Degree Of Decomposition Research Articles

Self-guided disentangled representation learning for single image dehazing

Image dehazing has received extensive research attention as images collected in hazy weather are limited by low visibility and information dropout. Recently, disentangled representation learning has made excellent progress in various vision tasks. However, existing networks for low-level vision tasks lack efficient feature interaction and delivery mechanisms in the disentanglement process or an evaluation mechanism for the degree of decoupling in the reconstruction process, rendering direct application to image dehazing challenging. We propose a self-guided disentangled representation learning (SGDRL) algorithm with a self-guided disentangled network to realize multi-level progressive feature decoupling through sharing and interaction. The self-guided disentangled (SGD) network extracts image features using the multi-layer backbone network, and attribute features are weighted using the self-guided attention mechanism for the backbone features. In addition, we introduce a disentanglement-guided (DG) module to evaluate the degree of feature decomposition and guide the feature fusion process in the reconstruction stage. Accordingly, we develop SGDRL-based unsupervised and semi-supervised single image dehazing networks. Extensive experiments demonstrate the superiority of the proposed method for real-world image dehazing. The source code is available at https://github.com/dehazing/SGDRL.

Modification mechanism, heavy metal coupling and ecological security risk assessment of phosphogypsum utilization in self-leveling mortar

Few researches on high efficiency modified phosphogypsum (MPG) and its resource utilization in bulding materials. This article investigated the effects of different lower temperatures and drying times on the thermodynamic modification mechanism of macroscopic performance and microscopic structure of MPG, and investigates its application in phosphogypsum-based self-leveling mortars (PBSLM). Then, the coupling mechanism of characteristic heavy metals in the modification process (original-modification-hydration) was discussed, and the safety evaluation was conducted on the content of heavy metal elements in the sample. Data from microscopic analysis showed that with the increase of temperature and drying time, the strength of MPG blocks and the decomposition rate of dihydrate gypsum crystal both increased, while the particle size decreased. The degree of crystal decomposition becomes more complete as the temperature rises if the holding time remains constant. As well as, the MPG at 180 °C/7 h, 195 °C/7 h/10 h met the Chinese standard of “Calcined gypsum” (GB/T9776). The heavy metal elements in MPG decreased obviously, caused by the substitution solid solution formed by Ca2+ and Fe3+ and heavy metal ions and the adsorption of calcium sulfate hemihydrate crystals. After hydration of MPG, As and Cd increased slightly because dicalcium phosphate was insoluble in water and soluble in acid, and iron oxide reduced and dissolved Cd. Then, the ecological hazards of heavy metals in hydrated MPG after hydration were evaluated. The results showed that there was no environmental safety problem in the hydrated MPG, but the As and Cr elements in it had an acceptable carcinogenic risk through oral intake. Based on ensuring the safety of MPG, MPG powder was used in PBSLM. The research demonstrates that the basic mechanical properties of the PBSLM produced, when the MPG powder content is 330 g, and cement is 40 g are the best. The heavy metal aqueous solution's leaching amount is lower than China's national standard limit value. (30min fluidity, 24 h-flexural and compressive strength were 154 mm, 5.7 MPa and 10.6 MPa). Finally, based on this research, a set of general evaluation system for safe utilization of solid waste was established according to national standards. This provides theoretical support for the research of heavy metal in PG at low temperature and the ways of harmless and resource utilization.

Результаты исследований пожароопасности торфа в зависимости от степени его разложения на землях сельскохозяйственного назначения

This article examines the most common types of natural fires in the Russian Federation, a country with some of the largest peat deposits on the planet, and the reasons for their occurrence. This type of fire causes enormous direct and indirect economic, socio-ecological damage, and indirect damage significantly exceeds direct damage and is distributed over time. The object of the study is drained peat soils and mined-out deposits suitable for crop production. The main reason for the use of peat deposits located in most of the territory of the Russian Federation as agricultural land is highlighted. The agrochemical characteristics of various peat soils are presented, which show that peat has high fertility and is of interest for growing crops. The purpose of the experimental studies was to determine the time before spontaneous combustion of selected peat samples at their natural density. The results of experimental studies of the ability of peat soil to spontaneously ignite depending on its degree of decomposition and bulk density are presented. As a result of the study, the degree of decomposition and ash content of peat samples were determined. The dependence of changes in the volumetric density of peat under natural conditions depending on the degree of decomposition and the dynamics of the heating process of the thermophysical center and the surface of peat samples are presented. It has been determined that the process of destruction of drained peat soils has a clear tendency of rapid growth.

