Resumen

SANCHEZ-DUQUE, Alexander et al. Magnetic parameters as indicators of major elements and lead contamination in urban soils from Aburrá valley, Colombia. Rev. mex. cienc. geol [online]. 2020, vol.37, n.3, pp.224-236.  Epub 22-Sep-2025. ISSN 2007-2902.  https://doi.org/10.22201/cgeo.20072902e.2020.3.1586.

We present a study of environmental magnetism in order to determine the relationship between magnetic parameters and heavy metals in urban soils of the Metropolitan Area of Valle de Aburrá (MAVA), Colombia, in order to establish magnetic indicators that allow estimating concentrations of magnetic minerals, mayor elements, and Pb, and to determine the area of their accumulations in the urban zone of the Metropolitan Area of Valle de Aburrá. The study was carried out on 83 samples of topsoil, which were subject to magnetic analyses. The concentration of mayor elements (Al 2 O 3 , Fe2O3 y MnO) and Pb was determined by energy dispersive X Ray Fluorescence. A variation of magnetic material in the urban soils was found, which contain a mixture of magnetic minerals of low coercivity or natural magnetite of anthropogenic origin. Particles of superparamagnetic size were detected at medium and low concentrations in soils with low anthropic activity, suggesting a natural origin. On the other hand, by the combination of magnetic parameters and thermomagnetic curves we found high concentrations of magnetic minerals of anthropic origin in the soils. The concentrations of Al 2 O 3 y Fe 2 O 3 are high and similar in the urban soil. Soils from areas of residential and public space use, which have few emission sources of anthropogenic particles, showed low concentration of Pb. On the other hand, soils from areas of industrial and commercial use, with high anthropogenic activity (vehicular traffic), showed high concentration of Pb. Soils from public space areas with low anthropic activity were employed to determine the reference threshold value for each element and magnetic parameter. The statistical analyses showed that the magnetic mineral content in the MAVA soils has a direct proportional relationship with the Pb concentration, and an inverse proportional relationship with the Al 2 O 3 , Fe 2 O 3 and MnO concentration. We developed a mathematic model that estimates the concentration of elements from magnetic parameters with a precision of 63 %. High accumulation of magnetic minerals and high Pb concentration occur in an area of 46 km 2 , which represents 25 % of the urban zone, and is the probable zone of health risk by accumulation of polluted material.

Palabras llave : Magnetic parameters; soil; contamination; lead; major elements; threshold value; spatial distribution; Aburrá valley, Colombia.

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