The effectiveness of remediation agents in detoxification of soils contaminated with heavy metals is studied in a laboratory experiment. The objects of the study are southern tundra soils functioning under conditions of anthropogenic impacts: haplic gleysols gelic and histic fluvisols oxyaquic. The chemical ability of remediation agents to bind metals (Ni and Cu), transferring them to a sedentary state compared to the reference variants (without adding a remediation agent), is evaluated. In the experiments, remediation agents are used in three doses (D1–D3): carbonaceous (shungite), of biological origin (diatomite), and mineral remediation agents (glauconite and bentonite). To assess the immobilization of Ni and Cu in soils, acid-soluble (AS) forms (extraction of 1 N HNO3), mobile forms (ammonium acetate buffer with pH 4.8), and water-soluble forms of Ni and Cu (1 : 20 aqueous extract) are determined by inductively coupled plasma mass spectrometry. The effectiveness of soil detoxification during the application of remediation agents is evaluated by the phytotoxic effect in an express test, a response of standardized test plants (Brassica rapa CrGC and Avena sativa) represented by higher plants. A decrease in the proportion of mobile forms of Ni and Cu by 50

The effectiveness of remediators in detoxification of soils contaminated with heavy metals was studied in a lab experiment. The objects of the study were the soils of the southern tundra, functioning under conditions of anthropogenic impact: Haplic Gleysols (Gelic) and Histic Fluvisols (Oxyaquic). The chemical ability of remediants to bind metals (Ni and Cu), transferring them to a sedentary state in comparison with the reference variants (without any addition of remediants), was evaluated. In experiments, remediants were used in three doses (D1, D2, D3): shungite; diatomite, glauconite and bentonite. To assess the immobilization of Ni and Cu in soils, acid-soluble (CR) forms (extraction of 1 n. HNO3), mobile forms (ammonium acetate buffer solution with pH 4.8), water-soluble forms of Ni and Cu (1:20 aqueous extract) were determined by inductively coupled plasma mass spectrometry. The effectiveness of soil detoxification during the application of remediants was evaluated by the phytotoxic effect in an express phytoassay with standardized tests (Brassica rapa CrGC and Avena sativa) represented by higher plants. A decrease in the proportion of mobile forms of Ni and Cu by 50% or more in Haplic Gleysols (Gelic) was revealed with the addition of any dose of ameliorants. The greatest effect of reducing mobility was exerted by shungite and diatomite at a dose of D1 - up to 15% Ni and Cu for Histic Fluvisols (Oxyaquic) soil. The use of the selected remediants in the indicated amounts did not reveal a phytotoxic effect on the tests in the experiment.

Sea coastal soils are functioning on the contact of terrigenous runoff and the seawater impact, which provides a unique geochemical environment. Migration and accumulation of elements can be partially promoted by the formation and oxidation of iron sulfides. We studied the content and spatial distribution of Fe, Mn and trace elements in the marsh soils of the Pomor coast of the White Sea. The work was carried out near the village of Kolezhma, Belomorsk district, Republic of Karelia. The study revealed the elevated concentrations of trace elements in these soils, such as As and Se, which are usually associated with metal sulfides in marine sediments. A high content of Fe and Mn was registered, i.e., up to 27 300 and 1500 ppm, respectively, which is typical for taiga landscapes. At the same time, the geochemical fate of Fe and Mn is different in coastal soils, probably partly due to the participation of Fe in mineral transitions from sulfides to sulfates. Such microelements as Ni and Cr are present in the soils in concentrations comparable to the background concentrations in the regional zonal soils. Only As and Se may be potentially toxic, if tombolo is used as a hayfield.

Comprehensive morphological and mineralogical studies of atmospheric microparticles sampled on the roof of the museum complex and near roads in the town of Istra, Moscow region, have been carried out. Morphological research at different hierarchical levels revealed the multicomponent composition of microparticles and made it possible to identify the most characteristic groups of microparticles of natural and anthropogenic origin. The composition of the studied atmospheric microparticles is dominated by mineral grains of quartz and feldspars; biotite and calcite are singly noted, which reflects the ecological and geographical conditions of their formation, namely the Central Russian mineralogical province. A small share of technogenic particles in the composition of aerosol fallout indicates a low level of technogenic load and a favorable environmental situation in the study area, largely due to the protective functions of the forest park zone. The results of determining the material composition and calculating the enrichment factors also indicate a low level of technogenic impact on the natural environment.

The long-term component composition of natural waters in the snow waters–soil solutions–soil–ground waters–surface waters system has been studied within the landscapes of the upper reaches of the Klyazma River . It has been determined that the regular excess of the content of the main macro- and microelements in soil solutions in comparison with snow waters is first replaced at subsequent stages by an increase in the concentration of components in soil–ground water, followed by a decrease in the content in surface waters — streams and river waters. It is shown that the relatively high mobility of sodium, magnesium, potassium, and calcium, and anions such as chloride and nitrate ions, is accompanied by a significant decrease in the mobility of elements of the family of iron, copper, and zinc at the transition from groundwater to surface water. This explains the wide distribution of segregated forms, which are presented by nodules in soils of semihydromorphic landscapes, up to ortsands, and the formation of typical bog ores in the boggy conditions of near-terrace depressions on the border with the superaquatic landscape. Thus, the composition of natural waters and its change serves not only as a good, but also a necessary tool for explaining the features of migration of elements in the soil — natural water system and explaining the mechanism of how soil formations arise.

