Seasonal Variations, Hydrogeochemical Processes and Health Risks of Nitrate and Fluoride in Groundwater of Greater Hyderabad, Telangana State

This study evaluates hydrogeochemical processes and associated health risks from nitrate and fluoride contamination in shallow hard-rock aquifers of the semi-arid Greater Hyderabad Municipal Corporation (GHMC) region, Telangana, South India. A total of 44 groundwater samples were collected during the pre- and post-monsoon seasons of 2023. Spatial analysis showed elevated nitrate levels in the south-western, northern, and central areas, with 36% (pre-monsoon) and 40% (post-monsoon) of samples exceeding the permissible limit (45 mg/L). Fluoride concentrations were high in the northern, southern, and south-western zones, where 64% and 59% of samples exceeded the acceptable limit (1.0 mg/L) during pre- and post-monsoon periods, respectively. Gibbs diagrams indicated that rock–water interaction and evaporation are the dominant processes controlling groundwater chemistry. Statistical and factor analyses revealed feldspar weathering, cation exchange, and combined geogenic and anthropogenic influences. Health risk assessment showed hazard quotient values (> 1.0) for both contaminants, with children more vulnerable than adults. The results emphasize the need for regular monitoring and sustainable groundwater management in the GHMC region.