A full-scale geophysical observatory in the North Caucasus, which was established to study volcanic activity in the Elbrus area, has been functioning for more than 10 years. Results of experimental studies performed at the observatory, located in the deep tunnel, are presented. Special attention is paid to the stability of metrologically significant parameters of precise information-measuring systems, taking into account different nature noises. Technical characteristics of installed geophysical instruments are given, and the principles of their operation are described. Examples of instrumental observations are also presented; for example, tidal deformations reflecting structural features of the geological environment in the area of the Elbrus volcanic edifice and associated with the presence of magmatic structures were investigated. It was shown that diurnal and semidiurnal harmonics observed in the microvariations of temperature can be caused, among other things, by the influence of tidal effects on the convective component of heat–mass transfer.

The study of mechanisms of carbon dioxide transformation in agroecosystems from the position of ideas about CO2 absorption exclusively by chlorophyll-containing parts of vegetative plants does not allow to objectively evaluate the ecosystem role of each component. To evaluate the contribution of root carbon nutrition to the formation of plant biomass, a model experiment was laid down using the author’s device, which allows isolating the root and leaf parts of the plant from each other and recording the CO2 values to calculate its balance. A paulownia seedling (Paulownia tomentosa (Thuns.) Steud., 1841) with a known initial mass, vegetating under a 12-hour light regime, was used as an experimental plant. The contribution of root carbon nutrition to biomass formation was calculated from the difference in C-CO2 in the leaf chamber atmosphere and the content of elemental carbon in the plant at the end of the experiment. The carbon content in plant parts was determined on a MultiEA 200CS carbon analyzer at a temperature of 1100 °C. As a result of 30 days of observations, it was found that the mass of C-CO2, which was present throughout the experiment (6960 ppm) in the atmosphere of the leaf chamber with a volume of 0.06 m3, corresponded to 210 mg of carbon. At the same time, the carbon content in the incremented mass of the seedling (690 mg) in absolutely dry form contained 274.9 mg of elemental carbon, which indicates the presence of another alternative source of carbon supply. According to the authors, 64.9 mg of elemental carbon (23.6 % of the total mass), which went to the formation of the incremented biomass of the experimental plant, came through the root system. The obtained results allow us to explain cases when forest areas can form a balance shifted towards the CO2 flow. An idea of the mechanism of root carbon of plants and its potential allows us to more accurately create models of CO2 transformation in soil-plant systems.

This paper reports results from an analysis of swarm seismic events that were recorded in 2018 in the area of the Elbrus Volcanic Center (EVC) by the North Caucasus Seismological Network of the Federal Research Center, Geophysical Survey, Russian Academy of Sciences (FRC GS RAS). The standard location procedure was used to find the hypocenters of recorded events in the EVC area. In the LOS program package, a complex combined location algorithm, methods for minimizing the time residuals at the source, and search over a grid with several trial depth values, were used to relocate the hypocenters of seismic events in swarm sequences. This approach enhances location reliability due to incorporation of the uncertainties related to erroneous onset identification and insignificant deviations of travel times that depend on the earth velocity model used here. A study of earthquake mechanisms for the larger earthquakes has determined the type of slip in agreement with the kinematics in the Elbrus–Mineralnye Vody normal-oblique fault zone. Correlation analysis of waveforms on the vertical component that have been filtered in the frequency range 1‒10 Hz, which includes P and S waves, at the nearest station shows a high agreement among the data under analysis (the correlation coefficient is R ≥ 0.85), thus indicating a high probability of all events having similar sources and propagation paths of seismic waves. Comparison of power spectral densities for individual earthquakes in the swarm sequences also demonstrates a high similarity.

