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Bas Van Geel - One of the best experts on this subject based on the ideXlab platform.
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vegetation history and human impact during the last 300 years recorded in a german Peat Deposit
Review of Palaeobotany and Palynology, 2008Co-Authors: Marjolein Van Der Linden, Emma Vickery, Dan J Charman, Peter Broekens, Bas Van GeelAbstract:A Peat core from the Barschpfuhl kettlehole mire in north-east Germany was analysed for multiproxy indicators (plant macrofossils, pollen/non-pollen microfossils, testate amoebae, colorimetric humification, carbon/nitrogen ratios, bulk density, loss on ignition), to investigate the effects of climate change and human impact on vegetation and Peat accumulation during the last c. 300 years. 14C wiggle-match dating was applied for high-precision dating. Testate amoebae assemblages were used to reconstruct past water table depths and compared with other proxies and instrumental climate data from the mid-18th century onwards. The mire hydrology of this relatively small bog was heavily influenced by forestry changes in the area. The climate signal was therefore obscured. Afforestation with fast-growing conifers and drainage for agricultural purposes resulted in a lowering of the water level, changes in trophic status, changes in mire surface vegetation and increased decomposition of the Peat. Variations in the openness and cultivated land indicators in the pollen data of Barschpfuhl reflect regional population density and land use changes.
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late holocene human impact and climate change recorded in a north swedish Peat Deposit
Palaeogeography Palaeoclimatology Palaeoecology, 2008Co-Authors: Marjolein Van Der Linden, Judith Barke, Emma Vickery, Dan J Charman, Bas Van GeelAbstract:Abstract A Peat core from a mire with poor fen lawns and ombrotrophic hummock strings in Northern Sweden was examined (plant macrofossils, pollen/non-pollen microfossils, testate amoebae, colorimetric humification, carbon/nitrogen ratios, bulk densities, loss on ignition) to investigate the effects of climate change and human impact on the plant species composition and Peat accumulation of the Peat forming vegetation during the last 1700 yr. 14 C wiggle-match dating was applied for high-precision dating. The Lappmyran region was dominated by Pinus and Picea forest. Changes in land-use patterns and population density were visible in the pollen record of the regional vegetation. Juniperus and Rumex acetosa -type pollen indicated the presence of grazed land in the area between AD 1500 and 1950. The vegetation at the coring spot gradually became ombrotrophic. The local plant and testate amoebae compositions reflect changes in surface wetness caused by changes in precipitation and the internal dynamics of the bog. A wet interval was observed during the Maunder minimum of solar activity. The presence of Drepanocladus fluitans indicates less ombrotrophic conditions during this period probably caused by the inflow of minerogenic water from upslope owing to increased precipitation. The reconstructed water table shows agreement with precipitation measurements which were available since AD 1860.
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Sub-fossil evidence for fungal hyperparasitism (Isthmospora spinosa on Meliola ellisii, on Calluna vulgaris) in a Holocene intermediate ombrotrophic bog in northern-England
Review of Palaeobotany and Palynology, 2006Co-Authors: Bas Van Geel, André Aptroot, Dmitri MauquoyAbstract:Abstract We analysed a Holocene Peat Deposit from an intermediate ombrotrophic bog in northern-England (Butterburn Flow), for micro- and macrofossils and discovered the hyperparasite Isthmospora spinosa together with its host, the ascomycete Meliola ellisii, which was a parasite on local Calluna vulgaris. This is the first fossil evidence for hyperparasitism in Quaternary palaeoecological research. The relationship between the three taxa is evident from the fossil record, but does not fit in with information from the mycological literature. Hitherto Isthmospora spinosa is only known from the tropics, and extant Meliola ellisii was observed on Vaccinium species and not on Calluna vulgaris
O G Savichev - One of the best experts on this subject based on the ideXlab platform.
