Transformation Of Matter Research Articles

Role of keystone drives polycyclic aromatic hydrocarbons degradation and humification especially combined with aged contaminated soil in co-composting

Accumulation of persistent organic pollutants polycyclic aromatic hydrocarbons (PAHs) in soil has become a global problem. Composting is considered one of the more economical methods of soil remediation and is important for the resourceful use of wastes. Agroforestry waste is produced in huge amounts and is utilized at low rates, hence there is an urgent need to manage it. Here, leaf (LVS) or rice straw (SVS) was co-composting with aged contaminated soil to investigate bacteria interaction to PAHs degradation and humus formation. The degradation rate of high molecular weight PAHs (HMW-PAHs) in LVS and SVS reached 58.9% and 52.5%, and the low molecular weight PAHs (LMW-PAHs) were 77.5% and 65%. Meanwhile, the humus increased by 44.8% and 60.5% in LVS and SVS at the end of co-composting. The topological characteristics and community assembly of the bacterial community showed that LVS had higher complexity and more keystones than SVS, suggesting that LVS might more beneficial for the degradation of PAHs. The stability of the co-occurrence network and stochastic processes (dispersal limitation) dominated community assembly made SVS beneficial for humus formation. Mantel test and structural equation models indicated that the transformation of organic matter was important for PAHs degradation and humus formation. Degradation of HMW-PAHs led to bacterial succession, which affected the formation of precursors and ultimately increased the humus content. This study provided potential technology support for improving the quality of agroforestry organic waste composting and degrading PAHs in aged contaminated soil.

Combined Remediation Effects of Sewage Sludge and Phosphate Fertilizer on Pb-Polluted Soil from a Pb-Acid Battery Plant.

Pb soil pollution poses a serious health risk to both the environment and humans. Immobilization is the most common strategy for remediation of heavy metal polluted soil. In this study, municipal sewage sludge was used as an amendment for rehabilitation of Pb-contaminated soils, for agricultural use, near a lead-acid battery factory. The passivation effect was further improved by the addition of phosphate fertilizer. It was found that the leachable Pb content in soils was decreased from 49.6 mg kg-1 to 16.1-36.6 mg kg-1 after remediation of sludge for 45 d at applied dosage of municipal sewage sludge of 4-16 wt%, and further decreased to 14.3-34.3 mg kg-1 upon extension of the remediation period to 180 d. The addition of phosphate fertilizer greatly enhanced the Pb immobilization, with leachable Pb content decreased to 2.0-23.6 mg kg-1 with increasing dosage of phosphate fertilizer in range of 0.8-16 wt% after 180 d remediation. Plant assays showed that the bioavailability of Pb was significantly reduced by the soil remediation, with the content of absorbed Pb in mung bean roots decreased by as much as 87.0%. The decrease in mobility and biotoxicity of the soil Pb is mainly attributed to the speciation transformation of carbonate, Fe-Mn oxides and organic matter bound Pb to residue Pb under the synergism of reduction effect of sludge and acid dissolution and precipitation effect of phosphate fertilizer. This study suggests a new method for remediation of Pb-contaminated soil and utilization of municipal sewage sludge resources.

Multiple Functions of Microbes to Improve Food and Soil Nutrition in Support of Environment Management to Maintain Global Agricultural Practices

Plant-microbe interactions are interesting phenomena Soil microbial biomass is considered the living part of the soil organic matter, which acts as an agent of transformation of organic matter and is a source of available nutrients. Activities of soil microbes can change the soil environment rapidly and influence the rate of nutrient cycling. Soil microbes also play a significant role in the formation of macro aggregates. The potential of soil microorganisms has been recognized widely for the improvement of soil quality, soil formation, aggregation, and revegetation. Soil microbes are involved in various ecosystem processes, such as litter decomposition, phosphate solubilization, nitrogen fixation, oxidation of various inorganic components of soil or mineralization of inorganic components, and mycorrhizal symbiosis. Implications of plants and their symbionts like mycorrhizal fungi, nitrogen-fixing bacteria, and free-living rhizosphere populations of bacteria promote plant establishment and growth. Therefore, active soil microbial biomass is an essential component for long-term soil fertility. The application of microbial technology which we can refer to as green technology has become an integral element of forestry as well as agriculture and has substantially contributed to forest and agricultural productivity and ensuring the ecosystem’s sustainability. This article reviews some of the important aspects of microbial applications in agriculture and forestry and discusses different facets of microbial functions, their interaction with plants and soil, and their role in the sustainability of natural resources, forests, and agroecosystems.

