Mineral Forms Of Nitrogen Research Articles

THE EFFECT OF DIFFERENT DOSES OF ORGANIC FERTILIZER ON THE MICROBIAL COMPOSITION OF SOUTHERN CHERNOZEM

In this paper, the effect of various doses of organic fertilizers from bird droppings on the spread of microorganisms in the rhizosphere of barley is investigated. Microbiological activity of southern chernozems was carried out before sowing barley. The use of organic fertilizers increased the predominance of the number of nitrogen-fixing bacteria absorbing ammonifiers and mineral forms of nitrogen, compared with fungi and actinomycetes. The favorable period for the growth of actinomycetes differentiated in the Gause nutrient medium coincided with the period of full ripeness of barley and a positive effect on their distribution on the variants 5 t/ha and 10 t/ha was noted. Cellulose destroying actinomycetes showed predominant results in relation to fungi, which is an indicator of the intensive destruction of plant residues and organic compounds in the soil. Studies show that increasing the dose of organic fertilizers in experimental variants has an adverse effect on the spread, growth and development of fungi. This may be due to the composition of the biological product used for composting organic fertilizers. The use of bird droppings in high doses promotes the reproduction of nitrogen-fixing bacteria.

Evaluation of the ecological and geochemical state of surface water in Donbas

The article covers evaluation of the ecological and geochemical state of surface water and bottom sediments in Donbas, as well as their pollution resulting from spatio-temporal changes of natural and anthropogenic factors. It was established that chemogenic pollution occurs due to penetration of polluting elements into surface water as a result of filtration leaks from sedimentation tanks and water discharges made by enterprises of coal, chemical, metallurgical, coke-chemical and petrochemical industries. Increased concentrations of biogenic elements (mineral forms of nitrogen and iron) were recorded in the water of the Siverskyi Donets and the Luhan Rivers. The most significant deterioration of groundwater quality because of high content of sulfates and chlorides is observed within the watersheds of the Luhan River's valley.
 Measurement results of the metals content indicated an increased content of copper and manganese. Some values even exceed the average annual concentrations specified by the existing normative values. In general, the results of the pollutants content analysis in the river basins under study did not reveal significant changes in the content of heavy metals during the period of military actions as compared to the results of government monitoring by 2014. The obtained experimental data indicate that vanadium, chromium and copper dominate in bottom sediments of all the studied objects. The greatest accumulation of heavy metals is observed in the Bakhmutka River and the Kryvyi Torets River. The research established that copper and plumbum in the bottom sediment samples taken from the Kryvyi Torets exceed the background values by 4-5 times. Zinc and vanadium exceed the background content values by 10 and 4 times, respectively. The same indicators are slightly lower in the Volyntsevske Reservoir and this fact is associated with more intense processes of water exchange and certain peculiarities of bottom sediments granulometric composition. Concentration of zinc is 3 times as much as the background level, vanadium and manganese – twice as much.
 Heavy metals in the bottom sediments of the studied water bodies are characterized by uneven distribution. Vanadium and copper dominate in the content of bottom sediments. Concentrations of zinc, vanadium and nickel at certain objects also exceed their regional background content values. Titanium was detected in minimum quantities.

Morphological and physiological-biochemical variability of spore-forming bacteria isolated from the agrocoenosis of winter wheat

