Tracing potential sources of hazardous contaminants, Fluoride, Nitrate, and Uranium, using an extended PCA-PMF statistical approach for the Semi-Arid Eastern Plains of Rajasthan, India

This study evaluated groundwater quality and identified possible sources of major ions and trace elements, including Fluoride (F^-) and Uranium (U) ions in the Semi-Arid Eastern Plains of Rajasthan. A total of 110 groundwater samples were analyzed following standard laboratory protocols. Elevated concentrations of Chloride, Sulphate, Calcium, Magnesium, and Sodium are found prominently in prevailing aquifer systems, indicating groundwater salinity and hardness. High F^- and U concentrations were observed in Alluvium aquifers comprising clay, silt, sand, gravel, and mixed concretions, suggesting their co-occurrence in these formations. Multivariate analysis using Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF) revealed that groundwater chemistry is predominantly influenced by geogenic processes, followed by agricultural activity, natural sources, and domestic pollution. However, Nitrate is attributed to agricultural activities. Moreover, F^- and U contamination is driven by geogenic factors such as carbonate weathering, dissolution, sorption, and leaching. Besides, the Entropy-weighted Water Quality Index (EWQI) classified poor to extremely poor-quality groundwater in the western and southern regions. These findings underscore the combined impact of natural and anthropogenic factors on groundwater composition. The western part of the Alluvium aquifer is especially vulnerable, underscoring the urgent need for effective groundwater management strategies to mitigate contamination, ensure potable groundwater availability, and safeguard public health.