Vol 51, No 11 (2018)

A specific swelling clayey strongly alkaline soil with gilgai microtopography is characterized. The profile of this soil displays diagnostic features of both Solonetzes and Vertisols. In the Russian soil classification system, it is classified as a crusty quasigley slitic (vertic) sulfate–sodic clayey dark solonetz. In the WRB-2015 system, it can be defined as a Nudinatric Vertic Stagnic Protosalic Solonetz (Clayic, Columnic, Cutanic, Humic, Hypernatric). The area with this soil is found on the northern spurs of the Kalach Upland in the Kamennaya Steppe (Talovskii district of Voronezh oblast). Data on the particle-size distribution, soil density, composition of extracts from water-saturated pastes, and the content of exchangeable cations in the soil profile are analyzed. The 2D distribution of the morphological features indicated by symbols of the soil diagnostic horizons and features is presented. Data on the contents of organic carbon and calcium carbonates; the activities of sodium, calcium, and chloride ions and their ratios; the contents of oxalate- and dithionite-soluble iron compounds and their ratios, and the swelling capacity of ground samples are also presented. Three levels of morphologically manifested deformation structures are identified in the soil profile. Their impact on the spatial distribution of the physical and chemical properties is discussed.

The notions of saline and solonetzic soils are compared in two Russian (1977 and 2004), American (Soil Taxonomy 1999), and the International (WRB 2014/2015) classification systems. The diagnostics and lists of soils referred to as solonchaks, solonetzes, and other soils containing soluble salts and exchangeable Na are presented. Some features of similarity and differences were revealed in the approaches to identifying salt-affected soils and their taxonomic position. In the Russian systems, data on soil water extracts (1 : 5) are used for the assessment of soil salinization; in addition, the contents of toxic salts are calculated. In western classifications, soil salinity is assessed on the basis of the analysis of extracts from water-saturated pastes. Solonetzes are estimated according to their morphological features and data on the content of exchangeable Na. In three classifications (except for Soil Taxonomy), solonchaks and solonetzes are distinguished at the high taxonomic level. In addition, in all classification systems, soils (both saline and containing exchangeable Na), whose saline and solonetzic horizons do not completely fit their definitions, are considered at a lower taxonomic level. While improving the classification of soils of Russia, some changes and corrections to the definitions of saline soils are recommended.

Geochemical features of copper and zinc in soils of background landscapes of northeastern European Russia have been revealed. Soils of accumulative landscapes are enriched with copper and zinc compounds compared to those of eluvial landscapes. Humus horizons serve as a geochemical barrier for elements. Analysis of the sorption parameters of humic acids (HAs) shows that the actual content of the studied heavy metals (HMs) in soils is far from the maximum sorption capacity. The contribution of HAs to the total sorption of metals makes up 4% for copper and 21% for zinc. The distribution of HMs among the genetic horizons is more contrast in loamy automorphic soils than in sandy semihydromorphic and hydromorphic soils. Paired correlations have been revealed between the contents of copper and zinc in sandy and loamy soils, which points to the similarity of their biogeochemical migration in landscapes. An actual database has been created, which is foundational to schematic maps of the spatial distribution of elements in background soils. The geochemical assessment of the environmental status of soils has allowed establishing norms for the regional background contents of copper and zinc in taiga and tundra soils.

A review of approaches to particle-size and microaggregate-size distribution analyses applied in soil science is given. The concepts of the structural organization of soils, primary soil particles, elementary soil particles, and soil microaggregates are considered. Methodological problems, such as the preparation of soil samples for the analyses and interpretation and comparison of the results obtained by different methods, are discussed. The authors suggest the theoretical substantiation of differences between the notions of primary soil particles (soil building units) and elementary soil particles. Primary soil particles are individual mineral particles. Elementary soil particles are solid-phase products of pedogenesis represented by fragments of rocks and minerals and by organomineral and organic particles, all the components of which participate in chemical and physicochemical interactions. Special attention is paid to the existing classifications of soils according to their textures. It is suggested that the upper boundary of the clay fraction in the Russian classification should be shifted from 1 to 2 µm.

Mineralogical, micromorphological, and physicochemical characteristics of soils developed on the outcrops of intermediate and mafic rocks in the central part of the Timan Range under northern taiga vegetation are discussed. These soils have been classified within the order or iron-metamorphic soils of the new Russian soil classification system and as Hyperskeletic Leptosols (Humic) in the WRB system. The in situ accumulation of nonsilicate iron compounds (ferrugination) controlled by the specific features of iron-rich parent rocks is the major process in these soils. In dependence on the composition of parent material, the direction of its modern weathering, the character of plant litter, the degree of its biological transformation, and the presence of features attesting to the mobility of silicate plasmic material, these soils are subdivided into two types: rzhavozems on colluvium of mafic rocks with some admixture of siliceous morainic fine earth and organic rzhavozems on the eluvium of mafic rocks with a predominance of specific polycrystalline aggregates of iddingsite and bowlingite (saponite) representing supergene postmagmatic pseudomorphs after pyroxenes and olivine with the initially different iron contents.

A study was done of soils in the Moscow, Omsk, and Samara oblasts subjected to hydrocarbon pollutant fluxes from industrial enterprises of the same production profile (carbon black plants) differing in (a) the type and environmental safety of production technologies, (b) the time of operation, and (c) the spatial location with respect to other possible sources of technogenic hydrocarbons. Polyarene and bitumoid geochemical fields in the impact zones of the enterprises were identified and investigated, and power functions reflecting the decrease in pollutant concentrations with increasing distance from the enterprises were determined. From the obtained functions, which are mathematical expressions for the generalizing vectors of hydrocarbon fields, their degrees of gradients were estimated. Polyarene associations and their localizations were determined using cluster analysis, and relationships of associations with the distance from the pollutant sources, the technological specialization of the enterprises, and the local factors of pollutant redistribution and transformation were revealed.