Peat Samples Research Articles

Preparation of highly effective carbon adsorbents based on high-moor peat from the European North of Russia

The study of active coals obtained from high-moor peat of the European North of Russia was conducted by method of thermochemical activation with NaOH with various types of pre-treatment (debituminization and pre-hydrolysis). Based on the results of the low-temperature adsorption of nitrogen, the derived active coals belong to the adsorbents in which the structure of the micro-agents predominates. The specific surface of the coal pores reaches 2330 m2/g, the total volume of pores – 1.44 cm3/g. It has been determined that the introduction of the pre-hydrolysis stage makes it possible to increase significantly the yield of active coals. For initial peat samples, the growth is 28%; for debituminized – 97%, moreover it significantly improve its sorption characteristics. It has been shown that weakly decomposed peat of the European North of Russia can be used as raw material for producing high-efficiency carbon microporous adsorbents.

КОРРЕЛЯЦИЯ ТОРФЯНЫХ РАЗРЕЗОВ НИЖНЕГО ПРИАМУРЬЯ ПО РЕЗУЛЬТАТАМ РАСЧЕТА ОТНОСИТЕЛЬНОЙ ПАЛЕОНАПРЯЖЕННОСТИ

The paper considers the possibility of determining the age and correlating peat sections by solving the inverse problem of magnetostratigraphy based on the findings of comprehensive (palaeomagnetic, petromagnetic, microprobe, and radiocarbon) studies on peats of the «Tyapka» and «Chlya» peat sections in the Lower Amur region. For this purpose, we used the values of relative paleointensity calculated following the technique described by Bagina-Petrova. There is no difference in the rate of magnetization fixation among studied peat samples, and the age of magnetization is comparable to the age of the peat deposits itself. The solution of the inverse problem of magnetostratigraphy using the values of relative paleointensity can be used to correlate peat sections among themselves and to estimate the rate of peat accumulation in different periods of the Holocene, even in the absence of radiocarbon dating for one of the correlated sections.

Investigating Holocene relative sea-level changes and coastal dynamics in the mid-Tyrrhenian coast, Italy: An interdisciplinary study

Understanding millennial changes in relative sea level (RSL) and coastal responses in stable regions is crucial for deciphering the intricate relationship between natural dynamics and human adaptation. This interdisciplinary study explores the interplay between mid-to-Late Holocene sea-level fluctuations and tectonic along the mid-Tyrrhenian coast.The study area, located between the Fondi and Garigliano coastal plains, held great significance in ancient times. In particular, the strategic role of Formia, a monitoring point for the Tyrrhenian Sea, made this city one of the most important commercial hub during Roman occupation, leading to a significant urbanization of the coastal stretch testified by well-preserved remains nowadays scattered along the submerged or semi-submerged coastal sectors.This study reconstructs the mid-to-Late Holocene morpho-evolution and RSL changes in the study area by creating a geodatabase made of 52 sea-level markers (SLMs) derived from direct geoarchaeological measurements, stratigraphic and palaeoecological interpretations of new borehole data, and previously published stratigraphic data. Specifically, the radiocarbon dating of three peat samples provided new data ranging between 7.62 ± 47 and 1.00 ± 51 ka BP on the sea level history in the area. Based on our dataset, between 9.0 and 8.0 ka BP, the sea level rose from −19 m to −6.5 m at a rate of about 15.6 mm/y, slowing to 0.8 mm/y afterwards, stabilizing at its current position. Results suggest that during the 1st century BC, local sea level was no higher than −0.55 ± 0.29 m.The collected RSL data support the hypothesis of tectonic stability of this sector during the last 2.0 ka, testified by the position of the SLMs in accordance with the glacio-hydro-isostatic adjustment (GIA) models and supported by the determination of average vertical ground movement rates of −0.017 ± 0.23 mm/y.Finally, in terms of coastal changes the overlay between new data from geoarchaeological surveys, reinterpretation of previously-published stratigraphic data, and geomorphological analysis allowed us to deduce a general coastal progradation trend in the historical time for both low-lying and rocky sectors, due to natural and anthropogenic forcing factors.

