Investigating spatial distribution of fluoride in groundwater with respect to hydro-geochemical characteristics and associated probabilistic health risk in Baruipur block of West Bengal, India.

Fluoride (F ^- ) enrichment in groundwater of the lower Gangetic plain in West Bengal, India is a major concern. Fluoride contamination and its toxicity were reported earlier in this region; however, limited evidence was available on the precise site of contamination, hydro-geochemical attributions of F ^- mobilization and probabilistic health risk caused by fluoridated groundwater. The present study addresses the research gap by exploring the spatial distribution and physico-chemical parameters of fluoridated groundwater along with the depth-wise sedimental distribution of F ^- . Approximately, 10 % of the groundwater samples (n = 824) exhibited high F ^-  ≥ 1.5 mg/l from 5, out of 19 gram-panchayats and Baruipur municipality area and the maximum F ^- was observed in Dhapdhapi-II gram-panchayat with 43.7 % of samples showed ≥1.5 mg/l (n = 167). The distribution patterns of cations and anions in fluoridated groundwater were Na ⁺  > Ca ²⁺  > Mg ²⁺  > Fe > K ⁺ and Cl ^-  > HCO ₃ ^-  > SO ₄ ^2-  > CO ₃ ^2-  > NO ₃ ^-  > F ^- . Different statistical models like Piper and Gibbs diagram, Chloro Alkaline plot, Saturation index were applied to better understand the hydro-geochemical characteristics for F ^- leaching in groundwater. Fluoridated groundwater is of Na-Cl type which implies strong saline character. The intermediate zone between evaporation and rock dominance area controls F ^- mobilization along with ion-exchange process occurring between groundwater and host silicate mineral. Furthermore, saturation index proves geogenic activities related to groundwater F ^- mobilization. All cations present in sediment samples are closely interlinked with F ^- in the depth range of 0-18.3 m. Mineralogical analyses revealed that muscovite is the most responsible mineral for F ^- mobilization. The probabilistic health risk assessment disclosed severe health hazard in the order of infants > adults > children > teenagers through F ^- tainted groundwater. At P95 percentile dose, all the studied age groups showed THQ >1 from Dhapdhapi-II gram-panchayat. Supply of F ^- safe drinking water is required through reliable water supply strategies in the studied area.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2023 Elsevier B.V. All rights reserved.)