Microbial Electrolysis Cell Exergy Evaluation

Bio-electrochemical systems have increasingly become the focus of research due to their potential in environmental biotechnology, particularly in the domains of waste utilization and energy recovery. A prominent method within this domain is the transformation of organic matter into hydrogen via microbial electrolysis cells (MECs). This study offers a thorough analysis of MEC performance, employing exergy analysis and incorporating relevant data from the existing literature. The findings of this research indicate a relationship between process efficiency and effective electron transfer originating from biological oxidation to the cathode reaction, facilitating hydrogen generation. The assessment performed revealed that the exergy efficiency of the process varies by a wide range, depending on conditions such as substrate type and concentration, applied external voltage, and the presence of specific inhibitors. This interplay between substrate concentration, overall efficiency, and energy requirement underlines the complex dynamics of optimizing MEC performance. Our insights provide understanding of the challenges in bio-electrochemical systems, offering implications for their sustainable and efficient use in environmental biotechnology. The theoretical analysis involved assessing the utilization of glucose and glycerol, along with the evaluation of electrical energy consumption and hydrogen yield. Our results demonstrate that a higher applied voltage is associated with greater exergy efficiency. Furthermore, after comparing the use of glucose and glycerol as substrates, our study supports the preferential application of glucose for enhanced efficiency.

Effect of long-term straw return on organic matter transformation by hydroxyl radical during paddy soil oxygenation

The generation of hydroxyl radicals (OH) mediated by Fe(II) has drawn increasing amounts of attention due to its significant role in the transformation of soil organic carbon (SOM) during redox fluctuations in paddy soil. This study further examined the effect of long-term (since 1984) straw return on Fe(II) on driving OH formation and SOM transformation upon paddy soils oxygenation. We found that long-term straw return could inhibit the OH and CO2 production in abiotic processes. The OH production decreased from 190.4 to 133.4 µM as the straw return amount increased from 0 to 19.16 t·hm−2·year−1. Moreover, 14.7–38.6 % of the CO2 production was associated with OH during oxygenation. By combining radical quenching and OM extraction, we determined that straw return could increase O2 reduction to H2O2 through a two-electron transfer pathway. Based on chemical extraction, Mössbauer spectra and multilinear regression model, we demonstrated that straw return resulted in more active Fe(II) species that controls the OH production. The results of 3DEEMs and FT-ICR MS showed that oxidative transformation can be accomplished by the introduction of OH to aromatic structures or olefins through ring opening and hydroxylation mechanisms. And OM at high straw return concentrations was likely oxidized by OH into bioavailable aliphatic compounds. Therefore, this study highlights the underappreciating effects of long-term straw return on Fe(II) oxidation in driving OH generation and SOM transformation in paddy soil redox fluctuation events.