The Holocene evolution of floodplain mire geosystems in the southeastern part of the Meshchera lowlands

The results of paleoecological studies of peat deposits in the area of the southeastern part of the Meshchera lowlands (Mostovoye mire) based on the analyses of peat properties, plant macrofossils, charcoal, pollen and radiocarbon dating are presented. The mire was formed in the oxbow depression on the floodplain of the Goose River around 9480 cal. yr. BP and was eutrophic throughout most of the Holocene. Drastic changes in the dynamics of the mire, namely its transition to the mesotrophic stage, characterized by a decrease in the degree of peat decomposition, occurred about 70 years ago. The results of the pollen analysis show the existence of birch-pine forests in combination with shrub thickets formed by Betula nana in the period 9480-8750 cal. yr. BP. In the subsequent stages, the vegetation cover turned to a combination of broad-leaved, birch-pine forests and riverine forests with alder. Frequent fires, both natural and anthropogenic, have favored the development of birch and pine forests over the last millennium.

Chemical composition and thermal stability of topsoil organic carbon: Influence of cropping system and tillage practices

AbstractAgricultural management practices play a significant role in regulating the potential for soil organic carbon (SOC) sequestration. The objective of this study was to determine the effects of cropping systems and tillage practices on the chemistry and thermal stability of topsoil SOC in a long‐term field study in Ontario, Canada. The cropping system is based on rotations including corn, alfalfa, cereals, soybeans and a red clover cover crop. Tillage practices of conventional (moldboard plow, CT) and conservation (no‐till, NT) were applied to each cropping system. A 130‐day laboratory incubation was conducted to measure the potentially mineralizable SOC. The thermal stability and molecular structure of SOC were investigated using thermal analysis‐programmed pyrolysis (PP) and solid‐state 13C cross polarization/total sideband suppression magic angle spinning nuclear magnetic resonance (CP/TOSS MAS NMR) spectroscopy, respectively. The SOC stocks were larger under NT practices and the crop rotations incorporating alfalfa and cover crops. Under NT practices, an abundance of aromatic‐C components was observed, however, soil under CT showed an abundance of aliphatic‐C compounds (p < 0.001), with a higher alkyl/O‐alkyl‐C ratio, indicating a higher degree of SOC decomposition. Soil under rotations that included soybeans demonstrated a significant increase in aliphatic‐C components, whereas those with cover cropping exhibited an enrichment in O‐alkyl‐C groups (p < 0.05), representing the presence of more resistant and easily decomposable SOC constituents, respectively. The results demonstrated that the thermal stability of SOC in CT systems was higher than that of NT practices (p < 0.05), while NT practices and crop rotations including cover crops are better capable of conserving the labile pool of SOC. Our findings confirmed the correlations among the parameters that characterize both the labile and stable pools of SOC as determined by the methods employed in this study. These results demonstrated that agricultural management practices significantly influence the chemical composition and thermal stability of soil organic matter (SOM), which can have significant impacts on soil health and C sequestration potential.

Моделирование трехмерного поля скорости в барабанной вращающейся печи

This paper deals with the problem of laminar axisymmetric incompressible flow in the working area of a rotary drum furnace. A system of second-order partial differential equations is derived and solved numerically using the finite difference method. The obtained solutions are tested for mesh convergence and compared with available analytical solutions for a laminar axisymmetric flow. The numerical results show that furnace rotation significantly affects the gas flow in the working section of the apparatus. Thus, the temperature distribution over the working area and furnace surface can be controlled through the furnace rotation velocity and gas flow rate. The input velocity profile also affects the flow pattern in the furnace. Vortex zones with counterflow occur near the walls, where the axial velocity profile is more elongated than the Poiseuille parabola. On the symmetry axis, the axial velocity is higher than that of the Poiseuille flow. The proposed mathematical model allows one to calculate more accurately the degree of thermal decomposition as a function of temperature and longitudinal coordinate along the furnace axis.

