Different Stages Of Decomposition Research Articles

Characteristics of the biochemical composition of plant litter at different stages of decomposition (according to thermal analysis data)

The composition of samples of needles, leaves, sheaved cottongrass (Eriophorum vaginatum) tissues, and the L horizon of the forest floor of different degree of decomposition, isolated from the plant litter in southern taiga ecosystems, was studied by thermal analysis. It was established that plant litter decomposition is accompanied by structural changes in celluloses and that the decomposition rates of hemicellulose and structured cellulose vary at different stages of decomposition. The structural specificity and incongruent thermal decomposition of grass lignocellulose were observed in all samples of plant material. The rates at which the content of components of the plant litter decreased depended on the type and stage of decomposition of plant material. The decomposition rate of biochemical components tended to increase in better drained soils.

Influence of preliminary deformation on the second-phase-particle size distribution in aging alloys

On the basis of a theoretical analysis of asymptotic states which are formed under the conditions of an enhanced density of matrix dislocations in different stages of decomposition of supersaturated solid solutions in concrete diffusion regimes, it is shown how the universal function of relative particle-size distribution is connected with the functional parameter m which is the only carrier of information on the amount of preliminary deformation e of an aging alloy. This parameter as a function of e is approximated by a step. The smearing and height of this step are determined from the found conditions of the realization of dislocation diffusion as the mechanism which controls coalescence in the initial and final (in the case of smallness of e, very remote in time) stages of the evolution of a heterophase structure. Thereby, an explicit dependence of the universal distribution function on the deformation and the temperature and duration of aging is established.

Classification of waste materials using Fourier transform infrared spectroscopy and soft independent modeling of class analogy

Fourier transform infrared (FTIR) spectroscopy combined with multivariate data analysis is under development as a method to classify waste materials. The chemical composition of the sample is reflected by a series of regions of the infrared spectrum which are used as variables for multivariate data analysis. In this study, separated biowaste collection, mechanically-biologically treated waste (MBT-waste), and old landfill materials were collected to provide materials representing different stages of decomposition. A total of 819 FTIR absorbance spectra were recorded. Principal component analyses (PCA) were performed followed by soft independent modeling of class analogy (SIMCA) for classification of waste materials. Strong classification occurred for an analysis where spectral carbonate regions were included, and for another analysis when they were not. The SIMCA model enabled the differentiation and the classification of unknown samples according to the three categories in both cases. The classification methods developed here provide an assessment tool that regulatory authorities may wish to explore when assessing whether a treated waste from an uncertain process can be classed as compost or MBT-waste.

Alaska Pink Salmon (Oncorhynchus gorbuscha) Spoilage and Ethanol Incidence in the Canned Product

Ethanol was quantified in canned salmon produced from whole fish showing different stages of decomposition due to storage at 1 and 14 degrees C for up to 3 and 16 days, respectively. Ethanol incidence in the canned salmon was correlated to results from skin aerobic plate counts and sensory evaluations of the whole fish and with sensory evaluations of the canned product. Panelists rejected whole salmon after 3 and 12 days of storage at 14 and 1 degrees C, respectively. Skin aerobic plate counts reached 4.8 log CFU/cm2 when fish were rejected, regardless of storage temperature. Panelists rejected canned salmon produced with fish stored for a maximum of 2 and 16 days at 14 and 1 degrees C, respectively. Ethanol concentrations in the cans produced with fish stored at 14 degrees C correlated well with sensory evaluation results; however, ethanol concentrations in the cans produced with salmon stored at 1 degrees C did not agree with sensory results. A correlation could not be established between ethanol concentration in the canned product and microbial content of whole salmon.

Evaluating the logistic mixture model on real and simulated TG curves

The aim of this paper is to evaluate and explain the fitting of dynamic TG curves by a mixture of logistic functions. This model assumes that more than one physical process may be involved in each mass loss step and that each physical process may extend along all the experiment. One of the main sources of difficulties in TG is that, very often, different stages of decomposition substantially overlap each other. Several real and simulated TG curves were analysed in this paper. An optimal fitting of the TG curves was obtained by a mixture of logistics. In many cases the optimal fitting reproduces accurately the TG curve. Accordingly, the TG curve can be understood as a sum of parallel reactions, where each single reaction is represented by one or a small number of logistic components. Additionally, making use of the analytical derivative of the fitting, a mixture of Arrhenius reaction order equations was applied to the same curves. In all the cases, the fitting obtained with the mixture of Arrhenius was worse than the obtained with the mixture of logistics. A software was developed to automatically perform these tasks. The physical meaning of the fitting was explained.

