首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 414 毫秒
1.
A peat deposit from the East European Russian Arctic, spanning nearly 10 000 years, was investigated to study soil organic matter degradation using analyses of bulk elemental and stable isotopic compositions and plant macrofossil remains. The peat accumulated initially in a wet fen that was transformed into a peat plateau bog following aggradation of permafrost in the late Holocene (～2500 cal a BP). Total organic carbon and total nitrogen (N) concentrations are higher in the fen peat than in the moss‐dominated bog peat layers. Layers in the sequence that have lower concentrations of total hydrogen (H) are associated with degraded vascular plant residues. C/N and H/C atomic ratios indicate better preservation of organic matter in peat material dominated by bryophytes as opposed to vascular plants. The presence of permafrost in the peat plateau stage and water‐saturated conditions at the bottom of the fen stage appear to lead to better preservation of organic plant material. δ15N values suggest N isotopic fractionation was driven primarily by microbial decomposition whereas differences in δ13C values appear to reflect mainly changes in plant assemblages. Positive shifts in both δ15N and δ13C values coincide with a local change to drier conditions as a result of the onset of permafrost and frost heave of the peat surface. This pattern suggests that permafrost aggradation not only resulted in changes in vegetation but also aerated the underlying fen peat, which enhanced microbial denitrification, causing the observed 15N‐enrichment. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

2.
The Holocene development of a treed palsa bog and a peat plateau bog, located near the railroad to Churchill in the Hudson Bay Lowlands of northeastern Manitoba, was traced using peat macrofossil and radiocarbon analyses. Both sites first developed as wet rich fens through paludification of forested uplands around 6800 cal. yr BP. Results show a 20th-century age for the palsa formation and repeated periods of permafrost aggradation and collapse at the peat plateau site during the late Holocene. This timing of permafrost dynamics corroborates well with that inferred from previous studies on other permafrost peatlands in the same region. The developmental history of the palsa and peat plateau bogs is similar to that of adjacent permafrost-free fens, except for the specific frost heave and collapse features associated with permafrost dynamics. Permafrost aggradation and degradation is ascribed to regional climatic, local autogenic and other factors. Particularly the very recent palsa development can be assessed in terms of climatic changes as inferred from meteorological data and surface hydrological changes related to construction of the railroad. The results indicate that cold years with limited snowfall as well as altered drainage patterns associated with infrastructure development may have contributed to the recent palsa formation.  相似文献   

3.
Bauer, I. E. & Vitt, D. H. 2011: Peatland dynamics in a complex landscape: Development of a fen‐bog complex in the Sporadic Discontinuous Permafrost zone of northern Alberta, Canada. Boreas, 10.1111/j.1502‐3885.2011.00210.x. ISSN 0300‐9483. The development of a peatland complex in the Sporadic Discontinuous Permafrost zone of northwestern Alberta, Canada was reconstructed using a series of dated profiles. Peat‐forming communities first established c. 10 230 cal. a BP, and by 8000 cal. a BP the site supported monocot fens or marshes in several isolated topographic depressions. Most of the current peatland area initiated between c. 8000 and 4000 cal. a BP, and involved the replacement of upland habitats by shrubby or treed fen and, in some areas, the establishment of Sphagnum on mineral terrain. Ombrotrophic hummock communities had established by c. 7000 cal. a BP, and permafrost was present at 6800 cal. a BP in at least some peat plateau areas. Macrofossil‐based reconstructions show considerable local diversity in vegetation succession and permafrost dynamics, with cyclic collapse and aggradation in at least one profile and relative stability in others. Lichen‐rich peat is rare in deep‐peat plateau cores, and where charcoal was recovered, fire effects on vegetation trajectories varied between cores. Organic matter accumulation was high in the early Holocene and declined after permafrost formation, with low rates especially over the past 4000 years. The site was burned in a wildfire in 1971, and by 1998 permafrost had disappeared from almost all peat plateau areas. In this part of the discontinuous permafrost zone, peat plateaus are likely to be unsustainable under a warming climate. The hydrology and carbon dynamics of former plateau areas following large‐scale permafrost degradation require further investigation.  相似文献   

