Humus Horizons Of Soils Research Articles

Analysis and forecasting of the scale and impact of forest fires on ecosystems of Ukraine

Forest fires are one of the most significant environmental problems that have a major impact on biodiversity and climate conditions. The purpose of the study was to investigate the impact of military operations on the ground cover in the area of the Bekhy forestry, which was disturbed by fire. It was revealed that for the period 2022-2023, 15 forest fires were recorded on the territory of the Korosten forest hunting enterprise of the state enterprise “Forests of Ukraine”, while the total area covered by fires was 15.13 ha. Overall, the number of fires increased from 5 to 10, but the total area covered by fires decreased from 12.1 to 3.03 ha. At the site of fires in 2022, the pH level increased to lower horizons, with the highest values at microhills (7.55) and microdepressions (7.35). There was a slight increase in the organic carbon content in the upper humus horizon of soils (0.42% on microhills and 0.46% on microdepressions). Bekhy forestry suffered a large forest fire in May 2023, which covered an area of 1.2 ha. The fire hazard assessment of each quarter was carried out separately. In the 50th and 51st compartments, Scots pine was the most fire-prone type of plantings. The 2023 fire site also showed an increase in pH in the lower horizons, with the highest values in microhills (7.35) and microdepressions (7.55). The 2023 fire site showed a decrease in organic carbon content compared to the background sites, with minimal values in the lower parts of the soil profile (0.33% on microdepressions and 0.38% on microhills). The results of the study can be used to develop and implement environmental measures and programmes aimed at restoring forests damaged by fire

Composition of soil water in mountain forest landscapes of the Upper Ussuri River and the estimation of export of chemical elements

This work provides new data on the concentrations and export of chemical elements with soil waters of various plant communities of slope and valley- fl oodplain landscapes in the basin of upper reaches of the Ussuri River. The data show that the most nutrient-rich waters are formed in humus horizons of soils developed under elm-ash communities of valley- fl oodplain landscapes. More than 80% of the content of these elements are accumulated in the soil profi le and support the functioning of communities. The waters of humus horizons of valley- fl oodplain communities are a potential source of elements entering river waters during periods of maximum precipitation. Soil waters of the mineral horizons of slope under mixed coniferousdeciduous communities are more acidic and transport relatively high amounts of dissolved organic carbon, iron, aluminum and phosphorus.

Storage of persistent organic matter in temperate gypsum soils –Relevance of the parent material and vegetation cover

By storing large amounts of terrestrial carbon (C), soils prevent it from being released into the atmosphere as carbon dioxide, the main greenhouse gas. We examined soils derived from gypsum and limestone, assuming the former had a special ability to accumulate and stabilise soil organic matter (SOM) under temperate climatic conditions when compared to limestone-derived soil. We compared the benefit of gypsum or limestone as a parent material and the effect of vegetation cover on the quantity and quality of SOM. Properties of the soil humus horizons were determined, including texture, available potassium (K) and phosphorus (P), pH, amount of gypsum and calcite, enzyme activity, and vegetation cover (biomass, K, P, sodium, calcium (Ca), and amount of lignin in the plant upper parts, coarse roots and fine roots). The structure and composition of humic acids (HAs), as indicators of SOM quality, were also studied. Stocks of organic carbon accumulated in 0–20 cm depth were much higher in gypsum soils (9.72 and 10.09 kg/m2) than in limestone soils (5.02 and 6.36 kg/m2). We found that the SOM in the gypsum soils was more mature, and contained more aromatic HAs, than in the limestone soils. Also, the gypsum soils had higher enzyme activity and a greater mass of vegetation cover, the fine roots providing higher amounts of lignin than the limestone soils. The factors that shaped the soil properties were identified and the interaction between the parent material and the vegetation cover and its effect on SOM storage was determined, indicating the importance of fine-root composition (lignin, Ca, K) and enzyme activity on C accumulation. Gypsum as a parent material favoured SOM accumulation through its physical stabilization, by providing active Ca cations to protect the SOM together with silt and clay, and its biochemical stabilization, through high enzyme activity and the quantity and quality of the biomass. Our results show that gypsum soils are important as a response to global warming through their ability to preserve SOM over the long term.