Effects of Short Retention Times and Ultrasound Pretreatment on Ammonium Concentration and Organic Matter Transformation in Anaerobic Digesters Treating Sewage Sludge

Anaerobic digestion of sewage sludge is limited at the hydrolysis stage of the process. The goal of this study was to assess the effects of sludge retention times and ultrasound pretreatment on the ammonium concentration and organic matter transformation in anaerobic digesters treating sewage sludge. To achieve this, two laboratory-scale semicontinuous anaerobic digesters were operated for a period of over 70 d, including a control reactor and another fed by pretreated sludge. Both anaerobic systems were fed with mixed sludge (50%/50% primary/secondary treatment) in mesophilic conditions (37 °C), with solid retention times (SRT) of 7.5 d (Phase I) and 3 d (Phase II). The performance of the anaerobic digestion process was assessed in terms of the methane yield and the total and soluble chemical organic demand, total solids, and volatile solids removal. The results showed that the ultrasound pretreatment caused an increase of around 22.2% in CODt removal for an SRT of 7.5 d. Meanwhile, an SRT of 3 d resulted in a decrease of up to 92.4% in CODt removal. The performance in terms of biogas production and organic matter removal was significantly affected by the SRT reduction to 3 d, showing that the process is not viable in these conditions.

Microbial transformation of soil organic matter under varying agricultural management systems in Ukraine.

This paper presents comparative studies on the content and structure of organic matter (OM) and the activity of microbiological cellulose destruction in three types of Ukrainian soils intensively used in agricultural production. The highest content of humus in the arable layer (4.9%), OM (410 t ha-1), and total carbon (30.9 mg C g-1 soil) was determined in chernic phaeozems, which is 2.2-2.5 times higher than in albic retisols. The soil of natural ecosystems is characterised by a high content of microbial carbon (Cmic) in the carbon fraction of organic soil compounds. In arable soils, the content and reserves of humus and soil organic matter (SOM) have decreased by an average of 1.5-2 times. The most considerable loss of humus reserves in the soil profile was identified in albic retisols (1.96-1.44 times) and the smallest in chernic phaeozems (1.27-1.81 times). During the long-term systematic application of mineral fertilisers, the Corg content decreased by 8-21% in chernic phaeozems, 12-33% in greyzemic phaeozems, and 6-38% in albic retisols. A significant difference of 2.1-8.0 times was determined regarding the number of aerobic cellulolytic microorganisms and 1.3-3.3 times in the potential cellulolytic activity of the studied soils. The high number of cellulose-destroying microorganisms is characteristic of chernic phaeozems with a high content of OM in the soil; the advantage over other types of studied soils was 1.4 times and 7.8 times for greyzemic phaeozems and albic retisols, respectively. Among the studied soil types, high values of CO2 emissions were identified in chernic phaeozems. Intensive agricultural practices in Ukrainian soils have significantly altered the content and composition of organic matter, leading to reduced humus and soil organic matter reserves. The study also underscores the importance of considering the abundance of cellulose-destroying microorganisms and their potential activity in assessing soil health and sustainability.

Polysaccharide preferred minority-dominant community assembly and exoenzyme enrichment in transparent exopolymer particles: Implication for global carbon cycle in water

The ubiquitous transparent exopolymer particles (TEPs) are an important organic carbon pool and an ideal microhabitat for bacteria in aquatic environments. They play a crucial role in the global carbon cycle. Organic matter transformation and carbon turnover in TEPs strongly depend on the assembly of their associated bacterial communities and enzyme activity. However, the mechanisms of bacterial community assembly and their potential effects on the organic carbon cycle in TEPs are still unclear. In this study, we comparatively explored the community assembly of TEP-associated bacteria and bacterioplankton from surface freshwater using metagenomics. It was found that the bacterial community assembly in TEPs followed a minority-dominant rule and was governed by homogeneous selection. Pseudomonadota and Actinomycetota, which are responsible for polysaccharide degradation, serve as taxon-specific biomarkers among the abundant and diverse bacteria in TEPs. The network of TEP-associated bacteria displayed stronger robustness than that of bacterioplankton. Bin 76 (majorly Acinetobacter) was the overwhelmingly dominant taxa in TEPs, whereas there was no clearly dominant taxa in TEP-free water. Exoenzyme analysis showed that 64 out of 71 identified polysaccharide hydrolases were markedly linked with the dominant bin 76 in TEPs, while no such linkage was observed for bacterioplankton. Generally, Acinetobacter, which is capable of utilizing polysaccharides, is preferred to be assembled in TEPs together with high polysaccharide hydrolase activity. This may significantly accelerate the turnover of organic carbon in the giant global TEP pool. These findings are important for a deep understanding of the carbon cycle in water.