4.
This paper presents the history and cryostratigraphy of the upper permafrost in the High‐Arctic Adventdalen Valley, central Svalbard. Nineteen frozen sediment cores, up to 10.7 m long, obtained at five periglacial landforms, were analysed for cryostructures, ice, carbon and solute contents, and grain‐size distribution, and were 14C‐ and OSL‐dated. Spatial variability in ice and carbon contents is closely related to the sedimentary history and mode of permafrost aggradation. In the valley bottom, saline epigenetic permafrost with pore ice down to depths of 10.7 m depth formed in deltaic sediments since the mid‐Holocene; cryopegs were encountered below 6 m. In the top 1 to 5 m, syngenetic and quasi‐syngenetic permafrost with microlenticular, lenticular, suspended and organic‐matrix cryostructures developed due to loess and alluvial sedimentation since the colder late Holocene, which resulted in the burial of organic material. At the transition between deltaic sediments and loess, massive ice bodies occurred. A pingo developed where the deltaic sediments reached the surface. On hillslopes, suspended cryostructure on solifluction sheets indicates quasi‐syngenetic permafrost aggradation; lobes, in contrast, were ice‐poor. Suspended cryostructure in eluvial deposits reflects epigenetic or quasi‐syngenetic permafrost formation on a weathered bedrock plateau. Landform‐scale spatial variations in ground ice and carbon relate to variations in slope, sedimentation rate, moisture conditions and stratigraphy. Although the study reveals close links between Holocene landscape evolution and permafrost history, our results emphasize a large uncertainty in using terrain surface indicators to infer ground‐ice contents and upscale from core to landform scale in mountainous permafrost landscapes.  相似文献   

5.
The fate of the Rare Earth Elements (REE) were investigated in different types of archives of atmospheric deposition in the Black Forest, Southern Germany: (1) a 70 cm snow pack collected on the domed part of a raised bog and representing 2 months of snow accumulation, (2) a snow sample collected close to the road about 500 m from the peat bog, (3) two species of lichens and (4) a peat profile representing 400 years of peat accumulation as well as a “preanthropogenic” sample and the living moss layer from the top of the core. REE concentrations in peat are significantly correlated to Ti which is a lithogenic conservative element suggesting that REE are immobile in peat bog environments. Snow, lichens and peat samples show similar PAAS (Post Archean Australian Shale) normalized REE distributions suggesting that the complete atmospheric REE signal is preserved in the peat profile. However, the annual flux of REE accumulated by the peat is ca. 10 times greater than that of the bulk winter flux of REE. This difference probably indicates that the REE concentrations in the snowpack are not representative of the average REE flux over the whole year. Despite the pronounced geological differences between this site (granite host-rock) and a previously studied peat bog in Switzerland (limestone host-rock) similar REE distribution patterns and accumulation rates were found at both sites. Given that both sites confirm an Upper Continental Crust signature, the data suggests both sites are influenced by regional and not local, soil-derived lithogenic aerosols.  相似文献   

6.
The initiation and growth of boreal peatlands developed on well‐drained, sandy landforms are closely associated with podzolic soil paludification processes. The origin of Sphagnum bogs extending on large deltaic plains was examined to test the hypothesis of the dual impact of indurated (ortstein) podzols and fire on forest soil paludification and concurrent peatland initiation and expansion. Mineral soil, basal organic matter and peat monoliths were sampled for soil and macrofossil analyses along an 800‐m toposequence starting from a mixed‐wood boreal forest to a Sphagnum bog (Lebel bog, eastern Quebec, Canada), and ending at a peat dome in the thickest section of the peatland. Mineral soils along the toposequence are ortstein humo‐ferric podzols distributed in the forest environment and beneath Sphagnum peat in the bog, except at the peat dome. Initial peatland growth occurred c. 6000 cal. a BP. Soil paludification coincided with the cessation of fire occurrence as recorded in the organic and mineral layers preceding Sphagnum expansion. Unlike most temperate and boreal raised bogs, the Sphagnum bog developed directly from a forest environment without passing through a transitional fen stage. Conifer forests regenerated successively after several fires between 4200 and 1600 cal. a BP before bog expansion. Pre‐bog forests were composed of fire‐prone black spruce (Picea mariana) and jack pine (Pinus banksiana) trees, and ericaceous species. Given the distribution and thickness of ortstein horizons progressively decreasing and disappearing towards the peatland dome, growth and expansion of the Sphagnum bog was not caused by soil induration processes, which could have potentially impeded vertical and horizontal drainage. The development of indurated podzols outside and several hundred metres inside the peatland preceded the initiation and expansion of the Sphagnum bog. Cessation of fire activity appears to be a key factor facilitating the lateral expansion of the Sphagnum bog under wet soil conditions.  相似文献   

