Carex Peat Research Articles

Plant species diversity of Carex peat mire in Changbai Mountains, China

We investigated the plant species richness both in cespitose Carex mires (C. schmidtii, C. meyeriana) and non-cespitose Carex mire (C. lasiocarpa) in Changbai Mountain. A total of 83 species (36 families, 59 genuses) was recorded in three sites. Among which, 71 species occurred in the C. meyeriana site, 61 species in the C. schmidtii site, and 26 species in the C. lasiocarpa site. The total species number and species richness in the two cespitose Carex mires were much higher than that in the non-cespitose Carex mire, while those on tussocks were much higher than between tussocks in the two cespitose Carex mires. Plant species richness on tussocks was positively related to the height, basal circumference and surface area of the tussocks, suggesting that tussocks were important for plant species diversity in Carex mires. Results of the canonical correspondence analysis indicated that the differences in soil water content, nutrient (soil organic carbon, total N, total P and C/N), and litter layer depth were the main factors influencing the differences of plant community composition on tussocks and between-tussocks. In the cespitose Carex mires, the hummock-hollow microtopography could foster high diversity by increasing surface area and creating multiple micro-habitats. Given its function in maintaining high species diversity, cespitose Carex could be a preferred species for vegetation restoration in degraded peat mires.

Identification of peat type and humification by laboratory VNIR/SWIR hyperspectral imaging of peat profiles with focus on fen-bog transition in aapa mires

AimsHyperspectral imaging (HSI) has high potential for analysing peat cores, but methodologies are deficient. We aimed for robust peat type classification and humification estimation. We also explored other factors affecting peat spectral properties.MethodsWe used two laboratory setups: VNIR (visible to near-infrared) and SWIR (shortwave infrared) for high resolution imaging of intact peat profiles with fen-bog transitions. Peat types were classified with support vector machines, indices were developed for von Post estimation, and K-means clustering was used to analyse stratigraphic patterns in peat quality. With separate experiments, we studied spectral effects of drying and oxidation.ResultsDespite major effects, oxidation and water content did not impede robust HSI classification. The accuracy between Carex peat and Sphagnum peat in validation was 80% with VNIR and 81% with SWIR data. The spectral humification indices had accuracies of 82% with VNIR and 56%. Stratigraphic HSI patterns revealed that 36% of peat layer shifts were inclined by over 20 degrees. Spectral indices were used to extrapolate visualisations of element concentrations.ConclusionsHSI provided reliable information of basic peat quality and was useful in visual mapping, that can guide sampling for other analyses. HSI can manage large amounts of samples to widen the scope of detailed analysis beyond single profiles and it has wide potential in peat research beyond the exploratory scope of this paper. We were able to confirm the capacity of HSI to reveal shifts of peat quality, connected to ecosystem-scale change.

Divalent Mercury in Dissolved Organic Matter Is Bioavailable to Fish and Accumulates as Dithiolate and Tetrathiolate Complexes.

The freshwater cyprinid Tanichthys albonubes was used to assess the bioavailability of divalent mercury (Hg(II)) complexed in dissolved organic matter (DOM) to fish. The fish acquired 0.3 to 2.2 μg Hg/g dry weight after 8 weeks in aquaria containing DOM from a Carex peat with complexed mercury at initial concentrations of 14 nM to 724 nM. Changes in the relative proportions of dithiolate Hg(SR)2 and nanoparticulate β-HgS in the DOM, as quantified by high energy-resolution XANES (HR-XANES) spectroscopy, indicate that Hg(SR)2 complexes either produced by microbially induced dissolution of nanoparticulate β-HgS in the DOM or present in the original DOM were the forms of mercury that entered the fish. In the fish with 2.2 μg Hg/g, 84 ± 8% of Hg(II) was bonded to two axial thiolate ligands and one or two equatorial N/O electron donors (Hg[(SR)2+(N/O)1-2] coordination), and 16% had a Hg(SR)4 coordination, as determined by HR-XANES. For comparison, fish exposed to Hg2+ from 40 nM HgCl2 contained 10.4 μg Hg/g in the forms of dithiolate (20 ± 10%) and tetrathiolate (23 ± 10%) complexes, and also Hg xS y clusters (57 ± 15%) having a β-HgS-type local structure and a dimension that exceeded the size of metallothionein clusters. There was no evidence of methylmercury in the fish or DOM within the 10% uncertainty of the HR-XANES. Together, the results indicate that inorganic Hg(II) bound to DOM is a source of mercury to biota with dithiolate Hg(SR)2 complexes as the immediate species bioavailable to fish, and that these complexes transform in response to cellular processes.