Niche separation in bacterial communities and activities in porewater, loosely attached, and firmly attached fractions in permeable surface sediments.

Heterotrophic microbes are central to organic matter degradation and transformation in marine sediments. Currently, most investigations of benthic microbiomes do not differentiate between processes in the porewater and on the grains and, hence, only show a generalized picture of the community. This limits our understanding of the structure and functions of sediment microbiomes. To address this problem, we fractionated sandy surface sediment microbial communities from a coastal site in Isfjorden, Svalbard, into cells associated with the porewater, loosely attached to grains, and firmly attached to grains; we found dissimilar bacterial communities and metabolic activities in these fractions. Most (84%-89%) of the cells were firmly attached, and this fraction comprised more anaerobes, such as sulfate reducers, than the other fractions. The porewater and loosely attached fractions (3% and 8%-13% of cells, respectively) had more aerobic heterotrophs. These two fractions generally showed a higher frequency of dividing cells, polysaccharide (laminarin) hydrolysis rates, and per-cell O2 consumption than the firmly attached cells. Thus, the different fractions occupy distinct niches within surface sediments: the firmly attached fraction is potentially made of cells colonizing areas on the grain that are protected from abrasion, but might be more diffusion-limited for organic matter and electron acceptors. In contrast, the porewater and loosely attached fractions are less resource-limited and have faster growth. Their cell numbers are kept low possibly through abrasion and exposure to grazers. Differences in community composition and activity of these cell fractions point to their distinct roles and contributions to carbon cycling within surface sediments.

“What makes every work perfect is cooking and grinding”: the ancient roots of mechanochemistry

The chemical replication of ancient recipes shed light on the importance of grinding in the old times, emphasizing the crucial role of this process in the transformation of matter.

Diel Patterns in the Composition and Activity of Planktonic Microbes in a Subtropical Bay

Planktonic microbes play a crucial role in the matter transformation and energy transfer of marine ecosystems. Marine microbial communities are profoundly influenced by various environmental factors, and their variations are typically investigated in a time-dependent manner. However, studies conducted on a monthly or annual basis do not offer sufficient temporal resolution to reveal changes that can occur on an hourly basis. We conducted a high-resolution time-series study using amplicon sequencing on seawater samples taken at 2-h intervals over a 3-d period from the subtropical Daya Bay to investigate changes in the microbial community composition and activity. The results showed that 46.8% of the microbial rRNA sequences exhibited circadian rhythms, including phytoplankton (e.g., Bacillariophyta, Cryptophyta, and Dinophyceae), heterotrophic bacteria (e.g., Actinomarinaceae, Flavobacteriaceae, and SAR11_clade), and zooplankton (e.g., Bestiolina and Phyllopharyngea). The genera of Bacillariophyta (e.g., Chaetoceros and Pseudo-nitzschia ) exhibited higher activity than those of Chlorophyta (e.g., Micromonas ). A similar trend was observed for zooplankton, where Choanozoa (e.g., Copepoda ) showed a strong circadian rhythm in abundance whereas Ciliophora (e.g., Pithites ) were more active. Light intensity and tides were identified as the driving factors behind the periodic succession and activity of the heterotrophic bacteria and phytoplankton with the exception of picocyanobacteria, which were mainly influenced by fluctuations in temperature, nutrients, and salinity. These high-resolution time-dependent observations showed that, despite the dynamic coastal environment, the periodic changes in the microbial community and activity were distinct and phylogenetically conserved. The findings may help in the development of ecosystem models for predicting microbial abundance and activity in rapidly changing coastal and estuary environments.

