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Using kukersite oil shale ash for the stabilization of organic-rich soils has been extensively studied but without much success. The main reason for this is the retarding effect of humic acids present in organic-rich soils on the formation of the C–S–H (calcium–silicate–hydrate) phase, which effectively prevents the solidification of cementitious materials in peat soils. Based on the studies performed at the University of Tartu, we have developed a novel method for the in situ mass stabilization of peat soils using waste materials (calcareous fly ash and silica fume). In this manner, the perfect hardening of peat–ash mixtures (to each 1 m3 of soil, 150–400 kg ash, 25–50 L pozzolanic additives, and 2.5–5 kaNaOH were added) can be achieved. A test road embankment was constructed under extremely hard conditions in a peat quarry that is currently in use. [ABSTRACT FROM AUTHOR]

The contents of chemical elements in the alluvial soils (Fluvisols) in the middle reaches of the Bolshaya Kokshaga River have been studied, The parent material of these soils inherits its composition from sediments of the Central Russian and Cisuralian mineralogical and geochemical provinces. Limits of the bulk contents of elements and their background concentrations have been established, which forms the basis for the environmental monitoring in the Bolshaya Kokshaga Nature Reserve. In total, 34 elements have been determined in the alluvial soils and sands of shoreline shoals; the most abundant elements with concentrations above 1 g/kg are Si, Al, Fe, Ca, K, Mg, Na, Ti, Mn, P, and S. Element concentrations in different types of soils differ in a statistically significant manner. The highest similarity in the elemental composition is observed for meadow and mucky gley soils. As compared with the alluvial soils, the sands of shoreline shoals display the maximum content of Si and the minimum contents of other elements. Soddy soils are characterized by the low content of all elements, except for Si. Meadow and mucky gley soils accumulate larger amounts of Al, Fe, K, Na, Mg, Ti, Mn, Ba, Cr, Zn, Ni, V and As, while eutrophic peat soils (highly mineralized peat deposits) accumulate more Ca, S, P, Sr, Cl, and Rb. Concentrations of As, Cu, V, P, Zr, Ni, and Zn in the alluvial soils exceed their natural abundance in the Earth crust (clarke values) by 1.5–2 times (Kc = 1.5–2), while concentrations of Al, K, Mg, Ti, Sr, Rb, Na, Cl, and Ca are below their clarke values (Kc < 1); concentrations of other elements are comparable to clarke values. [ABSTRACT FROM AUTHOR]

The calculation of the settlement of a peat soil foundation is based mainly on the formula obtained by data fitting or simply modifying the universal calculation formula. The deformation mechanism reflected by these calculation methods is indistinct. Therefore, several model tests were carried out using the embankment structure of the Dali–Lijiang expressway as a prototype, and the settlement was analyzed with the one-way consolidation deformation and in situ settlement of other researchers. First, the S − logt (S is the deformation) curve of peat soil showed no obvious inverse "S" change, which is different from that of soft soil or mucky soil. According to the S − t curve, the deformation process of peat soil can be divided into three stages. Second, the relationship between the compression modulus and load was analyzed and combined with the settlement calculation results. The compressive modulus between 12.5 and 25 kPa [En(0.125–0.25)] was proposed to be used when calculating the settlement of peat soil foundations by the layerwise summation method. Moreover, the compression modulus of the three consolidation stages was proposed to be used to calculate the settlement of peat soil foundations by the layered sum method. At the same time, the influence of confinement on the compression modulus of the third consolidation stage should be considered and corrected. The accuracy of the settlement calculation method proposed in this paper was higher than the accuracy of the standard layerwise summation method, regardless of whether the horizontal limiting conditions of the standard method are modified. [ABSTRACT FROM AUTHOR]

Peat is a problematic soil, and it is a common problem faced by engineers in construction. The characteristics that have been noted before are high moisture content, poor shear strength, great compressibility, and long-term settlement. For this research study, it focuses on stabilizing peat soil using EPP and CaO. There are three main tests that were conducted in this research study: index properties testing, compaction testing, and For Index Properties testing, five (5) experiments were conducted to study the index properties of disturbed peat soil, which are moisture content, fiber content, liquid limit, organic content, pH, and specific gravity. Next, for the Compaction Test, using a 4.5 kg rammer, define the optimum mixture of stabilizer that is mixed with different volumes of 5%, 10%, 15%, and 20% of stabilizer. In this study, the expected result is to inspire an in-depth study of the use of EPP material and chemical CaO as peat soil stabilizers for better utilization of problematic soil. The main finding was that the mixture with the exact amount of moisture, EPP, and CaO helped stabilize the soil and cure peat soil. Thus, this study confirms the idea of treating peat with EPP and CaO, enhancing the properties of peat soil, and sustaining the settlement over loading for a period of time accordingly. 20% mix of EPP and CaO produces the highest dry density, showing that dry density increases linearly with the amount of mixture to stabilize peat. The crystallization process between peat and EPP was pronouncedly observed where smaller particles identified as EPP filled the gaps in between the pores identified from SEM. The silicon (Si content developed from each spectrum ranged from 14.4% to 17.7%. The EDX results show significant results where mineral crystallization occurred in the coagulation process. [ABSTRACT FROM AUTHOR]

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Humic acid is one of the green materials for wastewater treatment including for removal dyes as an adsorbent. Humic acid was isolated from peat soil, Gambut Regency, South Kalimantan following International Humic Substances Society method, and used to adsorb Congo red. The adsorption process was carried out in a batch system and the effect of pH, contact time, and adsorption capacity of Congo red on humic acid were studied. The adsorbent characterization by using FTIR. The results showed that the adsorption of Congo red on humic acid occurred at the optimum pH of pH 6, the optimum contact time was 120 minutes. The adsorption capacity of Congo red onto humic acid of 33.33 mg/g and follows the Langmuir model with R² = 0.9926. The characterization of humic acid functional groups before and after adsorption of Congo red showed that the signal at 1,712.79 cm-1 were shifted to 1,705.07 cm-1 and 1,273.02 cm-1 were shifted to 1,265.30 cm-1. These suggested that the mechanism interaction was the electrostatic interaction between -NH3+ functional group of Congo red group and -COO- functional group of humic acid. It means that humic acid isolated from peat soil could be used as an adsorbent for the removal Congo red. [ABSTRACT FROM AUTHOR]

The purpose of the study was to determine the geotechnical properties of peat and relate them to the fibre content. Peat soil tested in this study was collected from the peatland in the north-eastern Poland, 250 km north-east of Warsaw. Peat samples were taken from eight different depths below the ground surface over an area of approximately 2500 m2. The research programme consisted of laboratory tests of the physical properties of peat and compressibility tests conducted in oedometers. Tests were performed in accordance with the current international and European standards using specialised research equipment. Based on the degree of decomposition, peat was divided into fibric (with more than 66% of fibres), hemic (fibre content from 33% to 66%) and sapric (less than 33% of plant fibres). The bulk and particle densities, natural water content, organic content, initial void ratio and the degree of decomposition were investigated as the physical properties of peat. Based on the oedometer tests, the constrained modulus, compression and secondary compression indexes were determined. It was concluded that the fibric peat is characterised by the lowest bulk and particle densities, the highest water and organic contents, void ratio and compressibility in comparison to hemic and sapric peat. The characteristics of peat have been related to the results presented in the literature. [ABSTRACT FROM AUTHOR]

