Toxic Risk Profiling of Potentially Toxic Elements in Coal Mines of Northern Pakistan and Their Phytoremediation from Soil: A Multivariate and Monte Carlo Simulation Approach

This study evaluated ecological and human health risks associated with potentially toxic elements (PTEs) in soil and plant samples from coal mines in northern Pakistan. Samples were acid-digested and analyzed using atomic absorption spectrophotometry for Cd, Cr, Cu, Mn, Ni, and Pb. Soil physicochemical properties were lower than those of reference soil. Mean soil concentrations (mg·kg-1) were Cd (2.7), Cr (48.8), Cu (531.1), Mn (218.9), Ni (21.5), and Pb (21.5). While most plants contained PTEs within WHO limits, Cd and Cr exceeded safe thresholds, particularly in Solanum virginianum. Single-factor and Nemerow contamination indices indicated contamination levels ranging from none to severe. Principal component analysis revealed negative correlations for Cd (r = −0.52) and Pb (r = −0.50), and positive correlations for Cu (r = 0.55), Mn (r = 0.55), and Ni (r = 0.66). Sensitivity analysis identified concentration and exposure duration as dominant risk drivers. Both carcinogenic and non-carcinogenic risks surpassed acceptable limits. Bioconcentration factors >1 for Cd, Cr, and Pb in Centaurea hyalolepis, Echinophora spinosa, Glinus lotoides, and Solanum virginianum indicate strong phytoremediation potential. Overall, coal mining has caused significant environmental and health risks, and native plants show promise for sustainable remediation.