hopanoid hydrocarbons and perylene in lake biwa japan sediments environmental control on their abundance and molecular composition abstract we examined the vertical distribution of hopanoid hydrocarbons and perylene in sedimentary sections from lake biwa japan and discuss the results with respect to paleoenvironmental information from around the lake region over the last 120 kyr moretene concentration was high above the sections where fall out events of tephra tephra at occurred ca 30 kyr before present bp this feature suggests that the tephra fall out events created o 2 deficient conditions resulting in high activity of methane producing bacteria and of methanotrophic moretene producing bacteria becoming active above the tephra layer five sections at 10 20 kyr ca 35 kyr ca 70 kyr ca 90 kyr and ca 110 kyr bp exhibited peaks in the ratio of 17 21 22r homohopane to 17 21 22r homohopane hopc 31 the n c 23 n c 31 alkane ratio in these sections was 0 6 0 1 n 49 very low if compared with typical characteristics of n alkanes for a sphagnum peat environment n c 23 n c 31 ca 3 6 bingham et al 2010 we conclude that sphagnum peat may not have been an important contributor of n alkanes over the past 120 kyr comparison with previous pollen records for the lake region suggests that high hopc 31 values may be caused by production of acidic soil from expansion of temperate conifer e g cryptomeria forest under cold and wet climate conditions the abundance of perylene relative to sediment or total organic carbon toc was high in the sections at ca 20 kyr ca 70 kyr and ca 90 kyr bp these sections were approximately in accord with those having a maximum in hopc 31 this concordance indicates that the climatic conditions suitable for the production of perylene quinone in soil surrounding the lake coincided with those for a high hopc 31 ratio thus hopc 31 and perylene toc might be useful as proxies of soil acidity temperature and humidity

ecological and biogeochemical change in an early paleogene peat forming environment linking biomarkers and palynology abstract sphagnum moss is the dominant plant type in modern boreal and sub arctic ombrotrophic bogs and is of particular interest due to its sensitivity to climate and its important role in wetland biogeochemistry here we reconstruct the occurrence of sphagnum moss and associated biogeochemical change within a thermally immature early paleogene 55 ma lignite from schoningen nw germany using a high resolution multi proxy approach changes in the abundance of sphagnum type spores and the c23 c31 n alkane ratio indicate the expansion of sphagnum moss within the top of the lignite seam this sphagnum moss expansion is associated with the development of waterlogged conditions analogous to what has been observed within modern ombrotrophic bogs the similarity between biomarkers and palynology also indicates that the c23 c31 n alkane ratio may be a reliable chemotaxonomic indicator for sphagnum during the early paleogene the 13c value of bacterial hopanes and mid chain n alkanes indicates that a rise in water table is not associated with a substantial increase in aerobic methanotrophy the absence of very low 13c values within the top of the seam could reflect either less methanogenesis or less efficient methane oxidation under waterlogged sulphate rich conditions

biomarkers as proxies for plant inputs to peats an example from a sub boreal ombrotrophic bog lipid distributions in modern peat forming plants were determined and compared to biomarkers recovered from a ca 2800 year old peat deposited in a dutch ombrotrophic bog the peat section spans a well constrained shift in local hydrology and vegetation and potential molecular proxies for plant inputs were directly tested against the macrofossil record based on the analyses of modern plants low molecular weight lmw n alkanes c23 c25 and high molecular weight n alkanes c33 are proposed as potential biomarkers for sphagnum and non sphagnum inputs respectively consistent with this in the bargerveen peat core lmw n alkane abundances increase and hmw n alkane abundances decrease coincident with the shift to sphagnum dominated peat additional potential proxies include the abundances of c22 alkanedioic acid and phytenyl phytenoate as sphagnum indicators and the abundances of the triterpenoids taraxer 14 ene and taraxast 20 ene as biomarkers for ericaceae rootlets