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mineralogical and geochemical features of a Peat Deposit in the eutrophic obskoye fen under anthropogenic load western siberia
Doklady Earth Sciences, 2020Co-Authors: O G Savichev, Maxim Rudmin, Aleksey Mazurov, N G Nalivaiko, V I Sergienko, Igor SemiletovAbstract:The chemical composition and mineral inclusions in Peats and the underlying soils of the eutrophic Obskoye fen (Western Siberia, Tomsk Region) are studied. The basic pattern of a change in the mineralogical and geochemical conditions at depth consists in domination of hydroxides on top of the Peat Deposit and sulfides at the bottom. The geochemical reduction barrier is formed at the bottom of the Peat Deposit. Its functioning is related to increased concentrations of U and Hg. The markedly pronounced influence exerted by sewage discharge is associated with an increase in the Na concentration in acid extracts from Peats and additional accumulation of the mixture of suspended, colloidal, and dissolved forms of some metals in the boggy environment.
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geochemical barriers in oligotrophic Peat bog western siberia
Applied Geochemistry, 2020Co-Authors: O G Savichev, Maxim Rudmin, Evgeniya Soldatova, Aleksey MazurovAbstract:Abstract Peat bogs play an important role in the functioning of the biogeochemical cycles of the chemical elements that are connected to climatological and environmental changes, at least at the regional level. For several decades, this has made the issue of wetland evolution of particular interest among the scientific community worldwide. A number of authors have studied different aspects of wetland geochemistry and evolution: the chemical composition of bog water and Peat, including nutrient dynamics, bog vegetation, hydrological characteristics, and the mineralogical composition of Peat. However, some issues remained insufficiently studied, including the distribution of chemical elements in Peat Deposits and, particularly, the causes of the formation of some minerals in the Peat Deposits. To research these issues, we estimated the geochemical conditions of the formation of some minerals in the oligotrophic pine-shrub-sphagnum bog and adjacent area (part of the Vasyugan Swamp, Western Siberia) in the winter period of 2017 and 2018. It was revealed that there were no less than two complex geochemical barriers in the Peat Deposit. These barriers correspond to changes in advective and diffusion flows and result in the accumulation of Fe and some other chemical elements in the Peat Deposit. The upper complex geochemical barrier of redox, sulfide, and sorption type is located approximately at a depth of 0.40–1.25 m. The bottom barrier, which is the combination of complex geochemical barrier of alkaline and sorption type with mechanical barrier, are located at the bottom layer of the Peat Deposit, at a depth of 2.25–2.50 m. Accumulation of substances in the upper geochemical barrier is always less significant than in the bottom barrier. Therefore, the probability of detecting high concentrations of various substances is very high in the bottom part of the Peat Deposit, the organomineral sediments, and the upper part of the underlying mineral ground.
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mechanisms of accumulation of chemical elements in the Peat Deposit in east part of the vasyugan swamp the western siberia
Доклады Академии наук, 2019Co-Authors: O G Savichev, V I Sergienko, Natalia Shakhova, о г савичев, Alexey Mazurov, а к мазуров, Maksim Rudmin, м а рудмин, н е шахова, в и сергиенкоAbstract:The results of mineralogical-geochemical studies of the oligotrophic pine-fruticulose-sphagnum segment of the Vasyugan Swamp (West Siberia) in the winter of 2017 are presented. A mathematical model is developed for the depth distribution of chemical elements in water and acid extracts of Peats, organo-mineral sediments, and inorganic soil. It is shown that two complex geochemical barriers related to the changes in filtration properties of soils and contributing to the formation and/or accumulation of Fe compounds and other chemical elements function in the Peat Deposit. The first (oxidizing, reduction, sulfide, and adsorption hydroxide) barrier is found approximately at a depth of 0.40-1.25 m; the second (alkaline carbonate and hydrolytic, adsorption hydroxide, clayey, and carbonate) barrier lies in the lower layer of the Peat Deposit (a depth of 2.25-2.50 m). The result obtained is important for understanding the production-destruction methane cycle.
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mechanisms of accumulation of chemical elements in a Peat Deposit in the eastern part of vasyugan swamp west siberia
Doklady Earth Sciences, 2019Co-Authors: O G Savichev, Maxim Rudmin, Aleksey Mazurov, V I Sergienko, Natalia Shakhova, Igor SemiletovAbstract:The results of mineralogical–geochemical studies of the oligotrophic pine–fruticulose–sphagnum segment of Vasyugan Swamp (West Siberia) in the winter of 2017 are presented. A mathematical model is developed for the depth distribution of chemical elements in water and acid extracts of Peats, organo-mineral sediments, and inorganic soil. It is shown that two complex geochemical barriers related to the changes in filtration properties of soils and contributing to the formation and/or accumulation of Fe compounds and other chemical elements function in the Peat Deposit. The first (oxidizing, reduction, sulfide, and adsorption hydroxide) barrier is found approximately at a depth of 0.40–1.25 m; the second (alkaline carbonate and hydrolytic, adsorption hydroxide, clayey, and carbonate) barrier lies in the lower layer of the Peat Deposit (a depth of 2.25–2.50 m). The result obtained is important for understanding the production–destruction methane cycle.