Soil-Geochemical Aspects of Land Use in Abandoned Land in Central Poland

Abstract It is observed increasing of abandoned land in Poland in last decade of 20th century.The part of abandoned land is usually covered by birch tree community. The entrance of birches, especially on pure sandy area, changes properties of soil. The samples of soil horizons, litter in different stages of decomposition and leaves from birch trees, were taken into analysis. The role of birch was analysed also in comparison to arable land, abandoned land without trees and different ages birch trees communities. After the entrance birch trees soil profiles were enriched in nitrogen and elements such as aluminium, iron, cadmium, lead, cobalt, zinc, which were moved from soil or come from atmospheric load and were accumulated in litter or humus horizon. Compared to arable land, some elements (for example calcium) had lower concentration under birch trees. After several years without fertilization the relationship between elements were changed. In early stages (until 10 years) in litter horizons potassium prevails calcium, later – calcium prevails potassium. Birch trees made soil environment more natural compared to arable land.

Spatial separation of litter decomposition and mycorrhizal nitrogen uptake in a boreal forest

Our understanding of how saprotrophic and mycorrhizal fungi interact to re-circulate carbon and nutrients from plant litter and soil organic matter is limited by poor understanding of their spatiotemporal dynamics. In order to investigate how different functional groups of fungi contribute to carbon and nitrogen cycling at different stages of decomposition, we studied changes in fungal community composition along vertical profiles through a Pinus sylvestris forest soil. We combined molecular identification methods with 14C dating of the organic matter, analyses of carbon:nitrogen (C:N) ratios and 15N natural abundance measurements. Saprotrophic fungi were primarily confined to relatively recently (< 4 yr) shed litter components on the surface of the forest floor, where organic carbon was mineralized while nitrogen was retained. Mycorrhizal fungi dominated in the underlying, more decomposed litter and humus, where they apparently mobilized N and made it available to their host plants. Our observations show that the degrading and nutrient-mobilizing components of the fungal community are spatially separated. This has important implications for biogeochemical studies of boreal forest ecosystems.

Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review

SummaryMechanisms for C stabilization in soils have received much interest recently due to their relevance in the global C cycle. Here we review the mechanisms that are currently, but often contradictorily or inconsistently, considered to contribute to organic matter (OM) protection against decomposition in temperate soils: (i) selective preservation due to recalcitrance of OM, including plant litter, rhizodeposits, microbial products, humic polymers, and charred OM; (ii) spatial inaccessibility of OM against decomposer organisms due to occlusion, intercalation, hydrophobicity and encapsulation; and (iii) stabilization by interaction with mineral surfaces (Fe‐, Al‐, Mn‐oxides, phyllosilicates) and metal ions. Our goal is to assess the relevance of these mechanisms to the formation of soil OM during different stages of decomposition and under different soil conditions. The view that OM stabilization is dominated by the selective preservation of recalcitrant organic components that accumulate in proportion to their chemical properties can no longer be accepted. In contrast, our analysis of mechanisms shows that: (i) the soil biotic community is able to disintegrate any OM of natural origin; (ii) molecular recalcitrance of OM is relative, rather than absolute; (iii) recalcitrance is only important during early decomposition and in active surface soils; while (iv) during late decomposition and in the subsoil, the relevance of spatial inaccessibility and organo‐mineral interactions for SOM stabilization increases. We conclude that major difficulties in the understanding and prediction of SOM dynamics originate from the simultaneous operation of several mechanisms. We discuss knowledge gaps and promising directions of future research.

Time and temperature-based study for the production of high TC phase by sol-gel technique in Pb-bscco system

The high TC superconducting phase Bi2Sr2Ca2Cu3Ox (2223) in the Pb-BSCCO system has been produced by EDTA-gel processing using nitrate solutions. The precursor has heated in two stages, at 300 and 800°C each for 2 h, to avoid the burning of the important species involved in the final product. The effects of time (6 to 48 h) and temperature (845 and 855°C) on the formation of the 2223 phase have been studied by sintering the samples in air. Thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and a vibrating sample magnetometer (VSM) have been employed to investigate the powder produced at different stages of decomposition, oxidation and formation of sintered materials from the powders. The volume-fraction of the 2223 phase at 845°C increases with time, the maximum value of the 2223 phase was obtained at 120 h. It has been observed that the formation of the high TC phase is remarkably enhanced at the temperature of the endothermic peak of the DTA curve. The best result has been obtained in the sample sintered for 24 h at the temperature 855°C (endothermic peak). This also indicated that at 855°C, the large volume-fraction of 2223 phase with TC 113 K grew in short time and as the sintering time increased, it decomposed into the Bi2Sr2CaCu2Ox (2212) phase and other phases.

