Articles

Despite the widespread adoption of modern, high-precision methods for assessing ecosystem carbon budgets, most primary data for calculating monthly, seasonal, and annual gas fluxes are obtained through daily soil or ecosystem respiration measurements. The question remains whether such one-time, albeit regular, measurements can reliably reflect the average daily flux. The objectives of this study included assessing patterns in the diurnal dynamics of soil CO2 emissions for two northern taiga ecosystems (green moss pine forests and frozen hummocky peatlands) and three spotted-medallion tundra ecosystems (mineral spot, overgrown area, and dwarf birch area) in northern Western Siberia. In August2016 and 2017, CO2 emissions from the soil surface were measured every four hours for two days using a chamber method, as well as soil temperature and volumetric moisture at a depth of 10 cm. Significant diurnal dynamics were observed for all studied ecosystems, despite different absolute values of CO2 emissions. Minimum fluxes were observed in the pre-dawn hours, around 2:00 AM, for all sites. Maximum fluxes were recorded at various times but generally occurred between 2:00 PM and 6:00 PM. For most sites, the diurnal variation in emission values correlated with soil temperature, but a pronounced hysteresis was observed in this relationship. This phenomenon is explained by both biological factors—root respiration dynamics depend more on photosynthesis than on soil temperature—and physical factors—impeded gas diffusion in dense mineral horizons. The most favorable hours for measuring CO2 emissions, in terms of subsequent calculations of diurnal fluxes for most of the studied ecosystemsduring peak vegetation, are morning (before 10:00 AM) and evening (from 6:00 PM to 10:00 PM).

Thearticlepresents the results of a comprehensivestudy of the soilcover of the islands of UrupandSimushir, which are partoftheKurilRidge. The mainfocus is on analyzing the impact of environmentalconditionssuchasclimate,vegetation,topography, andvolcanicactivityonsoilformationanddiversity.Duringthefieldwork, keysiteswithsoilsectionswerelaid,ageobotanicaldescription of plantcommunities was carried out, and samples were selected forlaboratoryanalysis. It has been establishedthat the soil-forming processesontheseislandsareintermittentand are associatedwith the periodicburial of soilhorizons with pyroclasticmaterial. Based on the morphological descriptions of the profiles of the surveyed territories, a stratotype of the soil pyroclastic cover (SPC) was compiled separately for the sites on Urup Island and Simushir Island, reflecting the history of the profile formation. A special feature of the soilsis the highcontent of organic carbon in the surfacehorizons,whichvariesfrom5.1to15.1%,reachingmaximumvaluesunderthickets of KurilbambooonUrup Island,as well as the presence of horizons with andic properties, usually associated with volcanic soils.Soilacidity(pH)rangesfrom3.7to6.4,increasingwithdepth. A CKrmarkerashhorizon with an age of ~2100years has been identified, which plays a keyroleinstratigraphy. The soils forming on Urup Island are characterized by a large accumulation of organic carbon compared to the soils of Simushir Island, where the soil cover is younger and formed on a substrate that is initially poor in organic matter, the slag from the eruption of Zavaritsky volcano (195 y. a.). The andicpropertiestestconfirmed the presence of reactivehorizonsin the lowerparts of the profiles. The density of the soilcompositionvariesfrom0.42to0.66gcm–3,which is typicalforvolcanicsoils. It is shownthatplantassociationsplay a keyrolein the processes of humus accumulationandsoilprofileformation. The dataobtained are importantforunderstanding the mechanisms of soil formation involcanicislandecosystems.

The work provides a detailed description of four stacked soil profiles that make up the “crimson clay” pedocomplex in two Urzhumian reference sections of the Middle Volga region, Cheremushka ravine and Grebeni. Paleosol profiles have a similar structure with eluvial-gley, illuvial-carbonate and structural differentiation of the profile. Pedogenic processes were reconstructed: gleyization from the surface and along the root network, redistribution and segregation of iron oxides, slitogenesis, redistribution of carbonates. Four stages of pedogenesis have been identified, with a total duration of at least 20–25 thousand years, which occurred on flat fluviolacustrine plains in conditions of a warm semi-arid climate with pronounced seasonality of precipitation. The difference in the structure of the pedocomplex in the studied sections is determined by differences in the facies conditions of pedosedimentogenesis: an alluvial-floodplain regime for the Cheremushka ravine section and a lake-playa regime for the Grebeni section. The pedocomplex of “crimson clays” reflects a long stage of geomorphic stability of the landscape, it has been traced in sections of the right bank of the Volga River over a distance of about 100 km and is a pedostratigraphic marker, or Geosol.
To discuss the actual results obtained, the article provides a review of the author's data on paleosols on Permian red beds of the Middle Volga region, including Ufimian, Kazanian, Urzhumian, Severodvinian and Vyatkian deposits. For each stratigraphic interval, characteristic pedogenic and sedimentary features of paleosols and host rocks are given, on this basis, soil-forming processes and landscape-climatic factors were reconstructed. In general, the Permian red paleosols have a chemical and mineralogical composition inherited from the host rocks and a high degree of weathering of the siliciclastic material associated with ancient soils and weathering crusts of the provenance areas. The autochthonous nature of the gley features of paleosols formed during the process of pedosedimentogenesis are shown. Most mature soils are classified as chromic stagnicvertic calcic Paleocambisols or chromic stagnicverticPaleocalcisols. Mean annual precipitation calculated from geochemical indicators of illuvial horizons of paleosols shows cyclical changes. The minimum amount of precipitation — 400 mmyear–1 — was typical for the Urzhumian (Wordian) time, the maximum values — 777 mmyear–1 — were revealed for the Severodvinian (Capitanian) time.
Evaluation of the pedostratigraphic potential of Permian red-bed deposits and identification of the role of microorganisms and organic matter in the formation of paleosols are tasks for further study.