Roads play an important role as a connection between locations and can facilitate the efficient mobility of people's economic activities. Five tests are involved in evaluating of the porous concrete, such as the slump test, compressive strength test, permeability test, flexure test, and load capacity test (loading test). Meanwhile, there are three types of soil: peat, clay, and hard. The compressive strength test measured an average compressive strength between 24.17-27.36 MPa. According to the permeability test, the average speed of water infiltration on the porous concrete rigid pavement was 20 seconds on clay soil and 55.344 seconds on peat soil, with large areas drained on porous concrete rigid pavement of 346.185 cm2 with 5 litres of water used, whereas it was 6.554 seconds with a flow area of 288.75 cm2 and 2 litres of water used on hard soil. The Loading Test was conducted with a 10-ton. The maximum difference in deflection was 1-2 cm. In addition, there were no cracks in the porous concrete rigid pavement with a porous concrete rigid pavement thickness of 15 cm in three different soil conditions. A track with porous concrete rigid pavement on clay, hard soil, or peat soil can accommodate a maximum payload of 10 tons. [ABSTRACT FROM AUTHOR]

The problem of pedo- and biodiversity of mire ecosystems under the long-term multiple anthropogenic impact was studied in one of the most intensively technogenically transformed areas of Shaturskaya Meshchera, adjacent to power station Shaturskaya in the north and stretching along the route Kerva – Dolgusha – Severnaya Griva. For more than a hundred years, mires in the Shatura area have been under the influence of drainage, peat extraction, fires, attempts to create agricultural land, secondary watering and pollution, resulting from the power station, transport, and settlements wastewaters. Currently, the bio- and soil diversity of secondary ecosystems has increased significantly compared to undisturbed mires. Instead of bog, in some cases there appeared secondary meadow, grass-shrub communities, small-leaved forests, and dry sparse areas. The remaining bogs experience stable eutrophication, which leads to the formation of mesotrophic and eutrophic phytocenoses and, accordingly, peat mesotrophic and oligotrophic secondary eutrophic soils. In addition, the proportion of eutrophic mires is slightly increased by the peat formation in shallow lakes, which at the initial stage of peat extraction were used for storing wood waste. The phenomenon of secondary oligotrophization of the disturbed bogs of Meshchera, noted in the literature, is not observed in the area under consideration due to a significant anthropogenic load. To preserve the local flora of oligotrophic bogs, marginal areas of flooded quarries and cofferdams with undeveloped peat deposits are of great importance. The increase in pedodiversity was facilitated by the agricultural development of drained peatlands for the cultivation of perennial grasses, which resulted in the formation of torfozems and agrotorfyano-gleyzems.

The high-elevation peatlands of the páramos of the northern Andes constitute a diverse environment that harbors large numbers of species and several types of plant communities along altitudinal, latitudinal, and environmental gradients. However, little is known about the structure and functioning of these ecosystems, including peatland vegetation types and their relative contribution to the production and accumulation of peat soils. In this paper we characterized the structure of peatland plant communities of the humid páramos of northern Ecuador by describing the distribution of plant growth-forms and their aboveground biomass patterns. Along an elevation gradient of 640 m we sampled vegetation in 16 peatlands and aboveground biomass in four peatlands. Three distinct peatland vegetation types were identified: High elevation Cushion peatlands, dominated by Plantago rigida and Distichia muscoides, Sedge and rush peatlands dominated by Carex spp. and Juncus spp., and Herbaceous and shrubby peatlands, with a more heterogenous and structurally complex vegetation. In terms of aboveground biomass, we found an 8-fold reduction in the higher peatlands compared to the lower sites, suggesting that the steep elevational gradients characteristic of Andean environments might be crucial in structuring the physiognomy and composition of peatland vegetation, either through its effects on temperature and other environmental factors, or through its effects on the age and development of soils. Additional studies are needed to evaluate the potential effects of temperature, hydrology, micro-topography, geological setting, and land-use, which are likely to influence vegetation patters in these peatlands. [ABSTRACT FROM AUTHOR]

An improvement of geoelectrical resistivity interpretation has been done through this research. Up to now, the geoelectrical resistivity data was interpreted qualitatively especially in the case of the aquifer intruded by seawater, and the percentage of seawater mixture content in the aquifer cannot be predicted. In this research, a valuable approach was used in the prediction of percentage seawater mixture in the shallow aquifer that is intruded by seawater. The study was conducted in the coastal area which is mainly covered by peat soil. The research employed the direct soil resistivity measurement and the ground surface resistivity survey. Geoelectrical resistivity with the Wenner configuration was used for both measurements. The soil character and the fluid content in the soil were measured to obtain their correlation to the direct soil resistivity value. The results show that resistivity value is about 2-5 ohm.m for 50% seawater content mixture in aquifer and it increase to be 5-10 ohm.m for 25% seawater mix to freshwater in the aquifer. The increasing seawater content in the pore soil caused the decreases in resistivity value drastically. The percentage of seawater mixture in the fluid pore soil has been successfully predicted through the geoelectrical resistivity measurement on the surface. [ABSTRACT FROM AUTHOR]

Structural indicators (abundance and diversity) of the fungal and actinomycete complexes of eutrophic peat soils in the zone of active organic detritus decomposition, namely, litter (L and F layers) and eutrophic peat horizon (TE), were analyzed. Samples were e taken in swamped forests (black alder, pine, birch, and mixed forest stands) of the Tver and Tomsk oblasts (Russia) in summer of 2021. The abundance of mycelial organisms was measured by fluorescence microscopy and plate method. Species of culturable representatives were identified by their phenotypic traits. The fungal mycelium in the litter is two–tenfold longer as compared with the TE horizons; the abundance of culturable fungi is bigger by two‒three orders of magnitude; and that of actinomycetes, by one‒two orders of magnitude. The litter fermentative layer (F) displays the maximum carbon content of the mycelial component (3‒10 mg C/g). The stocks of actinomycete biomass in the zone of active organic detritus decomposition varies from 23 to 60 kg/ha and of fungal biomass, from 1593 to 3718 kg/ha. The share of litter in the total stock of mycelial biomass across the profile is larger in deciduous forests. In total, 70 species of culturable fungi belonging to 43 genera and 42 actinomycetes species of 12 series and 4 sections were isolated from the zone of active organic detritus decomposition. Representatives of Penicillium,Talaromyces, and Trichoderma genera are prevalent in the fungal complex and of Streptomyces, in the actinomycete complex. The litter does not yield to the TE horizon in terms of species diversity of both fungi and actinomycetes. The species similarity of fungal complexes of the litter and TE horizon is 0.68 and that of actinomycetes, 0.27. [ABSTRACT FROM AUTHOR]

Peat is a soft soil with a very high organic content, which makes it highly susceptible to extreme differential settlement. Although cement stabilisation is highly effective, it is not common practice due to the high cost of treatment associated with a high binder dosage required. The use of a novel material, biochar, as a potential replacement for cement and an alternative filler to sand was investigated in this work. Biochar is more sustainable than traditional construction materials and has carbon dioxide sequestration ability. It could also potentially be cheaper than cement or sand, depending on the source of feedstock used. Cement-treated peat with sand was used as a benchmark to assess the performance of biochar-enhanced cement-treated peat. The samples with biochar finer than 75 μm performed better than the sand equivalent, with over 50% increase in compressive strength. Furthermore, it was found that the samples with 100 kg/m3 cement and 400 kg/m3 biochar had comparable performance to the control sample with 200 kg/m3 cement only, without biochar, highlighting the potential of biochar to partially replace cement. Scanning electron microscopy and X-ray diffraction results showed that the mechanisms behind the performance gain in biochar samples are of both mechanical and chemical nature. [ABSTRACT FROM AUTHOR]