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distribution of inorganic pollutants over the depth of upper Peat Deposit
Contemporary Problems of Ecology, 2015Co-Authors: O G SavichevAbstract:A model of distribution of inorganic substances in the polluted waters of an oligotrophic bog has been developed and geomigratory calculations have been carried out on the example of Vasyugan Bog. It is shown that the most significant changes of mineralization of bog waters caused by the inflow of industrial waste waters from oil and gas production enterprises are referred to the high layer with a thickness of approximately 0.5–1.0 m. The creation of loam as an insulating barrier in the active layer of the bog helps reduce the negative impact on the waters, but does not preserve their baseline state on the lower layer.
Shucheng Xie - One of the best experts on this subject based on the ideXlab platform.
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paleoclimate influence on early diagenesis of plant triterpenes in the dajiuhu Peatland central china
Geochimica et Cosmochimica Acta, 2013Co-Authors: Xianyu Huang, Philip A Meyers, Jiantao Xue, Junhua Huang, Xinxi Wang, Shucheng XieAbstract:Abstract Aromatic derivatives of vascular plant triterpenoids are common in recent and ancient sediments, coal, and petroleum. Understanding their early diagenetic alterations and their relation with environmental conditions can facilitate their applications in paleoenvironmental reconstructions. Here we present a high-resolution record of aromatic triterpenes in a Holocene Peat core collected in the Dajiuhu Peatland, central China. These aromatic triterpenes are derivatives of plant triterpenoids with oleanane, ursane and lupane carbon skeletons and exist in three different structural groups: aromatic des-A-triterpenes, aromatic pentacyclic triterpenes, and C-ring cleaved aromatic triterpenes. Such a high diversity of aromatic triterpenes in a young Peat Deposit is compelling evidence for rapid microbial mediation of these important degradation pathways during very early diagenesis. Of particular importance is the occurrence of C-ring cleaved aromatic triterpene and aromatic des-A-triterpenes in the Dajiuhu Peat samples, which until now have not been identified in recent sediments. The downcore profile shows that the microbial aromatization process of oleanoids positively correlates with paleoclimate change. During dry or warm intervals, highly aromatized products such as tetraaromatic triterpenes become predominant over their triaromatic homologs. In contrast, triaromatic triterpenes become dominant during wet or cold intervals. In addition, this study provides further evidence to support that the climate pattern in the middle reaches of the Yangtze River is different from that in north China during 13–9.4 ka. These findings suggest that aromatic triterpenes can be valuable tools for Holocene paleoenvironmental reconstructions.
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paleotemperature variability in central china during the last 13 ka recorded by a novel microbial lipid proxy in the dajiuhu Peat Deposit
The Holocene, 2013Co-Authors: Xianyu Huang, Philip A Meyers, Jiantao Xue, Xinxin Wang, Chengling Jia, Min Zheng, Shucheng XieAbstract:The Asian summer monsoon is a very important climatic component affecting the land ecosystem on the eastern Asian continent. Here we assess microbe-derived lipid biomarker evidence from a well-date...