Transformation of peat deposits and carbon accumulation in post-pyrogenic raised bogs within the taiga zone of West Siberia

The aim of the study was to assess of the transformation of the hydrologic and physical properties of peat deposits and peat accumulation rates in the post-pyrogenic sites of drained fens in the taiga zone of West Siberia. Location and time of the study. Field studies were conducted in 2022 on the Bakchar fen (drained for forestry, seven plots) and Ust-Bakchar fen (drained for peat extraction, three plots) located in the Tomsk region. Methods. Peat sampling was carried out from two boreholes at each plot in the hollow and the hummock. The sampling increment was 5 cm; the total depth was 45–90 cm. Peat samples were taken at nine subsites by the envelope method on each plot in 0–30 cm layer by 10 cm increment for water content determination in laboratory. Laboratory study of peat characteristics was carried out using the following methods: water and ash content measurements (GOST 11306-2013, GOST 11306-2013), estimation of peat decomposition and humification degree, botanical composition (GOST 28245-89), as well as measuring peat bulk density. Carbon stocks in the upper layer of peat deposits was estimated using the values of peat ash content and density. Results. The peat deposit of the upper layers was formed mainly by sphagnum peat with Sphagnum fuscum plant residues predominating. The differences between hollows and hummocks in their peat properties were manifested to a depth of 5–15 cm from the surface of depressions. The burnout of the hollows led to the changes of all peat properties to a depth of 10–15 cm: the changes were more pronounced in ash content, which was 1.5–9 times higher in the 0–5 cm layer as compared with the unburned site. The changes in peat properties on positive relief forms, i.e. moss hummocks, was less evident in the upper 0–5 cm layer, but reached a greater depth of 30 cm. The change was revealed mainly as an increase in peat ash content due to the migration of ash elements from the surface of burnt hollows and as an increase in bulk density due to subsidence of moss hummocks with the died-off sphagnum moss. Although the average water content in postpyrogenic and unburned sites was the same, amounting to 90–91% in the 0–30 cm layer, some difference was observed between the microrelief forms. The post-pyrogenic site in the Bakchar fen was characterized by water content decrease in hollows and hummocks, the maximum values being observed at an altitude near the average surface. In the Ust-Bakchar fen, water content was found to decrease from hollows to hummocks. In the Bakchar fen, 30 years after the fire peat accumulation occurred only on positive microrelief forms, where the 35 cm thick layer formed after the fire. Taking into account the microrelief heterogeneity, carbon accumulation over the post-fire period was estimated as 1.9 kg C/m2 or 60 g C/m2 per year. Peat accumulation seemed much slower in the Ust-Bakchar fen and was apparently absent on most of the surface. The average rate was estimated as 7 g C/m2 per year. Conclusions. The study found fen hollows to be most prone to burnout. The consequences of the fire manifest themselves in the drying of the upper layer of the peat deposit, thus preventing intensive overgrowth by sphagnum mosses 6–8 years after the fire. At the drained for forestry site in the Bakchar fen, 30 years after the fire the peat accumulation rate on moss hummocks was comparable to the rate in the unburned areas.

Potential for bioremediation of hydrocarbon-contaminated water by alkane-oxidizing actinobacteria

Water pollution with oil and its components is common in oil-producing and industrialized countries of the world. High molecular weight alkanes, constituting significant portion of oil, exist in a solid state at room temperature and exhibit resistance to decomposition when released into the environment. Bioremediation is the most promising technology for cleaning up hydrocarbon-contaminated aquatic ecosystems because of its environmental safety and economic efficiency. This article presents data on the potential for bioremediation of hydrocarbon-contaminated objects by the alkane-oxidizing bacterium Tsukamurella tyrosinosolvens PS2. Strain PS2 was isolated from petrochemical waste and showed a significant increase to 107 CFU/ml when cultivated on a mineral medium with solid paraffin as the sole source of carbon and energy. It was found that strain PS2 has high adhesion to liquid and solid alkanes, compared to cells grown in a medium with sucrose. The degree of decomposition of solid paraffin was evaluated using gas chromatography/mass spectrometry. The results indicated that strain PS2 metabolizes alkanes with a chain length of C20-C31 in 7 days with varying efficiencies. The findings of this study demonstrate the potential of the T. tyrosinosolvens PS2 strain for the bioremediation of sites contaminated with complex mixtures of hydrocarbons.