As global warming becomes more pronounced, climate change and human activities are leading to frequent peat fire incidents. Fire plays an important role in the environmental distribution of trace metals in peat soils. In the current study, we collected peat soils from six peatlands of the Great Khingan Mountains in Northeast China, where wildfires have often occurred in recent decades. To investigate the transformation of trace metals in peat soils by fire, burning experiments at 250°C (light) or 600°C (severe) and under aerobic (AE, flaming) and anaerobic (AN, smouldering) conditions (AE250, AE600, AN250, AN600) were carried out in the laboratory to investigate the effect of different burning intensities on the distribution of Cu, As, Pb, and Cd in peat soils. The European Community Bureau of Reference (BCR) sequential extraction method for metal fractions was applied for partitioning four fractions (exchangeable, reducible, oxidizable, and residual). The results showed that AE600 significantly decreased the percentages of oxidizable Cu, As, Cd and Pb (Cuoxi, Asoxi Cdoxi and Pboxi) compared with those of the original samples, e.g., Cuoxi decreased from 68.84% ± 12.76% to 15.82% ± 8.02% in peat under moss, which might result from organic matter decrease. Under AN250 conditions, the exchangeable As (Asexc) and Pb (Pbexc) significantly increased by more than twice. Different burning intensities significantly changed the various fractions of Cu, e.g., more than 20% Cuoxi transferred to exchangeable and reducible fractions as the temperature increased. Most of the available fractions of As transformed to residual As after burning. Our study suggests that the AE600 treatment increased the ecotoxicity and bioavailability of Cu, Pb and Cd in peat soils, while AN250 burning decreased the potential ecotoxicity of Cu, As, and Pb. Compared with lower temperature flaming burning (AE250), the ecotoxicity and bioavailability of Cu and Pb were greater in high temperature (AE600) conditions. Smouldering fires at both temperatures (AN250 and AN600) maintained a high potential ecotoxicity and bioavailability of Cu and Pb in peat soils. [ABSTRACT FROM AUTHOR]

This paper provides the results of a study on fungal species diversity in the active and permafrost layers of peatlands within frozen peatbogs in the flatland areas of the cryolitozone, European Northeast of Russia (forest-tundra zone, southern and northern tundra subzones). Fungal taxonomic list includes eighty-three species from seventeen genera and two forms of Mycelia sterilia. The phylum Mucoromycota is represented by fifteen species (18% of total isolate number), and these species exhibit the following distribution by genus: Mucor (four), Mortierella (seven), Umbelopsis (three), Podila (one). Ascomycota is represented by sixty-eight species from thirteen genera. The genus Penicillium dominates the species saturation (thirty-seven species, 44%). Soil microfungal complex is represented by rare species (51%), random species (32%), frequent species (15%), and dominant species (2%). In peat soils, dominant species are Penicillium canescens (72%) and non-pigmented (albino) Mycelia sterilia (61%); abundant species are Talaromyces funiculosus (41%), Pseudogymnoascus pannorum (36%), albino Mycelia sterilia (29%), Umbelopsis vinacea (25%), Mortierella alpina (17%), Penicillium decumbens (21%), P. spinulosum (20%), and P. canescens (17%). In active layers of peat soils, abundant species are Penicillium thomii (14%), Mycelia sterilia (13%), Penicillium spinulosum (13%), Penicillium simplicissimum (13%) in forest-tundra; Talaromyces funiculosus (21%), albino Mycelia sterilia (15%), Umbelopsis vinacea (14%) in southern tundra; Penicillium decumbens (23%), P. canescens (17%), P. thomii (13%) in northern tundra. In permafrost peat layers, abundant species are Penicillium spinulosum (17%), Talaromyces funiculosus (34%), and Umbelopsis vinacea (15%) in forest-tundra; Pseudogymnoascus pannorum (30%) and Mortierella alpina (28%) in southern tundra; Pseudogymnoascus pannorum (80%) in northern tundra. [ABSTRACT FROM AUTHOR]

Coastal wetlands, such as the Everglades, are increasingly being exposed to stressors that have the potential to modify their existing ecological processes because of global climate change. Their soil microbiomes include a population of organisms important for biogeochemical cycling, but continual stresses can disturb the community's composition, causing functional changes. The Everglades feature wetlands with varied salinity levels, implying that they contain microbial communities with a variety of salt tolerances and microbial functions. Therefore, tracking the effects of stresses on these populations in freshwater and brackish marshes is critical. The study addressed this by utilizing next generation sequencing (NGS) to construct a baseline soil microbial community. The carbon and sulfur cycles were studied by sequencing a microbial functional gene involved in each process, the mcrA and dsrA functional genes, respectively. Saline was introduced over two years to observe the taxonomic alterations that occurred after a long-term disturbance such as seawater intrusion. It was observed that saltwater dosing increased sulfite reduction in freshwater peat soils and decreased methylotrophy in brackish peat soils. These findings add to the understanding of microbiomes by demonstrating how changes in soil qualities impact communities both before and after a disturbance such as saltwater intrusion. [ABSTRACT FROM AUTHOR]

Peat organic soils play a major role in the accumulation of soil organic matter (SOM) and the mercury (Hg) cycle. Large mercury resources in peatlands can be a source of methylmercury for many decades and centuries, even if deposition is significantly reduced. The organic matter of peatland soils drained for agricultural use is subject to secondary transformation, which may affect the accumulation and resources of mercury. The aim of our work is to assess the secondary transformation of organic matter in the soils of drained peatlands of the temperate climate zone and to examine whether it affects mercury resources and profile distribution in organic soils. Field research was conducted in peatlands located in eastern Poland. In the present study, evaluation of secondary transformations occurring after drainage was based on observations of soil morphological characteristics, physical and chemical properties as well as fractional composition of organic matter of the identified soil horizons (to depth 70 cm). Standard cold vapor atomic absorption spectrometry (CV-AAS) was used to measure the total mercury content. In our research, we found a significant effect of the secondary transformation of organic matter occurring in drained peatlands of the temperate climate zone on the total mercury content and stock in soils. The highest content and differentiation of mercury occurred in murshic horizons (up to a maximum depth of 43 cm). The average mercury content of the distinguished soil horizons is grouped in the following series (in μg kg−1): M1 (212.0) > M2 (182.8) > M3 (126.3) > Pt (84.9). The mercury stock, up to a depth of 70 cm in the tested soils, ranged from 17.5 to 39.6 mg m−2. As much as 82.2% of soil mercury was found in the upper murshic horizons. We found strong correlations between soil properties characteristically variable in the secondary transformation process and total mercury content. The increased content of humic substances in murshic horizons caused a significant increase in the total mercury content. Our research is of great importance for soil monitoring, as the amount of determined mercury was greatly influenced by the depth of sampling (up to 25 cm). The results of the research should be taken into account when planning the restoration of peatlands of the temperate climate zone. There is a potential risk that elevated mercury concentrations in the upper murshic horizons may be a source of methylmercury for a long period of time. In peat soils with a high concentration of mercury, the risk of contamination with this toxic metal should be determined before re-irrigation. [ABSTRACT FROM AUTHOR]