assessment of peat quality by molecular and bulk geochemical analysis application to the holocene record of the chautagne marsh haute savoie france although it is primarily constituted in general from a limited variety of local plants peat is however sensitive to physicochemical changes in the medium in particular those induced by hydrological fluctuations the present study aims at confronting the information on peat quality provided by various families of biochemical components lipids lignin sugars especially in order to check the validity of a new organic matter om quality indicator the r400 index directly drawn from rock eval pyrolysis this parameter which is deduced from the sole s2 pyrolysis peak is extremely robust the chautagne marsh located between the le bourget lake and the rhone river lies in a key situation for recording lake level variations and rhone river floods all along its holocene filling the study was conducted on a 6 m long core which comprises 4 m of peat under 66 cm of pedogenetically altered om rich sediment classical rock eval pyrolysis revealed few qualitative and quantitative om changes with total organic carbon toc values close to 50 and hydrogen index values around 300 350 mg hc g 1toc in the peat the r400 parameter remains practically unchanged in the upper unit affected by pedogenesis it fluctuates however all along the peaty unit together with a progressive downward decrease ascribable to diagenesis molecular analyses show that samples with high r400 values are richer in sugars and in slightly oxidized lignin these results support the idea that the r400 parameter can be used as an indicator of om preservation since om preservation is mostly controlled by the water table in peat the chautagne marsh records hydrological fluctuations such as those of the le bourget lake water level all along the holocene

n alkane evidence for the onset of wetter conditions in the sierra nevada california usa at the mid late holocene transition 3 0 ka abstract n alkane biomarker distributions in sediments from swamp lake sl in the central sierra nevada of california usa provide evidence for an increase in mean lake level 3000 yr ago in conjunction with widespread climatic change inferred from marine and continental records in the eastern north pacific region length distributions of n alkane chains in modern plants growing at sl were determined and compared to sedimentary distributions in a core spanning the last 13 ka as a group submerged and floating aquatic plants contained high proportions of short chain lengths nc27 were dominant changes in the sedimentary n alkane distribution over time were driven by variable inputs from plant sources in response to changing lake level sedimentation and plant community composition a shift toward shorter chain lengths nc21 nc23 occurred between 3 1 and 2 9 ka and is best explained by an increase in the abundance of aquatic plants and the availability of shallow water habitat in response to rising lake level the late holocene expansion of sl following a dry mid holocene is consistent with previous evidence for increased effective moisture and the onset of wetter conditions in the sierra nevada between 4 0 and 3 0 ka

environmental influences over the last 16 ka on compound specific δ13c variations of leaf wax n alkanes in the hani peat deposit from northeast china compound specific carbon isotope ratios 13c of leaf wax n alkanes c21 c33 odd carbon numbered n alkanes were measured in the hani peat sequence from northeast china these data were compared with lipid biomarker compositions to assess changes in local vegetation and paleoclimate for the last 16 ka the 13c values of n alkanes range between 36 6 and 30 7 showing that the compounds originate from c3 plants much larger variations 5 4 in the n alkane 13c values than those of atmospheric co2 during the last 16 ka 0 5 indicate that the isotopic values were affected by environmental factors in addition to the postglacial 13c variations in the atmospheric reservoir the stratigraphic records of 13c reveal decoupled fluctuations among the individual n alkanes particularly between 15 5 and 11 4 ka synchronous excursions in the 13c offsets among individual n alkanes 13c and lipid biomarker paleoplant proxies paq and c23 c31 and c27 c31 from 14 9 to 13 2 ka and 12 7 to 11 6 ka suggest that vegetational changes are the most likely causes for the decoupled 13c variations parallel fluctuations of the 13c values of terrestrial higher plant derived c29 and c31n alkanes and the n alkane average chain length acl from 11 to 6 ka indicate that the 13c variations responded to net evaporation changes negative shifts in the n alkane 13c values coinciding with the acl decreases at 10 5 9 3 ka and 8 1 ka indicate the short term onset and fluctuations of the summer monsoon strength in eastern china during the early holocene

