Peat Types Research Articles

Characterization of peat structure using X-ray computed tomography and its control on the ebullition of biogenic gas bubbles

The structural arrangement of peat constituents controls the hydrological and thermal properties of peat. However, the importance of these structural characteristics on other physical processes within a peatland has not been fully assessed. Here, we evaluate the importance of peat structure on its ability to entrain biogenic gas bubbles and control ebullition, an important transport mechanism for methane. X-ray computed tomography (CT) was applied to characterize the structure of a range of peats at varying levels of decomposition. The structural properties of the peat were quantified from a vector representation of the CT images, and the potential of each sample to entrain biogenic gas bubbles was quantified using a rule-based Monte Carlo model that calculates the tortuosity of bubbles pathways through the peat. Sixty-six percent of the variability in the trapping potential of the peat results from porosity variations and 34% from structural variations between samples. A metric that represents this structural control was not identified for all peat types because of difficulties adequately representing some peats as a vector network. However, for S. magellanicum peat we were able to establish that the influence of peat structure on the entrainment of gas bubbles is characterized by (L) over bar (v), the average vector length of the stems and branches. Peat characterized by longer structural components (larger (L) over bar (v)) enhances the entrainment of gas bubbles. Our findings demonstrate the need to incorporate some representation of the peat structure in numerical models of biogenic gas transport in peat.

Influence of water table level and soil properties on emissions of greenhouse gases from cultivated peat soil

A lysimeter method using undisturbed soil columns was used to investigate the effect of water table depth and soil properties on soil organic matter decomposition and greenhouse gas (GHG) emissions from cultivated peat soils. The study was carried out using cultivated organic soils from two locations in Sweden: Orke, a typical cultivated fen peat with low pH and high organic matter content and Majnegarden, a more uncommon fen peat type with high pH and low organic matter content. Even though carbon and nitrogen contents differ greatly between the sites, carbon and nitrogen density are quite similar. A drilling method with minimal soil disturbance was used to collect 12 undisturbed soil monoliths (50 cm high, O29.5 cm) per site. They were sown with ryegrass (Lolium perenne) after the original vegetation was removed. The lysimeter design allowed the introduction of water at depth so as to maintain a constant water table at either 40 cm or 80 cm below the soil surface. CO2, CH4 and N2O emissions from the lysimeters were measured weekly and complemented with incubation experiments with small undisturbed soil cores subjected to different tensions (5, 40, 80 and 600 cm water column). CO2 emissions were greater from the treatment with the high water table level (40 cm) compared with the low level (80 cm). N2O emissions peaked in springtime and CH4 emissions were very low or negative. Estimated GHG emissions during one year were between 2.70 and 3.55 kg CO2 equivalents m-2. The results from the incubation experiment were in agreement with emissions results from the lysimeter experiments. We attribute the observed differences in GHG emissions between the soils to the contrasting dry matter liability and soil physical properties. The properties of the different soil layers will determine the effect of water table regulation. Lowering the water table without exposing new layers with easily decomposable material would have a limited effect on emission rates.

Denitrification from the horticultural peats: effects of pH, nitrogen, carbon, and moisture contents

Denitrification plays an important role in N-cycling. However, information on the rates of denitrification from horticultural growing media is rare in literature. In this study, the effects of pH, N, C, and moisture contents on denitrification were investigated using four moderately decomposed peat types (oligotrophic, mesotrophic, eutrophic, and transitional). Basal and potential denitrification rates (20°C, 18 h) from the unlimed peat samples varied widely from 2.0 to 21.8 and from 118.9 to 306.6 μg (N2O + N2)–N L−1 dry peat h−1, respectively, with the highest rates from the eutrophic peat and the lowest from the transitional one. Both basal and potential denitrification rates were substantially increased by 3.6–14- and 1.4–2.3-fold, respectively, when the initial pH (4.3–4.8) was raised to 5.9–6.5 units. Emissions of (N2O + N2)–N from oligotrophic, mesotrophic, and transitional peats were markedly increased by the addition of 0.15 g NO3–N L−1 dry peat but further additions had no effect. Denitrification rates were increased by increasing glucose concentration suggesting that the activity of denitrifiers in all peat types was limited by the low availability of easily decomposable C source. Increasing moisture contents of all peats from 40 to 50% water-filled pore space (WFPS) did not significantly (p > 0.05) increase (N2O + N2)–N emissions. However, a positive effect was observed when the moisture contents were increased from 60% to 70% WFPS in the eutrophic peat, from 70% to 80% in the transitional, from 80% to 90% in the oligotrophic and from 70% to 90% in the mesotrophic peat. It can be concluded that liming, N-fertilization, availability of easily decomposable C, and moist condition above 60% WFPS could encourage denitrification from peats although the rates are greatly influenced by the peat-forming environments (eutrophic > mesotrophic > oligotrophic > transitional types).