The water stress threshold is one of the most important indexes to evaluate the response of crops to water stress. Water control in the pot culture is also a commonly-used way to simulate drought stress conditions. The absorption of soil water by crops is mainly decided by the soil water potential. And the relationship between soil water content and water potential varies with matric medias. However, the water stress threshold of a crop is usually given in the form of mass water content. However, there is some inconsistency in the matric media under previous pot experiments. This study aims to rapidly obtain the water retention curves of base materials in the pot experiments, in order to predict the potting soil water retention curves. The peat soil, vermiculite, and perlite were taken as matric materials in the pot experiments. The water retention curves of various media were measured, including three kinds of matric materials and eight different proportional compositions. The van Genuchten model was used to fit these water retention curves. After that, the pedotransfer functions (PTFs) of water retention curves were established using multiple regression and artificial neural network. The normalized root mean square error (SNRMSE), determination coefficient (R² ), and mean error (SMR) were selected as the accuracy indicators of the model. Furthermore, the model stability was verified through 30 cycles to finally determine the optimal modeling and the predicted water retention curve. The results showed that an ideal fitting effect of the van Genuchten model was achieved in the water retention curves of (R² >0.99). There were some significant differences in the water retention curves of the three potting medias. Peat soil presented more invalid pores than vermiculite and perlite, resulting in a large water content in the high-water suction section (water suction>100 kPa). The high capillary pore content of vermiculite led to a high-water content in the middle and high-water suction sections (water suction 33-800 kPa). Pearlite shared the higher permeability and low water holding capacity. Water was rapidly released with the increase of water suction. The prediction accuracies of the artificial neural network model for the peat soil water retention curves and vermiculite media materials were better than the multiple regression model. However, the opposite trend was observed for the peat soil and perlite media materials. Two different prediction models had different errors for the water retention curve parameters in the different media materials combinations. The multiple regression models often underestimated the prediction of saturated water content. As such, the multiple regression models underestimated the water content of media materials, compared with artificial neural networks under different water suction. The artificial neural network with PTFs reached a higher accuracy than the multiple regression with PTFs. The accuracy of multiple regression with PTFs had smaller variation and higher stability (smaller SNRMSE, larger R², and mean error closer to 0), compared with the artificial neural network. Meanwhile, there was a large variance and distribution range of SNRMSE, R², and SMR of PTFs developed by artificial neural networks, compared with the multiple regression. Therefore, better stability was achieved in the PTFs developed by multiple regression. In terms of accuracy and stability, multiple regression can be selected as the best to develop the water retention curve PTFs in various plot experiment medias. The finding can provide a strong reference for the rapid acquisition of water retention curves using the comparison between the pot water control experiments. [ABSTRACT FROM AUTHOR]

Acacia mangium was planted on a large scale in the 1990s as it was thought to be the solution for afforestation in Sarawak. However, the trees are now being decimated by fungal diseases which attack its stem and its roots. The genetic variability of the species is limited and thus, there is little hope of saving the species through selection for resistance or tolerance. Hybridisation with A. auriculiformis holds some promise though, as witnessed in Vietnam. Selected hybrids show resistance to some of the diseases, grow well and can easily be propagated by vegetative means. The switch to A. crassicarpa presently holds much promise for poor and peat soils and some disease resistance, and there may be a few different acacia species still available for testing. Nevertheless, controlled hybridisation of the acacias is not easily accomplished. Except for the hybrid mentioned above, vegetative propagation is not easy, such as is with the eucalypts. The eucalypts (E. pellita, E. deglupta, E. brassiana, E. tereticornis var. tereticornis, possibly also E. leptophleba, especially Papua Island and northern Australian provenances) are a good starting point for eucalyptus cultivation in equatorial climates like Sarawak, along with the use of hybridisation and vegetative propagation. These species can form the pillar for selection, formation of landraces, hybridisation and vegetative propagation for the humid and hot equatorial climate. Eucalypts are more demanding on soil quality, but easy to hybridise and amenable to vegetative propagation and with a wide array of wood qualities. Their gene pools and the clones obtained can be widened with genetic inputs of a variety of other species being bred into eucalypts in sub-tropical regions where they are extremely successful. A wide genetic base and quick replacement for more productive and resistant clones form one of the bases for successful short-rotation forestry. About 25 additional species are suitable for hybridisation. Possibilities within the genus Corymbia are briefly discussed in this paper. [ABSTRACT FROM AUTHOR]

Peatlands are among the largest natural sources of atmospheric methane (CH4) worldwide. Microbial processes play a key role in regulating CH4 emissions from peatland ecosystems, yet the complex interplay between soil substrates and microbial communities in controlling CH4 emissions as a function of global change remains unclear. Herein, we performed an integrated analysis of multi‐omics data sets to provide a comprehensive understanding of the molecular processes driving changes in greenhouse gas (GHG) emissions in peatland ecosystems with increasing temperature and sulfate deposition in a laboratory incubation study. We sought to first investigate how increasing temperatures (4, 21, and 35°C) impact soil microbiome–metabolome interactions; then explore the competition between methanogens and sulfate‐reducing bacteria (SRBs) with increasing sulfate concentrations at the optimum temperature for methanogenesis. Our results revealed that peat soil organic matter degradation, mediated by biotic and potentially abiotic processes, is the main driver of the increase in CO2 production with temperature. In contrast, the decrease in CH4 production at 35°C was linked to the absence of syntrophic communities and the potential inhibitory effect of phenols on methanogens. Elevated temperatures further induced the microbial communities to develop high growth yield and stress tolerator trait‐based strategies leading to a shift in their composition and function. On the other hand, SRBs were able to outcompete methanogens in the presence of non‐limiting sulfate concentrations at 21°C, thereby reducing CH4 emissions. At higher sulfate concentrations, however, the prevalence of communities capable of producing sufficient low‐molecular‐weight carbon substrates for the coexistence of SRBs and methanogens was translated into elevated CH4 emissions. The use of omics in this study enhanced our understanding of the structure and interactions among microbes with the abiotic components of the system that can be useful for mitigating GHG emissions from peatland ecosystems in the face of global change. [ABSTRACT FROM AUTHOR]

Peatlands are recognized as one of the largest terrestrial carbon sinks and are pivotal in efforts to mitigate climate change. Given this, Indonesia has committed to managing its peatlands, which have been subjected to drainage, deforestation, fires, and conversion for development. As of 2015, the Center for Agricultural Land Resources has mapped 107,344 ha of peatlands in South Kalimantan Province. However, in 2019, forest fires destroyed 2,400 ha of land, leading to the decomposition of surface peat areas, land subsidence, and the release of carbon into the atmosphere as CO2. This study aimed to quantify the widespread loss of peat carbon using the PS-InSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) technique. Specifically, 66 Sentinel 1 SAR images of SLC were used to map subsidence in the peatland area between January 2019 and January 2021. The carbon content and bulk density of peatland were then quantified to estimate CO2 emission. The results obtained through the PS-InSAR technique showed that the highest level of peat subsidence was at -50 mm year-1 in the Landasan Ulin Sub-district of Banjarbaru Regency. Furthermore, subsidence was identified in 6,920.5 ha of peatland in the study area. Subsidence, peat area, and carbon content data from SAR images, optical images, and peat soils were gathered through field surveys and websites (GSOCMap and Zenodo) to estimate CO2 emission. The estimated CO2 emissions based on in-situ and website data were the highest at 0.29 t C ha-1 year-1 and 0.04 t C ha-1 year-1 in Beruntung Baru Subdistrict, Banjar Regency, and Bumi Makmur Sub-district, Tanah Laut Regency, respectively. [ABSTRACT FROM AUTHOR]