CHEMICAL STABILITY OF CELLULOSE NITRATES: REVIEW

The results of the analysis of literature data on updated methods for determining the chemical stability of cellulose nitrates are presented. The relevance of research is due to the need to control the operation and storage of a widespread component of solid rocket fuels and explosive compositions. The criterion for chemical resistance is the value of the decomposition rate or the time dependence of the degree of decomposition of the sample. It is shown that methods for assessing the chemical resistance of cellulose nitrates are based on determining the rate of its thermal decomposition, which is measured by a specific parameter accompanying decomposition. These parameters include weight loss, amount of gaseous decomposition products released, decomposition temperature or thermal effects. Studies are carried out at elevated temperatures and allow you to control the magnitude or rate of change in the parameter that accompanies thermal decomposition. The possibility of using modern analytical methods for evaluating chemical resistance is shown: differential scanning calorimetry, thermogravimetric analysis, chemiluminescent analysis, infrared spectroscopy, high-performance liquid and thin-layer chromatography, gas chromatography, electron paramagnetic resonance, mass spectrometry, X-ray diffraction analysis. The preference for methods of differential scanning calorimetry or differential thermal analysis is substantiated. The results of studies on improving the chemical resistance of cellulose nitrates and compositions based on it with the use of new stabilizers of the aniline series, stabilizers of natural origin with the advantage of the latter on the examples of curcumin and lignins are presented. Due to the insufficient stability of cellulose nitrates, stabilizers added to the formulation of explosive compositions lengthen the induction period of the decomposition of nitro compounds and do not allow the development of the autocatalytic decomposition stage. Methods for determining the chemical stability of cellulose nitrates obtained from alternative sources of raw materials are presented. For citation: Vdovina N.P., Korchagina А.А., Budaev I.А. Chemical stability of cellulose nitrates: Review. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 5. P. 6-20. DOI: 10.6060/ivkkt.20236605.6725.

Pristup pouzdanom načinu određivanja hemijske stabilnosti jednobaznih baruta primenom metode mikrokalorimetrije

Introduction/purpose: Gunpowder is a type of explosive material (EM), a mixture of chemical compounds capable of releasing their potential energy in a very fast exothermic chemical reaction. This paper investigates the single base gunpowder samples. Methods: Microcalorimetry (MC), or heat flow calorimetry (HFC), is the only modern method that monitors the direct cause of autoignition - the rate of heat release, which is a key factor for gunpowder storage explosive safety. It is based on high-sensitivity calorimeters which allow monitoring of chemical reactions at low speeds. The microcalorimeter "TAM III" was used and the method given by the NATO standard STANAG 4582. A very reliable result was obtained on the chemical stability of the observed single base gunpowder samples, as well as an assessment of its behavior in the next 10 years. Results: The thermal activity of gunpowder depends on several factors, the most important of which are: chemical composition, size and shape of the gunpowder grain, the degree of decomposition of the gunpowder, storage conditions, etc. Namely, it is a much more exact and consistent indicator of the chemical stability of gunpowder compared to the critical diameter. Conclusion: The MC method should be used both for monitoring the chemical stability of gunpowder during storage and for the prediction of the service life of gunpowder.

SURGICAL MANAGEMENT OF FOETAL MACERATION IN A 1½ -YEAR-OLD DWARF RUSSIAN SHEPHERD BITCH.

