An analysis is made of experimental data from studying the ecological and sanitary-bacteriological characteristics and biological activity of soil cover in the industrial city of Bratsk. The landscape and climatic conditions of the city and adjacent territories are described. Every year Bratsk is included on the Priority List of russian cities with a very high pollution level, because it is a major producer of primary aluminum in the world. The content of water-soluble fluorine in soils at a distance of up to 1 km from the Bratsk Aluminum Smelter (BrAZ) is 15 MACs. On the other hand, the concentration of water-soluble fluorine is 0.05 MAC in the background soil (control) 25 km from the city. Enterprises of the wood chemical industry are large polluters of the urban environment and soil cover of Bratsk. A detailed study is made of the indicators of the bacterial complex of heterotrophic saprotrophs that are the main representatives of the autochthonous microflora involved in the processes of soil self-cleaning from pollutants and gastrointestinal tract pathogens. The coli titer and coli index of the soil cover of Bratsk have been determined, which indicate the degree of pollution of the urban environment by industrial and household waste which can contain Salmonella, Shigella and infectious agents. Sanitary-indicatory coliform bacteria were identified to a species. By assessing the sanitary status of the soils of Bratsk, it was possible to assign them to polluted and moderately polluted soils. The sole exception is provided by the technogenically modified soil cover of the industrial area of BrAZ, which is associated with the toxic influence of aerotechnogenic emissions, especially of water-soluble fluorine, as the priority environmental pollutant. Indicators of acid-alkaline conditions have been determined, which are shifted within the city into the region of neutral and alkaline values (рН=7.0–8.6). An assessment of the ecological-biochemical status of the soils under study suggests that the neutral and weakly alkaline reaction maintains their biological activity at a high level. In the future, this can lead the soil system to an ecological regression and loss of biogenic nitrogen, which will have a negative influence on the urban ecosystem as a whole.

Makarova Al’vina Pavlovna, Candidate of Sciences (Biology), Associate Professor, Irkutsk State University, 1, K. Marx st., Irkutsk, 664003, Russian Federation, tel.: (3952) 24–18–70, e-mail: nadin_buk@mail.ru 

Naprasnikova Elizaveta Viktorovna, Candidate of Sciences (Biology), Senior Research Scientist, V. B. Sochava Institute of Geography SB RAS, 1, Ulan-Batorskaya st., Irkutsk, 664033, Russian Federation, tel: (3952) 42–27–17, e-mail: napev@irigs.irk.ru 

Bukovskaya Nadezhda Evgenyevna, Senior Lecturer, Irkutsk State University, 1, K. Marx st., Irkutsk, 664003, Russian Federation, tel.: (3952) 24–18–55, e-mail: nadin_buk@mail.ru

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