Geospatial and Temporal Distribution of Fluoride in Groundwater and Health Impacts in Hong Area, Adamawa State, North-Eastern Nigeria

Abstract

A study was carried out on the geospatial and temporal distribution of fluoride in groundwater and health impacts in Hong Area of Adamawa State, North-Eastern Nigeria. Groundwater samples, soil samples and rock samples were collected in both dry and wet seasons and subjected to field and laboratory analysis to determine the physico-chemical characteristics of groundwater with special reference to fluoride. Hanna HI 83200 Multi parameter photometer was used to analyze the fluoride Content. The water samples were analysed for cations and anions, using approved laboratory techniques. Results of analyses were compared with World Health Organisation (WHO) and Nigerian Standard for Drinking Water Quality (NSDWQ). The pH ranged between 5.5 to 6.94 with a mean value of 6.55, total dissolved solids varied from 70.00 mg/1 to 2690,0 mg/l with an average value of 776.0 mg/l while electrical conductivity ranged between 10.0 mg/l to 1320.0 mg with a mean value of 498.0 mg/1. The concentrations of the major cations and anions fall within the acceptable limits recommended by WHO and NSDWQ. The Hydrochemical facies analyses indicate the water in the area as Ca-Mg-HCO3 type, which implies slightly acidic water and this condition favours bedrock dissolution and weathering. Fluoride concentration in groundwater in Hong area ranged from 0.08mg/1 to 2.58mg/l as against the maximum permissible value of 1.5 mg/l for drinking water recommended by WHO and NSDWQ. The fluoride content in the area is categorized into fluoride non-endemic zone (<1.5mg/l) and endemic zone (1.5mg/1), XRD Empyrean diffractometre analyses of rock and soil revealed the presence of nacaphite (sodium calcium-phosphate-fluoride), a fluoride bearing mineral (Na2CaPO4F). The spatial distribution map showed fluoride content above WHO and NSDWQ tolerable limit of 1.5mg/1. The health risk map indicates that 16,600 people in 8 villages out of the 13 villages investigated have dental fluorosis out of a total population of 123,865, while 112,165 people are potential dental fluorosis carriers. Alternative source of drinking water for households and community within the fluoride endemic zone should be used.