From an agrocoenosis of winter wheat (Triticum aestivum L.; phylloplane and rhizosphere of the root system; typical chernozem, soil column measuring up to 40 cm), using the classical microbiological methods, we had isolated soil bacteria and characterized them according to the morphological features as representatives of Gram-positive and spore-forming bacteria of Bacillus sp. genus. In the earing-swelling phase of grain, the screening studies found non-pigmented forms of colonies of bacterial isolates, 19 of which were classified to colonial-morphological diversity of R-type with the diameter of 7 to 13 mm. The analysis of physiological condition of cells of populations of soil isolates revealed technologic specificity according to parameters of spore formation in different conditions and incubation time (up to 48–72 h). We observed 90.0% of free spores in axenic cultures as early as after 72 h of cultivation and no more than 10.0% of prospores in the studied monoisolates with stable morphologic traits. Isolates Н10 and Н45 demonstrated the ability to grow in higher cultivation temperatures (+37…+40 °С). According to environmental рН, isolates were able to grow in рН ranging 4.5–8.0. Differential diagnostic testing revealed that as the source of carbon, with formation of acid, soil isolates used arabinose, xylose, mannitol, glucose, galactose, fructose, maltose, sorbitol, glycerin, dextrin, starch, rhamnose and dulcite (with development of alkaline). There was observed active use of mineral forms of nitrogen: ammonium salt and nitrates, aminoacids and proteins. The isolates hydrolyzed casein, gelatin, starch, and litmus was being reduced in the young during growth in milk with litmus. They also exerted catalase activity and were oxidase-positive. Biochemical testing using API test system determined that the studied isolated bacteria differed by a range of fermentation carbohydrates, reduction of nitrates. In the conditions of submerged fermentation, isolates Н38 and Н40 grew in heightened temperature ranges of cultivation (40 °С) for 48 h (according to fact of spore development). Therefore, according to the key morphologic and biochemical traits, strains Н3, Н10, Н13, Н36, Н38, Н40, Н43, Н45 were similar to such of reference strain B. subtilis 8A, and were identified to Bacillus sp., species B. subtilis.

Soil Microbial Functional Diversity under the Single-Season Influence of Traditional Forest Management in a Sessile Oak Forest of Central Europe

This one-year study focuses on the responses of a soil environment to the implementation of traditional forest management practices in oak–hornbeam stands with the following treatments: cut (C), cut + litter raking (CR), cut + grazing (CG), cut + litter raking + grazing (CRG) and control (Ctrl). The cut was conducted in 2018 through extremely heavy thinning. In autumn of 2017 and 2018, we sampled the soils, focusing on microbial functional diversity (FD) assessments using BIOLOG EcoplateTM. After one season, the FD was the highest in the Ctrl stand and the lowest in the CRG stand. Furthermore, we detected significant seasonal differences in soil reaction, nitrate nitrogen content, phosphatase activity and microbial biomass among the treatments. In particular, the Ctrl stand was defined via FD indices and biochemical and biological soil properties that contrasted mainly with those of the CRG stand defined by the content of mineral nitrogen forms. The soil properties did not differ substantially in the remaining treatments. Of the 31 carbon sources defining FD, 6 were treatment-specific (putrescine, L-arginine, L-serine, L-threonine, D-cellobiose and glycogen), while the remaining carbon sources mainly displayed either uniform high or low activity across the treatments.

The Cumulative Effect of Various Tillage Systems and Stubble Management on the Biological and Chemical Properties of Soil in Winter Wheat Monoculture

Agricultural practices, including tillage systems and postharvest residue management, strongly affect a wide range of soil properties. Depending on the degree of soil inversion, both negative and beneficial changes of its structure, chemical composition, and biological activity may occur as a result of these treatments. The three-year experiment was carried out on the soil under winter wheat (cv. Arktis) monoculture. The effect of various tillage systems and stubble management on the soil environment’s biological and chemical features was investigated. The total number of microorganisms (TNM); bacteria (B); actinobacteria(A); fungi (F); soil respiratory activity (SR); pH in 1 M KCl (pH); organic carbon content (OC); content of available phosphorus (Pa); potassium (Ka); magnesium (Mg); and content of total nitrogen (TN) and mineral nitrogen forms were determined in soil samples. It was shown that manure application was the factor with the greatest influence on soil properties. The manure fertilization resulted in a higher number of microorganisms in arable soil. Conventional tillage procedures combined with manure application increased the amounts of available forms of phosphorus, potassium, magnesium, and mineral nitrogen. Introduction of the chopped straw in the field enhanced the beneficial effect of manure on soil properties.

