A Factor Model to Explain the Hydrochemistry and Causes of Fluoride Enrichment in Groundwater of Bhairmgarh Block in Bijapur District, Chhattisgarh, India

Rubina Sahin, Kavita Tapadia, Ghanshyam Jareda

High fluoride (>1.5 mg/l) in groundwater has been reported from many States of India. To understand the chemical behaviour of fluoride (F^-) in groundwater water in terms of local hydrogeological setting, aquifer level, climatic conditions and agricultural practices.  In the study, a factor model was developed to determine the major hydrochemical processes that control the variations and dissolution of fluoride-beraing minerals in groundwater of Bhairmgarh block of Biapur district in Chhattisgarh. A total of 36 groundwater were collected and of F^- chemically analyzed. The results of chemical analyses (pre-monsoon 2012) show F^- abundance in the range of 0.14 to 4.7 mg/l with 25% of the samples in excess of permissible limit of 1.5 mg/l. Present study finds that four major processes control the hydrochemistry of groundwater resources in the  study area: dissolution of soluble salts in the aquifer, high pH and Na⁺ concentration, maximum retention time and dissolution of bicarbonate minerals in the aquifers. Two major groundwater types have been distinguished in this study: fresh Na-Ca-HCO₃ groundwater type and Na-Ca-Cl- HCO₃ groundwater type. Presence of F^- bearing minerals in the host rock, the chemical properties like decomposition, dissociation and dissolution and their interaction with water is considered to be the main cause for F^- in groundwater. The suggested remedial measures to reduce F^- pollution in groundwater include dilution by blending, artificial recharge, rainwater utilization, well-organized agricultural practices and well construction.