CADANGAN, KEHILANGAN, DAN AKUMULASI KARBON PADA PERKEBUNAN KELAPA SAWIT DI LAHAN GAMBUT TROPIKA

Peat land conversion to oil palm plantation affects carbon stocks and can change a net sink of atmospheric carbon (C) into a net source. The influence of location, type of peat, drainage practices and fertilization is insufficiently known. A study was conducted in West Aceh from May 2008 until October 2009 in oil palm plantations of various age. Carbon stocks and C loss were calculated from data of bulk density (BD), ash content, carbon content, and peat depth. A new method for C loss estimates using ash as internal tracer was developed and tested. Peat land characteristics after drainage and conversion to oil palm plantation were investigated by field observation and laboratory analysis of peat soil samples in the laboratory. Results showed that: 1) Distance from the drain influences the rates of: a) water table depth, b) subsidence, with rates of 1,1 to 9,2 cm/year and 22.67 – 57.23% influence of C loss, and c) soil carbon loss. 2) Ash content and bulk density of the peat are related, indicating the partial loss of soil C during compaction. 3) An “internal tracer” estimate of peat C loss yields estimates of CO2 flux up to 48 t CO2-eq ha-1 y-1 for young oil palm, highly correlated with measured rates of subsidence of the surface and water table depth. 4) Patterns of weight loss of surface litter, measured in litter bags, respond to inherent quality (C/N). Some data for oil palm on shallow peat suggest that a net sink for C can be maintained under such conditions.Key words: Carbon stock, carbon loss, carbon accumulation, oil palm, tropical peat

Chemical properties of peat in three peatlands with balneological potential in Estonia

Peat and various peat preparations have been successfully used in balneology. When considering the biological effects of peat, humic substances have been found to be of particular importance. The content of humic, hymatomelanic and fulvic acids as well as main characteristics of peat were measured in three areas with balneological potential, selected according to previous research and mapping of Estonian peatlands. It appeared that the content of bioactive substances in the sampled peat layers was relatively high. The concentrations were highest in the Parika peatland: humic acids 39.3%, hymatomelanic acids 19.3% and fulvic acids 1.3%. The main factors influencing the levels of bioactive substances were the degree on humification (more humified peat had higher concentrations) and peat type (forest(pine)-cottongrass composition increased the concentration levels). As lipids had high correlation with hymatomelanic acids and trace elements with fulvic acids, the mentioned components could be respectively bound to these humic substances.

Assessing the factors limiting the Rosa gallica L. shrub occurrence in Romanian grasslands (case study)