The total content of rare earth elements (REEs) and the content of their oxalate-soluble fraction were studied in four soil profiles (Gleyic Umbrisols, Albic Gleyic Folic Retisols (Raptic), Dystric Albic Retisol) of the Central Forest Nature Reserve. The REE content was normalized to a local standard (the Russian Platform clay), and the cerium and europium anomalies were quantified [8]. In addition to the initial redistribution of REEs during the formation of rocks, REEs in the studied soils undergo geochemical fractionation, which results in the depletion of soil horizons of heavy lanthanides and europium. The negative europium anomaly is maximal in eluvial horizons and is weaker or absent in organic horizons. The oxalate-soluble REE fraction affects the redistribution of heavy lanthanides and cerium in the studied soils, and also results in the development of a positive cerium anomaly in some horizons.

Сhemical properties and content of acid-soluble and mobile compounds of heavy metals (HM) and arsenic in soils and street dust of the South-Eastern administrative district of Moscow were studied. The research time spans comprise the end of industrial (1995), transitional (2004 and 2012) and recent post-industrial period of city development (2017). During the research period, acid-base properties of soils and street dust have not changed. At the same time the content of exchangeable sodium (up to 20 times), calcium, and organic matter has significantly increased. The total content of HMs and arsenic in soils and street dust tends to decrease due to the reduction of industrial enterprises activity and periodic replacing the ground with a new one. Among the elements that have the highest concentration Clarke in soils are the following: Ag, Hg, Sb, Zn, and As, in street dust – Sb, Zn, Hg, Ag, Cu, Pb, Mo, As, Cd, Cr and Ni. A number of metals both in soils and street dust are characterized by a high degree of extraction of acid-soluble compounds, which decreases from 1995 to 2017. De-spite the decrease in number of mobile compounds of HM, the proportion of samples exceeding the maximum permissible concentrations of mobile forms of Cu, Zn and Pb in soils and street dust is still high.

The soils and street dust of the Southeastern administrative district of Moscow were analyzed for chemical properties and the content of acid-soluble and mobile compounds of heavy metals (HMs) and arsenic over three time spans: the end of industrial (1995), transitional (2004 and 2012), and recent postindustrial (2017) periods of the city development. The acid–base properties of soils and street dust have not changed during this period. However, the content of exchangeable sodium has considerably increased (to 20-fold), as well as the contents of calcium and organic matter. The total HM and arsenic contents in soils and street dust tend to decrease because of a reduction in the number of industrial facilities and periodic replacement of lawn soils. Ag, Hg, Sb, Zn, and As have the highest clarkes of concentration in soils and Sb, Zn, Hg, Ag, Cu, Pb, Mo, As, Cd, Cr, and Ni, in street dust. The degree of extraction of the acid-soluble compounds of several HMs in soils and street dust is very high but it decreases from 1995 to 2017. The amount of mobile HM compounds has decreased. However, the share of soil and street dust samples with the Cu, Zn, and Pb mobile compounds exceeding the maximum permissible concentrations is still high.

Competitive adsorption of scandium, yttrium, and lanthanides was studied for soddy-podzolic and gray forest soils and for leached chernozem. The chemical behavior of scandium significantly differs from that of other rare-earth elements (REEs) by the quick reaching of equilibrium in the soil–solution system and by the fact that its adsorption is not described by the Langmuir equation unlike yttrium and lanthanides. Individual chemical properties of REEs are the most pronounced in the experiments on competitive adsorption. In the yttrium–lutetium sequence, there is a tendency for a gradual decrease in the maximal adsorption capacity (from 0.025 to 0.010 mmol/kg in soddy-podzolic soil and from 0.100 to 0.050 mmol/kg in leached chernozem) and more pronounced increase in the Langmuir adsorption constants (from 5000 to 25 000 L/mmol in soddy-podzolic soil and from 5000 to 40 000 L/mmol in leached chernozem). This reflects the competition between different elements for soil sorption sites, which is directly related to the change in ionic radii of the elements (so-called “lanthanide contraction”). Unlike other soils, leached chernozem absorbs a large amount of REEs and provides their stronger fixation.

Isotopic composition of lead is a very sensitive indicator allowing us to determine even very low contamination of soils by this element, which is not noticeable from the change in its concentration against the background of the natural variability. Isotopic composition of loosely bound lead fractions (exchangeable and specifically sorbed) changes in soils of the Kologrivskii Forest State Natural Reserve under the impact of global or regional atmospheric transport and deposition of contaminants, though these soils are not subjected to the local technogenic pollution. The maximum portion of lead bound with the soil organic matter in the upper organic horizons reaches 75% of the total lead content. The portion of lead bound with iron and manganese (hydr)oxides increases down the soil profile. The portion of the residual fraction of lead also increases significantly down the soil profile. The most pronounced changes are observed for the 206 Pb/ 207 Pb ratio, which decreases from 1.20–1.24 to 1.15–1.18 under the impact of global pollution. The technogenic compounds of lead migrate down the soil profile. In the gray-humus gley alluvial soil (Fluvic Gleysol), low values of the 206 Pb/ 207 Pb ratio are observed for the exchangeable and specifically sorbed lead fractions in the entire soil profile, which is explained by the worse conditions for lead fixation in the profile of this soil in comparison with those in the podzolic soils.

