One of the features of the transition from traditional soil cartography to digital technologies for compiling and using soil maps is a qualitative change in both the concept of “map” and the concept of “map scale”. A map in digital cartography is a spatially coordinated database that can consist of many layers of information and can be visualized at any scale. The scale of traditionally compiled paper soil maps is of great importance for understanding the semantic load of the map and the degree of its generalization. When using digital soil mapping, the concept of “scale” loses its meaning. This happens because the level of generalization of soil information in this case is not determined by the scale at which the map is visualized on the computer monitor or printed, but by what pixel size the map was created (in the case of raster maps) or which map served the basis for creating a vector layer of the soil map. For raster soil maps it is more logical to use the concept of “pixel size” instead of “scale”. For vector soil maps it is more important to indicate the scale of the original soil map (which was vectorized), rather than the scale of their visualization. The scale of visualization of the digital soil map is not important in the computer (digital) applied analysis of soil data. When creating raster soil maps, it is impossible to use source materials of different scales without bringing them to a unified level of generalization. All this must be taken into account when using digital soil mapping technology.

In summer periods of 2015–2017 within the framework of complex expeditions in the eastern Priol’khonye soil geochemical researches were performed. More than 120 soil samples were collected for subsequent physical and chemical analyses. Ecological, chemical and physical properties of meadow and steppe soils of Ol’khon district were studied and the results are presented in the article. The research was conducted on the east coast of the Lake Baikal in its central basin, which is most visited by tourists. Several soil types can be found along the coast line and on gently sloped surface nearby, they are: castanozems, umbrisols, cambisols, gray soils, histic fluvisols gleyic, humic fluvisols gleyic, chernozems, umbric fluvisols, cambic fluvisols and other. Owing to a specific environmental conditions some original soil types (for example “chestnut soils”, “castanozems”) can be found nowhere else in the Irkutsk region but only here. The explored soil profiles are mainly thick and stony to various extent (from high to medium),these soils are sandy or sandy loams, rich in humus, predominantly with neutral and weakly alkaline reaction (pH), low content of nitrogen in relation to carbon content (C : N), that creates favorable conditions for preservation of the vegetable remains in meadow landscapes. The conducted research results revealed that soils near touristic tracks and also on the territory of the ancient settlement are polluted by heavy metals, and their content exceeds sanitary and hygienic standards. The ecological condition of soils at the present stage can be characterized as average degree of disturbance resulting from recreational activity. Geochemical barriers are represented by organic and alkaline ones. However, due to the sandy and sandy-loamy soil texture waters of the lake coastal zone can be polluted by heavy metals as well. Soils of meadow-boggy landscapes of the coastal area are not polluted by heavy metals as far as it is a hard-to-reach region for tourists using automobile transport.

The soil cover and soil salinity of the field were studied and the results are given in the article, the explored fileld is located within the Chervlenoye irrigated area belonging to Svetloyarskaya irrigation system (south of the Volgograd region). It was characterized by alternating dark and light wide strips visible on the satellite image. The field was irrigated until the mid-1990s and was subject to secondary salinization, since that time it has been used in dry-farming system. The soil combination is performed by steppe light chestnut solonetzic complex that was transformed due to the surface leveling and irrigation into agrozem accumulative-carbonate segregation saline (Sodic Endoprotosalic Cambisol (Loamic, Aric, Protocalcic, Ochric, Bathygypsic) and Cambic Calcisols (Loamic, Aric)) and deep saline, and agro-light-humus accumulative-carbonate stratified soil. The bright bands on the field mark soils rich in carbonates on the surface (12–13 % CaCO₃) (Calcaric Cambisol (Loamic, Aric)) among the other soils that contain less carbonates on the surface by 5–10 times. All the soils are saline, but the salt content varies in space in a wave-like manner, wich disagrees with the satellite image. Two-dimensional distributions of carbonates and salts in the soil combination are discussed. The residual signs of secondary salinization are revealed in the form of calcium and magnesium chlorides two decades after the cessation of irrigation and drawdown of the groundwater curve deeper than 7 m.

The method of soil samples preparation for measuring the (wetting) contact angle (CA) of the soil solid phase surface using membrane filters is proposed. The samples of kaolinite, a standard sample of chernozem and samples of agro-chestnut soil were taken for the experiment. The results of the CA measurements using two types of sample preparation for the analysis were compared. The first method of sample preparation was to apply a sample to a double-sided adhesive tape; the second method involved the deposition of suspensions of the studied samples of certain concentrations on membrane filters. The advantages and disadvantages of each sample preparation method are described. The significant difference in the obtained CA values depending on the sample preparation for measurement was revealed. The method of sample preparation with the use of membrane filters developed by the authors made it possible to reduce the CA measurement error by more than 2 times. Reducing the variation of the CA value of a single sample will allow comparing similar soil samples, including soils of the same type, but involved in different land use systems.

