Geospatial mapping, risk assessment and multivariate analysis of naturally occurring radionuclides and potentially toxic elements in agrarian soils of SAS Nagar, Punjab, India

Rapid urbanization, industrialization, and agricultural advancements underscore the need to monitor environmental radionuclides and potentially toxic elements (PTEs) for pollution and human health impact assessment. This study assessed human health risks associated with radionuclides and PTEs in agricultural soils of the SAS Nagar District, Punjab, India, using ICP-MS and XRF techniques. Mean radionuclide concentrations were found to be 34.7 ± 3.1 Bq kg^-1 (²³⁸U), 56.5 ± 8.4 Bq kg^-1 (²³²Th), and 556.8 ± 93.1 Bq kg^-1 (⁴⁰K), respectively, with levels all above corresponding global means. Elemental concentrations (ppm) followed a decreasing sequence: Fe (29,148) >  > Zn (67.4) > Cr (55.7) > Ni (25.5) > Cu (23.4) > Pb (18.6) > Th (13.9) > Co (8.8) > As (6.5) > U (2.8) > Cd (0.17). Pollution indices identified As and Cd as the dominant contributors to soil contamination, with U and Cr exerting moderate secondary effects. A multi-pathway exposure model indicates carcinogenic risks within the permissible range; however, As, Cr, and Ni remain within tolerable limits (10⁻⁶–10⁻⁴) but still signify potential concern. IDW-based spatial mapping of selected radionuclides and PTEs revealed zones of co-contamination across the study area. Spearman’s rank correlations show strong to very strong monotonic relationships among most soil variables. Principal Component Analysis (PCA) showcased that the first three components explained a major portion (78.2%) of the total variance. PCA separates variables driven by common environmental processes from those influenced by geogenic and anthropogenic factors, while Hierarchical Cluster Analysis (HCA) groups parameters with similar behavior reflecting these controls. Collectively, these findings emphasize the need for targeted soil quality monitoring to safeguard long-term soil quality and public health.