Heavy Metal Contamination and Risk Hotspots in Zacatecas Soils:  An Integrated Geoaccumulation and Multivariate Analysis

This study evaluates heavy metal contamination in soils from Zacatecas, Mexico, aiming to identify contamination hotspots, assess ecological risks, and explore potential sources through geochemical and multivariate approaches. Forty soil samples were collected across four areas with varying degrees of mining influence. Concentrations of As, Cr, Ni, Co, Cd, Pb, Zn, and Cu were determined using ICP MS. The geoaccumulation index (I _geo ), principal component analysis (PCA), hierarchical clustering, and heatmaps were applied to characterize contamination levels, spatial patterns, and source contributions. Area 1 exhibited extreme contamination, with Pb and As concentrations far exceeding regulatory thresholds and I _geo values > 6, indicating very severe pollution. Multivariate analyses clearly separated this area from less impacted zones, suggesting a dominant influence of mining residues. In contrast, Areas 3 and 4 showed concentrations close to geogenic background levels. The findings reveal a critical contamination hotspot in Area 1, representing potential risks to human health and the environment. The integrated use of geochemical indices and multivariate statistics proved effective for identifying priority areas for remediation.