Potential fluoride contamination in the drinking water of Marks Nagar, Unnao district, Uttar Pradesh, India.

This study was conducted in the summer season (May, 2007). The fluoride concentration along with other physico-chemical parameters in ground water samples was determined in Marks Nagar of Unnao district, Uttar Pradesh (India), since it is the only source of drinking water for the villagers. The fluoride concentration in the water varied from 0.8 to 13.9 mgl(-1) with a mean of 4.02 mgl(-1). The correlation analysis revealed that fluoride had a positive correlation with pH, CO(3), HCO(3), and sodium adsorption ratio (SAR), whereas a negative correlation with Ca and Mg was found. A soil profile was also dug in the area to assess depth-wise fluoride content in the soil. The soil samples and underneath calcium carbonate (CaCO(3)) concretion were analyzed for fluoride content. The percent of soluble fluoride to total fluoride in the soil varied from 25.15 to 4.76% down the soil profile. The soluble fluoride was found to decrease with the increase in the clay content in the soil. The total leachable fluoride in CaCO(3) concretions was found to be 6.08%. It was inferred from this study that the soil and underneath layer of CaCO(3) concretions may be the potential source of fluoride contamination in the shallow drinking water sources of the area.