ABSTRACT Foetal maceration is a pregnancy pathology that occurs as a result of Intra-uterine Foetal Death (IUFD). It occurs when the foetus fails to abort and decomposition occur in-utero leaving the foetal bones. The pathogenicity of the putrefying organism determines the degree of decomposition. There have been reports of foetal maceration in various species of animal but it rarely occurs in the bitch. In this case, a 1½-year-old dwarf Russian Shepherd bitch weighing 16.6 kg was brought to the Small Animal Clinic (SAC) of the Veterinary Teaching Hospital, University of Jos with a chief complaint of inappetance and weakness. The bitch was artificially inseminated over 60 days ago and had been passing out brown vaginal discharges about 3 days prior to presentation. The temperature, pulse rate and respiratory rate were all within normal values. A radiographic examination showed fetuses in the uterus, based on the findings, a case of fetal maceration was diagnosed and hysterotomy was indicated. Post surgically, systemic antibiotics was administered, periodic care of the wound was encouraged. No complications were encountered post surgically while stiches were removed fourteen days later. Maceration is not regularly seen in dogs; therefore veterinarians should always be abreast with issues of maceration while utilizing ultrasound scan to aid diagnosis.

The process of decomposition of tricalcium phosphate by phosphoric acid with partial replacement of P2O5 to sulfuric acid

The article covers the decomposition of tricalcium phosphate with thermal phosphoric acid with a concentration of 20, 30 and 40% P2O5 with the replacement of 10, 20 and 30% P2O5 with sulfuric acid and it has been established that, regardless of the content of ammonium nitrate, magnesium sulfate or their combined presence in phosphoric acid, with an increase in the proportion of sulfuric acid, the content of both total and aqueous forms of SO3 in the acidic pulp increases. The highest results of the decomposition coefficient were obtained when phosphoric acid was evaporated to a content of 32.22-25.77% P2O5 and 5.54-9.76% SO3. The SO3 content of both total and aqueous forms in dried products increases with increasing proportion of sulfuric acid. When the proportion of sulfuric acid increases to 20%, the degree of decomposition increases to 93.45% and to 99.55% when replacing 30% P2O5 with sulfuric acid.

Complex biopreparation for maintaining natural fertility in agrophytocenoses

The effectiveness of using a new biopreparation for the decomposition of wheat straw, which consists of cellulolytic bacteria CA3 and CU6 and strains-antagonist of the phytopathogenic fungi Pseudomonas laurentiana ANT 17 and Paenibacillus peoriae ANT 13, has been studied. AND 17 and ANT 13 additionally have growth-stimulating activity and the ability to mobilize inorganic phosphates. The greatest degree of decomposition of straw was observed when combined the biopreparation and ammonium nitrate (50.8% versus 25.2% in the control). At the end of the field experiment carrots were grown in soil with decomposed straw. When biopreparation and ammonium nitrate were used for straw processing, the weight of the carrot root crop was 14.4% more than in the control, and the diameter of the root was 55.6% bigger.

Postglacial peat accumulation in the interfluve of the Mologa and Sheksna rivers (NW East European Plain)

The Mologa-Sheksna Lowland peatlands represent incredibly valuable archives of information for reconstruction of the Holocene regional palaeoenvironmental dynamics. A profound application of multiproxy techniques (AMS dating, XRF scanning, testate amoebae and loss on ignition analyses), coupled with a palaeogeographical review, enabled us to perform a robust reconstruction of peat deposition and main palaeoenvironmental milestones during the Holocene. Peat accumulation started ~11.0 cal. ka BP over the upland watershed areas, preceded by mineral lacustrine sedimentation. In smaller enclosed basins, peat accumulation took place from ~8.7 cal. ka BP. Oscillations in accumulation rates and decomposition degree of peat along the cores provide evidence for dry Middle Holocene (8.6–4.4 cal. ka BP) and a 2-ka time lag in oligotrophic peat deposition onset between the two different geomorphological localities.

Анализ грейферной выемки волокнистого торфяного сырья

The purpose of the study was to confirm the possibility of implementing the operations of the working cycle of mining equipment with the determination of the range of forces required to introduce the elements of the grab into the deposit and close the jaws in the massif, taking into account the design features of the grab. Research methodology. A series of field studies was carried out using full-scale models of the working bodies of a fork grab in the conditions of a peat deposit to confirm the possibility of implementing the process of extracting raw materials of a low degree of decomposition. Results. It has been established that the average value of the force required overcoming the resistance to the introduction of the grab model: on the site with magellanicum peat – 44.4 kN, with fuscum-peat – 61.5 kN. The average value of the normal stress when immersed in an array of a clamshell equipment element, taking into account the end surface area, is 89 kPa for: magellanicum peat, 123 kPa for fuscum-peat. The average value of the total deformation modulus in the natural occurrence of a peat deposit is 116 kPa for magellanicum peat and 126 kPa for fuscum-peat. The rational distance between the teeth of the jaw model of the fork grab has been determined. With a distance between the teeth of the grab jaw model l=0.25 m, a single drawing body is formed when the captured area of the material is shifted. Conclusion. With the determination of the effort ranges for the implementation of the two main operations of the excavation process, as well as the establishment of the design features of the grab for surface excavation, it was concluded that it is possible to use grab equipment for the surface extraction of fibrous peat raw materials.

