Magnetic Susceptibility and Heavy Metal Contamination in Farmland Soils of Mangu Area, Plateau State, Nigeria

Magnetic susceptibility measurements of soil samples collected at depths 0, 15, 30, and 45cm from thirty-three different farmlands within the study area were made using MS2G Sensor connected to Bartington MS 2 susceptibility meter. The concentration of heavy metals in thirty-three soil samples and most used fertilizers in the study area was determined using a flame atomic absorption spec- trophotometer. Spatial distribution of mass-specific susceptibility (χmLF) with depth show highest χmLF values at the surface (0 cm) and 15 cm deep in most of the districts apart from Kerang district, which had the highest value at 45 cm depth for two sample locations, implying probable magnetic enhancement within the A-horizon of the soil profile.χmLF results also revealed that 81% of the dried soil samples exhibited ferromagnetic behaviour, and 19% exhibited paramagnetic behavior. The concentration of Cadmium, Copper, Iron, Lead, and Zinc obtained for soil samples were compared with the international regulatory standards, and this revealed that the soil samples were neither contaminated with these heavy metals nor toxic. Cadmium, Cobalt, Chromium, Copper, Iron, Nickel, Lead, and Zinc in the two most used fertilizer brands revealed that Cadmium, Cobalt, Chro- mium, Copper, Iron, Lead, and Zinc was more in Fertilizer A than Fertilizer B. At the same time, Nickel was more in Fertilizer B than A. Continuous application of these fertilizers can contaminate the soils. The relationship between χmLF and Fe, Cd, Pb, Zn, and Cu, respectively, showed a strong positive correlation or rela- tionship between χmLF and these heavy metals.