Evaluation of the trophic level and self-cleaning ability of small flows by hydrochemical indicators (through the example of the Rpen River)

Aim. Assessment by nitrification index values of the level of trophicity and toxicity for aquatic organisms in the waters of a small watercourse in an urbanized area by the content of nutrients in the water and its selfcleaning ability.Materials and Methods. The concentration of compounds of nutrients in the waters of the river was determined using the "Kapel 104T." system of capillary electrophoresis. Water was sampled for analysis according to GOST R 51592- 2000. The water content of readily oxidized organic compounds was assessed by the magnitude of permanganate oxidizability (PND F 14.1; 2.4.154-99) and difficultly oxidized compounds by the magnitude of the chemical oxygen consumption (RD 52.24.421-2012). Assessment of the water trophic level was evaluated by measuring the content of various forms of mineral nitrogen and mineral phosphorus. The aggregation index characterizing the toxicity of various forms of mineral nitrogen to aquatic organisms was calculated by their ratio to MPC for fishery reservoirs. The nitrifying ability of river waters was estimated by the value of the nitrification index (Initr.), calculated by the ratio of the concentration of nitrogen of nitrates in water to the sum of the concentrations of various forms of mineral nitrogen and the self-cleaning ability by the values of the nitrification index.Results. In terms of the aggregation index, water at all sampling points was found to be toxic. The river ecosystem is characterized by a weak ability to cleanse itself and a weak nitrifying ability, which is associated with the influence of numerous cyanotoxins on the microbiocenosis of the watercourse and filtration organisms.Conclusion. It was shown that the most sensitive indicator of trophicity of river waters is the concentration of the mineral phosphorus. Through measuring the ratio of the concentrations of mineral nitrogen to mineral phosphorus, it was established that blue-green algae (cyanobacteria), producers of cyanotoxins, dominate in the phytoplankton of the river in all the points studied.

Number of ecological-trophic groups of microorganisms depending on technology of winter wheat cultivation on ordinary chernozem of the Central Caucasus

Aim. To study the influence of cultivation technology on the number of ecological and trophic groups of microorganisms and the yield of winter wheat on the common chernozem of the Central Caucasus.Material and Methods. The number of microorganisms was determined by counting colonies on dense nutrient media according to generally accepted methods.Results. The number of microorganisms that transform organic and mineral forms of nitrogen and soil yeast was determined, depending on meteorological conditions, soil cultivation and fertilizers. Mineral fertilizers had the most significant effect on the activity of the soil microbiota. In years of varying moisture availability, fertilizers improved the nutrient regime of the soil, which contributed to increased plant development, microflora activity and increased winter wheat yield. In both the technologies applied, the largest number of all groups of microorganisms studied was observed when applying a complete mineral fertilizer -N52P52K52 .This dose of fertilizer also provided the highest yield of winter wheat - 6.07-6.33 t/ha. With a balanced plant nutrition regime (N52P52K52), the processes of decomposition and mineralization of plant residues proceeded at the same rate in both technologies. At the same time, without the use of fertilizers, the total activity of microorganisms in the no-till technology exceeded the minimum technology by 23.4х105 columnforming units, which indicates the beginning of the process of self-healing of the soil in the third year after the transition to direct sowing of crops.Conclusion. The number of microorganisms is one of the most sensitive indicators of the direction of complex biochemical processes, allowing us to assess the combined influence of all factors on the overall state of the soil microbiocenosis.