Разработка агротехнологии получения посадочного материала, устойчивого к фитофагам и фитопатогенам

Many seedlings die early during reforestation. Traditional bareroot technologies often fail in Western Siberia. As a result, containerized technologies have become relevant as they provide higher survival rate in the harsh climatic conditions.
 The study traced the development of Scots pine (Pinus sylvestris L.) seedlings grown in a container nursery in the Kemerovo Region. The milled high-moor peat had a degree of decomposition of ≤ 15%. The seeds were treated with fungicides before planting. The seedlings underwent a double treatment against phytophages and phytopathogens during growth.
 The article introduces a new agricultural technology for ball-rooted planting stock resistant to phytophages and phytopathogens. The study revealed the developmental stages of pine seedlings and the effect of pesticides on pathogen count. After phytosanitary monitoring and preventive treatments, the seedlings were tested for the effectiveness of pesticides, fungicides, and insecticides as part of pre-planting seed treatment. Such biochemical preparations as Fitoverm (0.4%), Decis Pro, Previkur Energy, and Fitosporin increased the survival rate of the test seedlings. The biological effectiveness of the experimental treatment was 49–53 and 44–50%.
 The technology was able to improve the survival rate of pine seedlings in forest container nurseries in the harsh climate of West Siberia.

Development and evaluation of a gas chromatography-mass spectrometry method for biogenic amines to assess decomposition in seafood

Biogenic amines (BAs) are low molecular mass compounds formed by the microbial-induced decarboxylation of specific amino acids. These molecules are markers of quality index and can indicate potential spoilage of a product. Currently, the FDA relies on sensory analysis as well as indole and histamine levels to evaluate the degree of seafood decomposition. However, there is a need for alternative analytical methods to corroborate those analyses. An optimized dispersive liquid-liquid microextraction (DLLME) method was developed for the extraction of four BAs (putrescine, cadaverine, histamine and tyramine) from various decomposition stages of nine seafood species previously tested by the FDA Seafood Sensory Experts. The BAs depicted very different concentration patterns between species and were able to distinguish within-species decomposition stages classified by the organoleptic analysis as “borderline increments”. The results suggest that all four analyzed BAs can be potentially used as biomarkers of seafood decomposition, but the choice of biomarker is species dependent. Some of the prominent associations were putrescine in shrimp, cadaverine in weakfish, histamine in canned tuna, and tyramine in scallops. The differentiation between “borderline” stages of decomposition also demonstrates the suitability of the method to support the FDA sensory analyses of seafood, ultimately leading to improved consumer protection.

Effect of Ferric Catalyst on Chemical Decomposition of Polyimide-Film-Surface for Enhancing Chemical–Mechanical-Planarization Polishing-Rate

In semiconductor devices, flexible displays and microelectromechanical systems (MEMS), polyimide has been utilized as a protecting layer, interlayer dielectric polymer for thin-film metallization and low-stress polymer for wafer-level packaging. Since, it has low stress, low thermal coefficient of expansion, low moisture, high modulus, good ductility, thermal stability, high glass transition temperature, and low process cost. However, the applications of polyimide required estentially chemical-mechanical-planarization (CMP) of the polyimide-film-surface. that can be challenging to enhance the polishing rate of the polyimide-film-surface because of the hard and covalently bonded nature of the polyimide-film surface.In this study, to enhance chemical dominant CMP, the chemical decomposition of the polyimide-film-surface was performed by hydrolysis reaction between ferric ions and oxygen atoms covalently bonded with pyromellitimide on the polyimide-film-surface during CMP, as shown in Fig. 1. The polyimide-film polishing rate was estimated as a function of ferric catanylst concentration in the CMP slurry;surprisingly, the polyimide film polishing rate(i.e., 1465A/min) peaked at a specific(i.e., 0.05wt%) ferric catalyst concentration, as shown in Fig. 2. This result indicates that the degree of chemical decomposition during CMP could be principally determined by ferric nitrate concentration. The details of both chemical and mechanical dominant polishing mechanisms will be presented. In addition, the evidence of the chemical composition of the polyimide-film-surface will be demonstrated, depending on the ferric catalyst concentation in the CMP slurry. Figure 1

How do stand features shape deadwood diversity?