The article provides research results and comparative analysis of humic acids in sod-podzolic soil of the Experimental Forest of the Russian State Agrarian University (protected area) and urban soils located in the Timiryazev district of Moscow. Humic acids of the zonal sod-podzolic soil of the Experimental Forest include four fractions with varying molecular weight: the 1^st fraction – ≥ 23 440 unified atomic mass units (amu), the 2^nd one – 13 340 amu, the 3^rd one – 5 500 amu and the 4^th one – 2 460 amu. The fraction with a molecular weight of 5 500 amu and a relative content of 38 % dominates among them, while the share of low-molecular fractions (< 20 000 amu) accounts for 70 % of the total mass of humic acids. When weight-average molecular mass of humic acids is 17 530 amu, the average molecular mass of the low-molecular fractions is 9 960 amu. Humic acids of urbanozems differ in molecular weight composition from humic acids of sod-podzolic soil. In most cases it consists of 5–6, less commonly of 3, fractions with molecular weight from 1 780 to ≥ 23 440 amu. The share of medium- and high-molecular fractions fluctuates from 31–37 % to 47–50 % of the total mass of humic acids. The characteristic feature of humic acids of urbanozems is the presence in their composition of low-molecular fractions with such molecular weights, which are not found in humic acids of sod-podzolic soil. Thus, humic acids of urbanozems are characterized by higher weight-average molecular mass ranging from 17 680 to 19 980 amu, as well as by higher weigh-average molecular mass of the low-molecular fractions which vary from 10 680 to 13 650 amu.

This research aim was testing the applicability of exogenic organic matter – extracted humic substances – for the remediation of technogenic barrens soils near Cu-Ni smelter (Kola Peninsula). In short-term laboratory experiments we studied the possibility of stabilization of heavy metals labile forms by commercial humic substances (HS) of different origin (peat humate “Flexom” and coal humate “Extra”) in comparison with HS, inoculated by microorganisms – nitrogen fixers and mycorrhizae-forming fungi and mineral fertilizers (NPK и CaCO3). Experiments were provided during 45 days after 14 days of pre-incubation under controlled conditions in climate chamber with light, temperature and humidity imitating the polar day conditions in Kola Subarctic. After experiments we evaluated changes in soil chemical properties, soil microbial community and test-culture (Deschampsia cespitosa). Peat humate application is ineffective without additional manipulations (e.g. combination with CaCO3), cooperation with biological applicants cannot be pointed out. Application of coal humate favours to metals stabilization, soil microorganism’s activation, test-culture growth. It may be effective to combine coal humate with biological applicants like mycorrhizae-forming fungi. So, coal-humates may be perspective growth-stimulator, ameliorant and detoxicant in remediation of degraded soils in conditions of polymetallic contamination.

The data on distribution of heavy metals in the soil profile (Yuan et al., 2017) of the province Guangxi in southern China in the zone influenced by lead and antimony plant were analyzed. The soil is sod-calcareous and rich in humus. The averaged over the years and depth (“apparent”) parameters of diffusion and convective-diffusion models of migration in the area of combined soil pollution (only soil aerogenic pollution and in combination with the sewage waters) are estimated. The largest values of the diffusion parameters were obtained for Zn and Cd (n∙10–7 сm²/sec), the smallest values were obtained for Pb and Sb (n∙10–8 сm²/sec). When soil was flooded by waste waters, a reliable convective component of migration for Zn and Sb was noted. At the same time the peak of Zn concentration moved to the depth of 40–60 cm. Under these conditions there was no clear inverse correlation between the migration mobility and the amount of sorption of elements by the soil.

This paper examines the patterns of ¹³⁷Cs migration in the alluvial soil of the central floodplain of the Iput River (Novozybkovsky district, Bryansk region). The effect of water filtration during flooding, bioremoval by plants and ¹³⁷Cs radioactive decay on the migration process of Cs ions in the soil was studied. The contribution of radioactive decay, filtration of water and bioremoval to the total removal of ¹³⁷Cs from the soil during the period from 1994 to 2007 was 50–79, 20–50, 0.3–2.2 % coorespondingly, depending on the treatment method, the dose of mineral fertilizers and the ratio of nutrients. It was found that the increased removal of ¹³⁷Cs from the soil layer of the floodplain during double-depth plowing, compared with disking and natural grass stands, is determined by a lower Peclet number, which indicates the prevalence of convective ¹³⁷Cs transfer in contrast to diffusion in the total solution flow.