A qualitative study of greenhouse carbon dioxide transformation in the soil-plant-atmosphere system requires appropriate tools to make ecosystem models, record the occurring transformations, and process the obtained data. To expand the methodology forstudying carbon dioxide flows, the authors developed an installation forstudying the mechanisms of CO2 transformation in the soil-plant-atmosphere system, simulating and ensuring autonomous vital activity of a plant organism with parallel recording and demonstration of the daily dynamics of CO2 concentration inside a completely closed system. For a more detailed assessment of carbon dioxide transformation, the installation ensures complete isolation of the leaf and underground parts of plants. Afoxglove tree (Paulownia) seedling weighing 7.47 g was used to test the installation; its formed roots were immersed in river sand enriched with a solution of nitroammophoska (NPK 16:16:16). For 30 days, the iMK LoRa measuring system recorded the absorption and emission of CO2 in two zones of the installation every 5 minutes. The model experimentshowed that the plant is able to continue its development and growth in the absence of an externalsource of carbon dioxide, and biomass (+111.8%) is formed due to the mechanism of root carbon nutrition. In this case, soil carbon partially (76.4%) goesinto the atmosphere as a result of plant respiration and is again absorbed in the light phase, thereby providing a “small carbon cycle”. Another part of the soil carbon (23.6%) takes direct part in the formation of plant biomass, bypassing the transformation through foliation. The proposed installation can identify the features of carbon nutrition modes of various agricultural crops for furtherselection of means and agrotechnical methodsfor biomassregulation.

The aim of the study was to evaluate the biotechnological potential of thermophilic mi-croorganisms isolated from chernozem soil during composting of poultry manure. The ef-ficiency of the strains was determined by their effect on organic matter degradation, humi-fication intensity, and nitrogen accumulation. The correlation between the quality indica-tors of composting process was assessed with the gross values, taking into account the proportion of compost fractions. The strains were identified as: Aeribacillus pallidus KCTC 3564T (cellulolytic), Neobacillus sedimentimangrovi FJAT-2464T, Aeribacillus composti N.8T, Caldifermentibacillus hisashii N-11T (nitrogen fixers) and Acinetobacter pittii CIP 70.29T, Pseudomonas plecoglossicida NBRC 103162T (nitrifies). It was found that all the bacteria increase the proportion of small fractions by 19.0-19.9%. The gross content of humic acids increases under the influence of nitrifiers (15.5%) and nitrogen fixers (5.5%). The total nitrogen content increases under cellulolytics (13.8%) and nitrogen fixers (20.2%). The smallest fraction (≤0.25 mm) in nitrogen fixers and nitrifies variants has the greatest bioreclamation properties, by 16.4% and 12.9%. Targeted microbial strains pro-vide the direction of the transformation processes while biocomposting. It can also be con-cluded that assessing the quality of composting based on the fraction distribution can be a promising element of the biofermentation process monitoring.

The aim of the study was to evaluate the biotechnological potential of thermophilic microorganisms isolated from chernozem soil during composting of poultry manure. The efficiency of the strains was determined by their effect on organic matter degradation, humification intensity, and nitrogen accumulation. The correlation between the quality indicators of the composting process was assessed with the gross values, taking into account the proportion of compost fractions. The strains were identified as: Aeribacillus pallidus KCTC 3564^T (cellulolytic), Neobacillus sedimentimangrovi FJAT-2464^T, Aeribacillus composti N.8^T, Caldifermentibacillus hisashii N-11^T (nitrogen fixers), Acinetobacter pittii CIP 70.29^T, and Pseudomonas plecoglossicida NBRC 103162^T (nitrifies). It was found that all the bacteria increase the proportion of small fractions by 19.0–19.9%. The gross content of humic acids increases under the influence of nitrifiers (15.5%) and nitrogen fixers (5.5%). The total nitrogen content increases under cellulolytics (13.8%) and nitrogen fixers (20.2%). The smallest fraction (≤0.25 mm) in nitrogen fixers and nitrifying variants has the greatest bioreclamation properties, by 16.4% (p < 0.001) and 12.9% (p < 0.001). Targeted microbial strains provide the direction of the transformation processes during biocomposting. It can also be concluded that assessing the quality of composting based on the fraction distribution can be a promising element of the biofermentation process monitoring.