Physical, chemical and biochemical properties of Western Siberia Sphagnum and Carex peat soils

Было проведено сравнительное исследование физических, химических и биохимических свойств акротелма (торфогенный горизонт) и катотелма (горизонт накопления торфа) участков с доминированием сфагновых и осоковых торфов в Западной Сибири. Концентрация общего азота прямо пропорциональна содержанию нитрат-ионов и ионов аммония, активности уреазы, объемной плотности, и обратно пропорционально отношению C/N, пористости и влажности в обоих рассматриваемых типах почв. Полученные результаты указывают на низкий уровень азотной трансформации и замедление процессов разложения органического вещества в сфагновых и осоковых типах почв. Исследование показало, что сфагновые торфа претерпевают значительные химические и биохимические трансформации (окисление, гидролиз, полимеризация) с аккумуляцией наиболее устойчивых соединений по сравнению с органическим веществом осоковых торфов.

Does underlying bedrock affect the geochemistry of drained peatlands?

The chemical composition of peat cores sampled from nine drained peatland catchments overlying either black schist or felsic bedrock was studied in Finland. Black schist is enriched in heavy metals, sulphur and graphitic carbon, and therefore it is susceptible to weathering whereas felsic rock types in the study region are more resistant and contain only negligible amounts of heavy metals, sulphur and carbon. A total of nineteen cores down to the underlying regolith were taken and electrical conductivity was measured in the field. The peat cores were divided into 160 peat samples for the determination of chemical composition and acidity. As a result of weathering, diffusion into the ground water and adsorption by the peat, concentrations of As, Co, Cu, Fe, Hg, Mn, Ni, Zn, and S, as well as electrical conductivity were expected to be greater in the peat overlying black schist than in peat overlying felsic rocks and this difference was assumed to be strong in the bottom layers and to weaken near the surface. The basal Carex (sedge) peat layer showed elevated concentrations of elements compared to the upper Sphagnum (moss) peat layers. The effect of peatland margins and flooding also exerts some influence on higher Cu, S and Fe concentrations. Ambient environmental features and conditions, such as slope and aspect affected peat chemistry in two catchments in particular. The first catchment showed high heavy metal and trace element contents associated with peat accumulation on sloping terrain, as ground water discharges at a spring on a rather steeply sloping surface. Another catchment with lower heavy metal and trace element contents represents peat accumulation in a well-leached watershed characterized by sandy deposits within a flat valley floor and an acidity that induced the development of a Sphagnum bog phase during the early stages of mire formation. In addition to the chemical concentration of underlying bedrock and soil, the factors affecting element concentrations in peat were the topography of the environment including paludification mode and species composition and the subsiding relations of the peatland and drainage. Special caution should be paid when excavation is carried out on sites containing high sulphide concentrations in bedrock, overburden or peat, e.g. ditch network maintenance or peat harvest can lead to enhanced leaching of acidity and heavy metals. Anthropogenic activities on sulphide rich peatlands pose an environmental risk.

