Kolguev Island (Barentz Sea, the subzone of typical tundra) was poorly soil surveyed until recently. During expeditionary research 2018–2023, it was revealed that a significant proportion of the soil cover is represented by soils that have horizons with a well-manifested structure, which were diagnosed as cryometamorphic ones. In this regard, the purpose of this work is to characterize the diversity and morphological features of tundra soils with a cryometamorphic horizon identified on the island. The cryometamorphic horizons most often had the specific angular-grainy structure with sharp edges or granular structure with rounded surfaces. The most typical size of aggregates is 1–3 mm; less common – up to 4 mm or less than 1 mm. In some cases, the structure was water-resistant and the soil aggregates had a denser, drier interior. A platy-grained structure with silty-sand coatings was less common. A key feature of the cryometamorphic Kolguev soils is lacking structure in the upper 5–10 cm of the profile. Such soils are the main component of the soil cover. The gleyic subtype of cryometamorphic soils and cryometamorphic gleezems are more often found as components of the soil cover micropatterns. Cryometamorphic soils with a morphologically pronounced spodic horizon were described in one of the central parts of the island. Based on the principles of Soil Classification of Russia, the following types of soils were identified: cryometamorphic, mucky-cryometamorphic, cryometamorphic gleezems; as well as soils, that were tentatively classified as a new type – cryometamorphic podburs and a new subtype – cryometamorphic peaty gleezems. Thus, the study of Kolguev soils showed that the cryometamorphic soils are distributed much extensive than previously assumed.

We studied the adsorption of fulvic acid (FA) obtained from the H horizon of peaty-podzolic-gleyic soil on sludge subfractions isolated from the ELG and Ecng horizons of the same soil: 0–0.2 µm (I), 0.2–0.06 µm (II) , 0.06–0.02 µm (III) and <0.02 µm (IV). It has been established that, in terms of unit mass, more FAs are sorbed by subfractions III and IV, which have a larger surface area. In terms of per unit surface area, an inverse relationship is observed: the larger the fraction, the more FA is sorbed on it. All subfractions of sludge isolated from both horizons sorb predominantly hydrophobic components of FA, but in the finer subfractions, which practically do not contain kaolinite, the contribution of hydrophilic components in total sorption increases. Under the experimental conditions, FA molecules with a molecular weight of 20 kDa were not adsorbed in micropores with an average size of ≈ 3.7 nm. The main mechanism of FA sorption on sludge subfractions is hydrophobic interactions. The hydrophilic components of FA are sorbed through electrostatic interactions, through ligand exchange on lateral cleaved clay minerals and with the formation of bridging bonds with the Ca²⁺ ion occupying exchange positions in clays.

The goal of the work was to assess changes in microbial carbon content and the properties of dissolved organic matter (DOM) of the Poa pratensis L. rhizopshere in response to the effects of soil drying and waterlogging. The vegetation experiment without plants and with dense sowing in vegetative vessels on Haplic Chernozem surfacewas used in the work. The properties of dissolved organic matter were evaluated based on the study of water-extractable organic matter (WEOM), in which the optical properties were assessed by UV-Vis spectrophotometry and spectrofluorimetry. Soil microbial carbon content was assessed by fumigation method. It has been shown that microbial carbon content in the bulk Chernozem does not depend on soil moisture, while in the rhizosphere it increases with drying and decreases with optimal and excess moisture. Soil moisture greatly affects WEOM properties of the bulk Chernozem, whereas the rhizosphere properties are influenced by the activity of the plant. Despite the lower microbial biomass compared to the bulk soil, the microbiome of P. pratensis L. rhizosphere is capable of more intense transformation of soil organic matter. The dynamic properties of P. pratensis L. rhizosphere ensure its more active and sustainable functioning compared to bulk soil.

The plant and soil cover of cities functions as their ecological framework. Soil invertebrates play an important role in urban ecosystems. Trophic activity of pedofauna is an integral indicator of its condition. The trophic activity of macroand mesopedofauna in the soils of the gardens of the Russian Museum (St. Petersburg) was determined by the express method baitlamina test. The average values of the degree of consumption of bait by pedobionts amounted to 10.9 ± 1.6% for the Summer Garden and 8.5 ± 3.5% for the Mikhailovsky Garden. The variability of trophic activity indices between different sample areas was established – in the Summer Garden it varies from 2 ± 6.2% to 21.8 ± 8.4%, and in the Mikhailovsky Garden – from 2.8 ± 4.5% to 19.3 ± 8.8%. Differences in trophic activity within the vegetation season were noted. The lowest degree of bait consumption (less than 2%) was observed in the driest and hottest months in the middle of the vegetation period, and the highest (within 19–22%) – at the beginning and end of the vegetation period under the most favorable hydrothermal conditions.