The influence of the moisture content on the CO2 emission from peat soils of palsa mires in the discontinuous permafrost area was studied in the north of Western Siberia (Nadym region). The СО2 flux was measured in Histic Cryosols of permafrost peatlands (palsas) and Fibric Histosols of surrounding bog using the closed chamber method for four years at the peak of the growing season (August). Despite a significant difference in the soil moisture (34.8 ± 13.2 and 56.2 ± 2.1% on average), no significant difference in the CO2 emission from these ecosystems was found in any of the observation years; the rates of emission averaged 199.1 ± 90.1 and 182.1 ± 85.1 mg CO2 m–2 × h–1, respectively. Experimental wetting or drying (with a twofold difference in the moisture content) of peat soils at the two sites via their transplantation to a different position showed no significant effect on the CO2 emission even three years after the beginning of the experiment. The absence of significant differences in the CO2 flux between the two different ecosystems was explained by the presence of permafrost and the influence of many multidirectional factors mitigating changes in the CO2 production by soils. An increased CO2 emission from the peat soils of bogs was possible due to the additional contribution of the methanotrophic barrier and the lateral runoff of dissolved CO2 over the permafrost table from the palsa toward the surrounding bog. The absence of response of the CO2 emission to a significant change in the soil moisture content may be indicative of a wide optimum of this characteristic for the microbiological activity of peat soils in the studied region. The obtained data suggest that, while studying CO2 fluxes in cryogenic soils of hydromorphic landscapes, it is necessary to take into account not only biogenic sources, but also other factors, often of a physical nature, affecting the balance of CO2 fluxes and CO2 emission from soils. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Issues related to groundwater sources in peat coastal areas are very complex. These include sea water intrusion and the quality of the groundwater itself. An additional issue is the source of water to extinguish peat fires. The study area of this research is located in the coastal zone of the Siak River delta, Indonesia. The coastal zone is covered mainly by peat soil, and it is vulnerable to fires in the peat during the dry season. This study investigates the potential of groundwater for preventing a peat fire disaster and for the possibility of domestic use in the community. Subsurface resistivity data were obtained by using 14 geoelectrical resistivity surveys with the Schlumberger configuration. Characteristics of the eight groundwater samples and 14 soil samples were analyzed. The resistivity of the peat soil ranges from 40 to 50 Ω-m, and the soil is distributed throughout the study area except the middle and east parts. Relative proportions of sand and gravel at various depths were observed through resistivity data. This zone is considered a potential aquifer. The water in the aquifer has a relatively high chloride content (63 to 1189 mg L−1). The brackish water in the aquifer is believed to be ancient seawater trapped in the aquifer during the sedimentation process in the geologic past. However, the groundwater in the study area is more than enough to mitigate a peat fire disaster in the entire study area. [ABSTRACT FROM AUTHOR]

Tropical peatlands are important carbon stores that are vulnerable to drainage and conversion to agriculture. Protection and restoration of peatlands are increasingly recognised as key nature based solutions that can be implemented as part of climate change mitigation. Identification of peatland areas that are important for protection and restauration with regards to the state of their carbon stocks, are therefore vital for policy makers. In this paper we combined organic geochemical analysis by Rock-Eval (6) pyrolysis of peat collected from sites with different land management history and optical remote sensing products to assess if remotely sensed data could be used to predict peat conditions and carbon storage. The study used the North Selangor Peat Swamp forest, Malaysia, as the model system. Across the sampling sites the carbon stocks in the below ground peat was ca 12 times higher than the forest (median carbon stock held in ground vegetation 114.70 Mg ha-1 and peat soil 1401.51 Mg ha-1). Peat core sub-samples and litter collected from Fire Affected, Disturbed Forest, and Managed Recovery locations (i.e. disturbed sites) had different decomposition profiles than Central Forest sites. The Rock-Eval pyrolysis of the upper peat profiles showed that surface peat layers at Fire Affected, Disturbed Forest, and Managed Recovery locations had lower immature organic matter index (I-index) values (average I-index range in upper section 0.15 to -0.06) and higher refractory organic matter index (R -index) (average R-index range in upper section 0.51 to 0.65) compared to Central Forest sites indicating enhanced decomposition of the surface peat. In the top 50 cm section of the peat profile, carbon stocks were negatively related to the normalised burns ratio (NBR) (a satellite derived parameter) (Spearman's rho = -0.664, S = 366, p-value = <0.05) while there was a positive relationship between the hydrogen index and the normalised burns ratio profile (Spearman's rho = 0.7, S = 66, p-value = <0.05) suggesting that this remotely sensed product is able to detect degradation of peat in the upper peat profile. We conclude that the NBR can be used to identify degraded peatland areas and to support identification of areas for conversation and restoration. [ABSTRACT FROM AUTHOR]

The organic matter (OM) properties of peat soils play an important role in maintaining the stability of the peatland carbon pool and carbon cycling under environmental disturbances. The environmental disturbances not only directly affect the peatland carbon pool, but also cause changing of the vegetation community, which potentially has direct effects on the OM properties of peat soils, especially for permafrost peatlands. To reveal the changing in the OM properties due to the changes of the vegetation community, we collected 137 surface peat samples from different vegetation communities in permafrost peatlands located in the northern Great Khingan Mountains. And the OM properties were analyzed by Fourier Transform infrared spectroscopy (FTIR). Here, we found that the aromatic contents in the moss surface soil were 27.77 ± 1.38%, which was higher than the other three types of surface soils. And the humification degree indicated by the FTIR 1720/1050 ratio in moss and herb surface soils was around 0.36, considerably lower than that in the shrub and tree surface soils, which was around 0.40. Considering there is no significant difference in available nutrients among different vegetation communities, we speculate that the potential reason for the changing of vegetation communities was the difference in the water table due to differences in micro-geomorphology. For predicting the vegetation communities based on the OM properties, the most suitable solution was to divide the vegetation community into three groups (i.e., tree/shrub, herb, and moss), thereby increasing the predictive accuracy to more than 80%. [ABSTRACT FROM AUTHOR]

Peatlands play a crucial role in mediating the emissions of methane through active biogeochemical cycling of accumulated carbon driven by methane-metabolizing microorganisms; meanwhile, they serve as vital archives of atmospheric heavy metal deposition. Despite many edaphic factors confirmed as determinants to modulate the structure of methanotrophic and methanogenic communities, recognition of interactions among them is limited. In this study, peat soils were collected from Dajiuhu peatland to assess the presence of heavy metals, and methanotrophs and methanogens were investigated via high-throughput sequencing for functional genes mcrA and pmoA. Further analyses of the correlations between methane-related functional groups were conducted. The results demonstrated that both methane-metabolizing microorganisms and heavy metals have prominent vertical heterogeneity upward and downward along the depth of 20 cm. Pb, Cd, and Hg strongly correlated with methanotrophs and methanogens across all seasons and depths, serving as forceful factors in structural variations of methanogenic and methanotrophic communities. Particularly, Pb, Cd, and Hg were identified as excessive elements in Dajiuhu peatland. Furthermore, seasonal variations of networks among methane-related functional groups and environmental factors significantly affected the changes of methane fluxes across different seasons. Concretely, the complicated interactions were detrimental to methane emissions in the Dajiuhu peatland, leading to the minimum methane emissions in winter. Our study identified the key heavy metals affecting the composition of methane-metabolizing microorganisms and linkages between seasonal variations of methane emissions and interaction among heavy metals and methane-metabolizing microorganisms, which provided much new reference and theoretical basis for integrated management of natural peatlands. [ABSTRACT FROM AUTHOR]