Application of industrial by-product waste as soil stabilising backfill material using a multi-layering method

Peat soil presents significant challenges for construction due to its inherent weak properties, including high water content, limited permeability, low shear Strength, low specific gravity, and acidity. Despite the potential of Mg-rich synthetic gypsum (MRSG) to improve soil properties, research on its use for stabilising severely poor peat soils is limited. This study addresses this gap by investigating the efficacy of MRSG in peat soil stabilisation using a novel multi-layering backfill approach. The methodology includes soil classification of peat soil. And, to understand the mechanical and chemical changes of stabilized peat soil, the unconfined compressive Strength (UCS) testing and microstructural analysis using SEM, EDX, and XRD before and after stabilisation are studied. Peat samples were treated with MRSG through backfilling method in 5, 7, and 9 layers and evaluated the strength increment after curing periods of 7, 28, and 60 days. Results demonstrate that MRSG significantly enhanced the compressive strength, increasing it to 210.33 kPa as early as 7 days for 9 layers of backfill incomparable with the untreated soil strength of 51.87 kPa. The new cementitious product in the soil known as ettringite was observed from SEM analysis and confirmed by the EDX and XRD analysis. By recycling industrial byproducts, this environmentally friendly method encourages sustainability and lessens dependency on raw resources, which is important for infrastructure construction and other projects in areas rich in peat.

Microbial DNA sample preservation and possible artifacts for field-based research in remote tropical peatlands

Surveying bacterial and archaeal microbial communities in host and environmental studies requires the collection and storage of samples. Many studies are conducted in distant locations challenging these prerequisites. The use of preserving buffers is an important alternative when lacking access to cryopreservation, however, its effectivity for samples with challenging chemistry or samples that provide opportunities for fast bacterial or archaeal growth upon exposure to an aerobic environment, like peat samples, requires methodological assessment. Here, in combination with an identified optimal DNA extraction kit for peat soil samples, we test the application of several commercial and a homemade preservation buffer and make recommendations on the method that can most effectively preserve a microbiome reflective of the original state. In treatments with a non-optimal buffer or in the absence, we observed notable community shifts beginning as early as three days post-preservation lowering diversity and community evenness, with growth-driven artifacts from a few specific phyla. However other buffers retain a very close composition relative to the original state, and we described several metrics to understand some variation across them. Due to the chemical effects of preservation buffers, it is critical to test their compatibility and reliability to preserve the original bacterial and archaeal community in different environments.

PENGUJIAN TIGA METODE PENGUKURAN BOBOT ISI PADA TANAH GAMBUT

This research aims to compare the methods of bulk density measurements in peat soils. The methods are ring sample, peat auger, and syringe. The research was conducted in peat soils in Pontianak City. The research was carried out from June to December 2023. Peat samples were the surface peat (0-10 cm). The samples were collected from five plots, and five replications. On average, the value of bulk density measured by the ring sample was 0.27 g cm-3, which is significantly different from bulk density values measured by the peat auger and syringe: 0.11 g cm-3 and 0.09 g cm-3, respectively. Bulk densities of peat auger and syringe are statistically indifferent. Soil compaction during sampling causes the ring sample's high bulk density value. Accordingly, carbon stock calculation based on ring sample bulk density is significantly higher than carbon stocks calculated by bulk densities of auger and syringe. The bulk density measurement with a peat auger took longer because a water displacement approach must measure the sample volume. Collecting bulk-density samples with a syringe is the easiest and fastest. The volume of the syringe sample is only 10 cm3, and the sample can be taken until the mineral substratum. The number of sample collected by syringe can be significantly increased at 5 cm sampling interval, or equals to 10 sub-samples per 50 cm peat core. Pearson linear correlations of these three methods are sufficiently strong.