Microbiologic assessment of accelerated solid-state fermentation of agricultural organic wastes

Livestock and poultry wastes, when effectively managed, become feedstock for organic fertiliser production. Researchers from the All-Russian Research Institute of Reclaimed Lands, the branch of Federal Research Center “V.V. Dokuchaev Soil Science Institute”, proposed an accelerated regimen of cattle manure solid-phase fermentation with peat: 48 h at 37 °C, then 48 h at 60 °C and 24 h at 37 °C, terminating with nat-ural cooling of the fermented mass. A distinctive feature of the proposed accelerated fermentation is maintenance of set-point temperatures. The aim of the work is to perform a microbiological evaluation of the process of accelerated solid-phase fermentation. An experiment was carried out in a 1.75 dm3 laboratory fermenter. During the fermentation, we studied the number of microorganisms, which use organic and mineral nitrogen forms, using the limiting dilution method, as well as the species membership by mass spectrometry. The experimental findings showed that the temperature regime of the main fermentation steps yielded the maximum number of mesophilic and thermophilic nitrogen-transforming microorganisms. Their active growth caused the intensive transformation of the fermented mixture, as evidenced by mesophilic and thermophilic mineralisation coefficients. At the end of the process, the linear mineralisation coefficients were used to assess the completion of the fermentation product transformation and stabilisation. The fermentation product comprised a high number of nitrogen-transforming microorganisms (on average, 3.5±0.3•108 COE/g on a dry weight basis). The determination of the microbiota species membership in the fermented mass and the final product confirmed that the process temperature regime ensured the elimination of the sanitary-indicatory microorganisms present in the original mixture (E. coli, Citrobacter, Proteus). In addition, during pasteurisation, this regime led to the active development of non-pathogenic Bacillus bacteria (B. megaterium, B. subtilis, B. licheniformic, B. pumilus and B. altitudinis). The fermentation product is recommended for use as an environmentally safe organic fertiliser based on the microbiological evaluation.

Effect of the effects of different doses of mineral fertilizers on the number of ecological-trophic groups of microorganisms

The results of studies on the effect of mineral fertilizers on the number of ecological and trophic groups of microorganisms and the yield of winter wheat in the zone of unstable moisture in the Stavropol Territory are presented. The soil of the experimental site is ordinary chernozem, a powerful low-humus heavy-loam, the precursor is pure steam. Mineral fertilizers have been applied in various doses for 30 years, and the aftereffect of fertilizers has been studied since 2006. The total number of microorganisms in the aftereffect of nitrogen or phosphorus fertilizers alone was low (5.53–8.0 mln columnforming units). The number of microorganisms that transform organic forms of nitrogen in the aftereffect of nitrogen or phosphorus nutrition alone ranged from 2.62 to 4.16 mln column-forming units, and using mineral forms of nitrogen from 2.91 to 4.32 mln column-forming units. The full dose of fertilizers significantly increased the number of microorganisms that transform nitrogen compounds in the soil by an average of 15.5 mln column-forming units. The maximum total number of microorganisms was obtained in the aftereffect of high doses of nitrogen against the background of P 120 K 120 and phosphorus together with N 120 K 120 — 28.58 mln column-forming units and 30.21 mln column-forming units, respectively. The coefficient of mineralization in the studied soils is greater than one. With the unilateral introduction of nutrients in the soil, the intensity of microbiological processes decreases, сoefficient of microbiological transformation of organic matter — 3,94–8,64.

Linking microbial taxa and the effect of mineral nitrogen forms on residue decomposition at the early stage in arable soil by DNA-qSIP

The decomposition of crop residues represents the largest organic carbon (C) input into agricultural ecosystems, and plays an important role in soil C sequestration and soil fertility. However, how different forms of mineral nitrogen (N) influence the decomposition of these residues, or their associated active microbes, is poorly understood. In this study, we investigated the impacts of ammonium ((NH4)2SO4) and nitrate (KNO3) on the early stages (14 days) of decomposition of highly enriched 13C-labeled (13C atom% = 77.0%) maize residues. Further, we characterized the contributions of various bacterial and archaeal taxa using quantitative stable isotope probing (qSIP). To our surprise, we found that the majority of measured parameters including 13C soil respiration, total 13C microbial assimilation in soil DNA, as well as the diversity and structure of these microbial communities, were not significantly different between these two N forms during our 2-week incubation. Slight differences were observed however, in the activity of straw-metabolizing microbes. The qSIP revealed variability in 13C assimilation (excess atom fraction, EAF) among different microbial taxa at the operational taxonomic unit (OTU) level, with Proteobacteria, Bacteroidetes, and Verrucomicrobia being the most intensively 13C-labeled phyla, suggesting their potentially dominant roles in residue decomposition. However, only the 13C EAF of Thaumarchaeota (genus Nitrososphaera) was significantly higher in the ammonium treatment than in the nitrate treatment. The Nitrososphaera might indirectly participate in the decomposition of residues by fixing CO2 or by directly incorporate 13C from organic matter. These results reveal a quantitative overview of the contribution of bacteria and archaea to residue decomposition. Further, we document that the similar effect of nitrate and ammonium on residue decomposition at the early stages is likely due to the unchanged activity of predominant bacterial taxa with the two N forms.