Calliphoridae (Diptera) coletados em cadáveres humanos no Rio Grande do Norte

This paper reports a study on Calliphoridae associated to human corpus in Rio Grande do Norte State, Brazil. Collections of Calliphoridae were made in cadavers in different stages of decomposition taken to the Instituto Tecnico e Cientifico de Policia / Natal, from different regions of the state. The following species were collected: Chrysomya megacephala (Fabr.), Chrysomya albiceps (Wied.), Cochliomyia macellaria (Fabr.), Lucilia eximia (Wied.), Lucilia cuprina (Wied.) and Lucilia sp.

Study on the degradation and stabilization of organic matter in waste by means of thermal analyses

During the biological treatment of waste organic matter undergoes considerable changes. Degradation and transformation, mineralization and humification take place. These processes correspond to different energy contents, which are reflected by the characteristic thermal behavior of the samples. Waste materials such as compost, municipal solid waste and waste from abandoned landfills have been investigated in this study to demonstrate the applicability of thermal methods in waste management. The use of the total sample, thus avoiding chemical extraction, has proved to be advantageous in the management of complex materials. Nevertheless, waste compounds were also characterized. TG/DTG and the curves of the CO 2 ion current have been recorded in order to shed light on changes occurring in humic acids during composting. Thermal characteristics were attributed to different stages of decomposition of landfill materials. Further to the assessment of unknown landfills process control was carried out to evaluate the efficiency of aeration. A simple procedure that it not based on the comparison of a series of data but rather enables assessment of an individual sample is described for use in the evaluation of organic matter present in municipal solid waste.

Autopsy Room : A Potential Source of Infection at Work Place in Developing Countries

Forensic pathologists/Autopsy surgeons and the forensic medicine personnel assisting to conduct an autopsy who come in direct contact with the body fluids, soft tissues of the dead and skeletal remains in different stages of decomposition, are at a continuous risk of acquiring various kinds of infections including blood-borne viral and other bacterial infections. However, limited data are available regarding these occupational risks to the persons who are usually exposed to dead bodies in the autopsy rooms. With the existing and growing HIV epidemic and high seroprevalence of hepatitis virus, safety becomes an issue not only relevant to the team performing the autopsy, but also has direct implications regarding the protection of the environment. Prevention strategies including immunization, exposure avoidance by the use of universal precautions and proper infrastructure in the autopsy rooms can go a long way in preventing the occupational hazards of the autopsy rooms.

Response of Biofilm Bacteria to Dissolved Organic Matter from Decomposing Maple Leaves

Stream bacteria play an important role in the utilization of dissolved organic matter (DOM) leached from leaves, and in transfer of this DOM to other trophic levels. Leaf leachate is a mixture of labile, recalcitrant, and inhibitory compounds, and bacterial communities vary in their ability to utilize leachate. The purpose of this study was to determine the effects of DOM from sugar maple leaves on bacterial populations in biofilms on decomposing leaf surfaces. Populations of Acinetobacter calcoaceticus, Burkholderia cepacia, and Pseudomonas putida were enumerated on decomposing maple leaves in a northeast Ohio stream using fluorescence in situ hybridization. Additionally, artificial substrata consisting of PVC-end caps filled with agar supplemented with leaf leachate and covered with cellulose filters were used to determine bacterial response to leachate from leaves at different stages of decomposition. Population sizes of bacterial species exhibited different responses. Leachate did not affect A. calcoaceticus. B. cepacia was tolerant of phenolic compounds released from leaves and the population size increased when DOM concentrations were greatest. In contrast, P. putida was inhibited by phenolic components of leachate when total DOM concentrations were greatest. Differences in response of the bacterial species to components of leaf leachate indicate the complexity of microbial population dynamics and interactions with DOM. Differences among species in response to DOM have the potential to influence transport and retention of organic matter in stream ecosystems.

