Correlation of soil magnetic susceptibility with heavy metals and physico-chemical profile

The present study was conducted to determine magnetic susceptibility and its correlation with the concentration of selected heavy metals, including arsenic, chromium, cadmium and lead, as well as the physico-chemical properties of topsoil samples collected from District 5 of Tehran Municipality, Iran. The specimens were collected from 13 stations (0–10 cm depth), and the location of the sampling points was recorded as well using the Global Positioning System. The specimens were then analysed for physico-chemical properties, heavy metal concentration (by atomic absorption spectrometry) and in situ magnetic susceptibility at low frequency (χ_lf, using a Bartington MS2 dual-frequency sensor). According to the results, the highest and lowest χ_lf values were 34.1 × 10⁻⁸ and 16.3 × 10⁻⁸ m³/kg at stations 3 (Azadi bus station) and 11 (Jannatabad neighbourhood), respectively. A significant correlation was found between χ_lf and the concentration of lead and chromium (P < 0.05). Moreover, there was a positive and significant correlation between χ_lf and the soil organic matter in the study area (P < 0.01). Based on the research findings, the magnetic susceptibility measure can be used to evaluate quickly the level of soil contamination with heavy metals and also to monitor the changes in soil organic matter.