Rajveer, S.C. Meena, Ranjeet Singh, R.B. Dubey, R.H. Meena, Jagdish Choudhary, Vinod Saharan, K.K. Yadav, B.S. Shekhawat, Jasveer Singh, Piyush Choudhary, Naseeb Choudhary, Siddharth Choudhary, Richa Sachan, Dinesh, Kishan Damor, Lakshya Choudhary, Jaipal
Abstract
A field survey was conducted in March 2025 to assess the chemical quality of underground water in Pisangan, Ajmer, Nasirabad, Pushkar, Arai, Kishangarh and Rupangarh tehsils of Ajmer district of Rajasthan. Two hundred sixteen water samples were collected from the whole study area from wells and tubewells which were used for irrigating the fields. The findings of the study revealed that the pH of underground water samples varied from 7.04 to 8.59, with a mean value of 7.54 which indicates a slightly saline nature of underground water, while electrical conductivity ranged between 0.42 to 8.54 with an average value of 2.64 dS m-1, indicating increased salinity hazard which may adversely affect sensitive crops under continuous irrigation. Fluoride concentration in underground water used for irrigation in the whole study area ranged from 0.21 to 6.65, with an average value of 3.10 mg l-1. Also, the nitrate content of underground water samples varied from 9.01 to 53.21 with the mean value of 29.90 mg l-1. The prevailing arid climatic conditions facilitate the dissolution of soil salts and rock-derived minerals. Moreover, high rates of evaporation increase the concentration of dissolved salts, resulting in greater salt accumulation in groundwater. Among the tehsils, the highest fluoride concentration was recorded in Rupangarh tehsil (4.29 mg l-1), while the lowest was observed in Pushkar tehsil (1.35 mg l-1). In contrast, the highest nitrate content was observed in Rupangarh tehsil (34.10 mg l-1) whereas lowest was observed in Pushkar (18.35 mg l-1). Overall, the underground water quality of Ajmer district reflected the influence of the regionâs dry climate and geological conditions. Limited rainfall, intense evaporation, and continuous interaction between groundwater and mineral-bearing rocks contribute to the observed variations in its chemical characteristics.