Fungal colonization of phyllosphere and litter of Quercus rotundifolia Lam. in a holm oak forest (High Atlas, Morocco)

The microfungal flora of holm oak living, senesced and litter leaves was studied at five different stages of decomposition using three different isolation methods. Holm oak leaves are first colonized on the tree by a variety of primary saprophytes such as Trichothecium, Aureobasidium, Cladosporium, Epicoccum and Alternaria. After leaf fall there is an intensive development of the fungal flora, including both species already present in the phyllosphere and new colonizers from the litter layer. With increasing decomposition initial colonizers gradually disappear, being replaced by other forms. When all isolation methods were pooled, maximum biodiversity (species richness) of the fungus flora was observed during the first three stages of leaf litter decomposition, but strong variation occurred according to the isolation method. Sterilization of the leaf material revealed that a number of fungal strains were present inside the holm oak leaves before abscission, increasing from living to senescent stages, and that a strong decrease in the internal colonization of leaf litter was observed at late decomposition stages.

Cadaver Dog and Handler Team Capabilities in the Recovery of Buried Human Remains in the Southeastern United States

The detection of human remains that have been deliberately buried to escape detection is a problem for law enforcement. Sometimes the cadaver dog and handler teams are successful, while other times law enforcement and cadaver dog teams are frustrated in their search. Five field trials tested the ability of four cadaver dog and handler teams to detect buried human remains. Human and animal remains were buried in various forested areas during the summer months near Tuscaloosa, Alabama. The remains ranged in decomposition from fresh to skeletonized. Cadaver dogs detected with varying success: buried human remains at different stages of decomposition, buried human remains at different depths, and buried decomposed human and animal remains. The results from these trials showed that some cadaver dogs were able to locate skeletonized remains buried at a significant depth. Fresh and skeletonized remains were found equally by the cadaver dogs along with some caveats. Dog handlers affected the reliability of the cadaver dog results. Observations and videotape of the cadaver dogs during field trials showed that they were reliable in finding buried human remains.

Precipitation kinetics of γ′ phase in nickel base superalloy SC16: an in situ neutron diffraction study

An in situ study of the kinetics of nucleation and growth of the γ′ phase in the single crystal Ni base superalloy SC16 was carried out by means of neutron diffraction. The investigation was aimed at a better understanding of the fundamental kinetic phenomena, in view of the optimisation of the heat treatments applied prior to the industrial use of the alloy. On heating above the solvus point (1525 K) the γ′ phase decomposes, and when cooling down back towards lower temperatures, it reappears. Measuring superlattice reflections allows the different stages of decomposition, nucleation, growth and concurrent coarsening to be followed. Results show that at temperatures T≤1490 K an increasing volume fraction of γ′ can be found with decreasing temperature, until saturation occurs at around 1100 K. Following classical kinetic theory, an Avrami like growth (time) law was used at each aging temperature and the isothermal reaction rates calculated. They show a maximum at around 1300 K, where the competing nucleation and growth processes find equilibrium. Nucleation and growth can be described with a modified Arrhenius law, analogous to that used for eutectoid reactions. The reaction rate first increases with the undercooling and then decreases. This implies a change in the character of the reaction, which was found to be initially surface and then bulk driven.

Concentrations of secondary compounds in Scots pine needles at different stages of decomposition

A litterbag experiment was conducted to study chemical changes in decomposition of Scots pine needle litter in central Finland. Concentration of secondary metabolites (terpenes, resin acids and total phenolics) and main nutrients (N, P, K, Ca and Mg) were analysed four times over a 19-month period. After 19 months decomposition, the mass loss by pine needle litter was about 22%. Initial concentrations of monoterpenes and total phenolics were 36 and 27% lower in needle litter than in green needles, respectively, while more (44%) resin acids were found in needle litter than in green needles. Concentrations of monoterpenes were 6%, resin acids 35% and total phenolics 17% of the initial concentration after 19 months decomposition. In green needles and senescent brown needles most common monoterpenes were α-pinene and 3-carene. During the decomposition monoterpenes, sabinene, myrcene, limonene+β-phellandrene, terpinolene and bornylacetat, were lost to a greater extent than α-pinene, camphene and tricyclene. At the end of decomposition experiment several oxygen-containing hydrocarbons were detected in terpene samples. The most commonly identified compounds were verbenone and verbenol. Resin acid composition also changed substantially during decomposition, neoabietic acid decomposed faster than other resin acids. Dehydroabietic acid was the main resin acid in needle litter after 19 months decomposition. The concentrations of N, P and Ca significantly increased during decomposition, while concentrations of Mg and K decreased. The results suggest that degradation of secondary organic compounds in needle litter is a slow process and these compounds might have effects on decomposer organisms for several years after needle abscision.