Analyses of water conditions in the Lower Basin of the Biebrza River and deposit stratigraphy were conducted in cross-sections through the valley, where geodetic measurements were also made. Peat type in particular layers of the soil profile was determined in selected cross-sections at 100 m intervals. The Lower Basin of the Biebrza River is diverse with regard to the type of water supply to a peatbog, the shape of the bio-accumulative basin’s bottom and the slope of peatbog surface along and across the valley. These factors resulted in the development of different habitats in the peatbog. Northern part of the Lower Basin, between the main road in the village Osowiec and the inflows of the Kosodka and Wissa rivers to the Biebrza River, is a narrow valley supplied mainly with overflowing water of the Biebrza River. Habitats and hydrogenic deposits of this area developed in relation to the type and layout of mineral substratum and to the duration and depth of seasonal flooding. North-west part is mainly supplied by ground water from the adjacent upland. Peat layers, developed on ground waters flowing out from the upland, markedly slope toward the bed of the Biebrza River. Considerable fluctuations of the ground water level can be observed there and most frequently the sites are periodically drying. Part of the valley, from the inflows of the Kosodka and Wissa rivers down to the Biebrza and Narew River confluence, is mainly supplied with underground waters from upland.

Effect of Granular Activated Carbon on the Enhancement of Cometabolic Biodegradation of Phenol and 4-Chlorophenol

Enhancement of the cometabolic biotransformation of 4-chlorophenol (4-cp) and phenol were studied using chemically and thermally granular activated carbons (GACs). It was found that both chemically activated and thermally activated GAC effectively adsorb phenol and 4-cp. More than 80% adsorped substrates were later desorpted, showing a reversible sorption behaviour in the GAC. For each activated carbon type, 4-cp was preferentially adsorbed over phenol and the desorption efficiencies of both phenol and 4-cp were found to increase linearly with the initial mass of adsorbate in the adsorbent. The biodegradation of 500 mg/L phenol by Pseudomonas putida took 24 h while the biodegradation of 4-cp took 32 h. Inhibitions during the cometabolic biodegradation of 4-cp and phenol were alleviated by the addition of the GACs. The system with chemically-activated coconut type GAC had better system stability over thermally-activated peat type GAC. The results show that GAC can be regenerated by the cells enhancement of the cometabolic biotransformation of 4-cp and phenol can be accomplished using chemically-activated coconut type GAC.

Spectral Variability and Discrimination Assessment in a Tropical Peat Swamp Landscape Using CHRIS/PROBA Data

In this study, we examine seasonal aspects and the potential of multi-angle CHRIS/PROBA data, acquired at two different dates, to improve forest classification. The test site is a typical peat swamp landscape located in Central Kalimantan, Indonesia. We focus on eight specific land use/cover categories from a single view angle and from a multi-angular perspective. We show that: (1) reflectance changes from the end of the monsoon to the beginning of the dry season in the visible were small and slightly positive for the forestry classes, whereas slightly negative for grassland classes; (2) reflectance increases according to the successional stages for a given angle and were higher in the beginning of the dry season; (3) reflectance values increase in the near-infrared with decreasing leaf area index (LAI); and (4) classification results using a multi-angular approach were statistically better at a 5% level of significance from a single view approach on both selected dates, showing that anisotropy information can improve differentiation between peatland landscape classes.

The n-alkanol paleoclimate records in two peat deposits: a comparative study of the northeastern margin of the Tibetan Plateau and Northeast China

A number of studies have revealed that the climate in the eastern margin of the Tibetan Plateau and Northeast China is sensitive to postglacial changes. Unfortunately, the link of the past climate evolution between the two regions is not well understood. In this study, two cores are analyzed to determine this link directly. The high-resolution n-alkanol distribution patterns from two typical peat sequences covering the past 16,000 cal years in the northeastern margin of the Tibetan Plateau and Northeast China, respectively, are closely examined by gas chromatograph–mass spectrometry analysis. In combination with other palaeoclimatic proxies, it is proposed that the n-alkanol average chain length and (C22 + C24)/(C26 + C28) ratio could reflect past climate changes in the two peat sequences. The n-alkanol proxies reveal several climatic intervals in the period from the last deglaciation through the Holocene. A comparison of n-alkanol records between the northeastern margin of the Tibetan Plateau and Northeast China indicates that the start and end of the warm Holocene Optimum differed at the two locations. The spatially asynchronous pattern of climatic change is possibly a result of different responses to change in solar radiation. The evolution of the Holocene paleoclimate is more consistent with changes in Northern Hemisphere solar radiation in Northeast China than on the Tibetan Plateau. The Holocene Optimum began and terminated earlier in Northeast China than in the northeastern margin of the Tibetan Plateau. Thus, the two n-alkanol proxies provide valuable insights into the regional Holocene climate and local environmental conditions.

