Genetic features of soils on sorted sand deposits of different origins in the Kola Peninsula

Differences in the chemical composition of soils developed from sorted sands of different origins are revealed. The iron-illuvial podzols on rich glaciofluvial and marine sands are characterized by well-pronounced Al-Fe-humus differentiation of the Si, Al, and Fe in the soil profile. These soils are relatively similar in their bulk elemental composition. The difference between them is seen in the degree of differentiation of the soil profiles; it is stronger in the soils developed from glaciofluvial deposits. This is particularly true with respect to the oxalate-soluble iron and aluminum hydroxides. The deposits derived from the red-colored Tersk sandstone and processed by the sea (in the coastal zone of the White Sea) have the poorest chemical composition. In the soils developed from them, the differentiation of oxalate-soluble compounds is slightly pronounced (for Fe) or completely absent (for Si and Al). These soils can be classified as podzolized ferruginous red-colored psammozems (within the order of poorly developed soils) with the following horizons: O-Ce-Cf-C. The Ce horizon has the features of podzolization, and the Cf horizon has some features attesting to the illuvial accumulation of Fe. The profile of these soils inherits a reddish tint from the parent material.     

Genetic features of soils in altitudinal natural zones of the Khibiny Mountains

The plant cover of the Khibiny Mountains is characterized by the well-pronounced altitudinal zonality: high-alpine barrens—lichen, dwarf shrub, and shrub tundra—elfin birch forest—spruce forest. Humic petrozems (Lithic Leptosols) under sparse vegetation are formed on the tops of the mountains. The soils of the tundra zone are represented by podburs on the eluvium of nepheline syenite; smaller areas are occupied by typical cryozems. Humus-illuvial podzols are developed from moraine deposits under elfin birch forests and open spruce woodland. The moraine deposits in the inner valleys of the Khibiny Mountains are enriched in the products of weathering of nepheline syenite. The humus-illuvial podzols developed from them differ from their analogues on plain territories in the higher humus content and less contrasting eluvialilluvial differentiation.     

Transformation of forest soils in Iowa (United States) under the impact of long-term agricultural development

The evolution of automorphic cultivated soils of the Fayette series (the order of Alfisols)—close analogues of gray forest soils in the European part of Russia—was studied by the method of agrosoil chronosequences in the lower reaches of the Iowa River. It was found that the old-arable soils are characterized by an increase in the thickness of humus horizons and better aggregation; they are subjected to active biogenic turbation by rodents; some alkalization of the soil reaction and an increase in the sum of exchangeable bases also take place. These features are developed against the background of active eluvial-illuvial differentiation and gleyzation of the soil profiles under conditions of a relatively wet climate typical of the ecotone between the zones of prairies and broadleaved forests in the northeast Central Plains of the United States.     

Specificity of the morphology of interglacial and interstadial paleosol complexes of the middle and late Pleistocene in the center of the East European Plain

Paleosol studies were conducted on the Moskva-Oka interfluve in the center of the East European Plain. Three paleosol complexes were distinguished in the sequence of soil-loess deposits: the Mezin complex of the Late Pleistocene age and the Kamensk and Inzhavin complexes of the Middle Pleistocene. Each of them consisted of the paleosols of two phases: the earlier interglacial phase and the later interstadial phase. In some cases, the paleosols of these two phases were separated by a thin layer of sediments with distinct features of cryoturbation. Paleosols of the interstadial phases are represented by the dark-colored humus-rich meadowchernozemic and chernozem-like prairie soils. During the interglacial periods in the Middle and Late Pleistocene, the soils with pronounced eluvial-illuvial differentiation of their profiles were developed under forest cenoses. Data on the morphology of paleosols; their physical, chemical, and physicochemical properties (particle-size distribution, pH, humus, carbonates, amorphous and crystallized iron oxides, etc.); and their micro-morphological features studied in thin sections prepared from undisturbed soil monoliths make it possible to judge the character of the pedogenesis during different epochs.     