Stable Carbon Isotopic Composition (δ13C) as a Proxy of Organic Matter Dynamics in Soils on the Western Shore of Lake Baikal

Abstract Assessing the main factors that control carbon dynamics in soils is an urgent problem in the context of modern climate change. The analysis of stable carbon isotope (δ13С) composition is one of the approaches to understanding this dynamics. The study was carried out in the landscapes of the southeastern slope and foothills of the Primorskii Range, characterized by contrasting physico-geographical conditions. Climatic parameters, spatial variations in the composition of stable carbon isotopes and their distribution in soil profiles, and soil physicochemical properties controlling carbon dynamics have been analyzed. The soil humus horizons formed in mountainous tundra and steppe landscapes manifest the highest δ13С values (–24.72 and –23.97…–24.75‰); whereas the lowest (–25.61…–27.18‰) values are registered in the mountainous taiga soils. Based on the calculation of linear dependence between δ13С values and the total carbon content in soil, which varies with the depth, the carbon turnover intensity was determined using the slope of linear regression. It was revealed that under the contrasting conditions of mountainous tundra and steppe landscapes, the climate (deficiency of heat and moisture) has a significant impact on the intensity of organic matter transformation, blocking the effect of edaphic (soil profile) factors. Under more favorable climatic conditions of mountainous taiga landscapes, the dynamics of organic matter in soils is controlled mainly by edaphic factors.

FEATURES OF VERTICAL MIGRATION OF HEAVY METALS IN SOILS OF VARIOUS TYPES OF FOREST BIOGEOCENOSIS DURING AEROTECHNOGENIC CONTAMINATION WITH LEAD-CONTAINING DUST

We obtained data on radial migration of pollutant elements in soils of spruce, birch and black alder forests that had been subjected to air-dust contamination with lead-containing wastes. This waste was stored in a waste dump during 2015–2018 and then the waste was moved to a special landfill. We sampled each layer of soil and forest litter at intervals of 2 cm. The study area has strongly and moderately acidic, non-saturated, medium and low-humus, well-drained forest soils. We used the element concentration (or anomaly) coefficient and the radial contrast coefficient to assess the TM migration activity.
 The highest levels of contamination are characteristic of forest litter. The intensity of element accumulation in litter is determined by two factors: the size of the litter itself and the distance of the sample site from the emission source. Well
 developed spruce litter is a biogeochemical barrier, which significantly reduces the risk of pollution of the humus horizon of soils with cadmium and lead, as well as the flow of metals into deeper soil layers and groundwater. At the same time,
 the migration mobility of iron, nickel and, to some extent, copper remains. The poorly size litter of birch and black-alder
 forests has less pronounced protective properties.

Forms of Copper in the Aspect of Anthropogenic Changes in the Profiles of Horticultural Soils in the Cities of South-Eastern Poland

The aim of the research was to show the changes taking place in soils as a result of the influence of anthropogenic factors in the form of intensive horticulture and pollution within the city. It was made on the basis of the distribution of individual fractions as well as available and total Cu forms in the profiles of garden soils located at houses and in the family allotment gardens in six cities in south-eastern Poland. The research took into account the granulometric composition according to which the cities were divided into two groups. The pollution assessment was based on the concentration indicator, Igeo, and indicators taking into account the forms available for plants: Cav/Ct and BF. There was no copper contamination with regard to legislation act and Igeo. The role of organic matter as an important component in copper in the humus horizons of soils in long-term horticultural cultivation has been considered. The content of all forms of copper was higher in humus horizon which also indicated the anthropogenic changes. Among the two groups of soils, a greater impact of the treatments used in horticulture on those made of sands was found in relation to the silty ones.

Rare earth elements in soils of saline agrolandscapes of the Baraba plain

The total content of rare earth elements in the soil profile of saline agricultural landscapes catena of the Baraba plain within Novosibirsk region was studied. The total content of zirconium, yttrium, scandium, gallium, including lanthanides - cerium, lanthanum and ytterbium was determined. Rare earth elements are extremely poorly analyzed. At present, their influence on plants, organisms of animals and humans is being actively studied, although the maximum permissible and tentatively permissible concentrations for them have not yet been developed. The total content of rare earth elements, determined in the soils of the catena, depends on the granulometric composition and the degree of humus content of the soil horizons. It was revealed that in the studied soils they are mainly contained in the number of clarkes of the earth's crust, with the exception of lanthanum in the humus horizons, where its content is almost 1.5 times (44-48 mg/kg) higher than the clarke in the earth's crust (29 mg/kg), and ytterbium (10 times higher than the clarke). Along the soil profile, an insignificant movement of rare earth elements in both vertical and horizontal directions was noted, which indicates a low mobility of their compounds. Zirconium predominates in the profile of the studied soils from the group of rare earth elements. Its content in the humus horizons of soils of eluvial positions is within the clarke of the earth's crust; variations along the profile are insignificant. Ytterbium is contained in large quantities - from 1.89 to 4.05 mg/kg of soil, which is significantly higher than the clarke of the earth's crust (0.3 mg/kg of soil). The role of lanthanides in the soil -plant - animal - human system requires further in-depth study.

