Microbiological activity in the soils of pingos and thermokarst depressions in the south of the Vitim Plateau (Transbaikalia, Eastern Siberia)

The intensity of microbiological processes in soils of pingos and thermokarst depressions in the south of the Vitim Plateau was studied. The number of dominant groups of microorganisms (Fungi; Bacteria, and Actinomycetes as a separate group) in Haplic Chernozems (Stagnic, Turbic) and Calcaric Gleyic Phaeozems were identified. Carbon accumulation in microbial biomass in soils of pingos and thermokarst depressions varies considerably in comparison with background soils. Bacterial microflora has been proven to prevail in soils under the study. The maximum indicators of actinomycete and fungal mycelium were found in the soils of thermokarst depressions. Microbiological activity for all studied parameters is higher in Calcaric Gleyic Phaeozems.

The change in carbonate state and other properties in chronosequences of abandoned soils in different parent rocks in the reserve «Galich'ia Gora» in the Lipetsk oblast

The article considers the change in the properties of Haplic Chernozems (Aric) on loesslike loams and Сalcaric Phaeozems (Aric) on Paleogene, Neogene red-colored sands with limestone eluvium of the Lipetsk region when they are transferred from cropland to fallow. The main attention is focused on the change in the carbonate status of soils. According to the results of the study, it was found that the transformation of both types of soils formed on different rocks obeys a single trend. Carbonates in Chernozems during their stay in fallow are washed down the profile; stable forms of carbonate pedofeatures gradually disappear. The content and stocks of carbonate carbon in the 0-200 cm layer in Haplic Chernozems (Aric) decrease by 27.5 t/ha by 25 years of fallow state. In Сalcaric Phaeozems (Aric), changes in the carbonate status are less pronounced; nevertheless, it was found that in the arable soil on the fragments of limestone, secondary carbonate films in the form of acicular calcite are formed on top of clay films, which was not observed in the abandoned soils. When the soil is in the fallow, the physical and mechanical properties of the soil improve: the structure of the arable horizons is improved, density decreases. The organic carbon content is reduced. This is an atypical result of postagrogenic transformation of Haplic Chernozems (Aric). In the fallow soils of other regions of steppe and forest-steppe, we observed the process of accumulation of organic carbon. The decrease in soil organic carbon while in the fallow is associated with the use of soil-saving technologies for agricultural use. The radiocarbon age of humus in subsurface horizons increases when soil is in the fallow. The radiocarbon age of carbonates in soils varies depending on the amount of lithogenic calcite inclusion.

Silver Ecotoxicity Estimation by the Soil State Biological Indicators

The use of silver in various spheres of life and production leads to an increase in environmental pollution, including soil. At the same time, the environmental consequences of silver pollution of soils have been studied to a much lesser extent than those of other heavy metals. The aim of this study is to estimate silver ecotoxicity using the soil state biological indicators. We studied soils that are significantly different in resistance to heavy metal pollution: ordinary chernozem (Haplic Chernozems, Loamic), sierosands (Haplic Arenosols, Eutric), and brown forest acidic soil (Haplic Cambisols, Eutric). Contamination was simulated in the laboratory. Silver was introduced into the soil in the form of nitrate in doses of 1, 10, and 100 mg/kg. Changes in biological parameters were assessed 10, 30, and 90 days after contamination. Silver pollution of soils in most cases leads to deterioration of their biological properties: the total number of bacteria, the abundance of bacteria of the genus Azotobacter, the activity of enzymes (catalase and dehydrogenases), and the phytotoxicity indicators decrease. The degree of reduction in biological properties depends on the silver concentration in the soil and the period from the contamination moment. In most cases, there is a direct relationship between the silver concentration and the degree of deterioration of the studied soil properties. The silver toxic effect was most pronounced on the 30th day after contamination. In terms of their resistance to silver pollution, the studied soils are in the following order: ordinary chernozem > sierosands ≥ brown forest soil. The light granulometric composition of sierosands and the acidic reaction of the environment of brown forest soils, as well as the low content of organic matter, contribute to high mobility and, consequently, high ecotoxicity of silver in these soils. The regional maximum permissible concentration (rMPC) of silver in ordinary chernozem (Haplic Chernozems, Loamic) is 4.4 mg/kg, in sierosands (Haplic Arenosols, Eutric) 0.9 mg/kg, and in brown forest soils (Haplic Cambisols, Eutric) 0.8 mg/kg.