“Gray Carbon” in Sewage Treatment Plants: A Neglected Carbon Sink

This study introduces the concept of “gray carbon,” emphasizing its critical role in carbon sequestration in sewage treatment. By focusing on recalcitrant dissolved organic carbon (RDOC) in sewage effluents and its subsequent transformation in marine environments, we underscore the significant impact of sewage-derived organic carbon on the efficiency of carbon sequestration. Through analysis of carboxylic-rich alicyclic molecules, this study illuminates the convergence in the molecular compositions of RDOC across various aquatic systems. Dark-culture experiments reveal marked variations in the microbial community structures of the aforementioned molecules, indicating that these changes may play an important role in the degradation and subsequent transformation of organic matter in marine environments. These insights lay the groundwork for advancing technologies designed to enhance wastewater alkalinity, which will improve the sustainability of wastewater treatment and preserve marine ecosystems. Enhancing sewage alkalinity can influence microbial processes and chemical equilibria, potentially affecting the formation and accumulation of gray carbon. Further investigation is necessary to understand the potential effect of alkalinity enhancement on the microbial communities and biochemical pathways involved in gray carbon formation. Our findings support the integration of gray carbon strategies into broader carbon neutrality initiatives, providing a scientific and technological blueprint for enhancing global carbon management and mitigating climate change.

Effect of elastic filler on the treatment effect and archaea community structure of ABR

This research endeavored to elucidate the influence of elastic fillers on the performance and archaeal community configuration of the Anaerobic Baffled Reactor (ABR). Utilizing high-throughput sequencing technology, the archaeal community structure was assessed in two distinct ABR sets. The findings revealed that the introduction of elastic fillers led to an enhancement in the average COD removal rate, BOD5 removal rate, effluent biodegradability, and fecal coliform removal rate of the ABR by 3.55%, 3.02%, 7.45%, and 96.85% correspondingly. Concurrently, it facilitated the transformation and degradation of organic matter within the ABR, thus resulting in an increased conversion of organic matter into Volatile Fatty Acids (VFA) within the initial compartment, and enhanced VFA degradation in the subsequent compartments. Indices such as Chao1, Observed species, Simpson, and Shannon concurred that the abundance and heterogeneity of the archaeal community within the ABR were augmented. The average relative abundance of dominant archaea (Methanosaeta and Methanobacterium) in the first compartment of ABR diminished by 3.44%, whereas in the second, third, and fourth compartments, the abundance escalated by 10.50%, 4.18%, and 2.78% respectively. The inclusion of elastic fillers not only amplified the hydrolysis and acid production process in the first compartment of the ABR but also fostered the methane production process in the subsequent compartments.

Ecological and Faunistic Analysis of Lumbricidae Species Composition of Natural Biogeocenoses and Man-made Territories

Earthworms make up the bulk of the soil mesofauna and play an important role in the transformation of organic matter, the formation of the pedosphere, the regulation of the flows of matter, energy and information in ecosystems. In this research, we have studied the species composition of earthworms in urban and suburban ecosystems of the foothills of the Trans Ili-Alatau. As a result of the work, 11 species of the Lumbricidae family of the Oligochaeta class were discovered. 6 species out of them have been discovered in our Republic: Aporrectodea rosea, Lumbricus rubellus, Lumbricus castaneus, Octolasion lacteum, Dendrobaena octaedra and Aporrectodea caliginosa are widespread. The genus Lumbricus is the most common in terms of the number of individuals in the studied territories. Significant differences have been established in the species composition of earthworms in technogenic and natural biogeocenoses. The lumbricides are the absolute dominants in two ecosystems. Along with the species composition of earthworms, seasonal dynamics were also studied, it was found that their maximum activity is observed at the most favorable ratio of temperature and humidity.