К вопросу о диагностике и защите почв от дефляции в Ставропольском крае

Abstract. The research aim is to assess the degree of deflation when comparing traditional crop cultivation technology using soil treatment and no-till. Object of research is located on the territory of the Ipatovsky district of the Stavropol territory, where the method of evaluating the deflation of ordinary chernozems (WRB 2006 Voronic Chernozems Pachic) by morphometric indicators and properties of the soil profile has been tested on the example of 2 farms using different technologies. Methods. In this research, a morphometric method for estimating deflation was used, based on measuring the capacity of the humus horizon of soils based on data from manual drilling of wells fixed by GPS in 5-fold repetition. Results and practical significance. The obtained data revealed a decrease in the capacity of the humus horizon in the treated soils (on average by 19-21 cm) compared to the soils of the farm that has been using no-till technology for the past 13 years. The forest belt serves as a buffer zone, it accumulates the dusty material of chernozems carried out during deflation with a capacity of up to 40-50 cm. Deflation of arable soils is caused by cultivation and use of pure steam in crop rotations (every third year). It leads to the transformation of the soil profile as a whole, changing the species composition of chernozems by one gradation from medium and carbonate (no-till) to low-power and high-carbon (traditional technology). The reduction or cessation of deflation of chernozems in the no-till technology is associated with its anti-deflation feature – the distribution of crop residues on the soil surface, the refusal to use pure steam, which together leads to the restoration of degraded properties of chernozems. Scientific innovation consists in testing a field morphometric method for estimating deflation in time and space, which can be used for monitoring soil cover (soil mapping, agrochemical surveys, etc.) or targeted research.

МИКРОЭЛЕМЕНТНЫЙ СОСТАВ ДЕРНОВО-КАРБОНАТНЫХ ПОЧВ СЕВЕРО-ЗАПАДНОГО КАВКАЗА

The aim of the work is to study the peculiarities of the formation of the microelement composition of sod-carbonate soils of the North-West Caucasus. Methods: Determination of the features of the formation of the microelement composition of sod-carbonate soils was carried out in the western part of the Labino-Malkinsky landscape district of forest-steppes and settled meadows. The Kuestov District occupies a band of ridges of the North-western Caucasus, composed of limestones, dolomites and sandstones of the Jurassic (K) and Cretaceous (k) periods. Chemical analysis of the soil was performed by conventional methods. The content of strongly bound compounds Pb, Cu, Zn, and Cd by acid decomposition using 5 M HNO3 was analyzed in the humus horizon of soils. The metal content was determined by the methods of inversion volt-amperometric and atomic absorption analyses. Results: In most cases, the microelement composition of sod-carbonate soils is characterized by the enrichment of Pb, Cu, Cd and depletion of Zn in comparison with the Clark soils. The constant anthropogenic input of pollutants into the soil as a depositing medium directly affects the trace element composition-the soils are intensively enriched with all the elements considered, especially strongly accumulated on CD and PB. In the radial distribution of trace elements between sod-carbonate soils and the soil-forming rock, a high intensity of accumulation of chemical elements in the humus horizon of soils was revealed. The intensity of the redistribution of trace elements in soils is largely determined by the position in the terrain. Within the Cretaceous cuesta, high Cd contents are typical for plakor soils, Cu and Zn-for the soils of the slope of the beam. On the slope of the Jurassic questi higher contents of Pb, Cd and Cu are typical for soils of placorestan cavage array Zn for soils of steep hillside with oak and beech forests. Conclusions: The microelement composition of sod-carbonate soils is a consequence of such soil-forming processes as humification, humus accumulation, leaching, glinting, and loess age, the specifics of which are largely determined by calcium carbonates. The microelement composition of sod-carbonate soils reflects the most significant features of the microelement composition of soil-forming rocks, which are characterized by low Zn content. The possible aerotechnogenic intake of trace elements affects the intensity of the radial accumulation of trace elements in the soil relative to the rocks. The degree of transformation of the microelement composition of anthropogenic disturbed soils depends on the intensity of anthropogenic impact on the soil. The conducted research is important in the aspect of revealing the regularities of the formation of the microelement composition of the soil as a depositing component of the landscape in modern conditions of anthropogenic pressure.