Preliminary Results of Effect of Rotational Grazing of Farmed Red Deer (Cervus elaphus) on the Biochemical Status of Soil

The aim of the study was to identify the trends and dynamics of changes in the chemical and biochemical properties of soil induced by rotational grazing of farmed deer. Soils pH and the content of mineral nitrogen forms, total nitrogen, and organic carbon were determined in the study and the activity of three soil enzymes. The monitored soils were slightly acidic and neutral, with pH in 1 mol KCldm−3 ranging from 6.37 to 7.03. The contents of content of organic carbon, total nitrogen in the monitored soils were in the range of 9.42–19.37 gkg−1 and 1.13–2.24 gkg−1, respectively, while the contents of N-NH4+ and N-NO3− of 1.34–7.08 mgkg−1 and 102.8–619.5 mgkg−1, respectively. The mean levels of nitrate nitrogen in the pasture soils were lower than that in the mown soil. The soils from the pastures were characterized by a higher level of available phosphorus, potassium, and magnesium forms than the mown soil. In the deer grazing areas, the activity of all enzymes was clearly higher than in the soil from the control plot. The results of the present pilot study have demonstrated a positive effect of cervid grazing on the biochemical parameters of the soil environment.

Изучение динамики численности эколого-трофических групп микроорганизмов эпифитной микробиоты Stellaria media и Urtica dioica

The dynamics of the strength of the epiphytic microbiota of the root zone and phyllosphere of the Stellaria media and Urtica dioica in the vegetation phase of plants (seedlings, flowering, fruiting) was studied. The data on the strength of microorganisms of ecotrophic groups are presented: ammonifying bacteria using mineral forms of nitrogen, bacteria of the Escherichia coli group, micromycetes and bacteria in the spore stage. It was determined that the medium-sized microbiota of the Stellaria media is more strengthen than the Urtica dioica, which is probably due to the morphoanatomical features of plants and the metabolites produced. The microbiota of the rhizosphere of plants of the Stellaria media and Urtica dioica is much more strength than the phyllosphere due to the root exudates of plants that provide food for microorganisms. The dynamics of the microbiota of the rhizosphere reflects the unequal level of metabolite production by plants in different phases of vegetation. The total strength of aerobic bacteria that metabolize organic nitrogen in the basal zone of Stellaria media increases in the flowering phase, and in the basal zone of Urtica dioica – in the phase of seedlings.The greatest strength of microscopic fungi during the flowering phase of Stellaria media is probably associated with the production of metabolites by plants and favorable weather conditions for the development of micromycetes. Micromycetes belong to the following genera: Trichoderma, Penicillium, Fusarium, Botrytis, Mucor, Aspergillus, Cladosporium. The strength of phyllosphere microorganisms varies according to the stages of plant vegetation. The Stellaria media and the Urtica dioica have a specific microbial complex, both in the aboveground and underground parts, which varies during the growing season and differs in a certain ratio of ecological and trophic groups of microorganisms.

