Geochemical appraisal of fluoride incidences in groundwater from granitic aquifers, parts of Jhansi and Tikamgarh districts (Bundelkhand region), central India: Lineament controls and human health

Abstract

A geochemical investigation based on the analyses of a total of 41 groundwater samples collected during the pre- and post-monsoon periods from tube/bore-wells points to human health issues due to fluoride levels above and below the tolerance limits specified by the World Health Organization (WHO) and the Bureau of Indian Standards (BIS). The study shows that the fluoride (F-) concentration in groundwater in the Bundelkhand granitoid varies from 0.13 to 2.55 mg/l and 0.17 to 2.2 mg/l in pre-monsoon, post-monsoon periods, respectively. The high F- values (>1.5 mg/l) were found in 13 samples (pre-monsoon), and 06 samples (post-monsoon) periods collected from shallow aquifers (120-200 ft) are causing dental fluorosis in the area. The hydro-geochemical processes like ion-exchange reactions, depletion of Ca2+ under alkaline medium (high pH) have been found as a favourable environment for the liberation of F- into groundwater. The weathering of rocks containing fluoride-minerals and evapotranspiration processes govern fluoride enrichment in groundwater. The principal F- hosting minerals like apatite, biotite, muscovite, chlorite, sericite, hornblende and kaolinite were the key geogenic sources of F- in the area. The presence of weak/shear zones delineated as lineaments facilitated F- to the groundwater release due to prolonged rock-water interaction. Dental deformities are more ubiquitous in minor and old aged inhabitants than adults.