Carbon leaching from peat soils of the north of Western Siberia under different hydrological conditions

Frozen peat soils in the north of Western Siberia are vulnerable to the on-going climate changes. The increase in temperature which affects the permafrost thaw returns the huge carbon stocks to the global element cycle. Its export in the form of dissolved organic matter from peatlands is determined by a number of factors, among which hydrological conditions are the least studied. The influence of hydrological regimes on carbon export from oligotrophic peat soils in discontinuous permafrost zone was investigated in laboratory conditions. The model column experiment allowed estimating the carbon yield from undisturbed (monolithic) peat samples of different degrees of decomposition. Three types of mesocosms were considered: undisturbed samples of the TO horizon, as well as the TO horizon with underlying material of different texture (sand and loam). The concentration of dissolved organic carbon in the lysimetric waters of a fibric peat does not differ for the “precipitation” and “snowmelt” simulating modes, and in the “stagnation” mode it is 1.4 times less. Sapric peat lysimetric waters show no differences under simulating hydrological regimes. The total export of organic carbon for three successive extractions for fibric peat is 32% higher than for sapric peat. An increase in carbon in the sandy material after three cycles of the experiment was revealed, the loamy material did not show significant differences. The carbon adsorption by mineral soil layers of the study area can be a protective mechanism that prevents increased runoff from the soils.

Horticultural additives influence peat biogeochemistry and increase short-term CO2 production from peat

Abstract Aims Peat is used as a major ingredient of growing media in horticulture. Peat extracted from bogs can be acidic and low in nutrient availability and is therefore mixed with liming agents, nutrients, surfactants, perlite and so on. This study aims to estimate the rates at which raw peat and the modified peat (‘growing media’) decompose to release carbon dioxide (CO2), to estimate the release of carbon (C) from liming agents and to estimate how peat biogeochemistry is changed. Methods We obtained 28 and 24 samples of raw peat and 24 growing media from four peat extraction companies in Canada. Growing media were treated with horticultural additives. We incubated the samples under laboratory conditions, measuring CO2 production, tracer using $${\updelta }^{13}{\text{C}}$$ δ 13 C -$${{\text{CO}}}_{2}$$ CO 2 , pH, C, nitrogen (N) content and humification indices (HIs) from infrared technology called Fourier transform-mid infrared (FT-MIR). Results C:N ratio, pH, dissolved organic carbon, bulk density and C content differed significantly (P < 0.05) between raw peats and growing media. There was more than a doubling of total $${{\text{CO}}}_{2}$$ CO 2 production from growing media compared to raw peat. HIs show higher values for the growing media, which could result from spectral band shifts in the growing media because of increased cation availability. $${\updelta }^{13}{\text{C}}$$ δ 13 C -$${{\text{CO}}}_{2}$$ CO 2 as a tracer showed an average 22% of the total $${{\text{CO}}}_{2}$$ CO 2 production orginated from added carbonate materials. Conclusion Our results provide the rates (0.15 ± 0.017mgCO2-Cg−1d−1) at which horticultural peat decomposes and on the source of emitted $${{\text{CO}}}_{2}$$ CO 2 . This will improve current estimates CO2 emissions from horticultural peat.

Tritium behavior in soil and mineral rock components used for plant cultivation

Immersion, percolation and tritium release experiments in peat and vermiculite soil samples were performed to analyze their behavior in this widely used medium for plant cultivation. Samples were immersed in tritiated water for 696 h and the isotope exchange capacity evaluated. A vertical flow regime was also considered with analysis for hydraulic conductivity to understand tritium mobility and therefore its availability. Peat soil showed a high tritium retention after percolation, but vermiculite seem to suppress its retention ability. The high moisture and organic content of peat enhanced its isotope exchange capacity. The falling head method was used to numerically evaluate the saturated hydraulic conductivity and outflow flux. Calculated isotope exchange capacity was 4.95×10-2 mol-T2O/g for peat and 3.38×10-2 mol-T2O/g for vermiculite. The tritium release experiment showed significant release of tritiated carbons in peat.

A HOMEMADE SEMIAUTOMATIC GRAPHITIZATION DEVICE FOR AMS 14C DATING AT NTUAMS LAB

ABSTRACT A low-cost and computer-controlled graphitization system connected to an elemental analyzer (EA) has been designed and built at the NTUAMS Lab. This semiautomatic system equips 6-unit reactors for the graphitization of CO2 with H2 on the iron catalyst. The entire procedure takes about 7 hours for iron conditioning, sample combustion and loading, and graphitization. The system can produce good-quality graphite for samples containing 0.5–1.6 mg carbon mass, with the pressure yield of graphitization ranging from 57.7% to 87.1%. The average values of OXI and OXII agree well with the consensus value, but the result of ANU sucrose was observed to be slightly higher than the reported one. The background samples of anthracite over ten months yielded an average of 0.38±0.10 pMC (n=21) corresponding to a 14C age of 45 kyr BP. Intercomparison samples L and M of FIRI exhibit that the measured 14C ages are almost identical to the consensus values and have a small spread in these values. The system has been carrying out graphitization for total organic carbon (TOC) of peat samples, and providing a more efficient and convenient way for AMS 14C dating.

