Association between Pb and Zn concentrations and magnetic properties in particle size fractions of urban soils

To explore the feasibility of using magnetic techniques for monitoring soil pollution in various particle size fractions, magnetic properties and heavy metals including Pb and Zn in the urban topsoils of Xuzhou, China, were investigated. Soils were partitioned into five size fractions (2000–300, 300–150, 150–75, 75–28, and < 28 μm). The magnetic properties and both metal (Zn and Pb) concentrations were measured in various fractions and the bulk soils. The magnetic measurements indicate that the dominant magnetic component is multidomain grains of ferrimagnetic minerals. Zinc exhibited a substantial enrichment in the finest particles whereas Pb seemed to be almost independent of the selected size fractions. Close associations between concentration-related parameters (χ, χARM, SIRM and SOFT) and both Pb and Zn concentrations were observed in the 75–150, 28–75 and < 28 μm size fractions. This result suggests that simple, rapid, and non-destructive magnetic measurements could provide useful information about Pb and Zn enrichment in fine particles in Xuzhou urban surface soils.

► Anthropogenic magnetic minerals into soils were preferentially linked with coarse particles.
► Zinc exhibited a substantial enrichment in the finest particles whereas Pb did not show this pattern.
► Magnetic measurements provide useful information about Pb and Zn enrichment in soils.