Geoarchaeological study of big Essentuksky 1 kurgan in Ciscaucasia, Russia

<p>The chrono-sequence of paleosols, buried under different constructions in the big kurgan Essentuksky 1 in Ciscaucasia (Stavropol region), built by people of the Maikop culture in the second quarter of the 4<sup>th</sup> millennium BC, was studied. The height of the kurgan was 5.5-6 m and diameter – more than 60 m. It had four earthen constructions and three – made of stones. We studied the composition of the material of kurgan’s constructions, paleosols buried under four earthen kurgan's constructions and the surface soil on the area adjoining to the kurgan. The macro- and micromorphological observations and set of analytical and instrumental methods were used to study the properties of soils in the chrono-sequence and composition of material from the earthen constructions. According to archaeological data, the kurgan was built for time-span from 25, but not more than 50 years. During this interval, the morphological and physicochemical properties of soils changed, namely, there was a decrease in the thickness of the humus profile and the content of organic carbon, an increase in the content of gypsum, carbon of carbonates, a shift of the area of their accumulation up the profile, and transformation of the forms of carbonate features. The percentage of the exchangeable sodium and magnesium in the composition of exchangeable bases increased and magnetic susceptibility decreased. The most “arid” properties are found in the paleosol buried last in the studied chronological sequence: the humus horizon is the lightest, the profile is most enriched in carbonates, there is the highest content of exchangeable sodium and magnesium in the composition of exchange bases, the lowest magnetic susceptibility and the maximum amount of gypsum in the second meter of the profile. During the indicated time-span of the construction of the kurgan, Haplic Chernozems Loamic changed in Calcic Chernozems Loamic. For the studied time-span, a palynological analysis revealed a decrease in forest area and an increase in the portion of grassy vegetation. In the composition of grasses, there was an increase in the proportion of steppe and xerophytic species. The climate of the studied interval (the beginning of the development of the Maikop culture in the Ciscaucasia) is characterized as drier and hotter in comparison with nowadays. The material for the earthen layers of the kurgan's constructions was taken from the gleyic horizons of the Gleysols (the lowest layer in the first and second constructions) and from the Ah and AhB horizons of the Chernozems (the overwhelming majority of the layers). This study was supported by the Russian Science Foundation, project no. 16-17-10280.</p>

Changes in soils of Central Russian forest-steppe under the impact of sulfur coal mining (the Moscow basin)

<p>In mining areas of the Moscow brown coal basin, soils are impacted by acid mine drainage (AMD), solid sulfide-bearing mine wastes and carbonaceous particles. Spoil heaps of overburden rocks and subsidence areas over the mined space are formed at abandoned mine fields. Most of the spoil heaps have not been remediated and erode intensively due to physical and chemical properties of waste rocks. AMD of sulfuric acid, Al and Fe sulfates as well as pyritized material, entering from the eroded spoil heaps, results in morphological changes in soil properties. Other environmental concern is the formation of subsidence areas over the mined space due to the dewatering of abandoned сoal mines. It results in alteration of the soil water regime. On deluvial and proluvial dump tailings around spoil heaps technogenically transformed soils are common.</p><p>The aim of the study was to examine the post-mining evolution of natural soils under the impact of supply of tecnhogenic material from the spoil heaps and changes of the terrain in abandoned sulfur coal mining areas.</p><p>We investigated two key sites within abandoned coal mine fields in the central part of the Moscow basin (the Tula region, Russia). Prevailing natural soils are Greyic Phaeozems and Haplic Chernozems (WRB 2014) (Grey forest and Leached Chernozems in Russian classification).</p><p>Soil samples and soil solutions were analysed for (acid-base properties, content and composition of readily soluble salts, content of Fe<sup>2+</sup> and Fe<sup>3+</sup>, H<sup>+</sup> and Al<sup>3+</sup>, carbonates, composition of exchangeable cations, particle size content, total content of S, Al, Fe and organic carbon). Soil solutions were displaced by ethanol (Ishcherekov-Komarova method, Russia) (Snakin et al. 2001). The level of saturation of soil solutions by gypsum, iron and aluminum hydroxides was evaluated.</p><p>Properties of newly formed soils differ significantly from natural soils. We identified the transformation of the composition of soil solutions. Key geochemical processes at mine sites in soils were:  (1) acidification and Fe-Al-SO<sub>4</sub> salinization of soil profile along with the increment in H<sup>+</sup> and Al<sup>3+</sup> ions content; (2) cation exchange, leading to displacement of Cа<sup>2+ </sup>and Mg<sup>2+</sup> ions by Al<sup>3+</sup>, H<sup>+</sup>, Fe<sup>2+ </sup>and, perhaps, by Fe<sup>3+ </sup>in soil ion-exchange complex; (3) alteration of radial differentiation of organic carbon and carbonates in soils; (4) mineral transformations.</p><p>  Semi-hydromorphic soils with signs of gleying and peat accumulation were formed in subsidence areas. In Greyic Phaeozems the intensification of podzolization process could be noted. In Haplic Chernozems gypsum neoformations (neogypsans) were observed. Post-technogenic soils have no analogues in natural forest-steppe landscapes of the Russian Plain.</p><p> </p><p> </p>

