Hydrogeochemical characterization and geospatial assessment of groundwater quality in the alluvial aquifer of southwestern Punjab in association with health risk assessment due to nitrate and fluoride pollution.

Groundwater contamination is a significant threat to human health and hygiene, particularly when high levels of nitrate and fluoride are present. Punjab is currently experiencing a crisis of groundwater depletion and contamination, particularly severe in the southwestern region due to the limited availability of surface water. So, the present study was planned in the Mansa district of Punjab to know the status of groundwater with special reference to nitrate and fluoride and its associated health risks. The study found that all drinking water parameters in the district exceeded the desirable limits. The order of cations found was Na  > Mg  > Ca  > K, and the anions were ordered as HCO  > SO  > Cl  > NO  > F. The variation in Na, K, Mg, and HCO levels is attributed to processes such as silicate weathering, evaporation, and direct ion exchange. The dominant types of groundwater in the area are mixed type and Na-Cl type. The concentration of NO varied from 13.3 to 56.9 mg L with mean 33.3 mg L, while F ranged from 0.09 to 1.81 mg L with mean 1.07 mg L. The study revealed that 23.2% and 12.6% of water samples in the district exceeded the acceptable limits for nitrate and fluoride, respectively. According to the water quality index (WQI), the majority of groundwater in the study area is categorized as very poor (36.6%) for drinking, with the largest contribution from the Budhlada (43.9%) and Sardoolgarh (41.1%) blocks. The hazard quotient (HQ) for NO was below 1 for adults. However, HQ was greater than 1 for children in all blocks except for the Bhikhi. Similarly, for fluoride, HQ was less than 1 in all blocks for both children and adults, except for children in Sardoolgarh block. The cancer risk due to nitrate exceeded acceptable limits in all blocks. Conclusively, the study results indicate that the Mansa district of Punjab is facing severe groundwater contamination due to nitrate and fluoride, with the highest contamination levels in Jhunir (47.4% of samples exceeded the acceptable limit of NO) and Sardoolgarh (87.18% samples exceeded the desirable limit of F) blocks of the district. The study recommends implementing strict policies to regulate the use of agrochemicals in fields to mitigate nitrate pollution in groundwater and reduce associated risks.