Results of Quantitative Estimation of Unconventional Oil Resources of the Russian Federation

Abstract —The estimation results of the initial total unconventional resources of hydrocarbon in Domanik type sediments, the Khadum and Bazhenov formations are provided. The reasonability of estimating hydrocarbon resources in these deposits by the volumetric method is substantiated. The stratigraphic interval of their distribution is given. The technique of oil and gas geological zoning based on the mapping of structural and facies zones, the degree of catagenetic transformation of organic matter, and the boundary values of the thickness of carbonaceous rocks in the section is described. The criteria for the allocation of pay intervals that make up the effective part of the section are determined. The choice of parameters such as porosity coefficient, oil recovery coefficient, oil saturation coefficient, correction factor and oil density is justified. For each complex of deposits, adjustments related to the features of the geological structure of the estimation targets, the conditions of their occurrence and the degree of geological and geophysical study have been introduced into the estimation of total geological resources. The volumes of total geological and recoverable resources of unconventional hydrocarbon sources for the Volga– Ural, Timan–Pechora, Black Sea–North Caucasus, West Siberian and Lena–Tunguska oil and gas provinces are given. The conducted research has rationalized extensive resources, the recovery of which can compensate for the decrease in oil volumes from traditional deposits.

Degradation of peat-forming plants at the first stages of decomposition in natural and post-pyrogenic peatlands of West Siberia

The aim of the study. Assessment of the phytomass stocks and decomposition rate of peat-forming plants’ residues in peat deposits of natural and post-pyrogenic peatlands at the initial stages of decomposition. Location and time of the study. The study was carried out in 2022 (May-September) at two oligotrophic bog sites: “Bakcharskoye” (field station “Vasyuganye”, IMCES SB RAS) and “Iksinskoye”, which are located in the north eastern spurs of the Great Vasyugan mire in the Bakcharsky and Shegarsky districts of the Tomsk region, Russia. Methods. The phytomass stocks were determined by the cutting method. The following fractions were separated: living phytomass (annual and perennial photosynthetic phytomass, i.e. green parts of grasses, shrubs leaves, mosses); perennial non-photosynthetic phytomass, i.e. shrubs stems, roots of grasses and shrubs; and dead phytomass (mortmass), i.e. litter, moss litter, standing dead phytomass. The decomposition rate of plant residues was determined by the method of litter bags placement in peat (Chamaedaphne calyculata, Sphagnum fuscum, Mixed sample consisting of 60% S. fuscum and 40% Ch. calyculata). In the initial and decomposed samples, the ash content was determined by the dry combustion method. The total carbon and nitrogen content, as well as the carbon and nitrogen isotopic composition, were determined using a DELTA V Advantage isotope ratio mass spectrometer. Results. This short-term study conducted during the growing season in conditions of undisturbed (Natural Ryam) and post-pyrogenic (Gar) phytocenoses showed that due to a significant amount of mortmass (2402 g/m2) Natural Ryam had organic matter stock exceeding that in the Gar by 1.7 times. On average, 59% of organic matter loss from the total losses during the growing season occurred in the first month. In both Gar and Natural Ryam conditions, minimal losses of organic matter were characteristic for Sphagnum fuscum (3.1 and 3.5% respectively). For the remaining samples the Gar conditions were more favorable for the degradation at the initial stages of decomposition. The Mixed sample occupied an intermediate position between its individual components in terms of mass losses. Carbon losses correlated well with mass losses both over 1 month of degradation (r=0.87) and over 4 months (r=0.96). In contrast to carbon, nitrogen accumulated in the Mixed sample at the initial stages of degradation, both after 1 month and 4 months. Conclusions. With smaller phytomass stocks in areas of post-pyrogenic succession, more active decay at the initial stages of organic matter decomposition occurs exactly under these conditions. The impact of post-pyrogenic succession on the rate of organic matter decomposition of Chamaedaphne calyculata plant residues and the Mixed sample was demonstrated. The most intensive decomposition of litter occured during the first month of degradation. Additionally, in the conditions of a burnt bog, a more intense release of nitrogen from all plant residues and accumulation of ash elements in Sphagnum fuscum samples were observed. The mixing of litter components influenced both the rate and dynamics of decomposition. The carbon and nitrogen isotopic composition began to change during the initial stages of decomposition, leading to enrichment with heavier isotopes 15N and 13C. This research emphasizes the importance of studying the processes of plant litter decomposition at the initial stages and considering the plant residue composition when studying the processes of organic matter transformation.