Dynamics of Changes in Selected Soil Traits in the Profiles of Arable Soils Anthropogenically Alkalised by the Cement and Lime Industry within the Kielecko-Łagowski Vale (Poland)

This study presents the influence of the cement and lime industry on the physical and chemical properties of arable soils. In spite of using modern forms of environmental protection against dust emissions, this type of industry causes unfavourable phenomenon of excessive alkalisation of soil. This process is relatively rare in Poland. However, in the Świętokrzyskie Province, it has been responsible for the largest transformation of soils in recent years. The analysis included soil samples taken from five profiles located in the vicinity of Dyckerhoff Polska Sp. z o.o. Nowiny Cement Plant. The study results obtained in 2019 were compared with those obtained in 1978 and 2005. The most attention was paid to soil pH; CaCO3 content; organic carbon and nitrogen content; concentrations of available components such as P2O5, K2O and Mg; and the saturation level of sorption complex with alkaline cations. It was found that long-term imission of pollutants caused significant changes in the basic soil properties, which remain in soils despite the evident decrease in the cement-lime dust emission. These include high pH values, excessive CaCO3 content, high soil saturation with alkaline cations and decreases in total carbon content, which were especially visible in soil humus horizons.

FEATURES OF Sr DISTRIBUTION IN ROCKS AND SOILS OF GEOCHEMICAL LANDSCAPES OF THE BLACK SEA COAST OF RUSSIA

The article considers the results of studying the features of Sr distribution in rocks of various ages and composition and soils of landscapes of the Black Sea coast of Russia (in the humus horizon and soil profile). The content of elements in the studied soils is compared with the regional background for the soils of the North Caucasus. A direct relationship between the content of the element in soils and underlying rocks, as well as the influence of technogenesis on the processes of accumulation and removal of the element in the soils of agricultural landscapes, has been revealed. The results of a comprehensive study of the south of Russia became the basis for studying the peculiarities of the distribution of Sr landscapes of the Black Sea coast of Russia. To establish the main parameters of the distribution of chemical elements in rocks and soils of various landscapes and the region as a whole, to identify geochemical features of geographical and technogenic differentiation, to assess the impact of various types of environmental management on changes in the geochemical spectrum of soils, to determine the influence of landscape-forming factors on the migration of chemical elements and the formation of geochemical barriers. The highest concentration of Sr was observed in carbonate-terrigenous rocks of the Paleogene and Cretaceous ages (marls and limestones). In the humus horizon of soils, the average metal concentrations vary in the range from 13.0∙10–3 to 95.0∙10–3 % with a regional clark of 22.0∙10–3 %.

Агрогенная трансформация почвенного покрова Присалаирской дренированной равнины (Западная Сибирь)

Plowing up is a widespread type of anthropogenic transformation of soils and soil cover (SC) in the forest-steppe zone of Western Siberia. As a result of plowing up agrogenic transformation (agrotransformation) of soils causes their form and properties change, as well as the spatial characteristics of the SC. In the example of a model territory the features of changes in the component composition and structure of the SC of the Pre-Salair drained plain under the influence of arable press are studied. Automorphic soil formation prevails in the studied area, and zonal natural soils here are chernozems (clay-illuvial and migrate-micellar) and dark grays. These soils have an upper dark humus horizon, which in arable soils becomes an agro-dark humus horizon. In the studied area, an increase in number of the SC components was found due to the soils of the agrozems section and different types of agricultural soils, which leads to a diversification of the component composition. It was found that the component composition of SC shows high degree of its agrotransformation: area of arable soils is 55.6% of total area of SC. We also showed the sequence of agrotransformation for the chernozems of the model territory: chernozems, agrochernozems, agrozems, abraded agrozems, agroabrazems. Agrozems occupy a large area and have a classification diversity. Factors affecting the diversity of agrozems at the type and subtype classification level are identified: the degree of agrogenic transformation of clay-illuvial and migrate-micellar chernozems are distinguished. The low thickness of the humus horizon of soils in the pre-agrarian period during plowing leads to various degrees of their agrotransformation and classification divergence of soils. The SC structure is characterized by geometric parameters in accordance with the concept of V.M. Friedland. These are areas and dissection coefficients (minimum, maximum, average and median) of elementary soil areal (ESA) and soil combinations areal (SCA). Geometries of ESA and SCA are caused by the combined influence of terrain features and anthropogenic impact. ESA of agrotransformed soils (agrograys, agrochernozems, agrozems) have largest sizes, besides undisturbed automorphic soils; ESA of strongly transformed soils developed in temporary flow hollows have smallest sizes. The overall result of the agrogenic transformation of the SC on the studied area is a new spatial agrogenic structure. In the component composition of SC specific soils of different taxonomic levels appear.