Unterscheidung der Subtypen Humus-, Eisenhumus- und Eisenpodsol

Differentiation of the subtypes humuspodzol, humus-iron podzol and iron podzol Humic podzols are characterized by a distinct Bh-horizon and deep humus illuviation (humic bands). They may be thus recognized by morphological features. Differentiation of humic podzols on layered sands, of humus-iron podzols and of iron podzols is only possible by quantitative analytical data. For that the ratio of pyrophosphate-extractable C/Fe is proposed: humic podzols (Bh) > 10, humus-iron podzols (Bhs) 3–10, iron podzols (Bs) < 3. For differentiation of soil varieties quantities of illuviated matter in the investigated illuvial subhorizons (Bh, Bhs, Bs) may be chosen.     

Zonal features of Al-Fe-humus pedogenesis on moraine deposits in the Kola Peninsula

Zonal differences in the genetic features of Al-Fe-humus podzols developed from moraine deposits in the tundra, forest-tundra, and northern taiga zones are revealed. The coefficient of profile differentiation of podzols with respect to the bulk content of aluminum increases from the tundra (1.16) to northern taiga (1.33); the analogous coefficient calculated with respect to the bulk content of iron increases in the same direction from 1.63 to 3.73. The zonal differences related to the contents of the amorphous forms of aluminum and iron are more contrasting: the coefficients of the profile differentiation increase from 4–6 in the tundra to 20–39 in the taiga. Differences in the humus contents of podzols developed in different natural zones are mainly seen in the podzolic horizon.     

The origin of sulfate salts in soils developed on Maikop clays in the North Caucasus region (According to data of the isotope composition of sulfur)

The ratio of ³²S/³⁴S stable isotopes was determined for soils developed on the Maikop clay sediments in the North Caucasus region in order to study the salt geochemistry in the soils. The soil sulfates were proved to be polygenetic. Three groups (generations) of sulfates of different geneses were distinguished according to their isotopic composition (³⁴S). In the underlying deposits and, partially, in the salt-bearing horizons of the soils, secondary sulfates originated from the oxidation of sulfides contained in the marine clay predominate. In the soil profiles, the sulfates inherited from the parent material (marine clay) are mixed with sulfates arriving with the atmospheric precipitation. The portion of the latter reaches about 30% of the total amount of sulfates in the soils. The salt (gypsum)-bearing horizons were formed in the course of the eluvial-illuvial redistribution of salts to the depth of seasonal wetting. The mobilization of sulfate salts from the underlying deposits and their transport to the upper parts of the soil profile with ascending water flows in the course of evaporation from the soil surface did not play a significant role in the accumulation of sulfates in the studied soils.     

Prokaryotic complex of newly formed soils on nepheline-containing industrial waste

The characteristics are given of the prokaryotic complex participating in the processes of the primary soil formation on nepheline-containing waste and depending on the time of the waste disposal and degree of reclamation. The total population density of the bacteria determined with the method of fluorescent microscopy in “pure” sand ranged within 0.34—0.60 billion CFU/g soil; in the reclaimed sand under different vegatation communities, from 2.6 to 7.2 billion CFU/g soil. Gram-positive bacteria dominate in the prokaryotic complex of the nepheline sands, whereas the Grarrmegative ones dominate in the zonal soils. The bacteria predominating in the nepheline sands were classified on the basis of the comparative analysis of the nucleotide sequences in the 16S rRNA genes within the Actinobacteria class (Arthrobacter boritolerans, A. ramosus, Rhodococcusfascians, Micrococcus luteus, and Streptomyces spp.). The evolution of the microbial community in the nepheline sands in the course of their reclamation and in the course of their overgrowing by plants proceeds in way toward the microbial communities of the zonal soils on moraine deposits.     

