Evaluation of hazardous element accumulation in urban soils of Cracow, Lublin and Torun (Poland): pollution and ecological risk indices

Purpose

This study assesses how urban soil transformation affects pollution levels and ecological risks in Cracow, Lublin, and Torun using specific geochemical indices.

Methods

The surveyed cities, namely Cracow, Lublin and Torun, are among the oldest in Poland, with origins dating back to the Middle Ages. Moreover, they did not experience significant destruction during World War II. A total of 135 sampling points were selected from three cities, and topsoil samples (0–20 cm) were collected from various areas, including industrial, residential, recreational areas, wastelands, traffic routes, allotments, cultivated fields, forests and cemeteries (45 topsoil samples in each city). The concentration of 8 elements (As, Cd, Cu, Cr, Ni, Pb, Sb, Zn) was measured to determine pollution and ecological risk indicators, such as geoaccumulation index (I_geo), pollution load index (PLI), cancer risk (CR), and ecological risk assessment (ERi).

Results

Findings reveal significant differences among the cities, with Cracow showing the highest pollution and ecological risk levels, influenced primarily by industrial activities. I_geo above 3 was found for Sb (4% of the sample population), Cr (33%), Ni (31%), Cd, Pb, Cu, Zn (11%). In the other two cities, high I_geo values occurred sporadically with most values ranging from 0 to 2. The concentrations of Cd, Pb, Sb, Cr and Ni were found to be highest in industrial areas, transportation areas and urban wastelands, and the lowest in the study plots located in forests. In Cracow, almost 58% of the surveyed areas are polluted. Almost the entire area of Torun (87%) shows high values of summed ecological risk assessment (PER_k). Lublin is characterized by the lowest ecological risk, almost 32% of the surveyed areas are polluted (PER_k—high and very high).

Conclusions

The application of pollution and ecological risk indicators allowed for the identification of elevated heavy metal and metalloid concentrations in the studied soils and evaluation of disease risk in people. The data were strongly correlated with the level of anthropogenic pressure, which varied depending on the different land use.