Soil cover patterns in the forest-steppe and steppe zones of the East European Plain

The soil cover of the forest-steppe and steppe zones of the East European Plain is characterized by diverse soil combinations revealed during large-scale and detailed soil mapping against the background of a traditional zonal sequence of dominant automorphic soils alternating from the north to the south and clearly displayed on small-scale soil maps. The composition, configuration and functioning of particular soil cover patterns are determined by the soil forming factors acting within a given area. The elementary soil areas (detailed scale) and elementary soil cover patterns maps (large scale) of the Central Russian, Kalach, and Volga Uplands are created by both traditional and digital soil mapping methods. Low-contrasting soil combinations with the background Haplic Chernozems (Loamic or Clayic, Pachic) alternating with zooturbated Haplic Chernozems (Loamic or Clayic, Pachic) on convex elements of the microtopography and Luvic Chernozems (Loamic or Clayic, Pachic) on concave elements of the microtopography prevails under conditions of thick clay loamy parent materials and free drainage. Under conditions of shallow embedding by low-permeable clayey sediments, the soil cover includes Chernozems or Chernic Phaeozems with stagnic features in some part of the soil profile or even Mollic Stagnosols. The presence of shrink-swell clays of different ages leads to the formation of Bathyvertic Chernozems, Vertic Chernozems, Vertic Chernic Phaeozems and/or Pellic Vertisols. The presence of soluble salts in the parent material leads to the development of solonetzic soil complexes consisting of Protosodic or Sodic Chernozems and different types of Solonetzes.

Suitability of World Reference Base for Soil Resources (WRB) to describe and classify chernozemic soils in Central Europe

Chernozemic soils are distinguished based on the presence of thick, black or very dark, rich in humus, well-structural and base-saturated topsoil horizon, and the accumulation of secondary carbonates within soil profile. In Central Europe these soils occur in variable forms, respectively to climate gradients, position in the landscape, moisture regime, land use, and erosion/accumulation intensity. “Typical” chernozems, correlated with Calcic or Haplic Chernozems, are similarly positioned at basic classification level in the national soil classifications in Poland, Slovakia and Hungary, and in WRB. Chernozemic soils at various stages of their transformation are placed in Chernozems, Phaeozems or Kastanozems, supplied with respective qualifiers, e.g. Cambic, Luvic, Salic/Protosalic, Sodic/Protosodic etc. Some primeval Chernozems thinned by erosion may still fulfil criteria of Chernozems, but commonly are shifted to Calcisols. Soils upbuilt (aggraded) with colluvial additions may also retain their original placement in Chernozems, getting supplementary qualifier Colluvic. “Hydromorphic” chernozemic soils, in many CE systems are placed as separate soil type (“czarne ziemie” or “čiernice”) at the same level with “typical” chernozems. Classification of these soils in WRB depends on the presence of chernic horizon, depth of secondary carbonate accumulation and depth of gleyic/stagnic properties, and may vary from Gleyic/Stagnic Chernozems/Phaeozems to Mollic Gleysols/Stagnosols. Although WRB classification differs from national classifications in the concepts and priorities of classification, it provides large opportunity to reflect the spatial variability and various stages of transformation/degradation of chernozemic soils in Central Europe.