Assessment and Mechanism of Fluoride Enrichment in Groundwater from the Hard Rock Terrain: A Multivariate Statistical Approach
Narsimha Adimalla
Abstract
Groundwater is only the primary source for drinking water in the northern Telangana, South India, where a number people suffers from fluorosis. With this concern a 34 groundwater samples were collected and studied to identify the occurrence, hydrochemical distribution of fluoride groundwater, using geo-statistical tool such as principal component analysis (PCA), saturation indices (SI), and correlation analysis were executed in this study. The concentration of fluoride ranges from 0.06 to 4.33 mg/L, with a mean of 1.13 mg/L and 30% of groundwater samples having above the maximum acceptable limit of 1.2 mg/L fluoride for drinking purposes. Fluoride shows a considerable relation with pH, and TDS, while fluoride also demonstrations an insignificant correlation with Ca2+. Moreover, alkaline nature, elevated HC$${\text{O}}_{3}^{ - }$$, Na+ and Na+–HC$${\text{O}}_{3}^{ - }$$ water type were also influenced to enhance the fluoride concentration in the groundwater. The two components from the principal components (PC) analysis reveals that chemical variable accounts for above 67% of the total variance of the groundwater chemistry. The PC-1 and PC-2 have high positive loadings reveals that the dissolution of fluoride bearing minerals like apatite and biotite are the chief source to larger concentration of fluoride in the study region groundwater. Further, groundwater also obviously approves the over-saturated with respect to calcite, fluorite, and dolomite are the major factors to upholds the enrichment of fluoride concentration, while the geogenic activities are also a principal controlling factors to influence the groundwater chemistry in the study region.