Assessment of the state of urban soils based on the content of pollutants

Abstract. The purpose of the study is to assess the ecological state of soils within urbanozems in relation to the degree of contamination with heavy metals using the example of the urban aggromeration of Orenburg. Methods. Sampling was carried out at 4 sites in the sanitary protection zone of industrial enterprises in Orenburg. Determination of mobile forms of heavy metals Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn in the samples was carried out by atomic absorption spectrophotometry. In the studied areas, the pollution index or concentration coefficient was taken into account, while taking into account the reference values of heavy metals. Contamination with toxic elements of soils in the reference areas was determined using the PINemerow coefficient. The pollution index of urban areas was calculated as the arithmetic or geometric mean of PINemerow for all reference areas in the city. Statistical processing of the material was carried out using the universal program Statistica 10. The scientific novelty of the work lies in the fact that for the first time data were obtained characterizing the accumulation of heavy metals in the sanitary protection zones of industrial enterprises in the city of Orenburg, and they were ranked according to the pollution index. Results. The analysis of the data obtained made it possible to reveal an increased content of Pb, Zn in all soil layers in the reference plot No. 1. The soils of site No. 2 had an increased content of Cu, Pb, Zn in the soil horizon of 20-30 cm, Pb was also found at a depth of 0-10 cm, which is explained by the passage of a major highway near the enterprise. Soil samples at a depth of 0-10 cm of site No. 3 were contaminated by 4 parameters (Cd, Mn, Pb, Zn) and had an average degree of anthropogenic pollution, which is due to the fact that the surface soils of the sanitary protection zone of the site are located near the enterprise associated with the processing of petroleum products. On the contrary, the studied areas No. 1; 2 and 4 sanitary protection zones of enterprises can be classified as low pollution. On the territory of the sanitary protection zone of site No. 4, an increased accumulation of Mn was found in the surface layers of soils.