molecular organic matter in speleothems and its potential as an environmental proxy abstract organic matter preserved in speleothems has considerable potential to record changes in the surrounding environment particularly in the overlying vegetation here we review three types of organic matter analysis relevant to speleothems organic fluorescence lipid biomarker analysis and amino acid racemisation organic matter luminescence provides a useful non destructive and rapid method for assessing dissolved organic matter quantity and quality while biomarker analysis amino acids and lipids has the potential to provide a more detailed signal related to specific parts of the surrounding ecosystem such as the dominant vegetation regime and bacterial activity amino acid analysis has yet to prove demonstrably useful in stalagmites due to the inability to characterise the sources of proteinaceous matter however the small but increasing body of work on lipid biomarker analysis in stalagmites has shown that a wide variety of recognisable biomarkers are preserved over long periods of time 100 ka can be recovered at temporal resolutions of

source rock facies distribution predicted from oil geochemistry in the central sumatra basin indonesia the molecular and compound specific isotopic composition of the n alkanes in 30 oil samples from the central sumatra basin were analyzed with the purpose of determining facies variations of the source rock in this basin the oil samples were generated by the eocene oligocene lacustrine brown shale formation biomarkers in the oil samples indicate varying contributions from algal and terrigenous organic matter primarily under oxic or suboxic depositional conditions five source rock facies were identified based on the relative concentrations of n alkanes isoprenoids tricyclic terpanes and steranes the individual facies were also distinguished by the compound specific isotopic composition of the n alkanes source rock depositional environments vary from deep lacustrine shallow lacustrine and lacustrine saline to coal and mixed coal and lacustrine shale deep lacustrine facies predominate in the aman and bengkalis troughs whereas saline and shallow lacustrine facies predominate in the south aman and kiri troughs respectively oils derived from coal and mixed coal and lacustrine shale facies predominate in the northern part of the central sumatra basin in the tanjung medan and north of the balam grabens

plant wax δd values record changing eastern mediterranean atmospheric circulation patterns during the 8 2 kyr b p climatic event abstract throughout the holocene the climate of the mediterranean region has been strongly influenced by variability in the atmospheric circulation of the high and low latitudes a prominent example for such holocene climate perturbations is the 8 2 kyr b p climatic event reorganization of northern hemisphere atmospheric circulation patterns resulted in variations of temperature and precipitation distribution across the mediterranean the effects of changing high and low latitude atmospheric circulation on mediterranean climate in relation to the 8 2 kyr b p climatic event are however not well understood here we present a high resolution record of stable hydrogen isotope composition of plant wax n alkanes dwax across the 8 2 kyr b p climatic event from the tenaghi philippon peat deposit ne greece in order to characterize patterns of precipitation and changes in atmospheric circulation in the eastern mediterranean region our record reveals pronounced changes in dwax that correlate closely with previously published palynological data a long term decline in dwax values characterizes the lower part of the section the 8 2 kyr b p climatic event itself is connected to two distinct positive dwax excursions a minor shift in dwax around 8 2 kyr b p and a major shift in dwax between ca 8 1 and 8 0 kyr b p the upper part of the section shows a progressive trend towards higher dwax values we link shifts in dwax to changes in mediterranean air mass trajectories supplying precipitation to ne greece caused by variations in the relative contributions of northerly derived d depleted moisture and southerly derived d enriched moisture possible control mechanisms for alternating air mass trajectories include changes in the influence of the siberian high and differences in the influence of the african and asian monsoon circulation on anticyclonic conditions in the mediterranean region as well as regional inflow of moist air masses from the aegean sea