The contents of five platinum-group metals (Ru, Rh, Pd, Ir, and Pt) in soils and street dust of the Southeastern administrative district (SEAD) of Moscow have been determined. The contents of these elements in soils may considerably exceed their natural abundances in the lithosphere and are characterized by considerable variability and asymmetric frequency distribution. A close correlation between Rh, Pd, and Pt contents in soils and street dust has been shown. The data on the contents of the elements and the ratios between them suggest that motor vehicles are the major source of pollution of soils and street dust in the studied district.

Dynamics and composition of snow cover in the system of a geochemical landscape typical of southern taiga landscapes and the urbanized landscapes were studied during winter seasons of 2011 – 2016. It is shown that the maximum heights and water equivalent of snow cover in natural landscapes are usually found on flood plains and forest openings on the first terrace whereas minimum values are typical of forest ecosystems. The cluster analysis revealed that the chemical composition of snow in the MSU Arboretum and within landscapes in the vicinity of Moscow is closer unlike that of true urban landscapes.

Contents of different lanthanide forms in soddy-calcareous soils at different distances from the Cherepovets steel mill (Vologda oblast) have been studied. Increased contents of Pr and Tb are found in soils near the pollution source. Less manifested increases in the contents of other lanthanides (from La to Gd) are also observed. Along with the increase in total content, technogenic pollution increases the content of acid-soluble lanthanides and affects their degree of extraction. The residual fraction strongly bound to aluminosilicates contains 80 to 95% of lanthanides. Soil processes result in the partial binding of lanthanides with organic matter (5–18% of their total content) and Fe and Mn (hydr)oxides (0.1–5% of the total content). The individual properties of lanthanides are clearly manifested in their interaction with these soil components. The highest share of the fraction bound to organic matter contains medium lanthanides, and the highest share of the fraction bound to Fe and Mn (hydr)oxides contains heavy lanthanides.

For the first time, nano- and submicron particles of street dust have been separated, weighted, and analyzed. A novel technique, sedimentation field-flow fractionation in a rotating coiled column, was applied to the fractionation of dust samples with water being used as a carrier fluid. The size and morphology of particles in the separated fractions were characterized by electronic microscopy before digestion and the determination of the concentration of elements by ICP-AES and ICP-MS. The elements that may be of anthropogenic origin (Zn, Cr, Ni, Cu, Cd, Sn, Pb) were found to concentrate mainly in <0.3 and 0.3–1μm fractions. It has been shown that the concentrations of Cr, Ni, Zn in the finest fraction (<0.3μm) of street dust can be one order of magnitude higher than the concentrations of elements in bulk sample and coarse fractions. For example, the concentrations of Ni in <0.3, 0.3–1, 1–10, and 10–100μm fractions were 297±46, 130±21, 36±10, and 21±4mg/kg, correspondingly. Though the finest particles present only about 0.1mass% of the sample they are of special concern due to their increased mobility and ability to penetrate into the deepest alveolar area of the lungs. For rare earth elements (La, Ce, Pr, Nd, Sm) that are evidently of natural source and may be found in soil minerals, in contrary, higher concentrations were observed in large particles (10–100μm). Sc was an exception that needs further studies. The proposed approach to the fractionation and analysis of nano-, submicron, and micron particles can be a powerful tool for risk assessment related to toxic elements in dust, ash, and other particulate environmental samples.

Literature data on the historical reconstructions of the atmospheric lead deposition in Europe and the isotopic composition of the ores that are potential sources of the anthropogenic lead in the atmospheric deposition in the lower Volga steppes during different time periods have been compiled. The effect of the increasing anthropogenic lead deposition recorded since the Bronze Age on the level of soil contamination has been investigated. For the first time paleosol buried under a burial mound of the Bronze Age has been used as a reference point to assess of the current contamination level. The contents and isotopic compositions of the mobile and total lead have been determined in submound paleosols of different ages and their recent remote and roadside analogues. An increase in the content and fraction of the mobile lead and a shift of its isotopic composition toward less radiogenic values (typical for lead from the recent anthropogenic sources) has been revealed when going from a Bronze-Age paleosol to a recent soil. In the Bronze-Age soil, the isotopic composition of the mobile lead is inherited from the parent rock to a greater extent than in the modern soils, where the lead is enriched with the less radiogenic component. The effect of the anthropogenic component is traced in the analysis of the mobile lead, but it is barely visible for the total lead. An exception is provided by the recent roadside soils characterized by increased contents and the significantly less radiogenic isotopic composition of the mobile and total lead.