FLUORIDE CONTAMINATION IN THE IRRIGATION WATER, SOIL, AND CROPS OF THE RANGAREDDY DISTRICT OF TELANGANA STATE, INDIA

The aim of present study was to assess the fluoride (F) content in the irrigation water, soil, and crop plants in the Amangal mandal of Rangareddy district, Telangana state, India. The F content in the irrigation water ranged from 0.27 to 4.40 ppm with a mean value of 1.75 ppm during the kharif (monsoon) season, while in the rabi (post monsoon) season, it was between 0.68 to 4.61 with an average of 2.22 ppm. The F concentration in the irrigation water was higher in the rabi season compared to the kharif season and found to be significantly positively correlated with pH, bicarbonate, sodium, sodium adsorption ratio, and residual sodium carbonate, and negatively with calcium. The available F content in the soils during the kharif season ranged from 0.04 to 0.29 ppm with an average of 0.13 ppm and during the post rainy season the range was 0.05 to 0.24 ppm with mean value of 0.14 ppm. The available F in the soil was significantly positively correlated with the soil pH and exchangeable sodium. Among the crop plants and their parts, the F concentration was lowest in the rabi green gram seed (0.008 mg/kg) and highest in the kharif spinach crop root (0.084 mg/kg). Although the F concentrations were higher than the maximum permissible limit (1.0 or 1.5 ppm) in most of the groundwater samples, the available F was low in all the soil samples collected from the farmers' fields irrigated with the groundwater. The F concentrations in the root, shoot, and edible portions of all the fifteen crops studied were well below the toxic limits.