A New Method for Determining the Bulk Density of Uncompacted Peat from Field Settings

Abstract A new method for determining the bulk density of uncompacted surficial peat from field settings is presented. Most importantly, a new peat sampler was developed to ensure minimum disturbance of the peat sample. The main benefits of the new device are (1) from the moment of field sampling, the peat sample remains undisturbed in an inner collecting liner, which has a fixed volume and fits perfectly in an outer cutting tube, until the sample is ready to be analyzed in a laboratory, (2) the risk of fracturing or disturbing the sample during lifting it to the surface is significantly reduced by using a vacuum pump or hose to reduce suction at the base of the peat core, and (3) the razor-sharp cutting edge of the outer tube easily cuts through all kinds of fibers by short rotational movements. Furthermore, sufficiently large samples can be extracted, thereby accounting for the heterogeneous character of peat. The device is relatively light and easy to operate, which is a great advantage in the often remote and difficult-to-access peatlands. The sampler was successfully used during test trials on different types of fen peat in the Biebrza National Park, Poland.

Subsidence and degradation of agricultural peatlands in the Fenlands of Norfolk, UK

Historical drainage of peatlands across the East Anglian Fenlands has led to subsidence and degradation of the vast majority of the regional peat resource, to the extent that many areas can no longer be classified as peatland. Water-table management strategies have been introduced to reduce the rate at which these peatlands subside and physically and biochemically degrade. We assessed the rate of subsidence and extent of peat soil degradation across an intensively farmed peatland where such water management measures have been introduced. When compared against historical reports of subsidence across the East Anglian Fenlands, the rate of subsidence does appear to have reduced over the last two decades. The rate of subsidence does, however, vary spatially and is dependent on the geographical distribution of peat types and underlying mineral deposits. The rate of subsidence and peat degradation has been greater in soil profiles which had a higher proportion of semi-fibrous and fibrous peats in 1982/3, compared against those with a higher proportion of humified peat in 1982/3. Over the last 22 years the proportion of more fibrous peat in all peat deposits has decreased to the extent that areas once classified as fibrous peat are now dominated by humified peat. This suggests that future subsidence will be less influenced by shrinkage and controlled by biochemical processes. Where Fen Clay underlies a peat deposit it acts as an impermeable boundary, thus keeping the overlying peat more saturated and reducing the degree of peat consolidation. However, the presence of Fen Clay also increases the degree of biochemical degradation of overlying fibrous peat horizons. Indeed, where drains have been laid within such mineral strata there is an increase in soil acidity. During autumnal drainage operations the environment is therefore optimised for sulfate reducing bacteria, resulting in acid sulfate soils with increased rates of degradation.

An evaluation of the functional significance of peat microorganisms using a reciprocal transplant approach

Our current knowledge on the relevance of microbial diversity and composition for the recovery and maintenance of soil biological processes is rudimentary, partly because experimental substantiation of the importance of community composition to function is scarce. Guided by this gap, we devised a reciprocal transplant experiment to examine the functional behaviour of different microbial communities exposed to two structurally distinct peats. Sterile peat samples representing two types, one humified (sedge) and the other dominated by coarse plant material (fibric), were inoculated with a 10 −1, 10 −3, 10 −5, or 10 −8 dilution of either the same or reciprocal peats. After 5 months of incubation, we used a nucleotide-analog technique to label the active bacterial taxa in samples receiving the 10 −1 and 10 −8 dilutions. We assessed both the peats' functional potential (respiration and nutrient-acquiring and lignin-degrading enzyme activities) and the structures of active and total bacterial communities (PCR-DGGE). In general, we found a decline in respiration rates and increase in enzyme activities with increasing dilution level, but the effect of dilution on bacterial richness was weak. The bacterial community structure and richness depended on both the inoculum source and the peat type. The activity of enzymes involved in nutrient acquisition depended mainly on the soil type, while the lignin-degrading activity was influenced by differences in community composition between peat types. Neither active bacterial populations nor respiration were significantly influenced by peat type or inoculum source. Our results suggest that the relationship between microbial community composition and function is not only related to the taxonomic breadth of the taxa that perform a given function, but may also be shaped by interactions between microorganisms in the inoculum source and the substrate being colonized.

