Evaluation of Nitrate Contamination and Spatial Distribution in Groundwater of Southwestern Ajmer District, Rajasthan

This study evaluates the spatial distribution of nitrate contamination in the groundwater of the Jawaja block in the southwestern region of Ajmer district, Rajasthan, and investigates its correlation with land use/land cover (LULC) characteristics. One hundred thirteen groundwater samples were obtained from shallow and deep bore wells, exhibiting nitrate amounts between 2 and 312 mg/L (mean: 60.38 mg/L). Approximately 36% of the samples were above the BIS allowed level of 45 mg/L, indicating a substantial contamination risk. Spatial research utilizing GIS indicated that elevated nitrate zones are primarily located in the central, eastern, and northern regions of the block, corresponding with areas of heavy agricultural cultivation and high population density. LULC mapping indicated that agricultural land constituted the most extensive category, followed by built-up areas, whereas wooded and rangeland zones were predominantly situated in highland regions characterized by reduced nitrate levels. The identified distribution pattern indicates that overuse of fertilizers, insufficient sanitary infrastructure, and hydrogeological susceptibility are the main contributors to contamination, whereas wooded and rangeland regions perform a protective function for groundwater quality. The findings emphasize the necessity of focused, land-use-specific interventions, such as optimized fertilizer management, enhanced wastewater disposal systems, and the safeguarding of natural recharge zones, to enable sustainable groundwater resource management in nitrate-impacted semi-arid regions.