Aerobic and anaerobic decomposition rates in drained peatlands: Impact of botanical composition

Drained peatlands in temperate climates are under threat from climate change and human activities. The resulting decomposition of organic matter plays a major role in regulating the associated land subsidence rates, yet the determinants of aerobic and anaerobic peat decomposition rates are not fully understood. In this study, we sought to gain insight into the drivers of decomposition rates in botanically diverse peatlands (sedge, reed, wood, and moss dominant) under oxic and anoxic conditions. Peat samples were collected from the anoxic zone and incubated for 24 h (short) and 15 weeks (long) under either oxic or anoxic conditions. CO2 emissions, hydrolytic and oxidative exoenzyme potential activities, phenolic compound concentrations, and several edaphic factors were measured at the end of each incubation period.We found that 15 weeks of oxygen exposure of anoxic peat samples accelerated the average CO2 emissions by 3.9-fold. Reed and sedge peat respired more than wood and moss peat under anoxic conditions. Interestingly, CO2 emissions from anoxic peat layers under permanently anoxic conditions were substantial and given the thickness of peat deposits in the field, such activities may play an important role in long-term land subsidence rates and total CO2 emissions from drained peatlands. The results from the long-term incubations showed that decomposition rates appear to be also controlled by factors other than oxygen intrusion such as substrate availability. In summary, the botanical composition of the peat matrix, incubation conditions and time of incubation are all important factors that need to be considered when predicting peat decomposition and subsequent land subsidence rates.

Tephra identification without pre‐separation in ashed peat

ABSTRACTCryptotephras in peat and sediment samples are traditionally separated for geochemical characterization using chemical or density floatation techniques following initial tephra identification and shard counting through analysis of ashed residue via light microscopy. However, these practices can be time consuming, subject to practitioner experience and material type, with a potential for sample loss. We present an alternative approach to identify cryptotephra in peat and sedimentary samples, where ashed material is mounted directly in epoxy resin and analysed through back‐scattered electron (BSE) imaging via scanning electron microscopy–energy dispersive X‐ray spectroscopy (SEM‐EDX). Semi‐quantitative, unsupervised chemical maps of epoxy mounts are created within 120 min using ‘Feature Analysis’ on AZtec software by Oxford Instruments. These maps locate grains of higher atomic mass and categorize phases based on geochemistry. We create a tephra identification method using an ombrotrophic peat sample doped with bimodal Vedde Ash, where recovery of the known tephra proportion in wet peat is 96%. We also propose an automated alternative to optical shard counting, whereby tephra counts identified via Feature Analysis can be ratioed to total grain counts acquired through ImageJ software and extrapolated to the inorganic fraction in wet peat. We apply the method to a minerotrophic peat from Brackloon Wood, Mayo, Ireland, where the Laki ad 1783–84 cryptotephra is successfully identified.

Microbial abundances and carbon use under ambient temperature or experimental warming in a southern boreal peatland