Open dumping systems as implemented by the Batu Layang landfill in Pontianak City, Indonesia can cause leachate pollution in the environment. The constituent soil condition affects the leachate distribution into the ground. One of the landfill constituents of the soil at the site of the Batu Layang landfill is peat soil, in which organic content (>75%), porosity, and permeability are high. Leachate that seeps below the earth’s surface can cause soil and groundwater contamination. Meanwhile, people around landfills use groundwater for their daily needs and use the land around the landfill to grow papaya, banana, sugarcane, and taro. Therefore it is necessary to prevent and minimize leachate spread. One of the efforts that can be done is to model the leachate distribution. In this study, leachate distribution modeling was done with a geoelectric method, the Wenner configuration, with a smallest electrode distance of 5 m. There were six tracks, with a length of 195 m each. The model obtained from this study was a 3D resistivity section. 3D data processing was done using the inverse distance method. The results showed that a resistivity value ≤10 Ωm identified the soil layer contaminated with leachate. The contaminated soil layers were estimated to be peat, clay, and loamy sand. The leachate distribution is suspected of seeping up to 195 m south of the landfill. The leachate distribution into the soil was estimated from the surface to 33.8 m. [ABSTRACT FROM AUTHOR]

Simple Summary: Disturbance mechanisms, both natural and human-induced, can lead to changes at all levels of biological organization, including soil biota. Understanding how soil biota has adapted to a dynamic system driven by natural disturbances responding to environmental change requires a taxonomic and functional approach. Although wetlands are naturally hydrologic disturbance-driven ecosystems, relatively little attention has been paid to soil biota responses to environmental changes in these disturbance-dependent ecosystems. It has been hypothesized that the drainage-related changes in mountain wetlands soils have an effect on the community composition and functional structure of soil biota. For the first time, a field study has demonstrated that hydrologic disturbances affect the functional and taxonomic composition of soil biota represented by earthworms. Abiotic-based environmental filtering was responsible for the earthworm species sorting and trait variation. The highest earthworm variation found in wetlands semi-natural hydrologic conditions emphasizes the impact of transient dynamics on earthworm assembly. Disturbances, both natural and anthropogenic, influence the patterning of species and species traits. The shift in species composition and distribution pattern of functional traits can demonstrate if the community is resistant, sensitive or resilient to the disturbance. Based on species- and trait-based approaches, we examined the response of the earthworm community to changing hydrologic conditions caused by the artificial drainage of mountain fens, in which cumulative effects of disturbance events over space and time are much less dynamic than in riverine wetlands. We hypothesized that the drainage-related changes of mountain fen peat soils have an effect on the earthworm community composition and its functional structure. We assume that the shift in species composition and value of community-weighted functional traits reflect changes in the resilience or resistance of the earthworm community to environmental change. Our results demonstrate that the total density of earthworms was almost three times lower under drained conditions compared to natural ones. Artificial drainage of fens had a neutral effect on the species-based diversity indices. However, there were species-specific traits that responded to hydrologic changes and which led to the species' replacements and to the co-occurrence of eurytopic, surface-browsing and more drought- and low-pH-resistant earthworm species in the drained fens. Based on these results, we conclude that abiotic-based environmental filtering was the main process responsible for sorting earthworms according to species and traits in the disturbed hydrologic conditions. The greater earthworm functional trait variations in semi-natural hydrologic conditions emphasizes the impact of transient dynamics in an altered disturbance regime on the earthworm assembly. Results also showed that in the changing hydrologic conditions of mountain fens, the functional trait approach revealed only slightly more predictive power than the taxonomic one, but it proved better with processes responsible for earthworm species filtering. [ABSTRACT FROM AUTHOR]

Peat has a lack of strength, making it unsuitable for foundations or road construction. The results of 104 unconfined compressive strength (UCS) on peat stabilized with various lime percentages are presented in this article. The strength performance of peat soils stabilized with lime in soaked and unsoaked conditions was also evaluated. Evolutionary Polynomial Regression (EPR) models are constructed to predict the UCS values using the data obtained from the tests. After evaluating the various functions, the EPR model with a hyperbolic tangent function is the best model for predicting the UCS. The proposed EPR models may benefit practitioners when determining the optimal amount of stabilizers to utilize in soft-ground improvement projects. In this section, we show and expand on applying the suggested models to the design of soft ground mixing. Additionally, by applying the created relationships to a new instance, the comprehensiveness of the established relationships is shown, as is the practicality of the suggested relationships for usage during the preliminary design stage. The findings of this study have important implications for estimating the quantity of lime required in ground peat improvement work. [ABSTRACT FROM AUTHOR]

Topsoil removal (TSR) is a management option performed before rewetting drained agricultural peatlands to reduce greenhouse gas (GHG) emissions and remove nutrients. Currently, its common practice to remove 30 to 60 cm of topsoil, which is labor-intensive, costly, and highly disruptive. However, optimal TSR depth for mitigating carbon emissions from rewetted peat soils has neither been determined nor linked to soil biogeochemical factors driving carbon emissions. We performed two mesocosm experiments to address this. In experiment 1, we removed the topsoil of two contrasting drained peat soils before rewetting (i.e., extensively managed, acid peat and intensively managed, near-neutral peat) with a 5 cm interval up to 25 cm TSR. In experiment 2, we combined TSR with the presence and absence of Typha latifolia on intensively managed, near-neutral peat soil. The experiments ran for 22 and three months, respectively, in which we measured carbon dioxide (CO2) and methane (CH4) emissions and porewater chemistry. Our experiments reveal that (i) 5 cm TSR greatly reduced CH4 and CO2 emissions irrespective of peat nutrient status during the 22-month experiment, and (ii) the presence of T. latifolia further reduced CH4 emissions during the 3-month experiment. Specifically, CH4 emissions were six to 10-times lower with 5 cm TSR compared to 0 cm TSR. Peak CH4 emissions occurred after three months with 0 cm TSR and strongly decreased thereafter. Random forest analyses highlighted that variation in CH4 emissions could mainly be explained by cumulative root biomass and porewater alkalinity. Furthermore, 5 cm TSR reduced porewater values of pH, alkalinity, CH4, and ammonium. The effectiveness of TSR in preventing the build-up of phosphorus, iron, and sulfur in porewater was site-specific. Our results show that only 5 to 10 cm TSR may already effectively prevent the adverse effects of rewetting former agriculturally peatlands by reducing undesirable CH4 emissions and avoiding nutrient release. Further, we argue that target setting and site-specific assessments are crucial to optimize the amount of TSR to reduce carbon emissions while minimizing disturbance and costs. [ABSTRACT FROM AUTHOR]

The input of exogenous organic materials is an effective way to improve soil organic matter (SOM) content in cropland. The exploration of the impact of new organic materials such as woody peat on black soil fertility can provide an important reference for preventing the degradation of black soil in Northeast China. In this study, the effects of adding woody peat to SOM and the soil-integrated fertility of black cropland were studied by seven treatments (no organic matter addition, CK; crop straw returning, SR; decomposed straw addition, DS; organic manure addition, OM; 6 t/ha woody peat addition, LWP; 10.5 t/ha natural humus material addition, MWP; and 15 t/ha natural humus material addition, HWP). The results show that natural humus material additions (LWP, MWP, and HWP treatments) could significantly increase SOM (increased by 4.79~9.41 g/kg), labile SOM (increased by 2.49~4.52 g/kg), and recalcitrant SOM (increased by 2.13~6.39 g/kg) components, respectively. For comparison, traditional organic material inputs (SR, DS, and OM treatments) had no significant effect on SOM but induced an increase in the labile SOM component in the following year. This study also found that natural humus material additions could improve soil-integrated fertility in a year term, especially in promoting SOM accumulation. However, organic manure amendment showed both the advantage of increasing soil fertility slightly and the disadvantage of increasing soil salt sharply. In conclusion, compared with traditional exogenous organic materials, the natural humus material amendment technique can rapidly increase the total SOM quantity and its different stability components and has a great effect in improving the integrated fertility of black soil. Thus, it is of significance to further study the potential of natural humus material amendment in the fertility of black soil in future. [ABSTRACT FROM AUTHOR]