Micromorphology of zheltozems on hard sedimentary rocks and products of their decomposition: Pedogenic and lithogenic features (with the Sochi arboretum as an example)

The analysis of the microfabric of soils developing from calcareous argillites (with sandstone interlayers) and their derivatives revealed the mechanisms of the transformation of the initial lithogenic features into pedogenic features. They include the release of primary carbonates and their segregation in secondary forms, the redistribution of iron oxides, and changes in the shape of the rock fragments and in the optical properties of the fine material in the lithomarge zone. The subsoil—the metamorphic BM horizon—is characterized by a high content of clay composed of chlorite-vermiculite and mica-smectite minerals along with kaolinite. The BM horizon is compact and has a massive microstructure with clay pseudomorphs over skeleton grains and with nonsegregational forms of iron oxide pedofeatures. The diagnostic properties of this horizon are clearly revealed in the soils on both hard rocks and loose colluvium deposits; in the latter case, they are supplemented with a stagnic marble-like pattern. The integrity of these features corresponds to the elementary pedogenic process of the metamorphism of the mineral mass in humid subtropics. In terms of micromorphology, this is a good example of pedoplasmation. The features testifying to the contribution of biota in the topsoils are few; dark compact nodules are common there. Zheltozems developed from hard rocks may be correlated with Cambisols in the WRB system; zheltozems developed from clayey colluvium display the features of clay illuviation; together with some physicochemical characteristics of these soils, they allow us to qualify such soils as Acrisols. There are also eluvial-gley variants of zheltozems with stagnic features.     

Zonal features of humus formation in Al-Fe-humus podzols of the Kola Peninsula

Natural zonality manifests itself clearly in the territory of the Kola Peninsula: subzones of southern tundra, forest-tundra (sparse birch forest), and northern taiga replace one other from the north, to the Barents Sea coast, and to the south. Sandy and sandy loamy sediments of glacial, marine, and glaciofluvial origin are parent rocks all over the territory. Al-Fe-humus podzols, the profile of which is characterized by clear differentiation of the chemical composition and organic matter content, were formed on these rocks. There is almost no difference in the particle-size and total chemical composition of the podzols, whereas the content and composition of the humus in the soils of different zones differ significantly, and this is especially obvious in the illuvial horizon. As the climatic severity increases, the humus content in the mineral profile and the organic matter enrichment with nitrogen increase.     

Soil catenas on denudation plains in the forest-tundra and northern taiga zones of the Kola Peninsula

Morphogenetic features of soils of two catenas developed on sandy to loamy sandy moraine deposits in the forest-tundra and northern taiga zones on denudation plains of the Kola Peninsula are discussed. It is shown that these catenas are similar with respect to the major directions of soil formation, regularities of soil distribution by the elements of mesotopography, and the factors of the soil cover differentiation. The differences between the catenas are of quantitative character and are related to the intensities of manifestation of the particular processes and features. Both catenas are characterized by the pronounced differentiation of soils with respect to their moistening with hydromorphic peat bog soils in the subordinate positions and Al–Fe-humus podzols in the automorphic positions.     

Distribution of rare-earth (Y,La, Ce) and other heavy metals in the profiles of the podzolic soil group

Along with Fe and Al, many heavy metals (Mn, Cr, Zn, Cu, and Ni) show a markedly pronounced eluvial-illuvial redistribution in the profiles of soils of the podzolic group. The intensity of the redistribution of the bulk forms of these metals is comparable with that of Fe and exceeds that of Al. Although the podzolic soils are depleted of rare-earth metals, the latter respond readily to soil podzolization. The inactive participation of Al is explained by an insignificant portion of the active reaction-capable fraction. Podzolization does not influence the profile distribution of Sr and Ba. The leaching degree of heavy metals such as Mn, Cr, Zn, Ni, and Zr is noticeably higher in the sandy podzols than in the loamy podzolic soils. Leaching of heavy metals from the podzolic horizons is of geochemical importance, whereas the depletion of metals participating in plant nutrition and biota development is of ecological importance. The leaching of heavy metals is related to the destruction of clay particles in the heavy-textured podzolic soils; the effect of the soil acidity on the leaching of heavy metals is less significant.     