Mitigating greenhouse gas fluxes from cultivated organic soils with raised water table

Cultivated organic soils are a remarkable source of greenhouse gases (GHG) in many countries. Keeping the ground water table as high as possible could lower the mineralization rate of the peat and thus the emissions of carbon dioxide (CO2) and nitrous oxide (N2O) from these soils. We studied the effect of raised water table on the emissions of N2O, CO2 and methane (CH4) from undisturbed peat soil profiles of six different Finnish cultivated organic soils during a 5-week outdoor mesocosm experiment. The aim was to determine an optimum water table that would enable grass cultivation but lower the net gas balance of the soil. Raised water table decreased the GHG emissions from each peat type ranging from weakly decomposed Sphagnum peat to highly humified Carex peat. Based on the results, the optimum water table would be 30 cm below the soil surface. The average reduction of the total net emissions with a raise of water table from a typical drainage depth of 70 to 30 cm was 42 % in the outdoors mesocosm experiment and 23 % at a constant temperature (+6 °C). The emissions of both CO2 and N2O declined and the net consumption of CH4 changed to net production as the water table rose. The results were confirmed by long-term measurements at one of the sampled sites. As a conclusion, we see that promoting drainage systems enabling raising of the ground water table and cultivation of crops capable of producing good yields also in wet conditions would be beneficial for the GHG mitigation in agriculture.

Long-term effects of ash fertilization on runoff water quality from drained peatland forests

The increasing use of wood and peat in energy production has created a potential to utilize wood and peat ashes as forest fertilizers on a wide scale. Previous studies have shown that tree growth in peatland benefits most from ash fertilization. However, possible harmful effects on recipient watercourses have prevented any larger-scale fertilization activity. The objective of this study was to examine the long-term changes in runoff acidity and the transport of nutrients, heavy metals and dissolved organic carbon via drainage water from drained boreal peatland catchments fertilized with wood or peat ash. The hypotheses were that the site’s peat type, the origin and formula of the ash and the time of application have an influence on leaching amounts. Therefore, the studied catchments represented different peat (Carex or Sphagnum) and site types with different standing tree stocks (8–127m3ha−1). Loose, self-hardened and drum-granulated ashes (wood and peat ashes) were used and applied (5000–6500kgha−1) either in winter on snow or in summer on bare ground. Water samples from the runoff were taken over a 10–11-year period following the applications. After 10–11years from the treatments, the concentrations of S, K, Na, Cl−, and Mg in the runoff water were still higher at the wood ash treatments compared to the controls. Leaching of elements from peat ash was lower than from wood ash due to the lower content of elements. We estimated that 15–52% of the added S and 2–28% of the added K were leached from the wood and peat ashes during the study period. Leaching of S was the highest after the winter application and higher from the Sphagnum than from the Carex peat dominated catchments. The leaching of K was the highest after the summer application and was the lowest from the catchments having the highest tree stock. No increased leaching of P, N, dissolved organic carbon or heavy metals was detected.

Abrupt ombrotrophication of a boreal aapa mire triggered by hydrological disturbance in the catchment

Summary 1. Hydrological changes due to drainage and climate warming can have great impact on the ecosystem balance of boreal mires. The possibility of ombrotrophication, i.e. the development from fen to bog, in response to altered hydrology has not been previously tested. Here, recent changes in vegetation and surface peat are studied in an aapa mire, a typical boreal mire system dominated by fen vegetation. Drainage in the catchment from 1968 onwards led to the change from richly minerogenous to ombrogenous hydrology, thus providing a long‐term ombrotrophication experiment. 2. A sequence of aerial photographs (1941, 1953, 1965, 1974, 1984, 1995, 2005) revealed a dramatic shift from fen vegetation to the nearly complete dominance of peat mosses (Sphagnum) within two decades after the catchment disturbance. 3. A distinct change from Carex peat to Sphagnum peat at the average depth of 23.3 cm (SE 0.8 cm) was found in 18 peat cores. All of the new Sphagnum peat had accumulated within the last four decades. This was verified by the relationship of age and rooting depth of 37 small pines (Pinus sylvestris) and by two pollen density profiles. The ratio Ca/Mg diminished towards the surface of peat profiles indicating change from minerogenous to ombrogenous hydrology. In accordance, extremely low pH (range 3.8–4.2) and conductivity (average 14.5 μs cm−1) were measured in the surface pore water. 4. The average total dry mass of new Sphagnum peat was 7042 g m−2 (SE 442) and the recent apparent rate of carbon accumulation was 100.6 g m−2 year−1 (SE 6.3), as calculated for a 35‐year period and 50% carbon content. 5. Synthesis. Remarkable potential for vegetation change and increase of peat growth is demonstrated in boreal aapa mires. Ombrotrophication can be initiated within a few decades in response to reduced input of minerogenous water. Future changes in the hydrological cycle, as indicated by climate change models, are similar to the impact of catchment disturbance in aapa mires. Diminished total water budgets during the summer cause a decrease of minerogenous input and a draw‐down of water level, both of which may promote the growth of Sphagnum over fen vegetation.

