Soil Contamination from Mining Activities in Maramures County, Romania: An Integrated Assessment Based on Pollution Indices and Statistical Analysis

This study evaluated potentially toxic element (PTE) concentrations in soil matrices sampled near historical mining sites in Maramureș County, Romania. A total of 36 samples collected from 14 locations across four legacy mining sectors (Ilba–Nistru, Baia Mare, Cavnic, and Băiuț) were evaluated using physicochemical analysis, Romanian regulatory thresholds for sensitive land use (Order no. 756/1997), pollution indices (geoaccumulation index, pollution load index, and potential ecological risk index), and multivariate statistics (Spearman correlation and principal component analysis). Pb, Zn, Cu, and Cd were the main contaminants, with the strongest hotspot identified at CA1, a roadside soil in the Cavnic sector, where maximum concentrations reached 3075.7 mg kg−1 for Pb, 2300.7 mg kg−1 for Zn, 845.7 mg kg−1 for Cu, and 52.8 mg kg−1 for Cd. The results showed marked spatial heterogeneity, with severe contamination concentrated in a limited number of hotspots rather than distributed uniformly across the investigated area. PLI ranged from 0.086 to 5.045 (median 0.765), while PERI ranged from 11.2 to 2800.1 (median 85.9), indicating strong contrasts between low-impact locations and high-priority hotspots. Under the regional reference framework applied in this study, Cd made the largest contribution to the overall PERI signal, followed by Pb and Cu. Index-based screening and multivariate analysis consistently identified CA1 as the most critical hotspot, followed by CA5, HI1, BO1, and BT3 as priority locations for follow-up investigation. Overall, the combined approach proved effective for hotspot identification and screening-level prioritization in a historically mining-affected region.