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Determining the origin and pathways of contaminants in the natural environment is key to informing any mitigation process. The mass magnetic susceptibility of soils allows a rapid method to measure the concentration of magnetic minerals, derived from anthropogenic activities such as mining or industrial processes, i.e., smelting metals (technogenic origin), or from the local bedrock (of geogenic origin). This is especially effective when combined with rapid geochemical analyses of soils. The use of multivariate analysis (MVA) elucidates complex multiple-component relationships between soil geochemistry and magnetic susceptibility. In the case of soil mining sites, X-ray fluorescence (XRF) spectroscopic data of soils contaminated by mine waste shows statistically significant relationships between magnetic susceptibility and some base metal species (e.g., Fe, Pb, Zn, etc.). Here, we show how qualitative and quantitative MVA methodologies can be used to assess soil contamination pathways using mass magnetic susceptibility and XRF spectra of soils near abandoned coal and W/Sn mines (NW Portugal). Principal component analysis (PCA) showed how the first two primary components (PC-1 + PC-2) explained 94% of the sample variability, grouped them according to their geochemistry and magnetic susceptibility in to geogenic and technogenic groups. Regression analyses showed a strong positive correlation (R 2  > 0.95) between soil geochemistry and magnetic properties at the local scale. These parameters provided an insight into the multi-element variables that control magnetic susceptibility and indicated the possibility of efficient assessment of potentially contaminated sites through mass-specific soil magnetism., (© 2024. The Author(s).)

This study evaluated the magnetic properties, magnetic susceptibility and isothermal remanent magnetization (IRM) of tissue samples from the brain, liver, spleen, pancreas, heart and lungs, resected from human corpses, with the aim of identifying the magnetic mineral structures and understanding their possible connection to diseases, professional activity, age and gender of the individual, smoking habits and the environment. The heart was the organ with the highest values of magnetic susceptibility and the pancreas showed the lowest values. No relationship was found between magnetic susceptibility, IRM values and ages of the individuals. However the samples obtained in females showed lower values of magnetic susceptibility than those resected from males. The samples collected from the lungs of smokers have higher values of magnetic susceptibility and IRM indicating the presence of magnetic particles with an anthropic origin. Moreover, the complexity of the magnetic behaviour of these tissues may suggest a contribution of both biogenic and anthropogenic magnetic particles also due to some professional activities. In the brain a heterogeneous distribution of the magnetic susceptibility values was found, which might be related mainly to the diamagnetic behaviour of myelin-rich structures. This study suggests that although the diamagnetic and paramagnetic behaviour is common to all structures, magnetite-type structures are always present in the tissues and hematite-type structures may also contribute to the magnetic signal of the sample. IRM values are only dependent on the presence of magnetite or hematite-type magnetic structures and so this technique seems more suitable to achieve the characterization of biomagnetic structures than magnetic susceptibility.

The Algarve is located at a very short distance from North Africa, in Southern Portugal, and as one of the most touristic regions of Portugal, it is accessible by air, land and sea. It is very susceptible to many illegal activities, such as illegal migration, drug trafficking, kidnapping, and murder, among others. Therefore, an Algarve soils database for forensic purposes is being conducted with the conjunction of geological and palynological methodologies on soils characterization, since this is of fundamental importance to assess reliable evidence on forensic investigations. In this study, the properties of soils from several proximate sites from the Algarve were investigated, namely: (i) colour determined by spectrophotometry; (ii) particle size distribution determined by laser granulometry; (iii) low-field magnetic susceptibility by a susceptibility meter; and (iv) pollen content using a light microscope. Finally, a hierarchical cluster analysis was applied to ascertain the capacity of the different soil properties for discrimination between samples. The study reveals the utility of geobotanical techniques for forensic discrimination of soils. Even though some similarities between some of the samples were found, each one presented a combination of colour, particle size distribution, magnetic susceptibility and pollen features that enable the determination of a fingerprint expected to reveal a specific site for future selection of coastal search areas in the Algarve region., (Copyright © 2010 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.)