7.
Lipid biomarkers from a peat plateau profile from the Northeast European Russian Arctic were analyzed. The peat originated as a wet fen ca. 9 ka BP and developed into a peat bog after the onset of permafrost ca. 2.5 ka BP. The distributions and abundances of n-alkanols, n-alkanoic acids, n-alkanes, n-alkan-2-ones and sterols were determined to study the effect of degradation on their paleoclimate proxy information. Plant macrofossil analysis was also used in combination with the lipid distributions. The n-alkanol and n-alkanoic acid distributions in the upper part of the sequence generally correspond to compositions expected from plant macrofossil assemblages. Their carbon preference index (CPI) values increase with depth and age, whereas those of the n-alkanes decrease. The different CPI patterns suggest that n-alkanoic acids and n-alkanols deeper in the sequence may be produced during humification through alteration of other lipids. Excursions in the n-alkanoic acid content also suggest an important contribution of invasive roots to the lipid biomarker composition. The CPIs associated with these compounds show that under permafrost conditions organic material from Sphagnum is better preserved than material from vascular plants. Increasing stanol/stenol ratio values and decreasing n-alkane CPI values indicate progressive degradation of organic matter (OM) with depth. The n-alkan-2-one/n-alkane and n-alkan-2-one/n-alkanoic acid ratios were shown to be useful proxies that can reflect the degree of OM preservation and suggest that both microbial oxidation of n-alkanes and decarboxylation of n-alkanoic acids produce n-alkan-2-ones in this peat sequence.  相似文献   

8.
Macrofossil analyses, pollen analyses, and 14C datings were carried out on profiles from a bog complex in southern Sweden. The development started with a Carex fen c. 6,000 B. P. which transformed to bog c. 1,000 years later. The bog has developed through three stages separated by highly humified peat layers, recurrence surfaces, 3 and 2m below the present bog surface, and formed c. 2,500 and 1,200 B. P., respectively. The fen formation and the initiation of the last two bog stages were contemporaneous with high water levels in lakes of the region. The transition to bog and the formation of the two highly humified peat layers may be related to low water levels in lakes. It is probable that changes in the development of the mire were caused by the climate, since varying water levels are thought to be dependent on variations in the climate.  相似文献   

9.
何大双  侯读杰  黄海平 《沉积学报》2018,36(5):1049-1058
通过对泥炭正构烷烃和正烷酮的地球化学特征的系统分析,以探讨阿萨巴斯卡地区Mildred泥炭沼泽的物源输入特征,以及正构烷烃和正烷酮的内在成因关系,从而揭示研究区泥炭记录的生物信息和植被演化特征。结果表明:Mildred泥炭正构烷烃和正烷酮均以高分子量C23~C33为主,呈后峰型分布,奇碳优势明显,物源以原地堆积的陆源高等植物为主,少量苔藓类、水生植物也有一定程度的贡献。根据主成分分析和正构烷烃指标,Mildred泥炭分子指示物源输入具有分段性,上段（地表至-17 cm）成炭植物以锈色泥炭藓为主,中段（-17 cm至-41 cm）沉积有机质主要来源于木质树根、杜鹃花科、黑云杉和莎草科等,下段（-41 cm至底部）莎草科类富集,少量松柏、杜鹃花科等木质植物发育。正构烷烃和正烷酮的分布极具相似性,同奇碳数正构烷烃与正烷酮极高的相关性论证了两者的内在成因联系。泥炭中正烷酮类化合物主要来源于相应正构烷烃的微生物氧化作用,剖面上部锈色泥炭藓的富集对正烷酮有一定程度的贡献;结合FT-MS资料,脂肪酸的微生物β-氧化和脱羧基作用是形成正烷酮的另一种有效路径,但不是主要的成因路径。  相似文献   

