shows a Sodium bicarconate water type. Fluoride concentration in the rocks and soils could be responsible for the high concentration of fluoride present in the groundwater. Eighty three point three-three (83.33%) percent of the samples analyzed have fluoride concentration above the 1.5 mg/l recommended by WHO, while only the remaining16.67 percent are within the WHO recommended level. In conclusion, the amount of fluoride in rocks as compared with the soils and water sources were significant (p<0.05) and this could be because nature weathering and leaching that takes place. Therefore, majority of the water sources both ground and surface will need defluoridation.

Keywords: Fluoride, ground water, surface water, rocks, soil.