sources and molecular composition of cryoconite organic matter from the athabasca glacier canadian rocky mountains cryoconite is a dark coloured dust like material found on the surfaces of glaciers cryoconite has received much interest recently because cryoconite holes which are produced by accelerated ice melt act as habitats for microbes on glacier surfaces to the best of our knowledge cyroconite organic matter com has not yet been chemically characterized at the molecular level in this study organic matter biomarkers and a host of nmr techniques were used to characterize com from the athabasca glacier in the canadian rocky mountains solvent extracts contained large quantities of fatty acids n alkanols n alkanes wax esters and sterols a large contribution of c23 c 25 and c27 relative to c29 and c31 n alkanes suggests that allochthonous com is mainly from lower order plants mosses lichens this is confirmed by the absence of lignin phenols after copper ii oxidation in extracts and nmr analyses of com solution state 1 h nmr reveals prominent signals from microbial components while solid state 13 c cp mas nmr analysis shows an atypically high alkyl o alkyl ratio suggesting that com is significantly different from organic matter found in nearby soils the nmr results suggest that com is dominated by microbially derived compounds which was confirmed by phospholipid fatty acid analysis revealing a significant microbial contribution primarily from bacteria with minor contributions from microeukaryotes both biomarker and nmr data suggest that com supports active microbial communities on the athabasca glacier given that such material is incorporated within the glacier in the accumulation zone or flushed by meltwaters into subglacial environments reworked com may provide nutrient sources for active microbial communities found within and under glaciers

impacts of paleohydrological changes on n alkane biomarker compositions of a holocene peat sequence in the eastern european russian arctic coupled analyses of n alkane biomarkers and plant macrofossils from a peat plateau deposit in the northeast european russian arctic were carried out to assess the effects of past hydrology on the m

the impact of water washing biodegradation and self heating processes on coal waste dumps in the rybnik industrial region poland abstract water washing biodegradation and self heating impacts on coal waste features were investigated on four sample sets fresh coal wastes sampled less than one week after dumping samples from gullies in coal waste dumps self heated material and bierawka river sediment mixed with coal coal waste particles rock eval pyrolysis petrography and gas chromatography mass spectrometry gc ms were applied to assess degree of organic matter alteration it was found that water washing and self heating did not influence the vitrinite reflectance rock eval pyrolysis results better reflected the secondary changes in organic matter namely s 2 toc and hi t max allowed their extent to be defined changes were noted in other geochemical e g n alkane parameters 2 1 increased and n c 23 n c 31 decreased whereas pr ph pr n c 17 and ph n c 18 ratios increased slightly compared to fresh coal waste the hunt diagram allows discrimination between water washed and biodegraded samples from unaltered fresh coal waste similarly changes in distributions of phenols alkyl aromatic hydrocarbons and polycyclic aromatic hydrocarbons pahs reflect degree of water washing self heating strongly affects distributions of some biomarkers such as n alkanes pr and ph whereas pentacyclic triterpane distributions were generally well preserved phenols occur in greatest amount in self heated wastes probably released from heated vitrinite domination of 2 3 ring pah rings indicated the bitumen precipitation zone and well differentiated burnt out wastes recent organic matter input is seen in increased cpi carbon preference index values

lipid biomarker δ13c and plant macrofossil stratigraphy of a scottish montane peat bog over the last two millennia abstract seven horizons of a peat core covering the last 2000 years from moine mhor a blanket bog in the cairngorm mountains scotland have been examined for the carbon number distributions of the long chain hydrocarbon alcohol and acid components using gas chromatography gc and gas chromatography mass spectrometry gc ms compound specific 13 c values for individual n alkanes were obtained using gas chromatography isotope ratio mass spectrometry gc irms the lipid biomarker distributions and the 13 c values have been compared with those of eleven species of living plant dominant at the contemporary surface of the bog the observed lipid stratigraphy shows only partial agreement with that calculated using macrofossil abundance data and the lipid distributions for the living taxa a result which reflects the inherent uncertainties in both the lipid biomarker and the macrofossil approaches to palaeoenvironmental stratigraphy the carbon isotope values for the individual n alkanes of the plants 27 6 to 36 6 and of the peat layers 29 to 31 7 are as expected for the c 3 photosynthetic pathway however the n alkanes from the surface samples were more depleted by 2 in 13 c than those from the rest of the core a negative shift which may in part reflect the shift 1 2 in 13 c estimated for co 2 in a pre industrialised to an industrialised atmosphere