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants widely detected in natural environments, primarily in freshwater sources and wastewater. Currently, an extensive database of cases of detection of PPCPs in soils has been collected, and the problem of pollution with these emerging substances is especially relevant for agricultural landscapes. The study aimed to assess the influence of selected PPCPs on the processes occurring in the soils, especially in the rhizosphere, on the example of a test plant. As a working hypothesis, it was suggested that the introduction of selected PPCPs could change the biochemical processes in the rhizosphere, affecting the activity of the microbial community and, therefore, the characteristics of the labile pool of soil organic matter represented by watersoluble forms could change. In a short-term incubation experiment on the humus horizon of chernozem soil, we studied the effect of PPCPs represented by the most frequently prescribed therapeutic groups and often found in natural environments: ciprofloxacin (antibiotic), ketoprofen (analgesic), atenolol (beta-blocker), clotrimazole (antifungal agent). Selected substances were applied to the soil in concentration gradients. Lettuce (Lactúca sativa L.) was used as a test plant. At the end of the experiment, the biomass of shoots and roots and urease enzymatic activity in variants treated by PPCPs differed significantly from the control. Mainly, differences from control samples were expressed in the inhibitory effect; at the same time, an increase in indicators values was observed in several cases. A change in the composition of dissolved organic matter in the rhizosphere soil was noted: in general, even in low concentrations, samples treated with ciprofloxacin, ketoprofen, and atenolol differed from the control variant. While the changes were irregular in terms of concentrations of PPCPs, the observed effects caused by the introduction of selected substances can be explained by both the studied soil’s buffer capacity and the soil’s biological activity, particularly the rhizosphere community.

The purpose of this work was to study both the separate and combined effects of the liquid-phase biological (LPB) product and Fe₃O₄ nanoparticles on the yield of potatoes of the Skarb variety, as well as on soil microflora. The biosynthesis of Fe₃O4 nanoparticles was carried out using green tea extract and FeSO₄∙7H₂O solution, concentration 0.1 mol/l. The effectiveness of the obtained LPB-Fe product was studied under field conditions against the background of NPK fertilizers application. The results of a three-year experiment (2020–2022) showed that when spraying plants at vegetative stage with a 1% LPB-Fe product, potato yield increased by 16.9%, and when treating tubers before planting – by 14.8% compared to the control. At the same time, when using LPB without the addition of Fe₃O₄ nanoparticles, potato yield increased by 9.8% after foliar treatment and by 6.8% after tubers treatment, compared to the control. Based on the results of microbiological analysis, the coefficient of soil mineralization was calculated and the correlation of potato yield and its value was established. Varying concentrations of LPB-Fe preparation resulted in strong but multidirectional dependence of potato yield on the soil mineralization coefficient: both when treating tubers (regression equation y = 0.2639x – 39.9329 with a correlation coefficient r = 0.72) and when spraying potato plants (regression equation y = -0.2536x + 55.882 with correlation coefficient r = -0.77). In addition, during foliar treatment of potato plants with a 1% solution of Fe₃O₄ nanoparticles, there was recorded a very strong inverse relationship between the yield and the number of nitrogen-transforming microorganisms (correlation coefficient r = -0.90, with the regression equation y = -0.0841x + 37.9421).

The features of vertical distribution of ¹³⁷Cs in the profile of clayeyilluvial agrochernozem, as well as biogenic migration of the radionuclide in the system “soil–plant” of potato agrocenosis have been studied. The research was conducted on the field, occupied by potato variety “Gala”, located in the central part of Plavsky radioactive hotspot of Tula region. It is shown that 35 years after the Chernobyl accident the density of surface radioactive contamination of arable soils in the region exceeds the permissible level by ≈5 times. The depth of ¹³⁷Cs penetration down the soil profile is mainly determined by methods of agrotechnical soil treatment, and the main part of its inventories is concentrated in the upper 30-cm arable layer. This results in the direct contact of the radionuclide with underground organs of potato (roots, stolons and tubers). However, no more than 0.02% of the total ¹³⁷Cs inventories contained in the system “agrochernozem–potato” is transferred to potato plants. It was also established that potato plants are characterized by contrasting distribution of ¹³⁷Cs specific activity values wich varies with organs and tissues. Stolons and thin roots accumulate the radionuclide to the greatest extent per biomass, while tubers, on the contrary, – to the least extent. In general, the levels of ¹³⁷Cs accumulation in the raw and dry weight of potato tubers, as well as in the products that have undergone culinary processing (boiling the unpeeled and peeled potatoes), correspond to sanitaryhygienic norms, which substantiates the low ecological risks of including potatoes in crop rotations on agricultural land in the area of the Plavsky radioactive hotspot of the Tula region.