Research of chemical and toxic properties of humic acids of low-moor woody-grassy type of a peat in Tomsk Region

In article results of research of a chemical structure of humic acids of low-moor woody-grassy type of peat of Tomsk Region are resulted by methods of the elemental analysis and infra-red spectroscopy. In this work results of toxicological research of humic acids also are described: acute toxicity, pathomorphology and flow properties of blood. It is shown, that humic acids of low-moor woody-grassy type of peat represent connection with a high share aliphatic fragments submitted long connected by circuits, have a small degree benzenoid, contain active oxygen and itrogen-containing functional groups (carboxylic, hydroxyl, amides, amino groups). It is established, that humic acids at intragastric introduction are nontoxic substances. At intraperitoneal introduction of lethal dozes, the destruction of animals comes from acute intimate insufficiency, thus the cause of acute infringement hemodynamics can be negative influence of humic acids on flow properties of blood.

Development of an alternative artificial soil for earthworm toxicity testing in tropical countries

The standard soil invertebrate toxicity tests developed by OECD and ISO use an artificial soil as the test substrate, which contains sphagnum peat as a component. This type of peat is not widely available. Investigation of possible alternative substrates using locally available materials therefore is vital for performing such ecotoxicity tests, particularly in the tropics. We studied the suitability of paddy husk (PH), saw-dust (SD), non-composted (NCCP) and composted coco peat (CCP) as a replacement for sphagnum peat. Artificial soil (AS) was prepared by mixing 70% sand and 20% kaolin clay with 10% PH, SD, NCCP or CCP. First, the reproduction potential of the earthworm Eisenia andrei was investigated in modified artificial soil (MAS) using the original OECD AS as the control. The number of juveniles produced in OECD AS, MAS PH and MAS CCP was not significantly different but it was significantly reduced ( p < 0.05) in MAS SD and MAS NCCP. The toxicity of chlorpyrifos, carbendazim and carbofuran for E. andrei was determined to validate the substrates. The 28-day LC 50s for the three pesticides in original AS, MAS CCP and MAS PH were not significantly different, but the EC 50 for effects on reproduction in the MAS PH was significantly lower ( p < 0.05) compared to OECD AS and MAS CCP. We conclude that composted coco peat might be a suitable replacement for sphagnum peat in AS for soil ecotoxicity studies.

THE EFFECTS OF RUNNER GRADE, HARVEST DATE AND PEAT GROWING MEDIA ON STRAWBERRY TRAY PLANT FRUIT PRODUCTION

Strawberry plugs are quickly replacing traditional bare-root transplants in Ireland. This is particularly the case for soilless culture in glasshouse and polythene tunnel production. The aim of this experiment was to study the effect of runner size, date of runner harvest and two peat types on subsequent fruit yield characteristics from the 'tray plants' grown. Runner tips were harvested from 'super elite' strawberry mother plants cv. 'Elsanta' and planted into peat modules and grown in a non-heated glasshouse. Runner tips were harvested on the 5 th and the 19 of July 2005. On both dates they were graded into small, medium and large sizes. These were rooted in one type of propagation tray and two different types of peat substrate. The final strawberry crown diameter ranged from 14.3 to 15.69 mm at harvest. The root score ranged from 3.55 to 4.36 out of a total score of five. There was no significant difference between the total yields recorded in either season one or two for any of the treatments. The lowest and highest average yield recorded over the two seasons was 11.33 and 12.73 kg per m 2 respectively. The average fruit weight was higher from plants propagated from large runners and when grown in the finer peat substrate. However, when large runners were used later in the season, the average fruit weight is lower. Strawberry crown dissection showed the regular pattern of flower formation throughout the growing season. The stage of flower development was closer for the three runner grades that were harvested later.

