ИСТИНА

This work presents data on the aerobic and anaerobic microbiological processes impact on uranium migration in upper aquifers polluted with sulfate and nitrate ions near to sludge depository of Novosibirsk chemical concentrate plant. Sludge depository was built in 1960x and it is still working by this time. Uranium concentration in subsurface water in several zones reached 1-2 mg/l and its migration process depends on some geochemical aspects of water horizon: mineral sorption capacity, TOC, Eh, oxidizers concentration (O2, NO3, Fe+3 etc.) and biogeochemical processes. We studied chemical and microbiological characteristic of water samples of polluted and not polluted areas and get main data for biogeochemical modelling of Uranium migration capacity. We have found different microbial community consist of aerobic organotrophic, denitrifying, sulphatereducing and fe-reducing bacteria and there where strains capable form biofilms on sandy minerals in aquifer. Due to biogeochemical modelling in PHREEQC software Uranium immobilization is possible in local areas, with high content of organic substances and the most important microbiological process is the redox potential reduction due to aerobic respiration. After that in anaerobic conditions redox-dependent uranium reduction can be expected. Moreover, in the presence of sulfate ions, further anaerobic processes of microbial sulfate reduction and iron reduction lead to the formation of iron sulphide, which plays the significant role of an antioxidant buffer in the case of oxygen migration.