Ecological evaluation of the urban soil in Perm

Abstract

Introduction. Representations of the impact of anthropogenesis processes on the soil’s ecological state are the basis for improvement of the environmental pollution monitoring system to make correct architectural and planning decisions. Material and methods. During 2016-2018 an environmental assessment of pollution of 214 samples of urban soils was performed. The soil analysis was carried out according to a random sample as one test site per 1 km². The concentration of heavy metals was determined by atomic absorption spectrometry. The analysis of organic compounds was carried out by gas chromatography-mass spectrometry. The total number of heterotrophic and gram-negative bacteria of the Enterobacteriaceae family was determined by direct seeding on selective media. Statistical data processing was carried out using software Statistica. Results. The level of chemical contamination with water-soluble forms of heavy metals of Perm soils was assessed. The concentration of heavy metals Cu, Pb, Zn, Fe, Cd, Ni, Mn in the control samples of sandy/loamy soils was 0.09/0.15; 0.08/0.22; 0.22/0.39; 5.57/16.14; 0.02/0.01; 0.06/0.13; 0.74/3.14 mg/l, respectively. The values of the total pollution index (Zc) above 16 were recorded at 4.7% of the soil samples, which corresponds to a moderate degree of pollution. It was shown that the soil type influenced Zc (KW-H (3; 214) = 30.73; p = 0.00001) and amounted to 6.24 ± 3.72 for loamy soils; for peat - 22.42 ± 12.32; for sand - 9.23 ± 5.70; for old urban soils - 8.37 ± 4.07. The median of the heterotroph bacteria content in the soils for I (Zc: 0-4) and IV (Zc ≤ 16) groups was revealed to correspond to the categories of «poor,» II (Zc: 4-8) and III (Zc: 8-16) groups - «inferior» soil. A correlation between the content of heterotrophs and the number of bacteria E. coli was not detected. According to Zc, for each soil group, no statistical differences in phthalate content were noted. Conclusion. Environmental assessment of soils should be comprehensive, as the types of anthropogenic chemical pollution, that have varying degrees of correlations between each other, affect quantitative changes in soil microbiota, which in the future may determine the ability to maintain homeostasis in this ecosystem.