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distribution of aliphatic des a triterpenoids in the dajiuhu Peat Deposit southern china
Organic Geochemistry, 2008Co-Authors: Xianyu Huang, Shucheng Xie, Chuanlun Zhang, Dan Jiao, Junhua Huang, Fang JinAbstract:Abstract Aliphatic des -A-triterpenoids have been tentatively assigned in samples taken from a 260 cm thick Peat sequence from the Dajiuhu Basin of southern China using gas chromatography–mass spectrometry (GC–MS). The compounds, possessing the carbon skeletons of oleanane, ursane or lupane, are generally considered as the microbial degradation products of plant triterpenoids under anoxic conditions. Abundant aliphatic des -A-triterpenoids were observed only in Peat samples during the transitional period from the last glaciation to the early Holocene (9.5–11.6 cal 14 C ka BP). Among these, des -A-lupane is the only saturated ring A-degraded compound, whilst mono- and di-unsaturated des -A-triterpenes are dominated by oleanane and ursane derivatives. The mono- and di-unsaturated des -A-triterpenes show a strong correlation ( R 2 0.94) in abundance, indicating that they may be derived from the same source or process. Des -A-lupane shows no correlation in abundance with the mono- or di-unsaturated des -A-triterpenes ( R 2 des -A-triterpenoids corresponds to the interval with relatively high sedimentation rate (> 0.3 mm per year). These data indicate that the abundance of aliphatic des -A-triterpenoids in the Dajiuhu Peat Deposit in the early Holocene may result from the prevailing reducing conditions in the water table or surficial sediment and/or rapid preservation of the early diagenetic products. Our study highlights the potential application of des -A-triterpenes in the reconstruction of palaeoenvironments based on Peat sequences.
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lipid biomarkers in the zoige hongyuan Peat Deposit indicators of holocene climate changes in west china
Organic Geochemistry, 2007Co-Authors: Yanhong Zheng, Philip A Meyers, Weijian Zhou, Shucheng XieAbstract:Abstract Lipid biomarkers extracted from a Peat core obtained from the northeast edge of the Tibetan Plateau have provided a 13 kyr record of regional climate change. A period of warmer climate corresponding to the Holocene Optimum between 9 ka and 5 ka is evident in greater alteration of n-alkanoic acids and n-alkanols and in the appearance of biomarkers indicative of greater microbial activity. Concomitant increases in local precipitation that raised the water level of the Peat bog are recorded by increases in the proportions of C23 and C25 n-alkanes that are mainly derived from submerged/floating plants. Alternations in submergent and emergent plant n-alkane proxies reveal multi-decimeter scale rises and falls in the bog water level that relate to variation in precipitation on the Tibetan Plateau during the Holocene. Major low water level events occurred around 12.6, 11.3, 10.7, 9.4, 8.3, 6.0, 4.5, 3.1, 2.1 and 1.0 ka. These events correlate well with cold dry events recorded in same region from other climatic proxies that reflect millennial-scale Holocene instability in the Asian monsoon system. Our biomarker results also indicate that Peat accumulation and preservation on the Tibetan Plateau are more sensitive to variability in monsoonal precipitation than in annual temperature.
Aleksey Mazurov - One of the best experts on this subject based on the ideXlab platform.
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mineralogical and geochemical features of a Peat Deposit in the eutrophic obskoye fen under anthropogenic load western siberia
Doklady Earth Sciences, 2020Co-Authors: O G Savichev, Maxim Rudmin, Aleksey Mazurov, N G Nalivaiko, V I Sergienko, Igor SemiletovAbstract:The chemical composition and mineral inclusions in Peats and the underlying soils of the eutrophic Obskoye fen (Western Siberia, Tomsk Region) are studied. The basic pattern of a change in the mineralogical and geochemical conditions at depth consists in domination of hydroxides on top of the Peat Deposit and sulfides at the bottom. The geochemical reduction barrier is formed at the bottom of the Peat Deposit. Its functioning is related to increased concentrations of U and Hg. The markedly pronounced influence exerted by sewage discharge is associated with an increase in the Na concentration in acid extracts from Peats and additional accumulation of the mixture of suspended, colloidal, and dissolved forms of some metals in the boggy environment.