Effect of Organic Waste and Inorganic Additives on Organic Matter Transformation and Mineral Availability in Composting Green Waste

Effect of Organic Waste and Inorganic Additives on Organic Matter Transformation and Mineral Availability in Composting Green Waste

Soil Microbial and Enzymatic Properties in Luvisols as Affected by Different Types of Agricultural Land-Use Systems and Soil Depth

Determination of the microbial and enzymatic properties in soil is primarily concentrated on the surface layers of the soil profiles; however, it is well known that the transformation of soil organic matter also occurs in the deeper horizons of the soil profile. The aim of this study was to assess any changes in specific sets of enzyme activities and their associated physicochemical properties as affected by two different agricultural land-use systems and soil depth. Changes in the studied properties were determined across four Luvisol profiles in two agricultural land uses (arable land and vineyards). The enzyme activities associated with the transformation of C, N and P were analyzed. Additionally, the activity of some oxidoreductases and the fluorescein diacetate hydrolysis (FDAH) rate were also determined. Moreover, the content of the various forms of soil carbon, nitrogen, phosphorus (including microbial biomass C, N and P) and some other properties (pH, clay and silt content) were assessed. Agricultural land use significantly affected the microbial biomass content and as well as the studied enzyme activities. Most of the studied enzymes exhibited a higher activity in the grapevine (GV) profiles, which was followed by the winter wheat (WW) profiles; however, the largest variability occurred for the urease activity. There was no clear differentiation between the two studied land uses for the activity of nitrate reductase, dehydrogenases, acid phosphatase, or endo- and exo-cellulase. Irrespective of the plant being cultivated, the soil variables decreased significantly with increasing soil depth, wherein the greatest changes were observed between the surface and sub-surface soil horizons (I–II). The activity of some enzymes (e.g., the urease activity in WW profiles) decreased gradually across the soil profiles, while others were located almost solely within the surface layers (e.g., the nitrate reductase activity in the GV profiles as well as invertase in the WW profiles). The α-glucosidase activity did not exhibit any statistically significant changes along the analyzed profiles. The activity of phenol oxidase and peroxidase also revealed different trends along the studied profiles compared to the other enzymes and did not decrease gradually with depth. The microbial biomass of the C, N and P content was generally the highest in the upper horizons and gradually decreased with depth, wherein the largest decrease was observed between the surface and sub-surface horizon. The studied enzyme activities were more dependent on the soil carbon content compared to the other soil properties. And thus, in the C-rich horizons (C > 4 g kg) for the surface and subsurface layers the enzyme activities were highly correlated with TOC, DOC and MBC content as compared to the deeper, C-low horizons (C < 4 g kg). By examining how the microbial and enzymatic properties change across the soil profiles, it is possible to gain valuable insight into the long-term biogeochemical processes that are involved in soil fertility and in the health of agricultural ecosystems.

Dynamics of the microorganisms’ number in the soil mass of podzolized chernozem after treatment with fungicides of various origins

