Vol 72, No 4 (2017)

Gleying and enhancement of hydromorphism in wetland soils due to Fe(III) reduction entail a series of degradation processes. The resistance of wetlands to degradation can be calculated from the content of potentially reducible iron, Fe(III)_pr, which is found from the van Bodegom equation taking into account the contents of oxalate-soluble iron Fe_ox and dithionite-soluble iron Fe_dit in the soil. In addition, this makes it possible to distinguish relict and actual gleysols. The van Bodegom equation is applicable to soils from which the oxalate solution extracts only amorphous and poorly crystallized iron compounds, which are quickly reduced by Fe-reducing bacteria. These soils have a low proportion of Fe(II) (no more that 15% of the total iron), as well as an accumulative profile distribution of Fe_ox. The van Bodegom equation is unsuitable for calculating the Fe(III)_pr content in soils with a high proportion of Fe(II) and a nonaccumulative profile distribution of Fe_ox.

The predicted dynamics of soil cover degradation are verified by a matrix model, system processing of multitemporal large scaled soil maps, and satellite images. The validity of the criterion for the dynamics of typical solonchak areas to assess the soil degradation intensity is shown.

Waste pits represent a significant ecological problem for oil–gas fields of the Khanty-Mansi Autonomous Okrug (Yugra) in Western Siberia. Drilling sludge contained in them results in chemical contamination of moors. Seven areas adjacent to waste pits were investigated. We determined the content of macro-, micro- and rare-earth elements in peat of undisturbed high moors in the middle taiga of the Middle Ob region and compared these data with their background contents and clarke values. The contents of macroand microelements in peat of the background areas of oilfields are higher for the Surgutskoe Poles’e deposit than for the Samotlor field. Waste pits increase in content of all investigated macro- and microelements in peat. The most intensively accumulated macroelements in the impact zones are typically chlorine, potassium, magnesium, and iron; the most intensively accumulated microelements are boron, strontium, nickel, and rubidium. Microelements accumulate in the top peat layer, while the accumulation of macroelements is more specific. Waste pits result in a one- to threefold increase in the pH of the peat water suspension, a threefold increase in the ash content in peat, and in sevenfold increase in the electric conductivity of peat water suspension. The impact of waste pits is stronger in the Samotlor oil-and-gas field than in the Surgutskoe Poles’e deposit, which can be explained by different histories of their development. Waste pits considerably alter the geochemical parameters of high moors, creating conditions for meso- and eutrophic vegetation.

Ants are the most widespread social insects. Many species of ants influence a range of soil properties when building their nests in soil. The paper discusses the effects of ants on soil biological activity (nitrogen fixation, denitrification), as well as on biomass and the diversity of microorganisms. In many cases, these processes were more active in anthills. Changes in soil pH caused by nest-building activity of ants were also. There were no patterns in the distribution of pH values. Specific differences between microbial complexes of anthills and corresponding reference soils were revealed.