Anna Vadimovna Arzamazova

The process of natural remediation of oil-polluted and salt-polluted raised bogs of KhMAO - Yugra reclaimed 14-16 years ago is analyzed. In general, the revegetation is proceeding successfully, although mesophytic grasses sown during reclamation have almost completely fallen out of the grass stand. In salt-contaminated areas, there is a gradual desalination of peat soil, accompanied by a succession of halophytic (hemigalophytic) plant communities dominated by Calamagrostis epigeios, Eriophorum angustifolium and Phragmites australis with the participation of sphagnum and brown mosses, as well as liverworts. A characteristic feature of these habitats is the settlement of a number of rare protected species ( Heterogemma laxa, Thelypteris palustris, Triglochin maritimum ). In oil-polluted bogs, during the re-vegetation, hydrocarbons often flow from the underlying peat soil horizons to form the surface crust. At the same time, grass stands from Eriophorum angustifolium and some other species with powerful root systems are replacing grass-sedge-cotton grass communities. Sphagnum riparium and Warnstorfia fluitans play also a certain role in the overgrowth of crusted surfaces. Unsuccessful recovery is typical for hollows with difficult runoff in the case of salt-contaminated bogs and the most dry locations in the case of oil - contaminated ones.

Mineralization rates of soil organic matter (SOM) decomposition of non-remediated and remediated oil)polluted, as well as background soils from the main types of West Siberian middle taiga’s ecosystems were measured in laboratory experiments. Rates of SOM mineralization were measured by alkali absorption of CO₂ released from wet soil samples at 20°C (basal respiration). Because of linear character of cumulative curves of CO₂ release SOM mi neralization rates were expressed by mineralization index K1 equal to the annual amount of CO₂ released per 1 gramm of soil. K1 values varied in a range 0,123—1,578 mg СО₂/g/day. Highest value was found in background forest soil, lowest — in oil-polluted peat soil with extremely high oil content (544 g/kg). K1 values negatively correlated (K = –0,57) with oil content. SOM mineralization rates in remediated oil)polluted peat soils varied in a range — 0,31—0,85 mg СО₂/g/day

The article provides data on a comparative analysis of the features of vegetation restoration in areas of oligotrophic bogs with a high degree of oil product pollution, located on the territory of an oil field in the Middle Ob region, reclaimed according to standard schemes, widely used in the 2000s, and by cutting off oil-contaminated soil. The total projective vegetation cover (TPVC) of all reclaimed areas mostly reaches standard values (above 30%). The TPVC in areas without cutting is slightly higher than in areas with cutting due to the difference in recovery time in favor of the former. At the same time, the average number of all recorded species in areas with cutting is slightly higher, and they include some oligotrophic vascular plants (heather shrubs, Drosera rotundifolia, Eriophorum vaginatum), which spread much less frequently in areas without cutting. The projective cover of the herb-shrub layer is higher in areas without cutting. The content of oil products in the surface layer of 0‒20 cm in areas with cutting is generally lower compared to areas reclaimed by traditional methods. However, even high concentrations (more than 250 g×kg^-1) do not have a significant negative effect on the total projective cover of the grass/herb-shrub layer, while its minimum values are primarily associated with a lack of moisture on high microrelief elements. Similarly, high concentrations of hydrocarbons do not serve as an obstacle to the development of moss cover dominated by sphagnum mosses in areas of cut-off hollows. At the same time, polytrichous and brown mosses were much more sensitive to oil pollution in the form of bitumen crust, and thus avoided areas without cutting.