Savanna Journal of Basic and Applied Sciences 2(2):171-182
Groundwater Fluoride Contamination in Shendam Area and Environs, North Central Nigeria
Abusu C. O.

Fluorosis is an endemic disease caused by excessive fluoride consumption in drinking water, and is a common manifestation in some rural communities in Nigeria. Groundwater quality was assessed in the environs of Shendam area with emphasis on fluoride. Fourty groundwater samples were collected from wells in the field, physical properties measured in-situ, with major and minor ions analyzed. Sodium, calcium and potassium were analyzed by Flame Photometry, bicarbonate, sulphate and chloride were measured by titrimetric method, atomic Absorption Spectrophotometry was used to measure magnesium while fluoride was analyzed using fusion method. Results show that all groundwater parameters fall within recommended limits except for calcium in two localities and fluoride in all groundwater samples which ranged from 1.81 to 3.12 mg/L (mean 2.50 mg/L). Water-rock interaction resulting in silicate weathering was a major determinant of groundwater chemistry. Dominant groundwater facies was of the order Na+K–SO4–Cl (35%) > Ca+Mg, Na+K–HCO3 (30%) > Na+K–HCO3 (22.5%) > Ca+Mg, Na+K–SO4 (7.5%) > Ca+Mg–HCO3 (5%). Fluoride in groundwater was believed to have originated from fluoride bearing minerals of biotite, apatite and hornblende found in rocks of the study area. The role of ion exchange and desorption in fluoride mobilization was found to be minimal as revealed from correlation plots, ionic ratios and pH of the groundwater. Leaching and weathering of fluoride bearing minerals under slightly acidic conditions led to enrichment in groundwater. The dissolution of secondary minerals like fluorite which may develop in rock fractures, was also suggested as additional sources of fluoride because groundwater was under-saturated in relation to the mineral. Local fluoride treatment techniques like adsorption using clay material and Naglonda technique were recommended due to their effectiveness, ease of implementation and low cost