Los parámetros magnéticos como indicadores de contaminación por elementos mayores y plomo en suelos urbanos del Valle de Aburrá, Colombia

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 (Al2O3, Fe2O3 y MnO) and Pb was determined by energy dispersive X Ray Fluorescence. A variation of magnetic material in the urban soils was Los parámetros magnéticos como indicadores de contaminación por elementos mayores y plomo en suelos urbanos del Valle de Aburrá, Colombia Alexander Sánchez-Duque1,3, Francisco Bautista1, Rubén Cejudo2,*, Avto Goguitchaichvili2 y Miguel Ángel Cervantes-Solano4 1 Laboratorio Universitario de Geofísica Ambiental (LUGA), Centro de Investigaciones en Geografía Ambiental (CIGA), Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex-Hacienda de San José de la Huerta, C.P. 58190, Morelia, Mich., México. 2 Laboratorio Universitario de Geofísica Ambiental (LUGA), Instituto de Geofísica Unidad Michoacán (IGUM), Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex-Hacienda de San José de la Huerta, C.P. 58190, Morelia, Mich., México. 3 Adscripción actual: Tecnológico Nacional de México, campus Valle de Morelia, km 6.5 Carretera Morelia-Salamanca, C.P. 58100, Morelia, Mich., México. 4 Escuela Nacional de Estudios Superiores Unidad Morelia, Antigua Carretera a Pátzcuaro 8701, C.P. 58190, Morelia, Mich., México. * ruben@igeofisica.unam.mx REVISTA MEXICANA DE CIENCIAS GEOLÓGICAS v. 37, núm. 3, 2020, p. 224-236 I: htt ://dx.doi.org/10.22201/cgeo.20072902e.2020.3.1586 225 Parámetros magnéticos como indicadores de contaminación RMCG | v. 37 | núm. 3 | www.rmcg.unam.mx | DOI: http://dx.doi.org/10.22201/cgeo.20072902e.2020.3.1586 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 Al2O3 y Fe2O3 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 Al2O3, Fe2O3 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 km2, which represents 25 % of the urban zone, and is the probable zone of health risk by accumulation of polluted material.