Anthropogenic pollutants on top soils along a section of the Salaria state road, central Italy

Abstract

Magnetic susceptibility (MS) is employed among others magnetic parameters to investigate pollution along a high traffic density road. In this study, MS field survey and magnetic laboratory analyses were applied to five sites along the Via Salaria road in the northern districts of Rome. Scanning electron microscope and energy dispersive spectroscopy analyses have also been employed to reveal the nature of Fe rich particles of anthropogenic origin. In general, the soil samples revealed to contain low coercivity minerals (e.g., magnetite) with different grain size, Fe-oxides occurring in various forms (spherules, aggregates, octahedral crystals and angular particles) are typically found close to the road side border at some of the analyzed sites. Magnetic minerals concentration in proximity of the road border resulted higher at sites with higher traffic volume and, in general, decreases with the distance from it. Evidences of anthropogenic material in topsoils were found within the first 5 m from the road border. The study confirms that the in situ measurements of the magnetic susceptibility are a valuable tool to rapidly investigate variations in the magnetic susceptibility profile related to anthropogenic contribution.