a new perspective on the δ13c signal preserved in speleothems using lc irms analysis of bulk organic matter and compound specific stable isotope analysis abstract the analysis of 13 c in speleothem calcite is established as a palaeoenvironmental proxy but records can often be complex to interpret due to multiple controls on the signal here we present a novel palaeoenvironmental application of non purgeable organic carbon npoc 13 c analysis and compound specific isotope analysis csia to speleothems and compare the resultant signals to a conventional calcite 13 c record by accessing the carbon pool held in molecular organic matter we are able for the first time to produce stable isotope records complementary to the co 2 derived signal from the speleothem calcite and begin to identify separate ecological and climatic controls in this sample from north west scotland the calcite 13 c record and the npoc 13 c both show fluctuations at a period of increasing wetness and change from birch woodland to more open peatland the npoc signal having a strong correlation with biomarkers for vegetation change we interpret an inverse correlation between the npoc and co 2 13 c signals as primarily driven by changes in soil conditions impacting upon microbial activity with decreased activity leading to a reduction in 13 c enrichment of the residual organic matter the npoc fraction and an increase in 13 c in the co 2 pool calcite due to a decrease in respired 12 c this opens the way for the application of parallel analyses to distinguish between soil conditions and vegetation parameters as the primary control on a record and highlights the advantage of combining both inorganic and organic geochemical techniques in the palaeoenvironmental interpretation of stable carbon isotopic records

composition and sources of lipid compounds in speleothem calcite from southwestern oregon and their paleoenvironmental implications we analyzed speleothem calcite from the oregon caves national monument southwestern oregon to determine the preservation distribution concentrations and sources of aliphatic lipid compounds preserved in the calcite maximum speleothem growth rate occurs during interglaciations and minimum during glacial intervals concentrations of the total lipid compounds range from 0 5 to 12 9 g g 1 they increase at times of low speleothem growth rate suggesting dilution whereas the apparent accumulation rate of lipid compounds tends to be highest during times of fastest speleothem growth rate such increased accumulation generally corresponds to times of warm interglacial climate suggesting either a greater source of organic materials during interglacial times and or greater efficiency of compound capture during more rapid calcite growth aliphatic lipid compounds include homologous n alkanoic acids n alkanols and methyl n alkanoates and sterols with concentrations ranging from 0 3 to 7 8 g g 1 0 4 to 1 1 g g 1 0 5 to 9 6 g g 1 and 0 1 to 2 7 g g 1 respectively minor amounts of branched methyl n alkanoates and dimethyl n alkanedioates are also present the high concentrations of methyl n alkanoates are the result of esterification reactions of free fatty acids in alkaline solutions with high ph values associated with the dripping cave waters the distribution patterns and geochemical parameters and indices indicate that the major sources of the aliphatic lipids involved leaching from higher plants and microbial residues derived from the soil zone above the cave system the estimated percentage of microbial inputs ranged from 42 to 90 of the total lipids and also showed an increase in accumulation during warm climates these well preserved lipid compounds in speleothem calcite could be used as biomarkers for paleoenvironmental study

climate induced variations in productivity and planktonic ecosystem structure from the younger dryas to holocene in the cariaco basin venezuela a high resolution molecular organic geochemical study of sediments in the anoxic cariaco basin indicates significant changes in primary productivity and planktonic community structure associated with the transition from the younger dryas to the holocene variations in climate conditions over the past 12 14c kyr have induced large scale changes in upwelling intensity which directly affected levels of primary productivity as reflected in accumulation rates of bulk productivity proxies concentrations and accumulation rates of sterol and alkenone biomarkers have been used to identify how productivity changes affected the structure of the planktonic ecosystem a shift in the dominant primary producer from diatoms younger dryas to coccolithophores holocene is identified if productivity and ecosystem variations like those identified in the tropical upwelling zone of the cariaco basin region occur throughout the tropical oceans they have the potential to affect global climate through perturbations in the biogeochemical cycle of carbon