Saproxylic species from different taxonomic groups often occur only on certain types of deadwood with specific qualitative characteristics. The various types of deadwood are very dynamic elements of forest ecosystems, associated with many site and stand features, as well as with the type of forest management. Using a pool of 29,098 sample plots spread across Poland, we analyzed 30 different deadwood types defined on the basis of three characteristics: position (standing, lying), degree of decomposition, and size. Statistical hurdle models were used to assess changes in the volume of individual deadwood types based on a broad range of independent variables. Depending on the type of management, terrain, site fertility, stand volume, tree density, and stand age, the models revealed substantial differences in the volume of different deadwood types, ranging from 0 to approx. 4 m3 ha−1. It was found that the volume of most deadwood types (except for a few, mostly with diameters under 15 cm) increases with stand age or stand volume. In managed forests at all stages of stand development there is a deficiency of thick deadwood. Both standing and lying deadwood at different decay stages is available continuously, irrespective of the values of individual independent variables, but considerable differences exist. While most lying deadwood exhibits higher levels of decomposition, in standing deadwood the proportions of different decay stages are strongly associated with tree diameter at breast height. The developed models make it possible to predict the volume of individual deadwood types for a broad range of independent variables. The current work presents several examples, with the results showing extremely complex relationships between deadwood diversity and site and stand features at every stage of forest development, with continuous changes in the volume and proportions of different deadwood types. In general, at the landscape level Polish forests contain both standing and lying deadwood at all decay stages in more or less equal proportions. However, in forest management one should pay special attention to the dimensions of retained deadwood. The absence of thick deadwood is particularly conspicuous in lowland managed forests.

ЭНЕРГЕТИЧЕСКИЙ ПОТЕНЦИАЛ И ОСОБЕННОСТИ БИОДЕГРАДАЦИИ ЗЕРНОВОЙ ПЫЛИ ПРИ ЕЕ ПЕРЕРАБОТКЕ В БИОГАЗ

The composition of the dust that is generated during the collection, transportation, processing and storage of grain is different and complex. The amount of grain dust can reach 26% by weight of the raw material. Due to the ability to ignite spontaneously, it is classified as a hazard class 3, and if it enters the human body, it can cause harm to health, therefore, grain processing enterprises take measures to reduce the concentration of grain dust in the air. On the other hand, the dust generated during grain processing is, due to its chemical composition, a valua- ble raw material, the loss of which is undesirable. The world literature describes such methods for processing aspiration grain dust as hydrolysis and the preparation of nutrient media for microorganisms, briquetting and combustion, use in composting, as well as conversion into biogas. The purpose of this work is to study the features of processing aspiration grain dusts of various agricultural crops into biogas and determine their energy potential and biodegradability. As a result of our laboratory studies, it was established that the specific biogas and methane yield from soybean grain dust was 186.37±58.89 – 230.30±21.90 and 95.54±36.95 – 122.17±15.39 ml/g VS respectively; from barley grain dust – 165.06±9.37 – 191.41±5.65 and 86.45±6.37 – 100.18±6.65 ml/g VS respectively. The concentration of methane in biogas in different variants ranged from 46.75±7.14 to 52.75±1.60%. When recycling 1 ton of these grain dusts at a biogas station, you can get from 278.70 to 382.25 kW of electrical energy and from 285.50 to 391.57 kW of thermal energy. The degree of decomposition of organic matter of substrates in our study is generally low – from 5.61±0.08 to 5.91±0.37%. Thus, it has been established that the grain dusts studied in this work can be considered as a promising cosubstrats for existing or planned biogas stations. The recommended processing time is no more than 35 days.