Magnetometric Assessment of Soil Contamination in the Vicinity of Selected Roads in Poland

The goal of the paper is to describe the degree of applicability of magnetic susceptibility measurements for determination of lateral and vertical extension of soil pollution in the neighborhood of selected sections of roads in Poland. Magnetic susceptibility measurements were supported by petromagnetic, geochemical and SEM analyses. In the case of subordinate roads, increased magnetic susceptibility values appears only at the shoulder of the road, i.e., within 3 m from the edge of the road, while in the case of main roads an anomalous band usually reaches about 15 m. Increased values of magnetic susceptibility were observed up to a depth of 30 cm. Main magnetic carriers are Fe and Ti oxides and metallic iron, appearing as irregular grains and spherules. At some grains containing Fe and Ti, fragments of crystal walls were observed. Other grains appeared as elongated slivers. Fe and Ti oxides with remains of crystal walls are of natural, i.e., geogenic nature. Their concentration in the vicinity of the road results from degradation (elution, erosion) of gravel and sand foundation of the road. Irregular grains and metallic iron are coming from traffic (shards of car bodies, combustion products). Magnetic susceptibility carriers of soil samples taken from anomalous areas are associated with elements such as zinc, lead, sulfur and (to a less extent) nickel. Increase of magnetic susceptibility at the topsoil level is accompanied by increasing content of these elements. The zone up to 15 m away, and somewhere even up to 40 m away from the road edges should be excluded from cultivation.