Alternative soilless media for growing Petunia × hybrida and Impatiens wallerana: Physical behavior, effect of fertilization and nitrate losses

The use of alternative soilless media for the production of potted plants requires knowledge of their physical and chemical characteristics to result in the best conditions for plant growth. We investigated the use of alternative soilless media based on river waste and Sphagnun sp. and Carex sp. from Argentinean peatlands on Petunia × hybrida and Impatiens wallerana production at two fertilization levels (200 and 400 mg l −1 N). River waste or ‘temperate peat’ is the name given to a material, resulting from the accumulation of aquatic plant residues under an anaerobic subtropical environment, which is dredged from river banks. Our results showed that alternative substrates based on river waste can be used to grow high quality plants. This result was not fully explained on the basis of established methods to evaluate substrate quality. Highly concentrated fertigation solution decreased the substrate quality parameters and plant growth. Nitrate leaching from the alternative substrates containing river waste was lower than the standard peat-based materials, which makes river waste desirable from a sustainable pot production system perspective. River waste and Carex peat are suitable alternatives to Sphagnum peat from the Northern Hemisphere.

Effect of treatment and application technique of cattle slurry on its utilization by ley: II. Recovery of nitrogen and composition of herbage yield

The effect of slurry treatment and application technique on theutilization of nitrogen and on the composition of herbage was investigated onley in a 3-year field experiment on clay loam in southwestern Finland and onfine sand and Carex peat in northern Finland. Untreated, aerated or separatedslurry (liquid fraction) was applied on ley after the first cut by broadcastspreading, band spreading or injection into the ground. The application rate ofslurry was 33 to 62 Mg ha−1 and that ofammoniacalnitrogen about 80 kg ha−1. The highest recoveryofapplied nitrogen was achieved with injection. The apparent recovery of theammoniacal nitrogen of injected slurry varied from 23% to 50%, whereas that ofbroadcast and band-spread slurries was from 16% to 33% and 17% to 38%,respectively. However, injection did not result in any higher dry matter yieldthan the other application techniques, because it damaged the grass sward.Separation seemed to somewhat increase the recovery of slurry nitrogen, excepton peat soil, but the effect was significant for the apparent recovery ofapplied total nitrogen on clay loam in one year, only. Supplementing slurrywith 50 kg ha−1 of inorganic fertilizer nitrogenon clay loam increased both dry matter yield and nitrogen recovery by about onethird. Large amounts of potassium applied in cattle slurry raised the potassiumcontent and lowered the contents of magnesium and sodium in herbage on peatsoil. The reduction in calcium content was not significant. On clay loam, whichhad a higher potassium content than the peat, the general effect of potassiumapplied in slurry was weaker, but injection led to a higher potassium contentand lower contents of calcium and magnesium in herbage than surfaceapplications.

