Fluoride contamination in ground water of Malaprabha sub basin

The fluoride contamination study has been carried out in ground waters of Khanapur, Bailhongal and Saundatti taluks of Malaprabha sub basin, Belgaum district, Karnataka (India). 21 samples were collected from different locations covering shallow and deep aquifers. The samples were collected during the pre-monsoon and post-monsoon season of 1999.The fluoride concentrations varied from 0.55 to 3.85 mg/L during pre-monsoon and 0.20 to 3.50 mg/L during post-monsoon seasons. Higher concentration of fluoride was observed in Ugargol village of Saundatti taluk. It was observed that about 28.60% of the Samples have fluoride concentration less than 1 mg/L, 23.80% have concentration in the range of 1.0-1.50 mg/L, 42.85% have concentration in the range of 1.50-3.0 mg/L and 4.75% have concentration more than 3.0 mg/L during the pre-monsoon. During post-monsoon, it was found that about 35% of the samples have fluoride concentration less than 1.00 mg/L, 25% have concentration in the range of 1.0-1.50 mg/L, 35% have concentration in the range of 1.50-3.0 mg/L and 5% have concentration more than 3.0 mg/L, A positive correlation of fluoride was observed with bicarbonate, alkalinity and pH during the pre-monsoon and with EC, TDS, carbonate, bicarbonate and potassium during the post-monsoon. This suggests that source of fluoride may be partially from potassium rich rocks and constituents of fertilizers leaching down to ground water. The regression equations have been developed between fluoride and other water quality parameters.