Organic peat soils occupy relatively little of the global land surface area but store vast amounts of soil carbon in northern latitudes where climate is warming at a rapid pace. Warming may result in strong positive feedbacks of carbon loss and global climate change driven by microbial processes if warming alters the balance between primary productivity and decomposition. To elucidate effects of warming on the microbial communities mediating peat carbon dynamics, we explored the abundance of broad microbial groups and their source of carbon (i.e. old carbon versus more recently fixed photosynthate) using microbial lipid analysis (δ13C PLFA) of peat samples under ambient temperatures and before/after initiation of experimental peat warming (+ 2.25, + 4.5, + 6.75, and + 9 °C). This analysis occurred over a profile to 2 m depth in an undrained, ombrotrophic peat bog in northern Minnesota. We found that the total microbial biomass and individual indicator lipid abundances were stratified by depth and strongly correlated to temperature under ambient conditions. However, under experimental warming, statistically significant effects of temperature on the microbial community were sporadic and inconsistent. For example, 3 months after experimental warming the relative abundance of Gram-negative bacterial indicators across depth combined and > 50 cm depth and Gram-positive bacterial indicators at 20–50 cm depth showed significant positive relationships to temperature. At that same timepoint, however, the relative abundance of Actinobacterial indicators across depth showed a significant negative relationship to temperature. After 10 months of experimental warming, the relative abundance of fungal biomarkers was positively related to temperature in all depths combined, and the absolute abundance of anaerobic bacteria declined with increasing temperature in the 20–50 cm depth interval. The lack of observed response in the broader microbial community may suggest that at least initially, microbial community structure with peat depth in these peatlands is driven more by bulk density and soil water content than temperature. Alternatively, the lack of broad microbial community response may simply represent a lag period, with more change to come in the future. The long-term trajectory of microbial response to warming in this ecosystem then could either be direct, after this initial lag time, or indirect through other physical or biogeochemical changes in the peat profile. These initial results provide an important baseline against which to measure long-term microbial community and carbon-cycling responses to warming and elevated CO2.

From acidophilic to ornithogenic: microbial community dynamics in moss banks altered by gentoo penguins.

The study explores the indirect impact of climate change driven by gentoo's penguin colonization pressure on the microbial communities of moss banks formed by Tall moss turf subformation in central maritime Antarctica. Microbial communities and chemical composition of the differently affected moss banks (Unaffected, Impacted and Desolated) located on Galindez Island and Сape Tuxen on the mainland of Kyiv Peninsula were analyzed. The native microbiota of the moss banks' peat was analyzed for the first time, revealing a predominant presence of Acidobacteria (32.2 ± 14.4%), followed by Actinobacteria (15.1 ± 4.0%) and Alphaproteobacteria (9.7 ± 4.1%). Penguin colonization and subsequent desolation of moss banks resulted in an increase in peat pH (from 4.7 ± 0.05 to 7.2 ± 0.6) and elevated concentrations of soluble nitrogen (from 1.8 ± 0.4 to 46.9 ± 2.1 DIN, mg/kg) and soluble phosphorus compounds (from 3.6 ± 2.6 to 20.0 ± 1.8 DIP, mg/kg). The contrasting composition of peat and penguin feces led to the elimination of the initial peat microbiota, with an increase in Betaproteobacteria (from 1.3 ± 0.8% to 30.5 ± 23%) and Bacteroidota (from 5.5 ± 3.7% to 19.0 ± 3.7%) proportional to the intensity of penguins' impact, accompanied by a decrease in community diversity. Microbial taxa associated with birds' guts, such as Gottschalkia and Tissierella, emerged in Impacted and Desolated moss banks, along with bacteria likely benefiting from eutrophication. The changes in the functional capacity of the penguin-affected peat microbial communities were also detected. The nitrogen-cycling genes that regulate the conversion of urea into ammonia, nitrite oxide, and nitrate oxide (ureC, amoA, nirS, nosZ, nxrB) had elevated copy numbers in the affected peat. Desolated peat samples exhibit the highest nitrogen-cycle gene numbers, significantly differing from Unaffected peat (p < 0.05). The expansion of gentoo penguins induced by climate change led to the replacement of acidophilic microbiomes associated with moss banks, shaping a new microbial community influenced by penguin guano's chemical and microbial composition.

Исследование параметров производства гранулированного топлива из торфа

Granulation technology is becoming an increasingly attractive one for the energy use of biomass. The problem to find a suitable method of compaction of various types of biomasses has existed for decades. The purpose of this study is to select the optimal mode to produce pellets from peat fuel. Peat samples collected in the Mezen district of the Arkhangelsk region have been selected as the data for study. Elemental analysis of the studied samples of peat and peat pellets has been carried out using X-ray fluorescence spectroscopy on an EDX-8000 spectrometer. Experiments on peat granulation have been carried out in a press granulator of the German company Amandus Kahl. The authors describe the procedure of selection of the operating mode of a press granulator to produce pellets from peat fuel. Optimal regime of pellets production has been selected corresponding to the national standard. An elemental analysis of the studied samples of peat and peat pellets has been carried out using X-ray fluorescence spectroscopy. The results have shown that the ash content of peat fuel from the Arkhangelsk region is no more than 2 %. Production of environmentally friendly high-calorific pellets from peat corresponding to the National Russian standards allows increasing the energy potential of the Arkhangelsk region. When converting peat into the pellets, the content of carbon, nitrogen, and hydrogen (C+N+H) increases, and the content of sulfur and oxygen (O+S) decreases, which leads to the increase of the heat of fuel combustion. Advantages of the use of peat to produce energy are low sulfur content, low ash content and high softening ash temperature.