Copper and zinc adsorption onto poorly humified Sphagnum and Carex peat

Peat generally has a high adsorption capacity and has been suggested as an adsorbent for metals in polluted waters. However, the adsorption potential of peat can be expected to be strongly dependent on the chemical properties of the water. In this study, the effect of pH, ionic strength (CaCl 2 and NaCl concentrations), and metal concentration on Cu and Zn adsorption onto poorly humified Sphagnum and Carex peat was investigated in batch experiments using a fractional factorial experimental design. The pH value was varied between 4 and 8, the CaCl 2 and NaCl concentrations between 1.2–6.2 and 0.4–43 mM, respectively, and the Cu and Zn concentrations between 0.05 and 0.5 mM. The amount of Zn adsorbed increased more with increasing pH than the amount of Cu adsorbed. The effect of NaCl/CaCl 2 concentration was minor. It was found that Zn adsorption in particular, but also Cu adsorption, increased more with pH onto Carex peat than onto Sphagnum peat. In the pH interval 4–8, the removal of Zn from the solution increased from 0% to 80% using Carex peat and from 10% to 65% using Sphagnum peat as the adsorbent. The Carex peat sample decreased the Cu concentration by 80% at pH 4 and by 95% at pH 8 and for Sphagnum peat a decrease of 85% was maintained in the pH range investigated. The differences between Sphagnum and Carex peat were attributed to the habitat conditions at the time of peat formation. Carex peat has higher ash, nitrogen and sulphur concentrations, while Sphagnum peat contains a higher amount of uronic acid. In treating polluted waters with peat, a higher degree of metal removal can be expected at high pH values than at low. The removal of Cu, which has a high affinity to the peat surface, was less dependent on pH than Zn removal. Poorly humified Carex peat should be chosen in treating wastewaters high in pH.

Poorly humified peat as an adsorbent for metals in wastewater

Metal adsorption and surface charge determinations were performed previously on well-characterised Sphagnum and Carex peat samples. The aim of this investigation was to determine metal adsorption from complex wastewaters onto these peat samples and compare it to the adsorption onto peat granules, clinoptilolite, glauconite and a flue dust from steel production. A sulphide mine leachate, a landfill leachate and a laundry wastewater were chosen, giving a variation in pH, ionic strength, total organic carbon and concentrations of metals. Metal adsorption was determined in batch and column experiments. The wastewater composition was of great importance for metal removal efficiency, mainly due to the difference in dominating metal species. In the sulphide mine leachate, containing free metal ions, a high metal adsorption was observed onto both peat and inorganic adsorbents. In the landfill leachate the metals formed carbonate and organic complexes and a low metal removal was achieved. Contrary to the leachates, the laundry wastewater contained suspended particles. The high amount of metals removed, 80% of the Cu and 30–60% of the Zn concentration, was probably withdrawn bound to the particle fraction. The highest removal of metal ions was obtained in the sulphide mine leachate with Carex peat, removing 97–99% of the Zn and 85–100% of the Cu content. The Sphagnum peat sample removed 37–77% of the Zn and 80–100% of the Cu content. The differences found between Sphagnum and Carex peat were attributed to the original chemistry of the plant material and the habitat conditions at the time of peat formation. Generally, the combination of glauconite or clinoptilolite with the peat samples in column experiments gave a minor improvement in metal removal.

Leaching of Phosphorus, Calcium, Magnesium and Potassium in Barley, Grass and Fallow Lysimeters

Abstract Leaching of total and dissolved phosphorus, calcium, magnesium and potassium from fallow, unfertilized and fertilized barley and grass ley was studied in a four-year experiment carried out in lysimeters filled with clay, silt, coarse sand and Carex peat. Half of the lysimeters were irrigated with 290–480 mm of water annually. Irrigation increased the nutrient leaching. Phosphorus losses were anyway small (tot. P 0.02–0.26 kg ha−1 a−1 from the fallowed soils) owing to omission of surface runoff. Leaching of cations was more comparable with field observations. The annual average varied in the bare soils from 50 to 120 and from 30 to 70 kg ha−1 a−1 for Ca and Mg, respectively. The average leaching of K was small (4–24 kg ha−1 a−1) in other than sand soil (56–94 kg ha−1 a−1). Cropping of soil generally decreased the leaching of dissolved and total phosphorus and cations compared with the fallow treatment. Fertilization did not have any consistent effect.

