No 10 (2024)

The chemical composition of the volcanic soils of the southern Kuril Islands (Iturup, Kunashir, Shikotan), which are affected mainly by ash falls of the main composition during volcanic eruptions, has been studied. The total content of metals (K, Ca, Mg, Na, Ba, Cu, Co, Cd, Cr, Fe, Mo, Ni, Pb, Sc, Sr, V, Zn) and the concentrations of their mobile forms extracted by an ammonium acetate buffer at pH 4.8 were determined. Concentrations of Sc, V, Fe, Zn is 1.5–5 times higher, and the content of Cr, Ni, Sr, Ba is 2–10 times lower than clarks values. Soils are characterized by a contrasting pH distribution of 3.75–7.81, which determines the lability of metals. The maximum activity of radial and lateral migration is noted at low values of the acid-base index, leading to a sharp differentiation of the chemical composition of the genetic soil horizons in various catenary positions, the coefficients of radial and lateral migration can increase to 12 and 29, respectively. The results of factor analysis showed the leading role of soil-forming rocks in the formation of the chemical composition of soils (about 63% of the sample variance); the processes of humus formation, transformation of mineral and organic substances in soils, and hydrothermal activity have a lesser influence. Soils formed on the middle and basic rocks of the Cenozoic volcanic sequence are characterized by Ca–Mg–Na paragenetic associativity, liparite-dacite complex – Ba–K–Pb–Mo, gabbroid – Ni–Cr–Cu, psammite – V–Sc–Fe–Co. Paragenesis Mo–Pb is typical for sites of modern hydrothermal activity. The influence of placer formation processes on the chemical composition of soils in the coastal areas of the Iturup and Shikotan islands is shown. The distribution of mobile forms is associated with chelation processes, geochemical barriers of acid-base, sorption and redox types. Local soil pollution has been identified, mainly due to the operation of motor vehicles. On the territory of the settlements of Krabozavodskoye and Yuzhno-Kurilsk, there is an increase in the concentration of Ba, Sr and K associated with the activities of fish processing plants, in Kurilsk – Cr, Ni, Cu, Co, Zn and Pb, the source of which is the repair base. The calculated soil toxicity probability index (MERMQ), as well as the results of biotesting for Daphnia magna Straus. and Chlorella vulgaris Beijer showed low soil toxicity. This is explained by the low population density and low degree of economic development of the islands.

Pyrolysis is considered as one of the promising methods for processing agricultural waste and producing fertilizers. The effectiveness of the resulting biochar as a fertilizer has been proven, but to this day questions remain open about the preferential ways of decomposition of organic substances in its composition – biotic or abiotic. In this work, the transformation pathways of biochar made from corn – a plant with the C₄ type of photosynthesis (with an increased content of ¹³C) – were assessed using the solid-phase CP/MAS ¹³C NMR spectroscopy method. The biochar was placed in the top layer of a soil monolith of gray forest soil, and for 90 days the precipitation regime characteristic of central Russia was simulated. In the obtained NMR spectra of soil samples with biochar, the peak at 129 ppm, characteristic of aromatic compounds, increased with the time of the experiment in the upper soil layer, but not in other layers. This suggests that biochar particles do not migrate down the soil profile during one season. At the same time, the intensity of cumulative microbial respiration in the presence of biochar increased – from 85.0 g CO₂ kg^–1 in the control sample to 201.4 g CO₂ kg^–1 in the sample with biochar (top soil layer). According to the NMR spectra of the salt formed during the mineralization of carbon dioxide released from the soil, it contains labeled carbon: the spectra have a peak at 169 ppm, characteristic of carbonates. The cumulative volume of CO₂ released from the soil with biochar was 1.9 times greater than from the control soil. The addition of decomposer microorganisms led to an additional increase in the volume of CO₂ – 2.4 times relative to the control, which indicates the role of microorganisms in the destruction of soil organic matter and biochar. However, based on the stability of the total carbon content in the soil, it can be concluded that only a small proportion of biochar components is susceptible to biotic decomposition.