In a laboratory model experiment, the dynamics of the number of bacteria and micromycetes in the soil mass of podzolized chernozem after a one-time treatment of its surface with fungicides of various origins investigated. Chemical fungicides based on the active substances carbendazim, tebuconazole and azoxystrobin, and biological fungicides based on the antagonistic fungi Trichoderma viride (lignorum) and Chaetomium cohliodes were used. The soil mass for the experiment was taken from the arable layer of the soil on the site without fertilizers in the field experiment of the Department of Agrochemistry NSC "Institute for Soil Science and Agrochemistry Research named after O. N. Sokolovsky" (NSC "ISSAR") on the territory of SE "EF Hrakivske" (Noviy Korotych village, Kharkiv district, Kharkiv region). During 110 days of composting at a constant temperature, changes in the state of microbial communities, in particular soil micromycetes, and the speed and completeness of their recovery compared to soil not treated with fungicides evaluated. The state of the microflora was monitored four times during the study period according to the parameters of the number of microorganisms belonging to various ecological-trophic and taxonomic groups, the total biological index (TBI) and indicators reflecting the functional state of microbial coenoses (oligotrophy and mineralization indices, the coefficient of microbial transformation of soil organic matter (MTSOM). On the fifth day after treatment with fungicides, the number of bacteria and micromycetes in the samples of the treated soil mass was slightly higher higher than in the control samples, and on the twentieth day, on the contrary, it was significantly lower. The number of bacteria was lower by 20-46 %, micromycetes by 16-34 % compared to the control. On the fortieth day, a partial restoration of the number of bacteria to the level of the untreated control soil observed, and the number of micromycetes remained lower by 9-36 % compared to the control in the case of chemical fungicides. When using biological fungicides, the number of micromycetes approached the values in control soil and accounted for 84-94 % of them. On the one hundred and tenth day, the number of microflora in the soil treated with chemical fungicides according to TBI was 79-89 % of the control values, and in the soil treated with biofungicides it was 102-104 %. The number of micromycetes decreased to a lesser extent and recovered most completely and quickly in the case of the application of the biological fungicide Hetomic. Given the important role of soil micromycetes in the functioning of soils, a decrease in their number due to the accumulation of residual amounts of chemical fungicides in the soil can have a negative impact on many soil-biological processes, in particular the decomposition of plant residues and further transformation of organic matter, as well as on the phytosanitary state of the soil. Therefore, in order to avoid the possible consequences of their excessive or repeated application and the associated threat of soil contamination, it is necessary to carry out microbiological monitoring of soils in areas with a high fungicide load.

Transformation and aging of organic matter during degradation and preservation in marine sediment of the northern South China Sea

Organic matter (OM) preservation in marine sediments is an important sink in the carbon cycle and the isotopic records of the preserved OM provide useful information on the sources, biodegradation, and transformation of organic carbon during early diagenesis. Here, we present radiocarbon data combined with stable carbon isotope measurements of total organic carbon (TOC) and four organic fractions, namely, total lipids, hydrolysable amino acids (THAAs), humic acids (HAs), and acid-base insoluble OM, separated from four sediment cores collected from the South China Sea (SCS), to reveal their sources and transformation. The total lipids, THAAs, HAs and acid-base insoluble OM fractions account for 1.1 ± 0.4%, 3.1 ± 1.6%, 12.7 ± 9.4% and 61.6 ± 10.0% of the TOC (the percentages of organic fraction in TOC), respectively, and the acid-base insoluble OM is the dominant fraction of TOC preserved in the sediments. Distinct differences in both 13C and 14C values are found among these organic fractions. The δ13C values are more depleted in total lipids and HAs (−23.1‰ to −30.2‰) than in THAAs and the acid-base insoluble OM (−15.3‰ to −20.6‰), which indicates that HAs could be polymerized from lipid-like materials. The acid-base insoluble OM has the lowest Δ14C values (−848‰ to −358‰), with the oldest 14C ages (mean of 7330 years before present) compared to total lipids (−574‰ to −253‰, 3860 years), THAAs (−331‰ to −66‰, 1527 years) and HAs (−569‰ to −168‰, 2916 years) in these sediment cores. The δ13C and Δ14C values of THAA in the sediment are similar to those of pore-water dissolved organic carbon (DOC), indicating that THAA is preferentially degraded and converted to DOC. These results reveal that OM derived from marine and terrestrial sources decompose selectively and contribute differently to the organic fractions during early diagenesis and preservation in marine sediment. The very aged acid-base insoluble fraction is likely formed as a complex of the most refractory OM during microbial degradation and alteration of TOC, representing a major mechanism of OM sequestration in marine sediments.