Thermokinetics and synergistic effect analysis of peat-lignite coal co-pyrolysis

ABSTRACT In this study, the synergistic effect between peat and lignite coal was investigated in terms of kinetic energy and mass loss trends using a thermogravimetric analyzer. Thermogravimetric non-isothermal studies were conducted at different heating rates under inert nitrogen atmosphere. Kinetic analysis was performed using model-free KAS, OFW, and Starink methods and the average activation energies varied between 88.62 kJ/mol and 204.28 kJ/mol. Differential mass loss trends were determined using experimental and theoretical data. An obvious deviation was obtained at a blend ratio of PT:CL40:60. Thus, results revealed that the PT and CL co-pyrolysis has synergistic effects, especially for sample PT:CL40:60. SEM and BET analyses were performed on the coke sample of peat, coal, and PT:CL40:60 blend ratio samples for further analysis. The surface area of peat and coal was determined to be 416 m2/g and 83.06 m2/g, respectively. It was concluded that the porosity and surface area of coal (187.02 m2/g) increased with the addition of peat. The results are expected to be useful in the design of peat biomass and coal co-pyrolysis systems.

Vacuum Pyrolysis of Brazilian coal, peat and biomass – Results on characterization of feedstock, solid residues, pyrolysis liquids and conversion rates

Pyrolysis of solid fuels such as coal, peat and biomass enables conversion into solid and liquid products, with noncondensable gas being a by-product. The present study evaluates conversion characteristics of Brazilian coal, peat and biomass samples using vacuum pyrolysis techniques. Feedstock and their respective solid residues (chars) and pyrolytic liquids obtained under vacuum pyrolysis conditions were characterized by proximate and ultimate analyses, gross calorific value, petrographic analyses, reactivity to CO2, Raman spectroscopy and organic geochemical methods (extraction, liquid chromatography). Chemical and physical properties in the feedstock samples and solid residues are highly variable. In the coals mean vitrinite reflectances ranged from 0.44% to 1.18% Rrandom indicating a rank range from subbituminous to high volatile/medium volatile bituminous coal. Reflectance measurements obtained from vitrinoid particles identified in solid residues from coal, peat and biomass varied from 2.10% to 10.64% Rrandom. Analyses of the liquid products indicate a tendency of the aliphatic fraction to increase in most of the samples during the pyrolysis process, as well as the predominant formation of polar compounds in the condensable liquids. The results of this study suggest that among the coal samples investigated major conversion to liquids and gases (29.7%–33.2%) occurs in the high volatile bituminous coals from Santa Catarina, whereas in the biomass samples Mamona (Castor Beans), wood chips (Eucalyptus), wooden bars (pinus) and signal grass have all conversion rates &gt; 60%. The conversion rates for the peat samples varied between 32.5 and 46.6%. Reflectance values determined on vitrinoid biomass chars indicate a potential use in soil amendment.

Translocation of tropical peat surface to deeper soil horizons under compaction controls carbon emissions in the absence of groundwater