The influence of soil microorganisms on heavy metal content in the substrate of waste rock dumps

The environmental effects of mining and its impact on natural resources are of a holistic nature. One of the modern methods employed for the remediation of technogenically disturbed soils is the application of microorganisms. This paper studies the impact made by soil microorganisms on the accumulation rate of heavy metals in the substrate of waste rock dumps in the process of soil reclamation. Suspensions of soil microorganisms (microorganisms utilising mineral nitrogen forms / MUMN; microorganisms decomposing silicates / MDS; microscopic fungi / MF) were applied to the rock dump surface. Separate groups as well as their combinations were applied. The heavy metal content analysis did not indicate a significant exceedance of the maximum allowable concentration limits (MACL) in the soil of the waste rock. The only metal whose content exceeded the maximum admissible concentration limits was nickel. It has found that the application of microorganisms influences the concentration of several heavy metals due to pH level changes of the rock dump soil.

Assessment of quality of spring waters of Valdai District of Novgorod Region by chemical indices

The article presents data on the chemical composition of water from springs of Valdai District of Novgorod Oblast. In twelve, the most known and frequently visited, sources concentrations of main ions, values of indices characterizing the pollution of springs with organic substances and mineral forms of nitrogen, as well as the content of ions of heavy metals were determined. Water from nine examined sources corresponds to sanitary and hygienic standards.

Arthroderma tuberculatum and Arthroderma multifidum Isolated from Soils in Rook (Corvus frugilegus) Colonies as Producers of Keratinolytic Enzymes and Mineral Forms of N and S.

Keratinolytic fungi representing the genus Arthroderma that were isolated from the soils of a rook (Corvus frugilegus) colony were used as biological agents for the disposal of waste feathers. The aim of this study was to assess the abilities of Arthroderma tuberculatum and Arthroderma multifidum fungi with a varied inflow of keratin matter to biodegrade waste feathers. The evaluation was based on the determination of feather mass loss, the activity of keratinolytic enzymes, and the content of mineral N and S forms. It was found that the activity of protease released by the fungi contributed to an increase in the level of soluble proteins and peptides and the concentration of ammonium ions, as well as alkalization of the culture medium. Keratinase activity was significantly correlated with sulfate release, especially in A. tuberculatum cultures. The strains of A. tuberculatum fungi isolated from the soil with the highest supply of organic matter, i.e., strains III, IV, and V, had the lowest enzymatic activity, compared to the A. multifidum strains, but they released mineral nitrogen and sulfur forms that are highly important for fertilization, as well as nutritionally important peptides and amino acids. A. tuberculatum strains can be used for the management of waste feathers that can be applied in agricultural practice.

Assessment of the Trophic State of a Small Plain Reservoir during Different Periods of Its Existence (a Case Study of the Penza Reservoir on the Sura River)

The present study provides comparative characterization of the contents of nutrients and organic matter and quantitative parameters of phytoplankton of the Sura (Penza) reservoir during 1984–1992 and 2016–2019. At present, the content of phosphates has increased by 3 times while the concentration of mineral nitrogen has remained unchanged. The seasonal dynamics of phosphorus and mineral nitrogen are different: the maximum phosphate concentrations are observed in summer and autumn, but nitrogen is the highest during the flood period. At the present time, phosphorus is mainly generated in intra-reservoir processes. Nitrates were the predominant form of mineral nitrogen in 2016–2019, and their spring maximum suggests predominant intake with the flood flow. The ratio of the mineral forms of nitrogen and phosphorus indicates that, at the present time, phosphorus is not the element that limits the development of algae. In certain periods (summer 2017–2018), a significant negative relationship was observed between the algal biomass and the total iron content in water (r = -0.81, p = 0.016). No Cyanoprocaryota “blooms” have been observed in recent years. In 2019, the abundance of Cyanoprocaryota increased, but in some regions, biomass was no more than 2.18–2.42 mg/dm3. In 2019, the dominant Cyanoprocaryota group did not contain Microcystis aeruginosa (Kütz.), but a new species was identified – Planktothrix agardhii (Gom.) Anagn. et Kom., which is resistant to low light and the low nitrogen to phosphorus ratio. The proportion of readily oxidized organic matter in the total organic matter, both at the end of the 20th century and recently, characterizes the reservoir as stably eutrophic, although the quantitative characteristics of phytoplankton in recent years indicate declining trophic status