Based on the results of a green pot experiment with mineral fertilizers on chernozem, a new method of plant diagnostics has been proposed, using the analysis of individual barley plants (Hordeum vulgare L.) according to their morphological characteristics of vegetative and generative development. Each plant was divided into three parts: the primary shoot, secondary shoots (together forming mature grain), and non-productive shoots. The dominant group of plants (Group D) was identified by total biomass, while the other two groups (Groups A and B) were distinguished by their level of generative development, determined by the quality of grain formed by different shoots. Structural differences among plants, shoots, and groups reflect the dynamics of barley development during the growing season. Different application methods for potassium fertilizer, namely localized and uniform, create different spatial heterogeneities of their content in the soil and, consequently, different dynamics of potassium's effect on the plants. Potassium fertilizers applied uniformly have the most significant effect during the first half of the vegetative period, when the primary shoot is most actively developing. The localization of potassium fertilizers in the soil, conversely, by promoting weaker fixation of potassium by the soil, prolongs its effect into the second half of the barley's vegetative period, when secondary-order shoots develop more actively. Therefore, the new method of structural division of individual plants made it possible to diagnose the physiological effect of the spatial heterogeneity of potassium fertilizer application on barley plants and crop quality. The traditional biomass accounting scheme, which averages all plants in a pot, was not sensitive enough to detect the effect of fertilizers on the formation of generative organs. Thus, the obtained data confirm the previously proposed concept linking the spatial heterogeneity of freshly applied potassium in the soil with its distribution within the plant throughout the vegetative period.

The characteristics of urban ecosystems, the morphological structure of profiles, the content of organic carbon, the amount of petroleum hydrocarbons, the pHН2О, and the density of soils were studied at 9 control sites in the floodplain along the Likhoborka River in the Northern Administrative District of Moscow. The river floodplain was dominated by Gleyic Fluvisol (Turbic) and UrbicTechnosol, which were heterogeneous in their morphological structure and properties. The organic carbon content in the AYtr horizon of reclaimed soils reaches 4% or more, while it is less than 1% in the UR and TCH horizons of UrbicTechnosol. Alkalization to pHН2О7.4–8.5 was observed not only in the upper horizons, but also in deeper layers (30–50 cm) of the soil, due to the numerous inclusions of construction materials and other waste. The density of the AY and AYtr horizons of Fluvisol varies from 0.8 to 1.3 gcm–3, while the TCH and UR horizons are compacted above 1.4 gcm–3. A paired analysis of the content of petroleum hydrocarbons in soils and bottom sediments was conducted, and contamination above 1000 mgkg–1.  was recorded along almost the entire 30-kilometer length of the Likhoborka River. Different types of distribution of petroleum hydrocarbons in soil profiles have been identified. Using correlation analysis, it has been found that a decrease in organic carbon content is accompanied by compaction and alkalization of the upper soil horizons. An increase in the level of petroleum hydrocarbon contamination is associated with an increase in organic carbon content and a decrease in pHН2О. The content of petroleum hydrocarbons is correlated across all layers of the upper 30-centimeter layer, but there is no correlation between the content of petroleum hydrocarbons in floodplain soils and bottom sediments along the Likhoborka River.

The article presents an algorithmic approach for separation of integral CO2 fluxes, allowing for a quantitative assessment of the contribution of field areas with different topsoil bulk densities to the overall carbon balance. The methodology is based on integrating eddy covariance data, dynamic footprint modeling, and digital soil mapping. The experiment was conducted in 2023 on spring barley crops under conditions of pronounced soil bulk density heterogeneity (1.45–1.80 g cm⁻³). The developed approach enabled the partitioning of the total net ecosystem exchange (NEE) into gross primary production (GPP) and ecosystem respiration (Reco) components, specific to the identified zones with contrasting densities. It was established that under the dry conditions of June 2023, overcompacted areas (>1.65 gcm⁻³) were characterized by higher values of gross primary production (up to 14 μmolm⁻2s⁻1) and water use efficiency compared to less compacted areas (<1.65 gcm⁻³), where these values did not exceed 10 μmol Cm⁻2s⁻1. In the second half of the growing season, during the ripening stage and with an increase in precipitation in August, an inversion was observed: GPP values in the overcompacted areas were 2.8 μmol C m⁻2s⁻1, and Reco intensity was 2.1 μmol C m⁻² s⁻¹, which is half the values recorded in areas with lower bulk density (4.2 μmolm⁻2s⁻1). The proposed approach made it possible to quantitatively capture the within-field variability of carbon balance components without using spatial averaging.