The observed climate changes and increasing groundwater levels in the forest-steppe region should be reflected in the water regime of the Gleyic Chernozem soils. This article analyzes the daily and seasonal dynamics of volumetric moisture in background Gleyic Chernozem (Siltic, Pachic) and two arable Gleyic Chernozem soils (Siltic, Aric, Pachic), as well as the level of groundwater in the Tokarevsky district of the Tambov region during the period from autumn 2022 to summer 2023. The obtained data is compared with regime observations of volumetric moisture and groundwater levels of these soils from 1969–1971. The use of automated monitoring systems for soil moisture and groundwater levels has allowed for continuous data collection on soil moisture, assessment of the diurnal dynamics, and detailed tracking of seasonal changes in soil moisture. The background chernozem soil is characterized by higher moisture levels compared to arable soils; the upper horizons of cultivated soils are characterized by a higher frequency of wetting-drying periods and a shorter continuous duration of these periods – which is confirmed both by moisture monitoring data and by the morphological features of the soils, such as the form of carbonate neoformations and the depth of their detection. During the observation period in 2022–2023, the meadow-chernozem soils were relatively dry, despite the higher than normal annual precipitation. Moisture levels conducive to wilting in the top 20 cm layer of cultivated soils were established from March 2023, and in the background soil from the end of April 2023. Periods with humidity exceeding the minimum moisture capacity within the entire 60 cm depth were not observed during the entire observation period. The soils were drier than in the dry year of 1972, when the humidity was less than the wilting point in the upper part of the profile from June to September. In the wet years of 1969–1970, the humidity did not drop below the wilting point in the upper 20 cm layer throughout the observation period. The main reason for this difference in humidity is the change in the level of groundwater: in 2022–2023, the majority of the groundwater was more than 4 m deep, whereas in 1969 it did not go deeper than 2 m and in 1971 – deeper than 4 m. As a result, the soil’s uptake of moisture through capillary action did not occur in 2022–2023, and the water regime of the meadow-chernozem soils more closely resembled the water regime of chernozems.

Long-term (2017–2023) year-round observations of soil CO₂ efflux (soil respiration, SR) in the area of typical Chernozems distribution (Kursk region, Medvensky district, Kursk Biosphere Station of the Institute of Geography RAS) were carried out using a unified technique based on field measurements with IRGA. Annual estimates of SR were calculated in the most representative local anthropogenic and natural ecosystems that form the forest–steppe agro–landscape in Chernozem zone of European Russia (permanently used arable land, non–fertilized vegetable garden, 2–8 yr fallow, meadow steppe, and broadleaved forests). According to estimates averaged by various models and calculation schemes, SR in the study area varies from 650.6 ± 88.2 (non–fertilized vegetable garden) to 1550 ± 215 (2–8 yr abandoned land) g C–CO₂ m^–2 yr^–1, amounting to 895 ±91 on permanently used arable land and 1040 ± 55 g C–CO₂ m^–2 yr^–1 in natural ecosystems. The share of microbial (heterotrophic) respiration (MR) in local soils averaged 55.5% (broadleaf forests), 77.6% (abandoned land), and 72.4% (meadow steppe) during the growing season. The ecosystem net carbon balance of the three broadleaf forest sites, calculated by the difference between net primary production (NPP estimated by CBM–CFS3 model and taxation data) and heterotrophic respiration (SR and CO₂ losses from decomposition of coarse woody debris, CWD) vary from atmospheric carbon uptake +130 g C–CO₂ m^–2 yr^–1 to its source –112 g C–CO₂ m^–2 yr^–1. In the latter case, the net carbon source is due to the accumulation of significant stocks of CWD as a result of tree mortality from xylophages. On arable lands, similarly, calculated by NPP and MR net carbon balance, according to the expert assessment of MR share, vary from +186 to –143.7 g C–CO₂ m^–2 yr^–1, with almost ultimate contribution of the crop type grown in a given year to inter–annual variations of SR (87.9%). It is concluded that the above approach is applicable to estimates of the net C balance in rather different ecosystems, however, the greatest uncertainty is introduced by estimates of the soil MR share.

