The ability of a number of microorganisms isolated from highly magnetic soil of the city Mednogorsk to oxidize Fe (II) under conditions of periodic cultivation in a liquid medium was studied. Among the studied microorganisms, two microbial isolates with maximum growth characteristics and iron-oxidizing activity were selected and identified: Bacillus megaterium 69.3 and B. megaterium 69.5. Individual levels of metal resistance of the isolates were determined: maximum tolerated concentration (MTC) for Fe (II) of the isolates B. megaterium 69.3 and B. megaterium 69.5 was 1200 mg L⁻¹, minimum inhibitory concentration (MIC) was 1800 mg L⁻¹. Both microbial isolates actively oxidized Fe (II) by reducing its high concentration in the medium (1.19 g L⁻¹) by 33 and 39% during 14 days of culturing. Total increase in the biomass of B. megaterium 69.3 and B. megaterium 69.5 after 14 days of culturing was 15.3 and 14.7 g L⁻¹; the active parts of the biomass increased 8.7- and 6.9-fold compared to the inoculum dose, respectively. These microbial isolates could be used in future in the biotechnological process of water purification with increased/high levels of Fe (II).

Monitoring of environment in regions of the location of waste landfills includes the implementation of the control over a sanitary condition of soils. The main origins of the spread ofpollutants into soils are the solid particles from aerosol emissions from the functioning of landfills transmitted to surrounding territories. Within zones of the impact of three largest waste landfills in the Saratov region (Aleksandrovsky, Guselsky in the city of Saratov and Balakovsky in the city of Balakovo) there were taken 152 soil samples. According to results of the estimation in soil concentration of gross and motile forms of heavy metals of the first (Zn, Cd, Ni) and the second danger classes (Cu, Cr, Pb) there was performed the analysis of coefficients of danger- K0 and total coefficients ofpollution - Zc. There was executed the assessment of both a sanitary and hygienic condition of soils and degree of danger ofpollution. The most contrast areal features of the distribution of the danger coefficient - Ko in soils are characteristic for motile forms of heavy metals. For all three studied objects persistently there is stood out the dangerous and areal pollution of soils by association of Ni and Cu . The danger ofpollution of soils by gross forms of heavy metals is minimum. The coefficient of total pollution of Zc exceeds admissible level on motile forms of heavy metals only for the soils surrounding the Balakovo landfill. In zones of the impact of waste landfills there are located the processed lands with an adverse sanitary and hygienic condition of soils. In the region of the Guselsky object soils of the processed agricultural grounds are dangerously polluted by motile forms of Ni and Cu. In vicinities of the Balakovo waste landfill considerable areas of private gardening enterprises are dangerously polluted by the motile forms of Ni, Cu and Zn.

Aim. To compare the results of studying the magnetic properties and concentration of heavy metals in the soils of the Dubravniy Forest recreational zone of Kazan to justify the use of the petromagnetic method in conducting ecological and geochemical studies in urbanised areas.Material and Methods. The object of the study is the soil cover in the "Dubravniy Forest", using petromagnetic methods (magnetic susceptibility, differential thermomagnetic analysis) and atomic absorption spectrometry.Results. According to the results of the studies conducted into the lightgray forest soil, the measurements of magnetic susceptibility and concentration of mobile forms of heavy metals do not contradict each other and indicate the absence of magnetic minerals and heavy metals of technogenic origin.Conclusions. The results of magnetic susceptibility studies indicate the absence of soil contamination with heavy metal compounds, which was confirmed by the results of the determination of mobile forms of heavy metals by the atomic absorption method.

In the course of this work, the total numbers of heterotrophic microorganisms and the numbers of microbes participating in the nitrogen cycle (ammonifying, denitrifying, nitrifying, and nitrogen-fixing ones) in urban and natural (background) soils of Kogalym were estimated. A relation between the results obtained and the geochemical indicators was revealed. Our microbiological analysis showed the predominance of nitrogen-fixing microorganisms in urban soils (5.0 × 10⁴– 2.0 × 10⁶ CFU/g of soil), which were, on average, 44 less than in natural soils. In the last ones, the average number of denitrifying microorganisms was 7.0 × 10⁴ CFU/g of soil, exceeding 1.3 times their number in urban soils. Based on the information obtained, the microbial contents in the soils of Kogalym were established as a series: nitrogen fixators > ammonifiers > heterotrophs > denitrifiers; in background samples: denitrifiers > ammonifiers > heterotrophs > nitrogen fixators. According to the data of ecological and geochemical analysis, an excess of the MPC of mobile forms of heavy metals, such as Cu, Ni, and Zn, was revealed in the Eastern Industrial Zone of the city. A significant inverse correlation was revealed between the number of denitrifying microorganisms in the Kogalym soil microbiocenoses and the content of mobile Ni and Cu forms, which points to a possible negative effect of these metals on the development of denitrifiers. The minimum number of ammonifying, denitrifying, and nitrogen-fixing microorganisms was found in the Eastern Industrial Zone, especially in the soil samples that were taken near the railway. On the whole, the absence of noticeable differences in the microorganisms’ content of the studied groups in urban and natural soils indicates a low level of soil pollution in Kogalym. The results obtained represent the basis for subsequent ecological monitoring of the soils in the city and adjacent oil-producing areas, forecasting the environmental consequences of anthropogenic activities on these territories.