The study of variation of soil properties of the subzone of ordinary chernozems was carried out on the basis of mathematical models of zonal and regional etalons of soils of the Altai Territory. These etalons are developed using information-logical analysis. The main indicators of soil heterogeneity are conditional uncertainty of soil properties within a taxon (Shannon index), information content, and the efficiency coefficient of information transfer. It has been shown that, given equal scale and area, the choice of classification system influences the variation in properties within soil taxonomic groups. The proximity of the classify boundaries of the properties of soils of different taxons indirectly indicates an increase an entropy in them. The evolution of agrogenic soils in line the agrochernozeme-agrozeme-agroabrozeme is accompanied by nonlinear dependence of changes of variation indicators. The Shannon index increases in agrozemsand decreases in agroabrozems. With an increase of scale and a decrease in the area of the estimated territory, the variation is determined by the geomorphological features of the soil region. Entropy decreases in soil areas confined to watersheds and slopes and increases in terraced areas of ancient hollows. The detailization of taxonomic groups at the genus level in regional etalons of meadow-chernozem soils is mainly accompanied by an increase in entropy compared to their zonal etalons.

The most important factor affecting the soil organic carbon (SOC) stocks is the degree and nature of soil moisture content. This factor is especially important when assessing SOC in forest soils. In this paper, the results of a comparative statistical analysis of the variability of SOC in automorphic, semihydromorphic and hydromorphic forest soils in Karelia are discussed. To estimate SOC stocks and calculate quantitative indicators of their variability, soil survey data were used over an area of 1 km2. The information was collected into a single array, which includes the characteristics of 95 soil profiles of forest ecosystems. Of these, 61 profiles characterize automorphic soils, 12 profiles characterize semihydromorphic soils and 22 profiles characterize hydromorphic soils. The results of the studies showed that the mineral horizons of forest soils are largely heterogeneous in terms of SOC content, while organogenic horizons are more heterogeneous in terms of thickness and density. The results of statistical analysis showed that the average SOC stocs in the 0–30 and 0–50 cm soil layers increase depending on the degree of hydromorphism. The results of statistical analysis showed that SOC stocks in semihydromorphic soils are characterized by higher variability, as evidenced by a larger range of changes, higher standard deviations and coefficient of variation. In automorphic soils, the 0–5 cm layer, corresponding to the litter, accounts for up to 30% of the total organic carbon reserves in the 0–50 cm layer. With increasing hydromorphism, this share decreases to 17% in semihydromorphic soils and to 6% in hydromorphic soils. The share of SOC reserves in the 30–50 cm layer in total reserves increases from 23% in automorphic soils to 43% in hydromorphic soils.

Spatial variability in metal content in soils can lead to an unreasonably overestimated or underestimated level of contamination in an area, as determined by the total contamination coefficient ZС. Calculating this indicator based on sample experimental data yields only one value. For more reliable estimates, it is necessary to understand the possible range of this indicator, which describes the spectrum of reliability of contamination knowledge, ranging from low to high probability. Modeling the statistical distributions of heavy metal content under the assumption of logarithmic normality of their contents in both contaminated and background areas allows us to estimate the probability of ZС values falling into specific pollution categories. When classifying an area into a given pollution level, it is proposed to focus on the probability of obtaining individual high ZС values, even if the value itself is in a safe zone.

In a model experiment, the effect of polymer sorbents of different origins on the content of mobile species of heavy metals (HM) in zonal soils of the East European Plain was examined in a case study using soils of the Tula Region. Both synthetic and natural sorbents were used: hydrolyzed polyacrylonitrile (HYPAN), a binary structure of HYPAN and potassium humate (Humate “Sakhalinsky”), and a fungi mycelium powder (Micosorbent A). The experiment was conducted on four types of agricultural soils (Umbric Albeluvisols, Greyic Phaeozems, Voronic Chernozems) sampled in the Tula region in 2024 and spiked with Cu+2, Zn+2, Pb+2, and Cd+2 salts in 6 threshold limit values (TLV). It has been established that the same sorbent showed a significantly different remediation effect on different soil types with the same level of metal contamination: copper was bind from 30% on Voroic Chernozems to 50% on Greyic Phaeozems soils. For lead, the highest percent of mobile species to total was observed in Umbric Albeluvisoils (72%) and the lowest in Voronic Chernozems (56%). The application of Alternaria alternata mycelium had an effective effect on the sorption of zinc and cadmium in the studied soils: up to 70% in Voroic Chernozems for cadmium and up to 85% in Umbric Albeluvisoils for zinc.