The paper presents the results of studies aimed at assessing the variability of indicators of the respiratory activity of soil microbiota (rate of basal and substrate-induced respiration), as well as the carbon content of organic matter and microbial biomass in soils, formed and functioning in natural (slightly damaged) biogeocenoses, along altitudinal gradient, from the foothills to the high mountain regions of the Central Caucasus (500–3500 m above sea level, elbrusvariant of altitudinal zonality, Kabardino-Balkaria). It is shown that with an increase in absolute height, from mountain chernozems to mountain-meadow subalpine soils, the average values of all studied parameters in surface horizons (0–10 and 0–20 cm, depending on soil type) increase significantly, and at maximum altitude, in mountain-meadow alpine soils, they significantly decrease. In addition, it was established how the parameters under consideration change in soils of various types located within the same altitudinal zone. It was revealed that the compared pairs of soil types differ statistically significantly in most of the studied indicators (t > 2.5; p < 0.02). The data obtained indicate that the influence of the altitudinal gradient is largely refracted by additional factors. To identify the degree of influence of the main factors characterizing the relief (height above sea level; aspect; slope) and climate (19 bioclimatic characteristics) on the formation of the studied parameters, a multi-regression analysis was carried out. He showed that the average cumulative contribution of all 22 factors to the variation of the studied indicators is: in mountain chernozems 40%; in mountain meadow chernozem-like soils 66%; in mountain-meadow subalpine steppe soils 31%; in mountain-meadow subalpine 67%; in mountain meadow alpine soils 67%. Thus, both for soils located along an altitudinal gradient and those functioning within the same altitudinal zone, the influence of the considered factors can differ significantly, and relief and climate play an important, but not the only role, in shaping the properties of mountain soils in the Central Caucasus.

The purpose of this work was to carry out an environmental assessment of the content Cr, Pb, Cd, Hg, As in arable soils and agricultural plants of the Central Chernozem economic region of Russia using the example of the Belgorod Region. During the studies, it was found that the average gross content of Cr, Pb, As, Cd, Hg in leached arable chernozem was – 19.8, 10.0, 4.15, 0.22, 0.021, in typical arable chernozems was 20.0, 10.3, 4.18, 0.23, 0.022, in ordinary chernozems – 20.9, 11.2, 5.48, 0.35, 0.023 mg/kg, respectively. The average content of mobile forms of Pb, Cr and Cd in leached arable chernozems was 0.52, 0.14, 0.06, and 0.46, 0.13, 0.05 for the typical arable chernozems, in ordinary chernozem – 0.55, 0.13, 0.04 mg/kg, correspondingly. These elements did not exceed the established UEC and MAC standards in the studied soils. The main source of heavy metals in the arable soils of the Belgorod region is organic fertilizers. The average content of Cr, Pb, As, Cd and Hg in cattle manure is 0.90, 0.78, 0.277, 0.060, 0.0084 mg/kg, respectively. Of the studied crops, sunflower seeds had the highest content of Cd, Pb and Cr, while winter wheat grains had Hg and As. The soy grain has the lowest average content of Pb, Hg and As, and the corn grain has Cr, Cd and As. In the grain of winter wheat, corn, soybeans and sunflower seeds, the content of Pb, Cd, Hg, As did not exceed the maximum permissible concentrations established for products intended for food purposes, and the concentration of Cr did not exceed the maximum permissible level established for feed.

One of the energy enterprises of the first hazard class, operating primarily on coal, the emissions of which have a negative impact on the environment of the Rostov region, is the Novocherkassk Power Station. The purpose of the study was to analyze the accumulation of Zn, Pb, Cu, Mn, Ni, Cr and Cd in soils and various types of medicinal plants in the impact zone of the Novocherkassk Power Station. The total content of Cr, Ni and Cd in soils was shown to be up to 1.4 times higher than the background and approximately permissible concentration. At the same time, it was established that the maximum permissible concentration of mobile forms of Cu in soils was exceeded by up to 4 times, Zn, Pb, Ni and Cr – by up to 2 times. It was revealed that wormwood, common chicory and tansy accumulate heavy metals mainly in the aerial parts, and bristly yarrow – in the roots. It was revealed that the maximum permissible level of element content in yarrow was exceeded by up to 3.5 times for Pb, up to 5 times for Cd and up to 3 times for Ni, in wormwood for Pb up to 5.5 times and Ni up to 2 times, in chicory for Pb and Cd up to 2 and 6 times, in tansy for Pb and Cd up to 3 times. The highest content of mobile forms of heavy metals in the soil and their accumulation in plants is observed within 3 km in the northwest direction from the power station. Based on biogeochemical indicators, an assessment is made of the degree of technogenic load on soils and medicinal plants in the impact zone.