Characteristics of current roadside pollution using test-monitoring plots.

The aim of the study was the qualitative recognition of the existing roadside pollutants deposited in topsoils located close to roads with high traffic volume. So far, the studies have helped to determine the content of pollutants that accumulated over a long period of time. Traditionally, it has been difficult to distinguish between roadside pollution and pollution from other industrial sources. In order to avoid such problems and to accurately recognize present threats originating from road traffic, test-monitoring plots were installed in Poland (Gliwice and Opole), Germany (Tübingen, Ulm and Böblingen), Finland (Helsinki), Tajikistan (Dushanbe) and China (Lanzhou). To install the monitoring plots, the upper 7 cm of topsoil was removed and replaced with boxes filled with clean quartz sand. The sand, with a known chemical composition and neutral magnetic (diamagnetic) properties, was considered as a neutral matrix for the accumulation of traffic pollutants. Within 24 months of exposure, both the magnetic susceptibility values and heavy metal content increased, but with highly diverse differences. The highest values were observed in Germany, Tajikistan and China. Correlation coefficients between the magnetic susceptibility values and investigated elements, as well as PAHs indicate that magnetic susceptibility is a geophysical parameter that can be used, under defined conditions, as an indicator of soil pollution caused by traffic emissions.