Features of the Composition of Humus Horizons of Arid Soils in the Barguzin Depression

Various types of arid soils that formed under the environmental conditions of the ultracontinental climate at the northern boundary of the steppe distribution in central Asia have been studied. The survey results for the surface horizons of the steppe soils and the soils of the contact forest–steppe zone according to the color characteristics and the humus properties are reported. The dominant cryo-humus accumulation in the soils of the steppe ecosystem and the light-humus soils of the contact zone are determined according to the Munsell scale and the CIE-L*a*b* color system. The ratio of labile and bioinert fractions of the humus compounds may serve as diagnostic parameters. Cluster analysis is performed based on 25 parameters of the soil humus horizons. The first cluster unites the steppe soils with the cryo-humus accumulation, while the second cluster involves soils with light-humus accumulation. Soils with the AK–BCA–Cca profile are classified at the current survey stage as cryo-humus soils. The obtained data can be used to correct the status of cryo-arid soils in the soil classification system.

Maximum humus horizon thickness as a criterion for identifying the soil standards of the plain Сrimea

When identifying the main categories of soil in the structure of the regional Red Book of soils, it is necessary to focus on typical soils formed taking into account the zonal soil-ecological conditions of the territory. The criterion for the extraction of soil standards can be the initial, pre-agrogenic thickness of the humus horizon, which fully realizes the soil-forming potential of natural factors of climax full-profile soils. But the search for such sites is associated with a number of methodological difficulties. A way out of this situation can be a mathematical modeling of the formation of the humus horizon of soils, which allows you to quantify the legitimacy of the allocation of soil standards in the structure of the Red Book of soils of the Crimea. The proposed method allows going to the cartographic models for determining the maximum thickness of the humus horizon. Analysis of the presented material allows asserting that in the majority of modern soils of agricultural lands of the Crimea, the profiles are destroyed by 30% compared with the calculated maximum thickness of the humus horizon, which takes into account the zonal soil formation processes. That predetermines the search for soil standards only in areas that did not function previously in agrogenic conditions, most often, these are protected areas that take into account the peculiarities of the zonal process of soil formation.

Diagnostics, Genesis, and Localization of Pedosediments within a Small Catchment (Central Russian Upland)

Results of a detailed analysis of pedosediments—sediments composed of transported material of soil humus horizons—are discussed. Five main morphological features of pedosediments attesting to the origin of the transported soil material are identified; their allocation to certain types of pedosediments is shown. A map of pedosediments for a small catchment in Tula oblast has been developed on the basis of their morphological analysis. Three types of pedosediments are specified by their morphological features and location: (1) leveling, filling depressions; (2) covering, extending on the slopes of the ravine; and (3) protruding above the surface of the slope represented by “napash”—agrogenic earthwork at the edges of fields. The covering pedosediments formed on the slopes are shown to be predominant both by area (60%) and by the volume of accumulated material (45%). The leveling pedosediments at the bottom of the ravine occupy 25% of the area and retain about 35% of all sediments of the small catchment. Only 2% of the total material of pedosediments in the catchment belongs to protruding pedosediments. The formation and localization of these pedosediments are controlled by the formation of napashes. In general, the material of pedosediments redistributed within the small catchment constituted about 12% of the total mass of humus horizons of the soils-donors. Pedosediments play a significant role in the soil cover and occupy about 10% of the total catchment area.

The effect of understory on cation binding reactions and aluminium behaviour in acidic soils under spruce forest stands (Southern Poland)

Acidic forest soils with two dominant understories, bilberry (Vaccinium myrtillus L.) or alpine lady fern (Athyrium distentifolium Tausch ex Opiz), have been investigated to evaluate the influence of the understory on sorption properties and aluminium behaviour. We investigated acidity, cation exchange properties, organic matter content (SOM) and quality as well as Al bonding to organic matter in humus horizons of soils taken from two different locations. SOM was the major contributor to total cation exchange capacity (CECt) and effective cation exchange capacity (CECe), and a strong relationship was found between SOM and both CECt and CECe, independently of the understory and location. SOM differed in quality, having more fulvic acids in soils under bilberry than in soils under alpine lady fern. For that reason, SOM in soils under bilberry complexed more Al in the exchangeable form in the soluble fulvic acid fraction such that they could be easily washed out, while in soils under alpine lady fern aluminium was mainly bound more stably. We also found that the chemical character of Al depended on the understory type. In soils under bilberry the relation between base saturation and pH could be successfully modelled by a modified Henderson–Hasselbalch equation when Al was considered as a base cation, which is typical for forest podzols. However, in soils under alpine lady fern, this model was efficient only when Al was treated as an acid cation. We concluded that alpine lady fern as the main understory species reduces solubility and potential toxicity of aluminium, thus significantly affecting soil biogeochemistry.