10.
The northwest region of the Iberian Peninsula is home to a unique ecosystem of bogs,which are particularly sensitive to projected climate cha nge.In this context,the rate of carbon(C)accumulation in Chao de Veiga Mol.an intact raised bog,was analysed.Changes in the accumulation rate over the past10 millennia were determined in a peat core of 847 cm in depth,with a high mean rate of peat growth(11 yr cm^-1,0.09 cm yr^-1).An age-depth model was generated from 22 14C dates and fallout radionuclides.Chronological,stratigraphical and physico-chemical data confirmed the existence of a single cycle of peat formation throughout the Holocene and the formation of ombrotrophic peat 9500 years ago.The total mean C content was 50.2%,and over 10 millennia 583 kg C m^-2 accumulated at a mean rate of 35.3 g C m^-2 yr^-1,with a long-term(apparent)rate of carbon accumulation in the catotelm of59.9 g C m^-2 yr^-1.These values are much higher than reported for other Iberian peatlands and are amongst the highest documented for peatlands in the northern hemisphere.The dynamics of C accumulation and other measured parameters reveals important variations throughout the Holocene.They could be associated with the main climatic events described in the northern hemisphere and are highly consistent with models established for northern latitudes.The Chao de Veiga Mol raised bog is unique and of great potential value for carrying out high resolution palaeoenvironmental studies,especially in relation to regional and Iocal modulations in southern Europe.  相似文献   

11.
The results of studies are presented for the elemental composition of peat from the Ilas ombrotrophic bog (White Sea drainage basin). The calculations of enrichment factors of trace elements over the section of the bog peat relatively to the average composition of the Earth’s continental crust showed that the concentrations of most of chemical elements is determined by the contributions of lithogenic and biogenic sources, and the content of trace elements is equal to the background level. Enrichment growth since the beginning of intense development of European industry until the early 21th century was revealed only for Zn, Sb, Pb, and Cd. These elements were supplied to the bog resulting from long-range air transport and precipitation from the atmosphere. No pronounced heavy-metal contamination caused by the Arkhangelsk agglomeration was revealed for the peat in the Ilas bog.  相似文献   

12.
Biogeochemical processes in a forested tropical peat deposit and its record of past atmospheric dust deposition were assessed using the vertical distribution of lithophilic and plant essential elements in a dated core profile from Borneo, SE Asia. Peat formation started ∼22,120 14C yr before present (BP), and Ca/Mg mass ratios of the solid peat and very low ash contents indicate a strongly ombrotrophic character throughout the deposit, implying that most of the inorganic fraction has been supplied exclusively by atmospheric inputs. Concentration profiles of Mn, Sr, and Ca suggest a very minor influence of chemical diagenesis in the underlying sediments. Silicon, Ca, Mg, P, S, and K show a strong and extended zone of enrichment in the top 200 cm of the profile, indicating that biological accumulation mechanisms are much more extensive than in temperate peat bogs.In the lower core sections, where the element distribution is dominated solely by past atmospheric deposition, average Al/Ti ratios are similar to the upper continental crust (UCC), whereas Fe is slightly enriched and Si is strongly depleted: this condition favors highly weathered tropical soil dust as the main inorganic mineral source. Significant correlation of Al, Fe, Si, S, Ca, and Ti with the lithophilic elements Y and Zr suggests that the distribution of these elements is controlled by sources of atmospheric mineral dust. The Ca/Mg, Ca/K, and Mg/K ratios of the collected rainwater samples are similar to the global average of continental rainwater and suggest a continental character for the site. This is supported by the similarity of the average concentration of Br, Mg, Ca, and S to that in temperate continental and maritime bogs in Switzerland and Scotland.The concentration profiles of Si, Fe, Al, and Ti show distinct peaks within the profile, implying enhanced dust deposition, reduced rates of peat accumulation, or possibly both owing to climatic changes during the Holocene. Enhanced dust deposition between ∼10,830 and 9060 14C yr BP is tentatively interpreted as a Younger Dryas-like event with dust fluxes of ∼10.8 mg/m2/yr. The variations in Al/Ti and Fe/Ti profiles suggest that mineral dust sources have been changing constantly during the Holocene, with local sources being dominant between ∼7820 and 9500 14C yr BP and long-range transport (derived most likely from China) being important during the late Pleistocene and early Holocene and from ∼7820 14C yr BP to the present.  相似文献   

13.
In the raised bog Draved Mose, rates of peat formation and degrees of humification were determined in two peat sections. Based on 59 calibrated C-14 dates, accumulation rates during the last 6500 years of 0.16 to 0.80 mm/year were found. The peat layers were analyscd for Sphagnum species, rhizopods, and pollen and spores. A clear relation between humification degrees and humidity at the time of formation was found, while the relation between measured growth rates and degrees of humification varied throughout the 2.5 m thick peat section. These variations are thought to be mostly a result of autocompaction.  相似文献   

