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Trace elements emitted by road transport cause long-term contamination of road soils. This study showed the effect of the noise barrier on the spatial distribution of metals in soils at the City Centre Ring Road in Wrocław (Poland). Samples were taken along the barrier every 150 m and across the screen at distances of 0.5, 2.5, 5 (only on the left side), 10, 20, and 50 m from the noise screen on both sides of road no. 5. The contamination of soils was assessed with the use of commonly used individual pollution indices, integrated pollution indices based on the PI index or metal concentrations, and a potential ecological risk index (RI). The geoaccumulation index (Igeo) and the single pollution index (PI) indicate moderate contamination of soils by Cu, Pb, and Zn at most measuring points. The significant risk was reported from Cd in all samples. Integrated pollution indices, especially the PI_Nemerow, PI_avg, and RI confirm the poor quality of studied soils. The presence of elements in soil is related to anthropogenic factors. The spatial distribution of pollution indices and results of statistical analysis (HCA) indicate that Cr and Ni are of natural origin. Remaining elements (Cd, Pb, Cu, Zn) are of mixed origin with a large share from car transport (the significant Spearman’s correlation coefficients). In the case of cadmium, dendograms suggest the existence of an additional anthropogenic source, which is also confirmed by moderately strong correlations of this element with other metals.

The quality of soils polluted by trace elements around the facilities with the Cu and Zn smelting activities and the post-flotation tailings pond from copper industry were assessed. The level of the contamination of soils was determined on the basis of the contamination factor and the geoaccumulation index. The geoaccumulation index allows to distinguish more degrees of soil contamination and simplifies the assessment of the useable value of soil. The degrees of soil contamination and the pollution load index were shown. It has been shown that the pollution indices are a useful tool in describing the soil quality and planning corrective actions in the areas contaminated as a result of industrial activity. Histograms of pollution indices were used in order to detect the distribution of trace elements in soils. The content of metals in biomass was assessed using bioaccumulation indices. Triticum L. and Brassica napus L. show low bioaccumulation of studied metals in cereal plants. The correlations were used in order to detect the relationship among trace elements in soil as well as the relationship of metal (soil)-metal (plant) and metal bioaccumulation (plant)-metal (soil). The highest values of indices were recorded for the Oława smelter, presumably due to the long operation period before technological changes limiting the emission of pollutants were introduced. This research area was classified as very highly contaminated with all trace elements. Soils around other facilities are at least moderately contaminated.

The pH and the EC of soil solutions display a typical character of urban soils, and the concentration of some metal content in the selected locations indicate a strong influence of the motor transport on the Wrocław's congested roads. Sampling stands were located at the busiest road junctions. Pollution of soils with Zn, Cu, Pb, Ni, Cr and Cd along the more important traffic roads of Wrocław within the borders of the city has been measured. The internal ring road (encircling the central districts of the city) and the external ring road (the Eastern Ring Road) of the city of Wrocław along with busy exit roads on the border of city were compared. Zinc concentration in soils was exceeded locally relative to standard for soils of group I, according to the Polish Ministry of Environment Regulation from September 1st, 2016. The pollution indexes compared to the geochemical background in the uncontaminated soils of Poland showed an enrichment of Wrocław's soils with trace elements in many locations. Mean values of indexes for all samples display the dominant influence of zinc, copper and nickel on the soil contamination in Wrocław. The results of the studies did not confirm the correlation between the decrease of all metals concentration with the distance from the city center. The Pearson's correlation coefficients between pairs of Zn-Cu, Zn-Pb and Cu-Pb show significantly correlated linear relationships of metals in soils. The frequency histograms of trace elements in soils reveal large deviations from the Gaussian curve due to a significant diversification of metal concentrations between different locations.

Metal concentrations (Cu, Zn, Pb, Ni, Cr) in soils and plants around the metallurgical waste landfill of Siechnice, Poland, have been determined. The soil samples were collected from the surface layer of 0-25 cm. The soils and plants were digested in HNO 3 , 60%, using the Microwave Digestion System (Milestone Start D). The analysis of metals has been carried out through the Flame Atomic Absorption Spectroscopy (FAAS) method. The pH and the conductivity of the soil solutions were measured. The pollution index (Wn) and the bioaccumulation coefficient (WB) have been determined. The permissible content of Cu, Zn, Ni and Cr in soils were exceeded compared to the geochemical background in uncontaminated soils of Poland. Chromium concentrations have also been exceeded relative to the standard for soils, according to the Polish Ministry of Environment Regulation from September 1 st , 2016. The assessment of the bioaccumulation coefficients of metals in plants ( Plantagolanceolata L. and Zea mays L.) has shown significant bioaccumulation of copper and zinc compared to the permissible concentrations of undesirable substances in feed in agreement with the Polish Ministry of Agriculture and Rural Development Regulation from January 23 rd , 2007.

The concentrations of heavy metals in soils along the motorway bypass of Wroclaw (AOW) and the Eastern Ring Road of Wroclaw (WOW), Poland, have been determined. The soil samples were collected from the levels of 0-25 cm within 2 m from the edge of the road. The mineralizates were prepared in HNO 3 , 60%, using the Microwave Digestion System. The content of Cu, Zn, Cr, Ni and Pb in soils were determined using FAAS method. The physicochemical parameters, the conductivity and pH of the soil solutions were measured to evaluate the salinity of the soils and their active and exchangeable acidity. The pollution indexes (W N ) showing the enrichment of soils in metals have been determined. Excess of metal concentrations in soils compared to the geochemical background in uncontaminated soils of Poland has been observed. Permissible concentrations of heavy metals relative to the standard for soils, according to the Polish Ministry of Environment Regulation from September 1 st , 2016, have not been exceeded.