Peat fires contribute to global warming and environmental destruction. Once ignited, the fires tend to spread deep, underground and are difficult to extinguish using solely water. Mixtures of soap-based firefighting agents and water are expected to improve suppression efficiency by enhancing the permeability of water, a cooling material. Nevertheless, peat fire suppression is rarely studied. We performed peat fire extinguishing experiments in Palangkaraya, Indonesia to evaluate the efficiency of an environmentally friendly soap-based agent; and we conducted field experiments on 1.5 m × 1.5 m as well as 7 m × 7 m of peatlands. We conducted firefighting activities by applying (1) groundwater as well as (2) a solution of groundwater and 1 vol% of a soap-based firefighting agent. Surface temperatures of peat fires were approximately 160°C and 66°C after initial firefighting activities using solely water and a 1 vol% soap-based solution, respectively. The quantity of water required to extinguish the fires was 7.2 L/m2 using solely water, and decreased to 3.6 L/m2 using the soap-based solution. The soap-based solution exhibited a higher heat removal effect on the peat soil surface and higher permeability into peat soil than solely water, and can therefore be used to quickly extinguish peat fires. 10 months after the experiment, experimental sites sprayed with the soap-based solution demonstrated recovery of vegetation to the same degree as the sites sprayed solely with water. Thus, the soap-based firefighting agent is environmentally friendly, has promising firefighting properties, and is a reasonable tool for mitigating peat fires. [ABSTRACT FROM AUTHOR]

Cutaway peatlands in the midlands of the Republic of Ireland are rarely the focus of scientific studies. The soil quality and related microenvironment have been severely impacted by peat extraction. Returning them to a 'near-natural state' would require greater insights into this ecological niche. The current research took the initiative to study the microbiology of vast cutaway sites in the midlands of Ireland. Peat was collected over two seasons in January, February and April. Homogenised peat was aseptically cultured on a range of specific and non-specific culture media. Microbial enumeration, Gram staining and other microscopic observations of morphologically distinct microorganisms were performed. The total viable bacterial and fungal numbers were highest in February (1.33 × 105 CFU ml−1 and 5.93 × 106 CFU ml−1, respectively) and were lowest in April (1.14 × 103 CFU ml−1 and 5.57 × 106 CFU ml−1). Penicillium spp. and Trichoderma spp. were common in all the sites. The highest values of phosphate solubilisation index were recorded in peat collected in April (SI = 3.167 & 3.000). Overall, there is a statistically significant difference (p ≤ 0.0001) among the microbial numbers across the three months. This variation could be due to the temperature and pH differences across peat soil. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the impact of groundwater level, soil temperature and general soil chemistry on greenhouse gas (GHG)—carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)—fluxes from tree stems in deciduous stands with nutrient-rich naturally wet and drained peat soils. In total, nine sample plots were established in the central and north-eastern part of Latvia. The studied tree species were silver birch (Betula pendula Roth.) and black alder (Alnus glutinosa (L.) Gaertb.). Tree stands of different ages and tree dimensions were selected for the study. GHG fluxes were measured with a circular-type non-transparent chamber of fixed area and volume, which was connected to the "Gasmet DX4040" mobile spectrometer. Ambient and soil temperature at a depth of 10 cm were measured, soil parameters (pH and content of carbon (C), nitrogen (N), potassium (K), phosphorus (P)) down to 30 cm depth were analyzed, and groundwater levels and weather conditions (wind, cloudiness, precipitation) were determined. The study found that CO2 fluxes from tree stems show a distinct seasonal pattern and a strong positive correlation with soil temperature. Significant differences in CO2 fluxes were found between temperature ranges below and above 5 °C, indicating that this temperature represents a threshold value. CH4 emissions from the tree stems increased with increasing groundwater levels. The impact of groundwater level becomes insignificant if the depth of the groundwater exceeds 30 cm. No significant N2O fluxes from tree stems were detected for most of the study period, except for March, April and June in black alder stands. As with CH4, N2O emissions exhibit an increase as groundwater levels rise. The C and N contents in soil have a significant impact on N2O fluxes from tree stems. There is a tendency for the N2O flux to increase along with increasing C and N contents in soil. [ABSTRACT FROM AUTHOR]

The drainage and cultivation of peatlands will lead to subsidence and mineralisation of organic matter, increasing carbon (C) loss as more CO2 is emitted. There is little information about carbon emissions from bare peat soil. A study was undertaken to measure the CO2 emissions from a logged-over peat swamp area that was purposely vegetation-free. We aimed to report CO2 emissions from a bare, drained peatland developed for an oil palm plantation. For 12 months, we used eddy covariance (EC), closed chambers, and soil subsidence measurements to derive CO2 emissions from a logged-over peat swamp area. Significant variations in the estimated soil CO2 efflux were observed in the three tested measurement techniques. The average CO2 flux rate measured by the EC technique was 4.94 ± 0.12 µmol CO2 m−2 s−1 (or 68.55 tonnes CO2 ha−1 year−1). Meanwhile, the soil CO2 efflux rate measured by the closed chamber technique was 4.19 ± 0.22 µmol CO2 m−2 s−1 (or 58.14 tonnes CO2 ha−1 year−1). Subsidence amounted to 1.9 cm year−1, corresponding to 36.12 tonnes CO2 ha−1 year−1. The estimation of the C loss was found to be highest by the EC technique, lower by the soil chamber technique, and lowest by the peat subsidence rate technique. The higher CO2 emission rate observed in the EC technique could be attributed to soil microbial respiration and decomposing woody residues in the nearby stacking rows due to the large EC footprint. It could also be affected by CO2 advection from oil palms adjacent to the study site. Despite the large differences in the CO2 emission rates by the different techniques, this study provides valuable information on the soil heterotrophic respiration of deep peat in Sarawak. Carbon emissions from a bare peat area cover only a fraction of the soil CO2 respiration component, i.e., the soil heterotrophic respiration. Further investigations are needed to determine the CO2 emissions by soil microbial activities and plant roots from other peat areas in Sarawak. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Global distribution of peatland sites included in the meta -analysis. [Display omitted] • Peatland drainage increase soil N while decrease soil C. • The response of peat soil P to drainage in different peatlands is inconsistent. • Climatic factors such as MAT and MAP influence peat soil C:N:P ratios. Peatland ecosystems around the world exhibit distinct stoichiometric characteristics for soil carbon (C), nitrogen (N), and phosphorus (P), which are influenced by anthropogenic activities such as drainage. This study aimed to investigate the effects of drainage on C:N:P stoichiometry across various types of peatlands worldwide. A comprehensive global meta -analysis synthesized 735 pairwise observations from 41 published articles was conducted to examine the effects of drainage on the C:N:P stoichiometry of peat soils. The collected data included climatic variables such as mean annual temperature (MAT) and mean annual precipitation (MAP). Our findings indicate that drainage resulted in a significant increase in N content by 426.59%, while C content decreased by 20.95%. Additionally, drainage led to a significant increase in P content in bogs and swamps, whereas a decrease in P content was observed in fens. Overall, the C:N and C:P ratios significantly declined by 25.13% and 1.60%, respectively, while there was a notable positive increase in the N:P ratio by 499.24%. Climatic factors were found to influence C, N, P, and their ratios. The response ratios (RRs) of C and N increased with higher MAT, while the RRs of C:N ratios showed a decreasing relationship with an increase in MAT. Changes in drainage-induced P content, as well as C:N, C:P, and N:P ratios, exhibited a negative correlation with variations in MAP. The RRs of C and P contents showed a positive yet non-significant correlation with MAP. These findings contribute to a deeper understanding of global nutrient dynamics in peatlands, providing essential insights for ecological restoration and the effective management of these unique environments. [ABSTRACT FROM AUTHOR]