14.
Since the Carboniferous, tropical latitudes have been the site of formation of many economic coal deposits, most of which have a restricted range of mineralogical composition as a result of their depositional environment, climatic conditions, and diagenesis. Mineralogical and microscopic investigations of tropical peats from Tasek Bera, Peninsular Malaysia, were performed in order to better understand some of these factors controlling the nature, distribution and association of inorganic matter in peat-forming environments. Distribution and nature of the inorganic fraction of peat deposits give insight into the weathering conditions and detrital input into the mire system. Because the inorganic composition of peat deposits is determined by plant communities, height of water table, and climate, the results of the quantitative and qualitative analysis can be used to reconstruct palaeoclimatic conditions.Tasek Bera is a peat-accumulating basin in humid tropical Malaysia with organic deposits of low- to high-ash yield and thus representative of many ancient peat-forming environments. Clay minerals dominate the mineralogical composition of the peat and organic-rich sediments, while quartz and clays dominate the underlying siliciclastic deposits. Kaolinite is the most abundant clay mineral in the organic deposits with minor amounts of illite and vermiculite. Particle size analyses indicate that >50% of the inorganic detrital fraction is <2 μm. Most detrital quartz grains range in size from fine silt to fine sand. The fine sand fraction accounts for a maximum of 5 wt.% of the inorganic constituents. In addition, abundant biogenic and non-biogenic, Al- and Si-rich amorphous matter occur. In the ombrotrophic (low-nutrient) environment, biogenic inorganic material contributes up to >75% of the ash constituents. As a consequence, the vegetational communities make an important contribution to the inorganic and overall ash composition of peats and coals. The ash content of the often inundated peat consists on average of 10% opaline silica from diatoms and sponge spicules, while the ash of the top deposits may have up to 50% biogenic silica. Hence, Al- and Si-hydroxides and the opaline silica from diatoms and sponges represent a large repository of Al and Si, which may form the basis of mineral transformation, neoformation and alteration processes during coalification of the peat deposits. As a result, most coal deposits from paleotropical environments are anticipated to have little to no biogenic inorganic material but high amounts of secondary clays, such as kaolinite (detrital kaolinite, resilisified kaolinite, or desilisified gibbsite) or illite, and various amounts of detrital and authigenetic quartz.  相似文献   

15.
Ombrotrophic bogs are useful records of the impact of historical human activity on heavy metal contamination. Several studies concerning the trace element record (mainly Pb and Hg) in these particular environments have been carried out in recent years, although the role of humic substances has often not been considered. In particular, of the components of peat organic matter, fulvic acids and low molecular weight compounds are generally responsible for the mobility of trace elements through the profile, while humic acids (HAs) are involved in the formation of more stable organo-mineral complexes. In order to study the parallel distribution of As, Cr, Ni, Rb, Ti and Zr in bulk peat and the corresponding HAs, a peat core (10 × 10 × 81 cm) was collected from Etang de la Gruère (Switzerland) and cut into 27 slices of 3 cm. The samples were freeze-dried and milled very finely, and HAs extracted from each sample. Both peat and HAs were analyzed using an energy-dispersive miniprobe X-ray fluorescence multielement analyser (EMMA-XRF). Of the considered elements, Ni showed a great affinity for the humic acid component, while Cr was concentrated mainly into humic material from the deeper layers. On the other hand, Ti, Zr and Rb seemed to reflect the variation in mineral material both in peat and HA samples, while the As content of both materials reflected the environmental conditions characterizing the bog.  相似文献   

16.
Here we present research on previously uninvestigated frost peat mounds occurring on a peat bog in the southern part of Hermansenøya, NW Svalbard. Detailed characteristics are given of the environmental conditions of the peat bog and of the morphological features and surface structure of the frost peat mounds, as well as an analysis of the internal structure of one mound. Three types of frost peat mounds have been distinguished: disc‐shaped mounds (low), mid‐sized mounds with gentle sides, and high mounds with steep sides. Radiocarbon dating of the peat within the frost peat mound performed for the first time on Svalbard and a detailed analysis of the deposits demonstrated that in the high mound (1.3 m) there is an ice‐peat core and peat cover without ice. There are three layers of peat of different ages separated by at least two hiatuses. A generalized history of the development of the peat bog from about 8 ka BP is established. The studied mound displays two development cycles unknown elsewhere. The older relict part of the peat mound was formed during a climatic cooling about 3.0–2.5 ka BP, while the younger part originated during the Little Ice Age (c. AD 1550–1850). Despite certain similarities of these mounds to some palsas, this term should not be applied to the mounds because they are smaller and their cores consist mostly of layers of massive injection ice, the presence of which indicates a pressurized system in their genesis.  相似文献   