Survival and infection of root-knot nematodes added to soil amended with rye at different stages of decomposition and cropped with cotton

The incorporation of a rye ( Secale cereale L.) cover crop into the soil prior to planting cotton ( Gossypium hirsutum L.) has been shown to restrict damage caused by root-knot nematodes ( Meloidogyne incognita (Kofoid and White) Chitwood). A greenhouse study was conducted to determine the duration of the effectiveness of rye decomposition in controlling root-knot nematode damage in relation to the time between rye incorporation and cotton planting. Fresh, chopped-rye foliage was mixed into pots of soil and root-knot nematode eggs were added to the rye + soil mixture or a non-amended soil at 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21 days following rye incorporation. This resulted in a sequence of pots containing nematode eggs exposed to rye at different stages of decomposition. Cotton plants were transplanted into the pots after the addition of nematode eggs and assessed for damage after 28 days of exposure. Although the effectiveness of the rye treatment declined over the 21 days of the incubation, the root-knot nematode populations were significantly reduced by the rye treatment for all planting dates. This suggests that it is not necessary to plant cotton immediately after plowing in a rye cover crop, thereby providing some flexibility in the cotton planting date, minimizing any associated phytotoxicity to the young cotton plants.

Biological influences on the morphology and micromorphology of selected Podzols (Spodosols) and Cambisols (Inceptisols) from the eastern United States and north-east Scotland

Biological activities greatly influence the formation of many soils, especially forest soils under cool humid climates. The objective of this study was to investigate the effects of vegetation and soil biota on the formation of selected soils. Field morphology, micromorphology, and carbon and organic matter analysis were determined on six Podzols (Spodosols) and two Cambisols (Inceptisols) from the eastern United States and north-east Scotland. Humification of plant material by soil fauna and fungi occurs in all organic horizons. Thick organic coatings are observed on soil peds and rock fragments from the E1 to the Bs horizon in a Haplic Podzol from Clingmans Dome Mt., TN. Thin sections reveal large accumulations of root material in different stages of decomposition in the spodic horizons of a Haplic Podzol from Whiteface Mt., NY. Organic carbon ranges from 5.4 to 8.5% in the spodic B horizons of the Whiteface Mt. Podzol. Earthworms and enchytraeids have a great effect on the structure of the surface and subsurface horizons in the Dystric Cambisols from Huntly and Clashindarroch Forests, Scotland and a Cambic Podzol from the Corrie Burn Basin, Scotland. Podzols from Speymouth Forest, Scotland (Gleyic Podzol), Clingmans Dome Mt., and Whiteface Mt. have thick organic horizons. The Podzols from the Flatwoods in Georgia, the Pine Barrens in New Jersey, the Corrie Burn Basin, and the Cambisol from Huntly Forest have only A horizons at the surface. The Clashindarroch Forest soil has a very thin organic horizon. Warm and humid climates and sandy parent material are responsible for thick E horizons and lack of thick organic horizons in the Flatwoods (Carbic Podzol) and Pine Barrens (Ferric Podzol) soils. Earthworms and enchytraeids thrive in the Corrie Burn Basin and Huntly Forest soils due to the vegetation and the highly weathered basic parent material. The site at Clashindarroch once carried oak, and then birch forest, both of which produce a mild litter and also encourage earthworm and enchytraeids. This fauna is responsible for much mixing of the topsoil. The present conifer vegetation will eventually produce a deep litter and cause podzolization.

Nutrient stores and dynamics of woody detritus in a boreal forest: modeling potential implications at the stand level

Concentrations of 14 chemical elements (Al, B, C, Ca, Cu, Fe, K, N, Mg, Mn, Na, P, S, Zn) were measured in wood and bark of 126 sample trees representing different stages of decomposition in three major tree species of northwestern Russia: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), and birch (Betula pendula Roth.). Changes in nutrient stores in decay classes were calculated with adjustments for the loss of density and volume by dead trees. Although the concentration of many nutrients increased relative to the estimated initial level, the total amount of most nutrients contained in dead trees declined with decay. For example, nitrogen stores declined from decay class 1 to 4 by 45% for birch, 39% for spruce, and by 60% for pine. The rate and pattern of these losses varied by nutrient and by species and were primarily related to the patterns of bark loss. Pine lost bark early in the process of decomposition and released many essential nutrients (i.e., N, P, Ca) at the early stages, while birch retained most of its bark throughout the decomposition process and lost nutrients more gradually. The temporal dynamics of N, Ca, and K loss in pine were examined using a chronosequence approach, and the results were used in stand-level modeling. The analysis of modeling results suggests that, in northwestern Russia, post-disturbance release of nutrients from woody detritus can potentially supply a large proportion of the net N, Ca, and K accumulation in live forest biomass.