Compaction is recognized as an effective method for mitigating the risk of fires by enhancing soil moisture levels. This technique involves restricting peat pore spaces through compaction, facilitating improved capillary action for water retention and rehydration. The compaction of tropical peatlands, while beneficial for fire prevention, has the potential to influence biogeochemical processes and subsequent carbon emissions. The magnitude of compaction and groundwater level are strongly coupled in such environments, making it difficult to distinguish the control of physicochemical properties. Therefore, this study seeks to understand how peat compaction affects its properties, carbon emissions, and their relationship, with a focus on geophysical processes. Intact peat samples were collected from a secondary peat swamp forest and an oil palm plantation in Selangor, Peninsular Malaysia. Compaction treatments were applied to achieve three levels of volume reduction. CO2 and CH4 emissions were measured using an automated gas analyzer, and the physicochemical properties of the peat were determined. The results revealed that mechanical compaction significantly altered the physicochemical properties of the secondary forest peat, displaying an opposite pattern to the oil palm plantation, particularly regarding total nitrogen and sulfur. Moreover, the average reduction percentage ratio of CO2 emissions (from 275.4 to 182.0 mg m-2 hr-1; 33.9%) to CH4 uptakes (from -17.8 to -5.2 µg m-2 hr-1; 70.1%) (~1:2) indicated distinct stages of decomposition and translocation of less decomposed peat to deeper layers due to compaction, predominantly in secondary peat swamp forest samples. The oil palm plantation samples were unaffected by compaction in terms of physicochemical properties and carbon emissions, indicating the ineffectiveness of this approach for reducing fire risk in already drained systems. This study underscores the necessity of understanding the effects of compaction in the absence of groundwater to accurately evaluate the widespread application of this technique.

Impacts of forestry drainage on surface peat stoichiometry and physical properties in boreal peatlands in Finland

Management of drained peatlands may pose a risk or a solution on the way towards climate change mitigation, which creates a need to evaluate the current state of forestry-drained peatlands, the magnitude of degradation processes and indicators for carbon (C) loss. Using a large dataset (778 profiles, 891 peat samples, collected between 1977 and 2017) from peatlands having different fertility classes across Finland, we investigate whether the surface peat profiles of undrained and forestry-drained peatlands differ in C:N, von Post and dry bulk density. The utility of element ratios (C:N:H stoichiometry) as site indicators for degradation were further analyzed from a subsample of 16 undrained and 30 drained peat profiles. This subsample of drained sites had carbon dioxide (CO2) and methane (CH4) fluxes measured allowing us to link peat element ratios to annual C gas effluxes. Element ratios H:C, O:C and C:N and degree of unsaturation (combining C, N, H changes) were found widely valid: they captured both differences in the botanical origin of peat as well as its potential decomposition pathway (C lost via a combination of dissolved organic C and C gas loss and/or the gaseous loss predominantly as CO2). Of the stoichiometric indexes, peat H:C ratio seemed to be the best proxy for degradation following drainage, it indicated not only long-term degradation but also explained 48% of the variation in annual CO2 emission. The O:C ratio positively correlated with annual CH4 flux, presumably because high O:C in peat reflected the availability of easily degradable substrate for methanogenesis. The differences in C:N ratio indicated notable decomposition processes for Sphagnum-dominated peatlands but not in Carex-dominated peatlands. Degree of unsaturation showed potential for an integrative proxy for drainage-induced lowering water table and post-drainage changes in peat substrate quality.

Assessment of two grainsize methods for peat sediments and their paleoenvironmental significance: the Yueliangwan Peatland in northeast Asia

Grainsize is an important indicator in paleoenvironmental research. Over the past few decades, different pretreatment methods have been proposed for grainsize determination of peat sediments. Assessing the reliability of the grainsize measurements is critical to ensure the paleoenvironmental significance represented by different grainsize components. In this study, using peat sediments from the Yueliangwan peatland in northeast Asia, the effects of two pretreatment methods on grainsize measurement were compared. It was found that these two pretreatment methods on peat sediments produced grainsize features with totally different parameters and distribution characteristics. Grainsize method 1, which used a hydrogen peroxide water bath treatment, did not reflect accurate results for grainsize in peat sediments. Grainsize method 2, which used muffle furnace combustion, does reflect the true results because the organic matter, such as plant residues, spores and pollen, is totally removed. The presence of this stubborn organic matter in peat samples greatly disturbs the accuracy of grainsize measurements, and the reliability of grainsize measurements can be affected by the presence of stubborn organic matter. Based on the grainsize grade-standard deviation analysis using method 2, the East Asian Winter Monsoon evolutionary history in northeast Asia during the Little Ice Age (1300–1750 CE) was reconstructed and divided into three stages: the strengthening stage (1346–1425 CE), the strongest stage (1425–1525 CE) and the weakening stage (1525–1725 CE).