17.
The paper reports geochemical parameters of units in a peat bed in a raised bog in the southern Tyumen territory. Based on radiocarbon dates and the variability of the geochemical data, the following four evolutionary stages of the bed in the Holocene are distinguished: an ancient lake (5600–5750 years B.P.), low-land-bog peat (4550–5600 years B.P.), transitional-type peat (4200–4550 years B.P.), raised-bog peat. The major-component technique was applied to analyze relations between various parameters of the bed and evaluate the variations in the condition under which the bog evolved with time, including climatic conditions (in relative units). An anthropogenic signal of the accumulation of certain metals in bog systems is distinguished.  相似文献   

18.
X‐ray fluorescence (XRF) core scanning has become widely available for geological studies during the last decade. The data obtained from XRF core scanning, however, may be strongly influenced by the amount of organic matter, water content, density and porosity of the sediment matrix. In this study we discuss the usefulness of XRF core scanning to distinguish different kinds of organic‐rich sediments and peat based on examples from tropical Lakes Kumphawapi and Nong Leng Sai in Thailand. We examined how sedimentary factors influence XRF core scanning analyses by comparing elemental and scattering ratios to lithological changes and quantitative LOI, TOC, biogenic silica (BSi) and grain‐size values. Our comparison suggests that the (inc/coh) scattering ratio is of limited use as an indicator for variations in LOI and TOC in peaty gyttja or peat. In Lake Kumphawapi's sediments, Si/Ti ratios reflect clastic input associated with grain‐size variations rather than BSi contents. The Ti‐normalized ratios of Si, Zr, Sr, K and Rb are linked to mineral input and associated grain‐size variations. We conclude that XRF core scanning of organic‐rich tropical lake sediments and peat is useful to infer palaeoenvironmental conditions. However, XRF core scanning data does not stand‐alone and needs to be underpinned by additional proxies.  相似文献   

19.
The A5 London to Holyhead trunk road suffers from large and varied settlements at Pant Dedwydd where it crosses a geotrophic peat bog developed on the glacial drift that overlies bedrock of Silurian Denbigh Grits Group. Recent carriageway settlements have created an undulating profile over a 100 m stretch, restricting forward visibility and posing recurring and persistent difficulties for highway maintenance. The highly compressible peat underlies almost 400 m of highway, ranges up to 7 m deep and a typical profile consists of an upper sphagnum peat layer and a basal reedy, woody and sedge grass peat. The highway was originally constructed by Thomas Telford in 1819 as a low floating embankment over the organic terrain. Increases in traffic over the intervening period together with successive asphalt overlays have resulted in a history of major repairs and although records are incomplete it is likely that the carriageway is now over 2 m thick over parts of the bog. Comprehensive geological investigations carried out to characterize the peat deposit included dynamic probe holes, boreholes and a trial pit. No unusual subsurface conditions were identified. However, scrub willow or grey sallow (Salix cinerea) was observed growing in spiraea thickets alongside the deepest hollows in the highway. The willows may contribute to the road subsidence by extraction of water from the peat beneath the carriageway. Accordingly, removal of the scrub willow and conventional re-grading of the carriageway have been recommended to correct the existing problem.  相似文献   

20.
The peat-forming systems of the Okefenokee Swamp are viewed as modern progenitors of coal. Taxodium and Nymphaea-derived peat-forming systems were characterized in terms of (1) organic fractions and (2) the distribution of organic/inorganic sulfur in each organic fraction (water soluble, benzene/methanol soluble, humin, humic acid, fulvic acid). The humin fraction is the largest organic fraction in both environments, approaching 70% of the total organic matter in the Nymphaea-derived environment. Humin origins are discussed in terms of a humic acid precursor, and undecomposed plant material. It is suggested that each depth of peat represents a diagenetic history of events which the authors believe occurred primarily when the currently buried peat was at the surface. The sulfur content of both peat-forming areas is low (0.23–0.27%); organic sulfur is the dominant sulfur form. Humin contains 50–80% of the total sulfur and of this, 80% is organic sulfur. Ester-sulfate appears to be especially prevalent in the fulvic acid fraction. The sulfur content of freshwater-derived peats is similar in quantity and distribution to that found in low sulfur coals.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号