Effects of heat on the alkali extraction of humic substances from peat

Abstract Solutions of 0.1M and 0.25M potassium hydroxide (KOH) were used to extract the humic substances from two different types of peat (sphagnum and Carex) at 20, 50 and 80°C. The effects of temperature on the yield of humic and fulvic acids (HA and FA) and on the characteristics of the former were investigated. The highest extraction yields were obtained at the two higher temperatures and by using the most concentrated alkali solution. The higher temperatures resulted in a decrease of the HA/FA ratio in the sphagnum peat although the opposite generally occurred with the Carex peat. As shown by chemical analyses and gel permeation chromatography, the HA released from sphagnum by hot KOH solutions exhibited less oxidized molecules, a lower content of functional groups and larger molecular size than it did at room temperature; whereas the characteristics of the HA released from Carex peat by heat depended on both the alkali concentration and the temperature employed for the extraction.

Comparative evaluation of methods employing alkali and sodium pyrophosphate to extract humic substances from peat

Abstract Humic substances from two different types of peat ‐ Sphagnum and Carex ‐ were obtained by using either alkali extractants, O.IM NaOH, O.IM KOH, and 0.25M KOH, or solvents containing sodium pyrophosphate (O.IM Na4P2O7, or O.IM NaOH/Na4P2O7). The alkalis released considerably greater amounts of humic substances from the Sphagnum peat than the extractants containing pyrophosphate, whereas the opposite occurred in the Carex peat, the two greatest yields being obtained with 0.25M KOH in Sphagnum peat and with O.IM NaOH/Na4P2O7 in Carex. As shown by the spectroscopic and chemical analyses, humic acids released from both peats by extractants containing Na4P2O7 are generally more oxidized than those obtained by any of the alkali solutions. Also, humic acids extracted from the Sphagnum peat by any of the solvents generally exhibit lower molecular sizes, more pronounced aliphatic characteristics, and a higher degree of oxidation than those extracted from the Carex peat. Results of gel permeation chromatogr...

Leaching of nitrogen in barley, grass ley and fallow lysimeters

The leaching of nitrogen from fallow, fertilized and unfertilized spring barley, and grass ley was studied in a 4-year lysimeter experiment tcarried out on clay, silt and sand soils, and Carex peat. The experimental factors included also irrigation and treatments where the nitrogen fertilizer was applied in the first year as 15N-labelled ammonium nitrate. During four years, 41-66% of the nitrogen applied in the first growing season was recovered in plants harvested. Most of it, 91-96%, was taken up in the year applied. Mostly, the water drainage was lowest in silt and sand soils. The irrigation increased clearly the leaching of nitrogen almost in all treatments. Crops decreased the drainage of water through the lysimeters and the leaching of nitrogen, grass more than barley. The effects of plants and irrigation were similar in all soils, but most marked in sand. The largest amount of nitrogen was leached in irrigated, fallowed sand, 440 kg ha-1, during four years. The majority of the leached nitrogen was nitrate. Only in peat soil a significant amount of nitrogen was leached in some another form. The leaching of 15N-labelled fertilizer during four years was highest in sand, 2.3 kg ha 1 of N or 2.3% of the nitrogen applied in the first experimental year.

Dewatering of peat slurry produced by wet milling technique

The effects of slurrying, long distance pumping, chemical dosage, pH, dry solid load and pressure on the dewatering of Carex Peat slurry ware studied. Raw peat at 75% moisture was slurried and pumped through a pilot-scale pipeline simulating 20 km transport. The goal was to establish the conditions to achieve a dry solids content (DS) of 35%, which would make the peat a suitable fuel for advanced power plants. It was found that slurry was dewatered to a solids content of 40–45% with a capacity of 10–15 kg(DS)/hm 2. Pressure was a dominant factor, optimized at 50–60 bar. Long-distance pumping lowered the DS content of the cake only slightly. The required dosage of anionic flocculant was only 0.5 kg/t(DS), and lowering the pH level of the slurry to <3.7 from the natural value of 4.7 was also beneficial. The results indicate the feasibility of obtaining a DS content of 35% with high capacity, and there is at least one suitable type of chamber filter press available on the market. However, more extensive experiments are needed.

