Magnetic Monitoring and Source Traceability of Heavy Metal Pollution in the Urban Topsoil of Xuzhou, China

This study integrates environmental magnetism, geochemical analysis, and multivariate statistical methods to investigate heavy metal pollution in the urban topsoil of Xuzhou, China. A total of 142 samples were collected, and concentrations of Cr, Cu, Fe, Mn, Ni, Pb, Zn, and magnetic parameters (χ, χfd, SOFT, SIRM, χARM) were measured. Results reveal elevated levels of Cu, Ni, Pb, and Zn in both 0–2 cm and 3–10 cm soil layers, with concentrations in the 0–2 cm layer (1.3–2.0 times background values) significantly exceeding those in the 3–10 cm layer, indicating anthropogenic inputs primarily accumulating at the soil surface. Magnetic parameters (χ, SOFT, SIRM, χARM) correlated strongly with Pb and Zn, and the pollution load index (PLI), highlighting their potential as rapid indicators of pollution. Spatial analysis identified hotspots in city centers and industrial zones, aligning with moderate to severe PLI values. Principal component analysis and magnetic source tracing uncovered four pollution sources: transportation/fossil fuel combustion, industrial activities, natural soil formation, and other natural processes. By linking magnetic signatures to anthropogenic activities, the study provides a scientific basis for ecological restoration, safe land use, and pollution mitigation strategies in resource-based cities, directly contributing to urban environmental sustainability.