Soils of karst sinkholes in the southeast of the Belomorsk-Kuloi Plateau

A series of soil-geochemical microcatenas on the slopes of karst sinkholes in the southeast of the Belomorsk-Kuloi Plateau have been studied. Several types of karst sinkholes have been specified according to the character of surface deposits overlying karstic rocks. The morphological characteristics of the soils of these microcatenas and their chemical and physicochemical properties have been analyzed. On the slopes of the sinkholes, various variants of iron-illuvial podzols and texturally differentiated soils with superimposed profiles of podzols in their upper coarse-textured parts are developed. It is shown that the combinations of the particular factors of soil formation in karst landscapes can both reduce and enhance the vertical differentiation of the soil profiles forming in the sinkholes of different types, which is manifested in the properties of these soils and in the specific of their catenary variations by the elements of the karst topography.     

Hydromorphism and Al-Fe-humus pedogenesis on sandy parent materials in the Kola Peninsula

Al-Fe-humus podzols developed from sandy materials of continental and marine origins can be arranged into the following sequence with respect to the degree of soil hydromorphism: iron-illuvial podzols—humus-illuvial podzols—dark (high-humus) humus-illuvial podzols—peat podzols. These soils do not differ much in their particle-size distribution and bulk elemental composition. The most informative indices reflecting the effect of soil hydromorphism are the contents of oxalate-extractable iron and aluminum compounds and the contents and composition of the soil organic matter.     

Soils developed from alluvial and proluvial deposits in the Gr?ndalselva River valley in West Spitsbergen

The genetic characterization of soils developed from alluvial and proluvial deposits in the Gr?ndalselva River valley (West Spitsbergen) is presented. These soils are compared with analogous soils formed on marine terraces along the coasts of Isfjord and Gr?nfjord. Gray-humus (soddy) soils with an O-AY-C profile have been described on parent materials of different origins, including alluvial and proluvial sediments. The texture of the soils in the Gr?ndalselva River valley varies from medium to heavy loam and differs from the texture of the soils on other geomorphic positions in the higher content of fine particles. The soils developed from the alluvial deposits are characterized by their richer mineralogical and chemical composition in comparison with the soils developed from proluvial deposits, marine deposits, and bedrocks. All the deposits are impoverished in CaO. No differentiation of the chemical composition of the soils along the soil profiles has been found in the soils of the coastal areas and the river valley. Some accumulation of oxalate-soluble Al and Fe compounds takes place in the uppermost mineral horizon. The soils of all the geomorphic positions have a high humus content and a high exchange capacity.     

Altitudinal distribution of soil fauna in the Khibiny Massif

Data on the taxonomic and trophic composition, population density, and biomass of invertebrates in the soils of the main mountain vegetation zones of the Khibiny Mountains—taiga, subalpine, and alpine—are obtained. The degree of similarity between soil faunal complexes in different vegetation zones within the studied slope is higher than that between zonal biocenoses of Murmansk oblast. The mountain tundra zone differs from the zonal tundra in a higher population density and taxonomic diversity of invertebrates, which are similar to those in the northern taiga podzols. At the same time, invertebrate complexes in the mountain taiga zone are poorer than those in the zonal plain taiga soils. The analysis of invertebrate taxa present in all the studied mountain vegetation zones demonstrates similar effects of the altitudinal and latitudinal zonality on the species composition of invertebrates. A conclusion is made about a higher functional activity of saprotrophs in the high-humus soils enriched in biogenic elements of the Khibiny Mountains in comparison with the functional activity of saprotrophs in the zonal plain podzols.     

Ecological-geochemical assessment of hydrocarbons in soils of Northeastern European Russia

The background contents of hydrocarbons (HCs) in soils of the far-northern and northern taiga of the Komi Republic were assessed. It was found that the soils of accumulative landscapes are enriched with HCs in comparison with the soils of eluvial landscapes. The differentiation of the HCs among the soil genetic horizons is more pronounced in the soils developed on loamy parent rocks (gley-podzolic and bog-podzolic soils) and less pronounced in the soils developed on sands (podzols and humus-illuvial bog-podzolic soils). The organic, litter, and illuvial horizons serve as a geochemical barrier in the pathway of the HC migration within the soil profile. A database for the mass fractions of HCs in the soils was created using GIS technologies, and a sketch map of the HC distribution in the soils was developed on its basis. The results obtained for the back-ground content of HCs are used for assessing the contamination of soils with oil and oil products and for gaining ecological expertise in the development of regional deposits of natural resources (raw hydrocarbons).     

