Assessing anthropogenic contribution in highly magnetic forest soils developed on basalts using magnetic susceptibility and concentration of elements

• Published in: Catena (Giessen) 2021-11, Vol.206, p.105480, Article 105480
• Main Authors: Grison, Hana, Petrovsky, Eduard, Hanzlikova, Hana
• Format: Article
• Language: English
• Subjects: Andosol; Anthropogenic magnetic particles; Soil magnetism; Toxic elements
• ISSN: 0341-8162; 1872-6887
• DOI: 10.1016/j.catena.2021.105480

•Soil magnetometry can help in assessing soil contamination in Fe-rich lithology.•Soil contamination can be determined by comparing topsoil and parent rock material.•SOC correlates significantly with content of S and Pb.•Frequency-dependent susceptibility discriminates anthropogenic elements in topsoil. Mineral magnetic properties are sensitive indicators for evaluating environmental changes, including environmental pressure caused by atmospherically deposited anthropogenic magnetic particles. The most commonly and easily measured magnetic parameter of soils is magnetic susceptibility, which reflects the combined ferromagnetic minerals of lithogenic, pedogenic, and anthropogenic origins. In volcanic soils rich in ferrimagnetic minerals, unfortunately, contributions of pedogenic and anthropogenic origins are masked by the lithogenic contribution. More study is therefore needed of soils developed on highly magnetic lithologies. This work aimed to determine links between magnetic susceptibility and concentration of potentially toxic elements derived from anthropogenic activities in soil (Aluandic Andosols) developed from highly magnetic parent material in a locality where contamination is not expected. The approach is based on relationships between magnetic properties and geochemical signatures of the investigated soils. Magnetic properties are represented by mass-specific magnetic susceptibility (χ) and frequency-dependent magnetic susceptibility (χFD%). Geochemical signatures are represented by concentrations of the elements Fe, Si, Ti, Zr, Sr, Al, Nb, Mn, Ca, Rb, K, P, Zn, S, Pb, Cr, V, Ni, Cu, and As; pH in H2O; soil organic carbon content; and granulometry. Soil contamination was evaluated using two indexes: enrichment factor and geo-accumulation index. Our findings show that χFD% correlates with presence of the toxic elements S and Pb, derived from human activities, while χ exhibits strong correlation with elements Al, Ti, V, and Fe, reflecting natural origin of parent material. In case of soils with well-developed humus horizon, χFD% can be used as a proxy parameter for identifying anthropogenic influence. Our findings are beneficial also for archaeologists using magnetic susceptibility of soils as a link to chemical signatures of past settlement activities.