Regional Appraisal of the Fluoride Occurrence in Groundwaters of Andhra Pradesh

Abstract

Fluoride (F−) is essential for normal bone growth, but higher concentration in the drinking water causes health problems which are reported in many states of India. Andhra Pradesh is one of the states which suffer from excess fluoride in groundwater particularly in the hard rock terrain. In this context, a study was conducted in Andhra Pradesh based on chemical analysis of water samples from hydrograph net work stations (dug wells) and exploratory bore wells. The concentration of fluoride in groundwaters ranges from traces to 9.75 mg/l. The occurrence of fluoride is mostly sporadic, uneven and varies with depth. The highly affected districts include Nalgonda and Warangal in Telangana region, Prakasam in coastal region, Anantapur and Kurnool in Rayalaseema region. In certain areas of Nalgonda district, 85% of wells have fluoride more than permissible limit (> 1.5 mg/l) for drinking water. High F− is present in all the geological formations, predominantly in granitic aquifers, compared to the other formations. The average value of fluoride is high in the deeper zone (1.10 mg/L), compared to the shallow zone (0.69 mg/L). The fluoride-rich minerals present are the main sources for fluoride concentrations in groundwater. Residence time, evapotranspiration and weathering processes are some of the other supplementary factors for high fluoride concentrations in groundwater. Long-term data of hydrograph net work stations (dug wells) reveal that fluoride concentrations do not show any marked change of trend with respect to time. The concentration of fluoride is found to increase with increase of Na+and HCO3−, and decrease with increase of Ca2+. Sodium bicarbonate waters are more effective in releasing fluoride from minerals into groundwater. High fluoride waters are of Na+ type. The paper presents a brief account of the study and its results.

Quality and degree of pollution of groundwater, using PIG from a rural part of Telangana State, India

“…The F − content was from 0.26 to 2.30 (with an average of 0.99) mg/L in the present study area. The country rocks, containing the F − bearing minerals (apatite, biotite and hornblende), and the occurrence of clays are the main responsible for the F − content in the present study area, as also suggested by Rao et al (2014) and Subba Rao et al (2017b). The extensive use of phosphate fertilizers for higher crop yields is the secondary source for enrichment of F − in the groundwater (Subba Rao 2017b).…”

Fluoride occurrence in the groundwater in a coastal region of Andhra Pradesh, India

“…indicates its lower geochemical mobility and its absorption on clays (Hem 1991;Drever 1997). Fluoride minerals, agro-chemicals, etc., are the sources of F -in the groundwater (Ayoob and Gupta 2006;Ahmed 2014;Rao et al 2014).…”

Deleneation of groundwater quality in the presence of fluoride in selected villages of Simlapal block, Bankura district, West Bengal, India

“…indicates its lower geochemical mobility and its absorption on clays (Hem 1991;Drever 1997). Fluoride minerals, agro-chemicals, etc., are the sources of Fin the groundwater (Ayoob and Gupta 2006;Rao et al 2014).…”