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geochemical barriers in oligotrophic Peat bog western siberia
Applied Geochemistry, 2020Co-Authors: O G Savichev, Maxim Rudmin, Evgeniya Soldatova, Aleksey MazurovAbstract:Abstract Peat bogs play an important role in the functioning of the biogeochemical cycles of the chemical elements that are connected to climatological and environmental changes, at least at the regional level. For several decades, this has made the issue of wetland evolution of particular interest among the scientific community worldwide. A number of authors have studied different aspects of wetland geochemistry and evolution: the chemical composition of bog water and Peat, including nutrient dynamics, bog vegetation, hydrological characteristics, and the mineralogical composition of Peat. However, some issues remained insufficiently studied, including the distribution of chemical elements in Peat Deposits and, particularly, the causes of the formation of some minerals in the Peat Deposits. To research these issues, we estimated the geochemical conditions of the formation of some minerals in the oligotrophic pine-shrub-sphagnum bog and adjacent area (part of the Vasyugan Swamp, Western Siberia) in the winter period of 2017 and 2018. It was revealed that there were no less than two complex geochemical barriers in the Peat Deposit. These barriers correspond to changes in advective and diffusion flows and result in the accumulation of Fe and some other chemical elements in the Peat Deposit. The upper complex geochemical barrier of redox, sulfide, and sorption type is located approximately at a depth of 0.40–1.25 m. The bottom barrier, which is the combination of complex geochemical barrier of alkaline and sorption type with mechanical barrier, are located at the bottom layer of the Peat Deposit, at a depth of 2.25–2.50 m. Accumulation of substances in the upper geochemical barrier is always less significant than in the bottom barrier. Therefore, the probability of detecting high concentrations of various substances is very high in the bottom part of the Peat Deposit, the organomineral sediments, and the upper part of the underlying mineral ground.
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mechanisms of accumulation of chemical elements in a Peat Deposit in the eastern part of vasyugan swamp west siberia
Doklady Earth Sciences, 2019Co-Authors: O G Savichev, Maxim Rudmin, Aleksey Mazurov, V I Sergienko, Natalia Shakhova, Igor SemiletovAbstract:The results of mineralogical–geochemical studies of the oligotrophic pine–fruticulose–sphagnum segment of Vasyugan Swamp (West Siberia) in the winter of 2017 are presented. A mathematical model is developed for the depth distribution of chemical elements in water and acid extracts of Peats, organo-mineral sediments, and inorganic soil. It is shown that two complex geochemical barriers related to the changes in filtration properties of soils and contributing to the formation and/or accumulation of Fe compounds and other chemical elements function in the Peat Deposit. The first (oxidizing, reduction, sulfide, and adsorption hydroxide) barrier is found approximately at a depth of 0.40–1.25 m; the second (alkaline carbonate and hydrolytic, adsorption hydroxide, clayey, and carbonate) barrier lies in the lower layer of the Peat Deposit (a depth of 2.25–2.50 m). The result obtained is important for understanding the production–destruction methane cycle.
Xianyu Huang - One of the best experts on this subject based on the ideXlab platform.
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Occurrence of a tetraaromatic hopane in the late Holocene Peat Deposit, central China
Organic Geochemistry, 2017Co-Authors: Liduan Zheng, Xianyu HuangAbstract:Abstract Hopanoids are important cell membrane components of many prokaryotes. These compounds are commonly found in sediments and are used as biomarkers for bacteria. During the diagenesis, biological hopanoids can be transformed into geological hopanoids, including aromatic hopanoids. Our understanding of the processes active in the aromatization of hopanoids in young sediments and their paleoenvironmental implications, however, remains somewhat limited. In this study, we report the occurrence of a C 25 tetraaromatic hopane in the late Holocene Peat horizons at Dajiuhu, central China. Similar fluctuations of a C 25 tetraaromatic hopane and diploptene suggest that the latter may be an important precursor for the aromatic hopane in this Peat sequence. The concentration of the C 25 tetraaromatic hopane is greater in Peats Deposited between 2.2 and 1.6 ka when other proxies record a wetter climate and the Peat water would have been less acidic than in other intervals. The possible mechanisms underlying the relationship between aromatic hopanes and hydrological settings in immature sediments should be considered further in the future.
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cryptic abundance of long chain iso and anteiso alkanes in the dajiuhu Peat Deposit central china
Organic Geochemistry, 2014Co-Authors: Xianyu Huang, Philip A Meyers, Jiantao Xue, Xinxin Wang, Liduan ZhengAbstract:Abstract Long chain 2-methyl and 3-methyl alkanes occur widely in modern plants and in recent and ancient sediments, but their presence in Peat Deposits has not been reported. Here, we document an early Holocene enrichment of long chain 2-methyl alkanes in the Dajiuhu Peat Deposit, accompanied by traces of 3-methyl alkanes. The 2-methyl alkanes showed a strong odd/even predominance and were dominated by C 27 and C 29 homologs. Their δ 13 C values were 5–7‰ less negative than those of the n -alkanes with the same carbon numbers. Our previous paleoenvironmental reconstruction for this Peat sequence indicated that the interval enriched in long chain 2-methyl alkanes corresponded to a period with a very wet climate. Although not resolved, possible sources of the long chain 2-methyl alkanes with relatively enriched 13 C composition include submerged aquatic plants utilizing bicarbonate or heterotrophic microbes in the Peatland and its catchment.
