Further evidence for magnetic susceptibility as a proxy for the evaluation of heavy metals in mining wastes: case study of Tlalpujahua and El Oro Mining Districts

Abstract

Magnetic susceptibility is nowadays used in most areas of environmental research as a proxy for heavy metal pollution in industrial and urban areas. Although the relationship between magnetic susceptibility and concentration of toxic elements in different environments has been pointed out in several studies, mining wastes (tailings) have hardly been investigated by magnetic methods. We report the relationships between magnetic susceptibility and potentially toxic elements monitored at 12 vertical ground profiles of the Tlalpujahua and El Oro mining districts, western Mexico. Specific bulk magnetic susceptibility (k) measurements, percentage frequency-dependent susceptibility (%XFD) determinations as well as the identification of the magnetic carriers within the samples were accomplished using standard rock-magnetic techniques on geochemically well characterized sister samples. Magnetite and/or Ti-poor titanomagnetite seem to be the main magnetic carriers in the samples. Tight correspondence between k and Fe concentrations, as well as Pb and As with the iron content were found. This association seems to hold also for pH variations.