The Influence of Spent Mushroom Substrate Fertilization on The Selected Properties of Arable Soil

Abstract In the last decades, Poland has become the leader in mushroom Agaricus bisporus production in Europe. Mushroom production generates large amounts of spent substrate, which as a waste material must be recycled. Significant in this macronutrient content, inducing nitrogen, encourages the use of this organic waste material to fertilize, especially light soils. The aim of the study was to assess the effect of spent mushroom substrate fertilization on the properties of A horizon of the Stagnic Luvisol, especially for the variation in the nitrogen fraction, in the two-year cultivation period. The following laboratory analyses were performed: soil pH, organic carbon content, total content of nitrogen and sorption properties. The sequential extraction of nitrogen compounds was performed with a 0.25 M KCl solution (for the extraction of mineral nitrogen forms and the most labile organic nitrogen compounds) and with 0.25 and 2.5 M H2SO4 (hot hydrolysis for sequencing of organic nitrogen compounds that are easily hydrolysing and difficult to hydrolyse). The application of spent mushroom substrate to the A horizons of the experimental objects had an effect on differentiation of soil properties and increased their value (pH, Corg, N-tot, Hh, CEC) in comparison to the control object to a greater degree after the first, then after the second year of cultivation. As the content of nitrogen mineral forms was differentiated, more nitrogen was found in an ammonium form (N-NH4) than in a nitrate form (N-NOx). The organic nitrogen content formed the following series of increasing amounts: soluble organic nitrogen NOS < NOEH < NODH < NONH.

Geoecological study of the soil microbial communities of the natural and agricultural ecosystems in the south-eastern Baltic sea region

ABSTRACT The number of different groups of soil microorganisms in the natural and agricultural ecosystems of the Kaliningrad Peninsula and the Curonian Spit was studied. It has been established that the studied ecosystems are distinguished by different types of soil, physicochemical parameters and the ratio of the main representatives of the soil microbial community: ammonifying microorganisms; microorganisms using mineral forms of nitrogen; nitrogen-fixing and oligonitrophilic microorganisms; cellulose-depleting microorganisms; aerobic spore-forming bacteria; microscopic fungi. The total content of different groups of microorganisms reflects the biological activity of the soil, which characterises its resistance and self-cleaning ability, which can be used in the study of modified soils under anthropogenic conditions.

Hydrochemical Structural Patterns of the Lena River–Laptev Sea Mixing Zone in the Autumn Period

This study was based on data obtained during the cruise 63 of the R/V Akademik Mstislav Keldysh in September 2015. We examine the features of the hydrochemical structure of the Lena River–Laptev Sea mixing zone. The studies were carried out in the eastern part of the Laptev Sea on a quasi-meridional transect, with the length of 710 km along 130°30' E. The distribution of dissolved oxygen, pH, alkalinity, major nutrients (phosphates, silicon, nitrate, and ammonium nitrogen), and chlorophyll a was analyzed. The relationship between the main hydrochemical parameters and chlorophyll a was considered. The distribution of hydrochemical parameters is similar to the data of previous studies: significant removal of silicon by waters of the Lena River (66.6 μM) with a moderate nitrate content (3.87 μM) and low concentration of mineral phosphorus (0.08 μM) in the area of strong influence of river runoff (salinity of 3.012 PSU). The presence of a near-bottom stagnant water zone in the part of research area affected by river runoff was detected. It is shown that the influx of mineral forms of nitrogen and phosphorus into the marine region of the Lena River delta occurs mostly as a result of nutrient recycling rather than due to the continental runoff.

Нітрогену ясно-сірого лісового поверхнево оглеєного ґрунту за тривалого антропогенного впливу

Нітрогену ясно-сірого лісового поверхнево оглеєного ґрунту за тривалого антропогенного впливу