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paleoclimate influence on early diagenesis of plant triterpenes in the dajiuhu Peatland central china
Geochimica et Cosmochimica Acta, 2013Co-Authors: Xianyu Huang, Philip A Meyers, Jiantao Xue, Junhua Huang, Xinxi Wang, Shucheng XieAbstract:Abstract Aromatic derivatives of vascular plant triterpenoids are common in recent and ancient sediments, coal, and petroleum. Understanding their early diagenetic alterations and their relation with environmental conditions can facilitate their applications in paleoenvironmental reconstructions. Here we present a high-resolution record of aromatic triterpenes in a Holocene Peat core collected in the Dajiuhu Peatland, central China. These aromatic triterpenes are derivatives of plant triterpenoids with oleanane, ursane and lupane carbon skeletons and exist in three different structural groups: aromatic des-A-triterpenes, aromatic pentacyclic triterpenes, and C-ring cleaved aromatic triterpenes. Such a high diversity of aromatic triterpenes in a young Peat Deposit is compelling evidence for rapid microbial mediation of these important degradation pathways during very early diagenesis. Of particular importance is the occurrence of C-ring cleaved aromatic triterpene and aromatic des-A-triterpenes in the Dajiuhu Peat samples, which until now have not been identified in recent sediments. The downcore profile shows that the microbial aromatization process of oleanoids positively correlates with paleoclimate change. During dry or warm intervals, highly aromatized products such as tetraaromatic triterpenes become predominant over their triaromatic homologs. In contrast, triaromatic triterpenes become dominant during wet or cold intervals. In addition, this study provides further evidence to support that the climate pattern in the middle reaches of the Yangtze River is different from that in north China during 13–9.4 ka. These findings suggest that aromatic triterpenes can be valuable tools for Holocene paleoenvironmental reconstructions.
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paleotemperature variability in central china during the last 13 ka recorded by a novel microbial lipid proxy in the dajiuhu Peat Deposit
The Holocene, 2013Co-Authors: Xianyu Huang, Philip A Meyers, Jiantao Xue, Xinxin Wang, Chengling Jia, Min Zheng, Shucheng XieAbstract:The Asian summer monsoon is a very important climatic component affecting the land ecosystem on the eastern Asian continent. Here we assess microbe-derived lipid biomarker evidence from a well-date...
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distribution of aliphatic des a triterpenoids in the dajiuhu Peat Deposit southern china
Organic Geochemistry, 2008Co-Authors: Xianyu Huang, Shucheng Xie, Chuanlun Zhang, Dan Jiao, Junhua Huang, Fang JinAbstract:Abstract Aliphatic des -A-triterpenoids have been tentatively assigned in samples taken from a 260 cm thick Peat sequence from the Dajiuhu Basin of southern China using gas chromatography–mass spectrometry (GC–MS). The compounds, possessing the carbon skeletons of oleanane, ursane or lupane, are generally considered as the microbial degradation products of plant triterpenoids under anoxic conditions. Abundant aliphatic des -A-triterpenoids were observed only in Peat samples during the transitional period from the last glaciation to the early Holocene (9.5–11.6 cal 14 C ka BP). Among these, des -A-lupane is the only saturated ring A-degraded compound, whilst mono- and di-unsaturated des -A-triterpenes are dominated by oleanane and ursane derivatives. The mono- and di-unsaturated des -A-triterpenes show a strong correlation ( R 2 0.94) in abundance, indicating that they may be derived from the same source or process. Des -A-lupane shows no correlation in abundance with the mono- or di-unsaturated des -A-triterpenes ( R 2 des -A-triterpenoids corresponds to the interval with relatively high sedimentation rate (> 0.3 mm per year). These data indicate that the abundance of aliphatic des -A-triterpenoids in the Dajiuhu Peat Deposit in the early Holocene may result from the prevailing reducing conditions in the water table or surficial sediment and/or rapid preservation of the early diagenetic products. Our study highlights the potential application of des -A-triterpenes in the reconstruction of palaeoenvironments based on Peat sequences.