Humus Horizons of Soils in Urban Ecosystems

The origin, structure, composition, and properties of soil humus horizons in functional zones of St. Petersburg have been studied. The radiocarbon age of organic matter in the humus horizons varies from 500 to 2700 years, which attests to the natural origin of humus. The structure of microbiomes in the humus horizons of soils under different plant communities has its specific features. The taxonomic structure of microbial communities at the phylum level reflects both genetic features of natural soils and the impact of anthropogenic factors, including alkalization typical of the studied urban soils. Tomographic studies have shown that the transporting system of humus horizons is less developed in the anthropogenically transformed soils in comparison with the natural soils. It can be supposed that the intensity of water and gas exchange in the anthropogenic soils is much lower than that in the natural soils. The fractional and group composition of humus in the urban soils is specified by the long-term pedogenesis, on one hand, and by the impact of metabolic products of the city and the factors of soil formation in the megalopolis, on the other hand. Bulk density of the humus horizon in the urban soils is higher than that in the natural soils; the portion of overcompacted humus horizons in the urban soils reaches 44%. Humus horizons of the lawns along highways are most contaminated with heavy metals: Pb, Zn, and Cu. There are no definite regularities in the distribution of major nutrients (NPK) in the humus horizons of anthropogenic soils.

Effect of Contrasting Trophic Conditions on the Priming Effect in Gray Forest Soils

Priming effects initiated by the addition of 14С glucose have been compared for humus horizons of soils existing under continuous input of fresh organic substrates and for buried soil horizons, in which entering of organic matter has been essentially limited. The effect of microrelief on the manifestation of priming effect in the humus horizons of gray forest soil on microhigh and in microlow has been estimated. Humus horizon in soils on microhigh, not activated by glucose, produced two times more СО2 in comparison with soils of microlow. However, the introduction of glucose canceled the effect of microrelief on СО2 emission. The intensity of absolute priming effect correlated with the Сorg pool, initial microbial biomass, and enzyme activity, decreasing from humus horizons to the buried ones, and did not depend on microrelief. The effect of microrelief was observed, when assessing the priming effect relative to control (soil not activated by glucose): the value of relative priming effect was 1.5 times greater in А horizon of gray forest soil in microlow in comparison with that on microhigh being the result of increasing activity of enzymes.

Содержание и подвижность кадмия, кобальта и цинка в гумусовых горизонтах почв Республики Татарстан

Содержание и подвижность кадмия, кобальта и цинка в гумусовых горизонтах почв Республики Татарстан

Long-term dynamics of heavy metals in the upper horizons of soils in the region of a copper smelter impacts during the period of reduced emission

The 23-year-long dynamics of actual acidity (pHwater) and acid-soluble heavy metals (Cu, Pb, Cd, Zn) in the forest litter and humus horizon of soils in spruce-fir forests were studied in the area subjected to the long-term (since 1940) pollution with atmospheric emissions from the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast). For this purpose, 25 permanent sample plots were established on lower slopes at different distances from the enterprise (30, 7, 4, 2, and 1 km; 5 plots at each distance) in 1989. The emissions from the smelter have decreased since the early 1990s. In 2012, the emissions of sulfur dioxide and dust decreased by 100 and 40 times, respectively, as compared with the emissions in 1980. Samples of litter and humus horizons were collected on permanent plots in 1989, 1999, and 2012. The results indicate that the pH of the litter and humus horizons restored to the background level 10 and 23 years after the beginning of the reduction in emissions, respectively. However, these characteristics in the impact zone still somewhat differ from those in the background area. In 2012, the content of Cu in the litter decreased compared to 1989 on all the plots; the content of Cu in the humus horizon decreased only in the close vicinity of the smelter. The contents of other metals in the litter and humus horizons remain constant or increased (probably because of the pH-dependent decrease in migration capacity). The absence of pronounced removal of metals from soils results in the retention of high contamination risk and the conservation of the suppressed state of biota within the impact zone.