Differentiation of layered silicates and biogenic silica in meadow podbel soils of the Central Amur Lowland

Mineralogy of the fine component of meadow podbel soil in the Central Amur Lowland significantly varies depending on texture differentiation within the profile and clay categories with different binding strengths (water-peptized and aggregated clay). In the eluvial part of the profile, hydromicas are predominant, which are accompanied by kaolinite and mica-smectites with a low content of smectite layers; there are many finely dispersed quartz and feldspars; plagioclases are less abundant. The illuvial part of the profile is characterized by a high content of smectite minerals (mica-smectite and kaolinite-smectite interstratifications). Kaolinite, chlorite, and chlorite-vermiculite are also found. Fragmentary components pass into a peptized state: micas-hydromicas, kaolinite, finely dispersed quartz, feldspars, plagioclases, amphiboles, and diatom skeletons (mainly in the illuvial part of the profile). Aggregated clays are characterized by a high content of interstratifications with smectite layers. The mineral composition of two clay categories is strongly differentiated according to eluvial-illuvial type. The bulk chemical composition confirms the textural differentiation of the finely dispersed component within the profile. The chemistry of silty sand cutans on the faces of structural units in the illuvial part of the profile significantly differs from the chemistry of the enclosing horizon and is analogous to that of the eluvial part of the profile. The involvement of silica in the meadow podbel fractions with different binding strengths has been revealed.     

Mineralogical Composition of Particle-Size Fractions of Solonetzes from the North Crimean Lowland

Data on the mineralogical composition of clay (<1 μm), fine silt (1–5 μm), medium silt (5–10 μm), and coarser (>10 μm) fractions of meadow solonchakous solonetzes (Calcic Gypsic Salic Stagnic Solonetz (Albic, Siltic, Columnic, Cutanic, Differentic)) developing from loesslike loam and clay in the North Crimean Lowland are presented. Fractions >5 μm constitute nearly 50% of the soil mass and are characterized by the same mineralogical composition in the entire profile; they consist of quartz, plagioclases, potassium feldspars, and micas (biotite and muscovite). The eluvial-illuvial redistribution of clay in the course of solonetzic process is accompanied by changes in the portion of mixed-layer minerals and hydromicas in the upper part of the profile; a larger part of the smectitic phase is transformed into the superdisperse state. In the eluvial SEL horizon and in the illuvial BSN horizon, the clay fraction is impoverished in smectitic phase and enriched in trioctahedral hydromicas. Upon calculation of the content of clay minerals per bulk soil mass, the distribution of mixed-layer minerals is either eluvial, or eluvial-illuvial, whereas the distribution of hydromicas has an illuvial pattern without distinct eluvial minimum in the SEL horizons. The eluvial-illuvial distribution pattern of clay minerals in solonetzes of the North Crimean Lowland is compared with the distribution pattern of clay minerals in solonetzes of the West Siberian Lowland. Coefficients characterizing differentiation of solonetzes by the contents of particular mineral components are suggested.     

Soils of pine-birch forests on high Pleistocene terraces in the Selenga delta region

The soils of pine-birch forests on Pleistocene lake-river terraces in the Selenga delta region were studied. These soils are characterized by their weak differentiation into genetic horizons, pale or light brown color, and the weak structure of their mineral horizons. The high base saturation, weakly acid or close to neutral reaction, and homogeneous bulk chemical composition evidence the absence of the eluvial-illuvial differentiation of the soil profiles. The humus is of the fulvate-humate type. Among the humic acids, the brown acids predominate; the content of black humic acids is slightly lower and that of the nonhydrolyzable residue is elevated. In the mineral horizons, the clay and iron-clay autochthonous formations on the primary mineral grains point to the weakly pronounced process of metamorphism. In the Bm horizon, the formation of crystallized iron compounds in the form of films and fine iron segregations is observed.