Solvent-extractable lipids of Sphagnum, Carex, Bryales and Carex-Bryales peats: content and compositional features vs peat humification

The effect of humification on the content and composition of the lipids in Sphagnum, Carex, Bryales and Carex-Bryales peats has been studied by capillary GC and GC-MS. The content of lipidic matter and those of its principal parts, i.e. lipid monomers (30–50% of total lipids), non-volatile matter (30–50%) and other volatiles (10–20%) mainly increased with increasing humification in all peat types. The extract content increased in the order Bryales, Carex-Bryales Sphagnum Carex, ranging from the average 4–5% on dry weight basis in Bryales and Carex-Bryales peats up to 11% in highly humified Carex peat. Fatty and ω-hydroxy acids comprised 65–90% of the lipid monomer fraction; normal 1-alkanols and sterols together comprised up to 25%. Sphagnum peat was rich in sterols, Carex peat contained high amounts of fatty and ω-hydroxy acids, and Bryales peat showed a comprehensive 1-alkanol content. In Carex-Bryales peat the characteristics of both Bryales and Carex peats were found. Peat lipids originate in mosses and higher plants. Under oxygen-poor or anaerobic conditions they are, however, subjected to microbial changes, e.g. to hydrogenation and degradation, as reflected by the stanol/stenol ratios and changes to the CPI values of n-alkanes. The one-carbon loss in the degradation of n-alkanoic acids was also found to occur under aerobic conditions in the low-decomposed Sphagnum peat samples. The long-chain ω-hydroxyalkanoic acids with other longer-chain (⩾C 22) lipid monomers accumulate in polymerized lipids, resulting in increased decay resistance of the various peat-forming plants. Polymerized polyhydroxyalkanoic (9,16- and 10,16-dihydroxyhexadecanoic and 9,10,18-trihydroxyoctadecanoic) acids are thought to be responsible for the especially high decay resistance of Sphagnum mosses. It also seems likely that the primary reaction type changes from degradation to polymerization at the low-decomposed (H3H4 on the von Post scale) stage of peat.

Water-Soluble Lipids inCarexandSphagnumPeats

Abstract Samples of Carex and Sphagnum peats of different degrees of humification were extracted with water at 20–25°C for 20 h. Water-soluble lipids were isolated by dichloromethane extraction and analyzed by gas chromatography and mass spectrometry. The amount of lipidic matter (0.021–0.083% of dry peat, 0.54–2.70 mg/100 g of water, 4–5% of total dissolved organic matter) depended on the peat type and the degree of humification of the peat material. In Sphagnum peat the amount of total water-soluble lipids increased with increasing peat humification, while the reverse occurred in Carex peat. The concentration of dissolved organic carbon (DOC) compounds was found to be directly proportional with the concentration of the water-soluble lipids.

Molecular characterization of total organic matter and carbohydrates in peat samples from a cypress swamp by pyrolysis-mass spectrometry and wet-chemical methods

The organic matter present in coarse- and fine-grained sample preparations of a peat core from Minnie's Lake, Okefenokee Swamp (Georgia, USA) was analysed on a molecular level by gas chromatography-mass spectrometry of alditol acetates obtained from polysaccharides after acid hydrolysis and derivatization and by flash pyrolysis-mass spectrometry. We found that the coarse-grained fraction is dominated by neutral monosaccharides derived from vascular plants whilst the fine-grained fraction is dominated by neutral monosaccharides derived from microorganisms. Relatively high contributions of xylose discriminate the Taxodium derived peat from the underlying peats derived from Carex and Nymphaea which show relatively low contributions of this sugar. Factor-discriminant analysis of the Py-MS data indicates that most carbohydrate degradation is restricted to the upper peat levels and that guaiacyl and syringyl type lignins are better preserved than carbohydrates. Resinous organic matter - presumably derived from Taxodium — is selectively preserved in the fine-grained fraction. Deviant monosaccharide concentrations and Py-MS results observed for the top sample of the Carex peat were explained by oxygenation of the peat, a concomitantly high microbial activity and subsequent preservation of the organic material due to the action of phytotoxins derived from Taxodium.