Comparative IR spectral characteristics of humic acids from peats of different origin in the Tomsk area

Results obtained from comparative studies of the structures of humic acids from peats of different origins in the Tomsk area by infrared spectroscopy are presented. These data showed that the IR spectra of humic acids extracted from different types of peat had high levels of similarity, demonstrating similarities in their chemical structures. Humic acid from lowland woody-grassy peat had very significant differences from other types of peat and consisted of compounds with high proportions of aliphatic fragments and, perhaps, lower benzenoid levels, as well as higher contents of active acid groups (carboxyl, hydroxyl).

Ground beetle Assemblages of Peat bog Remnants in Northwest Germany (Coleoptera: Carabidae)

This is a study of the ground beetle fauna of different habitat types in peat bog remnants. Its aim was a breakdown into different carabid assemblages and to verify whether a typical peat bog assemblage exists. Based on these results, we would then try to evaluate habitat quality. The study was conducted in three peat bog remnants in Northwest Germany (North Rhine-Westphalia). Carabids were sampled with pitfall traps between May and July 2008 in 21 study sites. A total of 4,201 individuals belonging to 75 species were captured. By using nonmetric multidimensional scaling, we were able to define five carabid assemblages. For each assemblage, indicator species were defined with the IndVal procedure. The definition of a peat bog specific community was controversial. However, the occurrence of the tyrphobiontic species Agonum ericeti showed that at least some parts of the study area had a high habitat quality. With suitable peat bog management the unique character of these peat bog remnants could be preserved or advanced.

Biological activity of water-ethanol extracts from peat and alkaloids isolated from them

The biological activity of water-ethanol extracts from various types of peat were studied. Alkaloids were isolated from peat and its extract for the first time. It was found that the biological activity of the alkaloids was higher than that of the water-ethanol extracts. In addition to a growth-stimulating activity, the extracts from peat and peat-forming plants exhibited a fungicidal activity toward the causative agents of glume mold and bacteriosis.

Hydraulic properties of fen peat soils in Poland

The hydraulic properties of fen peat soils from the Biebrza River Valley in the north-east of Poland were investigated. 87 soil samples were collected from nine typical peat-moorsh soil profiles representing three types of peat: moss with fibrous structure, herbaceous and wooden peat characterised by amorphous structure with high humus content. The multi-step outflow method was used to determine the parameters of the Mualem-van Genuchten model (MVG) that describes soil moisture retention characteristics and the unsaturated hydraulic conductivity function of each soil sample. The agglomerative hierarchical cluster analysis of the parameters of MVG model was applied in order to obtain typical hydraulic functions for the three types of peat considered. As a result of the analysis, the hydraulic properties of the fen peat soils were agglomerated into five clusters. The MVG model parameters as well as hydraulic functions were analysed for distinguished clusters. The parameters of the moss peats with low degree of decomposition and fibric structure were different from those of the herbaceous and wooden decomposed peats with high humus content. The largest values of the hydraulically active pore space (difference between saturated and residual moisture content) were observed for moss peat samples, while the lowest values were observed for wooden peat samples. The empirical parameters describing the shape of the unsaturated hydraulic conductivity function were depended on the type of the peat and therefore the degree of decomposition. The L parameter values of the herbaceous and wooden peats were generally greater than 0, whereas for the moss peat samples they were ranging from − 5 to 5. The unsaturated hydraulic conductivity of the herbaceous and wooden peat soils was close to that of very fine-textured mineral soils.

MICROBIOLOGICALLY IMPROVED PEAT-BASED MEDIA FOR NURSERY PRODUCTION BY ADDITION OF ARBUSCULAR MYCORRHIZAL FUNGI

MICROBIOLOGICALLY IMPROVED PEAT-BASED MEDIA FOR NURSERY PRODUCTION BY ADDITION OF ARBUSCULAR MYCORRHIZAL FUNGI