Fluoride and nitrate in groundwater of south-western Punjab, India-occurrence, distribution and statistical analysis

Prevalence of fluoride and nitrate in groundwater has become major concern due to their potential environmental related health impacts. High fluoride and nitrate concentrations have been reported from many parts of rural southwestern Punjab causing serious health threats to the inhabitants. The present study is focussed on evaluating the recent status of fluoride and nitrate contamination of drinking water sources from Ferozepur, Faridkot, and Bathinda districts of Punjab. The sampling sites were selected after comprehensive surveying and preliminary analysis of the data collected through questionnaire. Other physico-chemical parameters analyzed were the pH, TDS, electrical conductivity, phosphate concentration along with depth, and age of source. Findings showed that 59 and 95% groundwater samples were found to have fluoride and nitrate content, respectively, beyond permissible limits (WHO). High fluoride concentration up to 10.6mg/L and nitrate concentration up to 90mg/L in drinking water is observed from Faridkot and Bathinda districts. Mean fluoride and nitrate concentration was found to be 3.0302 and 25.14 with standard deviation 1.317 and 10.32, respectively. Statistical analysis was also done to study the correlation/association between various studied parameters viz. nitrate, fluoride, pH, EC, and depth, and it was found that fluoride showed positive correlation with pH (R-2=0.82) and negative correlation with depth and EC (R-2=0.4118 and 0.9169, respectively). Similarly, nitrate showed negative trend with depth, EC, and pH (R-2=0.95, 0.9199, and 0.395, respectively). Phosphate concentration was also analyzed but none was found conclusive as all the samples were found within permissible range. Geospatial variation with fluoride was also observed at certain locations.