• Dissolved organic matter (DOM) from peat and forest soil showed high biodegradation. • Leonardite-derived DOM yielded very low microbial adaptability and degradability. • Aromatic, carboxyl-rich alicyclic molecules were less degradable and longer-lived. • Carbohydrates and peptides sustained microbial biomass and regulated biodegradation. • DOM molecular composition-controlled biodegradation dynamics. Dissolved organic matter (DOM) is a heterogenous mixture of plant- and microbial-derived compounds at various stages of decomposition. However, there is a lack of detailed information about the biodegradability of DOM from different terrestrial sources that have varying molecular compositions. To circumvent this, incubation experiments were conducted for two months using DOM isolated from three different terrestrial sources: forest soil, peat and leonardite, all with distinct extents of diagenesis. The dissolved organic carbon (DOC), total dissolved nitrogen (TDN) contents, pH, and headspace CO 2 production were measured. DOM composition was monitored using solution-state 1H nuclear magnetic resonance (NMR) and ultraviolet–visible (UV–VIS) analyses. To further understand microbial responses, microbial biomass and community composition was analyzed with phospholipid fatty acid (PLFA). DOM isolated from forest soil and peat demonstrated high biodegradability and decreased DOC concentrations, higher CO 2 production rates and higher microbial biomass over the course of incubation. Forest soil-derived DOM composition had decreased aliphatic, and carbohydrate and peptide components in the early and late stages, respectively. Peat-derived DOM exhibited lower carbohydrate and peptide concentrations and higher carboxyl-rich alicyclic molecules (CRAM). In contrast, CRAM and aromatic enriched leonardite-derived DOM had low CO 2 production and microbial biomass, and no major changes in DOM chemical composition, suggesting limited biodegradability. Further, CO 2 production, microbial biomass, and DOM molecular weight and degradation indices were positively correlated with carbohydrates and peptides, and inversely related to CRAM and aromatic components. Overall, these results corroborated distinct biogeochemical dynamics with varied DOM molecular composition, and highlight that DOM enriched in bio-recalcitrant components limited microbial processing, and exhibited high geochemical stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Classification of multi-year airborne radiometric data identified peat and mineral soils. • Excellent identification of transition from peat to non-peat soil using machine learning. • Validation made possible by a comprehensive Loss on Ignition dataset. • Revision of peat area estimates possible due to radiometric data. Peat soils are high in soil organic matter (SOM) and are recognised stores of carbon. Knowledge of the spatial distribution of peat soils is becoming the focus of many studies and is related closely to peatland mapping. Accurate maps of peat soils have many applications of international importance e.g., gaseous emission inventory reporting or soil organic carbon stock accounting. Traditional mapping methods include in-situ soil auger sampling or peat probing (for depth) while modern methods also incorporate satellite data (optical and radar). However, both methods have limitations. Traditional sampling often omits boundaries and transition zones between peat and mineral soils, while satellite data only measure the surface and may not be able to penetrate landcover, potentially omitting areas of peat under, for example, grassland or forestry. Radiometrics is a measurement of naturally occurring gamma radiation. Peat soils attenuate this radiation through high soil moisture content. For the present study in Ireland, the supervised classification of gridded airborne radiometric data, acquired over multiple years, is performed using neural network pattern recognition to identify areas of peat and non-peat soils. Classification confidence values are used to identify the transition zone between these soil types, providing a simplified visualisation of this transition. Validation is performed using Loss on Ignition (LOI %) point data and several different (blanket bog, raised bog, transition zone) sites in Ireland, showing classified data can detect the presence of peat soils from broad to local scales. Airborne geophysical methods, in particular airborne radiometrics, can bridge the gap between the accuracy of point measurement and the spatial coverage of satellite data to identify peat soils by providing uniform data and objective analysis. The resulting map is a step towards understanding the true spatial distribution of peat soils in Ireland, including transition zones. [ABSTRACT FROM AUTHOR]

Labile carbon and nutrients of the rhizosphere promote the activity of trace gas oxidizing bacteria (TGOB), but the capacity of the rhizosphere effect to support their persistence upon activation has received less attention. Here, we hypothesized that the activation response of TGOB in soil before planting is proportional to the persistence of their activity after wheat growth. The TGOB were activated in sandy-loam and peat soils under a static atmosphere containing elevated concentration of hydrogen (H 2), carbon monoxide (CO) or methane (CH 4). Our hypothesis was proven to hold true in sandy-loam soil, whereas higher organic matter in peat soil was less favourable for the persistence of TGOB activity. We conclude that the energy potential of the trace gas oxidation reaction and soil nutrients both intervein in the persistence of TGOB activity. [Display omitted] • H 2 , CO and CH 4 oxidizers were activated in sandy-loam and peat soils. • Activation of gas oxidizers did not change the soil microbiome structure. • Gas oxidation activity can persist for weeks after activation. • Rhizosphere conditions are favourable to sustain the activity of gas oxidizers. [ABSTRACT FROM AUTHOR]

Laboratory and field studies with other grazer species suggest that reindeer (Rangifer tarandus L.) grazing on northern peatlands could shape the peat soil microbial communities and lead to higher ecosystem methane (CH 4) emissions. We investigated this at two sedge fens in northern Finland, Lompolojänkkä and Halssiaapa, in experiments where reindeer grazing presence or absence was achieved with exclosure fences, and the effects of reindeer droppings were evaluated comparing dropping additions either on peat surface or trampled into the peat to controls with no droppings. Active soil methanogen and methanotroph communities were analyzed by metatranscriptomics. Soil CH 4 fluxes were quantified with manual chambers and portable gas analyzer. Reindeer presence and dropping additions were both connected to differences in the soil communities as compared to controls (no presence or no droppings). The responses differed between the two fens. Activity of rumen microbes in peat could not be detected. Structural equation models indicated that the ecosystem CH 4 flux in both fens depended on measurement year and sedge leaf area. At Halssiaapa trampled droppings, and at Lompolojänkkä both surface and trampled droppings reduced the sedge leaf area. While at Halssiaapa the dropping effect was not altogether statistically significant, in Lompolojänkkä surface droppings reduced the CH 4 flux both directly and through the reduced leaf area. In conclusion, while both reindeer presence and dropping addition were diversely reflected in the active soil communities, reindeer effects on the CH 4 flux were indirect and mediated via vegetation. The results contrast our earlier laboratory findings, and i) caution against liberal generalizations from lab studies to field conditions in peatlands, as well as ii) point to a need for rigorous multivariate analyses for deciphering the complex interactions governing the functions of these ecosystems. • Field study in two fens examined patterns previously observed in laboratory. • Like in laboratory, reindeer shaped methanogenic and methanotrophic communities. • Unlike in laboratory, active rumen microbes from droppings not observed in peat. • Unlike in laboratory, methane emission from peat did not increase. • Droppings rather decreased methane emission. [ABSTRACT FROM AUTHOR]