SSU im. Pitirim Sorokina (participant of the REC "Russian Arctic") on biological aspects of ecological and toxicological monitoring and remediation of soils of territories affected by emergency oil spills.

The Arctic zone of the Russian Federation is known for its rich oil and gas reserves. However, the development and extraction of minerals is associated with the risk of contamination of northern ecosystems: according to experts, accidents occur at fuel and energy companies every half hour. This explains the relevance of the project "Ecological and toxicological monitoring of soils of territories affected by emergency oil spills and oilfield waters", jointly implemented by Syktyvkar State University. Pitirim Sorokin and Murmansk State Technical University.

A group of researchers of SSU named after Pitirim Sorokin, under the guidance of Associate Professor of the Department of Ecology and Geology, Candidate of Biological Sciences Sergey Plyusnin, is engaged in monitoring tundra and taiga ecosystems, selecting plants and microorganisms that can be used for their speedy restoration.

Oil-contaminated soils have pronounced morphological features: high density, oily and iridescent films on the surface and columnar structures in the lower part of the profile. They always contain such organic pollutants of petroleum origin, such as toxic polyaromatic hydrocarbons, polychlorinated biphenyls, phthalates, etc. It is necessary to take these features into account when preparing recommendations for the restoration of contaminated soils.

Despite unfavorable climatic conditions—low temperatures, a small amount of sunlight — tundra and North taiga soils are capable of self-purification, in which microorganisms play a major role.

Self-purification of soils takes place in three stages, during which there are regular changes in the structure of communities of organisms. The first stage of ecosystem restoration begins in the second or third year after pollution as a result of reducing the concentrations of pollutants under the influence of abiotic factors to levels acceptable for the life of soil microorganisms. Its indicator is the activation of ammonifying microorganisms, while the number of oligonitrophils and cellulose-decomposing microorganisms is small, the activity of soil fungi is also suppressed. The participation of these groups increases by the end of the second stage, which lasts more than 10 years in tundra conditions, which serves as an indicator of the successful restoration succession of the ecosystem. Also, at the second stage, species of fungi and bacteria sensitive to contamination begin to appear. The third stage is characterized by the assimilation of the ecosystem into the surrounding landscape, and in tundra conditions lasts for a long time and depends on a complex of ecological and climatic conditions. In parallel with these changes in the community of microorganisms, there is a complication of the structure of the plant community, beginning with the primary herbaceous grouping of pollution-tolerant grasses, and ending with the formation of a full-fledged tundra ecosystem, through the stage of meadow-like phytocenosis.

The task of scientists in the search for optimal ways to restore ecosystems is not only to identify microorganisms capable of recycling, neutralizing pollution, but also to find their optimal concentrations, speed and completeness of soil purification. Based on the data obtained, it is necessary to choose the best biologics-oil destructors in order to include them in the plans for biorecultivation of oil-contaminated soils. Successful combinations of biorecultivation techniques, physico-chemical methods of soil treatment, the use of grass mixtures to create sustainable phytomass products on disturbed lands, make it possible to return the land to economic circulation in a relatively short time.

The conducted studies of the composition and number of communities of microorganisms selected in the tundra zone of oil-contaminated soils showed the presence of four ecological groups: microorganisms using mineral forms of nitrogen, ammonifiers, saccharolytics and oligonitrophiles. Each of these trophic groups of bacteria performs its own special functional role in the destruction and mineralization of petroleum products and normalization of soil microflora. Strains of microorganisms capable of using petroleum products as a carbon source and strains resistant to toxic compounds contained in oil were isolated from microbial communities of soils in areas previously exposed to oil spills.

The most effective strains also have emulsifying activity, which increases the efficiency of biodegradation of petroleum products. Biosurfactants (surfactants of biological origin) facilitate the absorption of hydrocarbons by bacterial cells by dispersing petroleum products and increasing the bioavailability of hydrocarbons. Microorganisms that are not oil destructors often also produce effective biosurfactants, which may be antibiotics, and provide protection of cells from other microorganisms. Their presence is important for the speedy restoration of ecosystems. By reducing surface tension and increasing the solubility of hydrocarbons, biosufractants accelerate the purification of soils from petroleum products. Surfactants secreted by bacteria play the role of an "intermediary" between the cell and organic pollutants.

Thus, scientists consider it expedient for the purposes of soil bioremediation to isolate and use strains of microorganisms that have the ability to destroy hydrocarbons and synthesize biosurfactants. And the process of restoring tundra ecosystems at the sites of oil pollution needs to be studied in detail to understand the main stages and ecological mechanisms of environmental normalization in conditions of anthropogenic pollution.