Alexander S. Kostin

The distribution of stable iodine and humus in the upper horizon (0–20 cm) of various types of soils of the Bryansk and Oryol regions used as pastures has been studied. Soil sampling was carried out with a hand stick drill in layers in the depth interval: 0–5 cm, 5-10 cm and 10–20 cm. Iodine content was determined by kinetic rhodanide-nitrite method. Corg content was determined by the bichromate method of Tyurin. The work includes data from both long-term studies of the iodine content in the soil cover of the Bryansk region (2008–2020) and new data from expeditionary studies in the Oryol region (2022). It is shown that the soils of the Bryansk pastures are depleted of iodine and organic carbon (OC) in comparison with the Oryol region, which corresponds to the change of soil cover composition from west to east. The humus content in soils was determined and statistically significant correlation between iodine and C org. content in pasture soils were obtained (from r = 0.28 in Chernozems to r = 0.49 in Haplic Albeluvisols; in addition, for the whole sample (n = 48) the correlation coefficient ranged from 0.31 in the 0–5 cm layer to 0.43 in the 10–20 cm layer). The dependence of iodine accumulation on the OC content in different types of soils (Chernozems, Grey-Luvic Phaeozems, Umbric Albeluvisols, Haplic Albeluvisols) and their hydromorphism has been established. The identified differences in soil iodine fixation should be considered as they may influence iodine intake levels in pasture animal milk and local rations.

Long-term coal mining (more than 50 years) in the Moscow basin has a complex negative effect on soils. Because of underground mining at coal fields spoil heaps with a high content of iron sulfides, aluminosilicates and organic carbon of coal origin were formed. Oxidation of sulfides and acid hydrolysis of aluminosilicates in waste dumps results in the producing of toxic sulfuric acid, Al and Fe sulfates (Nordstrom and Alpers 1999). Acid mine drainage (AMD) entering from eroded spoil heaps, leads to physico-chemical and morphological changes in soil characteristics. On foreslopes around spoil heaps technogenically transformed soils are common. Our study aimed at evaluation of post-mining geochemical evolution of chemical composition and properties of solid and liquid soil phases.We examined two key sites within abandoned coal mine fields in the central part of the Moscow basin. Predominant natural soils are Greyic Phaeozems and Haplic Chernozems (WRB 2014) (Grey forest and Leached Chernozems in Russian classification).Soil samples and displaced soil solutions (by ethanol) were analysed for acid-base properties, content and composition of readily soluble salts, content of Fe2+ and Fe3+, H+ and Al3+, composition of exchangeable cations, heavy metals (HM) and organic carbon) by standard methods. The composition of clay minerals in soils were determined by X-ray diffractometry. The saturation degree of soil solutions by gypsum, iron and aluminum hydroxides was estimated.Properties of technogenic soils differ significantly from natural soils. We observed the transformation of the composition of soil solutions. Key geochemical processes at mine sites in contaminated soils were: (1) acidification and Fe-Al-SO4 salinization of entire soil profile along with the increment in H+ and Al3+ ions content; (2) cation exchange, leading to displacement of Cа2+ and Mg2+ ions by Al3+, H+ and, probably, by Fe2+ and Fe3+ in soil cation-exchange complex (CEC); (3) alteration of radial differentiation of organic carbon and carbonates in soils; (4) clay mineral transformations.Topsoil features a high content of technogenic organic carbon (reaches 12%) due to the inflow of coal material particles from the dump. Ca2+ and Mg2+ ions predominate (for 70 to 90%) in CEC of natural soils. Exchangeable Al3+ accounts for more than 75% of the acidity formation in transformed soils. The share of exchangeable Ca2+ and Mg2+ in CEC of contaminated soils depletes on 22-38%.Extracted soil solutions from polluted soils are heavily oversaturated by Al hydroxides. Even though the activity of Ca2+ and SO42- ions in some samples reaches the gypsum saturation level, gypsum neoformations are not distinguished morphologically.The content of Co, Сu, Ni and Zn in displaced solutions of transformed soils in tens or even hundreds times exceeds the background values. The clay minerals of natural soils are represented by kaolinite, illite, vermiculite and mixed-layer minerals. The sharp increase in smectite fraction (up to 75-80%) and slightly in chlorite fraction was revealed in transformed soils.Post-technogenic soils have no analogues in natural forest-steppe landscapes of the Russian Plain. 

This paper examines effects caused by erosion products and seepage waters spreading from sulfuric coal dumps for more than 50 years on the chemical composi

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.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.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).Soil samples and soil solutions were analysed for (acid-base properties, content and composition of readily soluble salts, content of Fe2+ and Fe3+, H+ and Al3+, 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.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-SO4 salinization of soil profile along with the increment in H+ and Al3+ ions content; (2) cation exchange, leading to displacement of Cа2+ and Mg2+ ions by Al3+, H+, Fe2+ and, perhaps, by Fe3+ in soil ion-exchange complex; (3) alteration of radial differentiation of organic carbon and carbonates in soils; (4) mineral transformations.  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.