Spatial distribution of soil magnetic susceptibility and correlation with heavy metal pollution in Kaifeng City, China

• Similar spatial distribution patterns of heavy metals and χLF were found.
• As, Cd, Cr, Cu, Ni, Pb, Zn and PLI showed a significant correlation with χLF.
• The heavy metals and χLF in soil of Kaifeng were mainly produced by anthropogenic factors.
• The concentrations of heavy metals can be predicted from χLF simply and quantitatively.

The characterization of heavy metal pollution is urgently needed in modern environmental studies. However, traditional geochemical methods for detecting soil heavy metals are rather time-consuming and expensive. In recent years, non-destructive and rapid magnetic techniques seem promising in monitoring soil pollution but it is questionable how this relates to heavy metal concentrations. Therefore, in order to understand the correlation of heavy metal pollution with environmental magnetism, magnetic susceptibility (χLF) and the concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn were measured in the topsoil (0–15 cm) collected from Kaifeng City, China. In this study, the spatial distribution of heavy metals and χLF, as well as the correlation between pollution load index (PLI) and χLF were carried out. Results show that the contamination factor (CF) values of different heavy metals follow the order: Cd (10.48) > Zn (2.28) > Pb (1.68) > Cu (1.51) > Ni (0.81) > Cr (0.80) > As (0.65). The average pollution load index (PLI) of the metals is 2.53, representing a moderate pollution level as a whole of the city soil. In general, similar spatial distribution patterns of heavy metals and χLF were found in this research, which decrease progressively from the southeast/east to the northwest/west in the study area. High concentrations of heavy metals and high levels of χLF appears around the southeast, the north of the older city (within the ancient city wall), and along the Longxi–Haizhou Railway. Moreover, contents of As, Cd, Cr, Cu, Ni, Pb and Zn in soils and PLI are significantly positively correlated with their χLF. The results further attest that the measurement of χLF is a simple, rapid and quantitative method for the assessment of heavy metal contamination of soils. When χLF ≤ 71 × 10− 8 m3 kg− 1, the soil is considered to be non-polluted; 71 × 10− 8 < χLF ≤ 162 × 10− 8 m3 kg− 1 represents slightly polluted soils; 162 × 10− 8 < χLF ≤ 253 × 10− 8 m3 kg− 1 moderate pollution, and χLF ≥ 253 × 10− 8 m3 kg− 1 corresponds to heavily polluted soils. However, the standard is exclusively valid for the study area and cannot be simply “transferred” to other polluted areas.