quantitative assessment of precipitation seasonality and summer surface wetness using ombrotrophic sediments from an arctic norwegian peatland article i nfo article history received 18 april 2008 available online xxxx seasonality of precipitation is an important yet elusive climate parameter in paleoclimatological reconstructions this parameter can be inferred qualitatively from pollen and other paleoecological methods but is difficult to assess quantitatively here we have assessed seasonality of precipitation and summer surface wetness using compound specific hydrogen and carbon isotope ratios of vascular plant leaf waxes and sphagnum biomarkers extracted from the sediments of an ombrotrophic peatland bostad bog nordland norway our reconstructed precipitation seasonality and surface wetness are consistent with regional vegetation reconstructions during the early holocene 11 5 7 5 ka fennoscandia experienced a cool moist climate the middle holocene 7 5 5 5 ka was warm and dry transitioning towards cooler and wetter conditions from the mid holocene to the present changes in seasonality of precipitation during the holocene show significant coherence with changes in sea surface temperature in the norwegian sea with higher sst corresponding to greater percentage of winter precipitation both high sst in the norwegian sea and increased moisture delivery to northern europe during winter are correlated with a strong gradient between the subpolar low and subtropical high over the north atlantic positive north atlantic oscillation

sphagnum δ13c values as indicators of palaeohydrological changes in a peat bog late holocene peat stratigraphy of a canadian boreal peat bog was examined to evaluate the poten tial of sphagnum 13 c values as surface moisture proxy indicators isotopic measurements were compared to tes tate amoebae inferred water table depth reconstructions plant macrofossil assemblages and past decompo sition levels inferred by colorimetric humification ams radiocarbon dates were coupled with 210 pb dates to establish peat chronology although the mechanisms underlying carbon fractionation processes in peatlands are not well understood we demonstrate that sphagnum 13 c values have potential for palaeohydrological recon structions since variations presented by the isotopic values can generally be correlated with the other proxy records especially during drier episodes

peatland evolution and associated environmental changes in central china over the past 40 000 years central china has experienced stronger summer monsoon during warm periods such as marine isotope stages mis 1 and 3 and weaker summer monsoon during cool periods such as mis 2 the evolution history of dajiuhu subalpine peatland in central china can help investigate how the expansion and shrinkage of peatland were associated with monsoonal strength over the last glacial interglacial cycle here we apply bulk organic carbon and molecular biomarkers hopane and n alkane to reconstruct the evolution history for the dajiuhu peatland over the past 40 000 yr the results indicate fluctuations between lacustrine and peat like deposition during mis 3 steady lacustrine deposition during mis 2 and peatland initiation and expansion during mis 1 in the dajiuhu peatland therefore at the glacial interglacial scale warmer summer and cooler winter conditions in interglacial periods are crucial to trigger peat deposition whereas reduced evaporation in glacial period instead of decreased monsoonal driven precipitation would have played a predominant role in the regional effective moisture balance however within the holocene mis 1 monsoonal precipitation changes appear to be the main controller on millennial scale variations of water table level of the dajiuhu peatland

molecular and isotopic stratigraphy in an ombrotrophic mire for paleoclimate reconstruction a 40 cm deep sphagnum dominated peat monolith from bolton fell moss in northern england was systematically investigated by lipid molecular stratigraphy and compound specific 13c and d analysis using gas chromatography gc gc mass spectrometry gc ms gc combustion isotope ratio ms gc c irms and gc thermal conversion irms gc tc irms techniques 210pb dating showed the monolith accumulated during the last ca 220 yr a period encompassing the second part of little ice age while the distributions of lipids including n alkan 1 ols n alkan 2 ones wax esters sterols n alkanoic acids alkandioic acids and hydroxy acids display relatively minor changes with depth the cooler climate event was recorded in the concentrations of n alkanes and organic carbon cpi values of n alkanes and n alkanoic acids and the ratio of 5 n alkylresorcinols sterols superimposed on the fossil fuel effect the relatively cooler climate event was also recorded by 13c values of individual hydrocarbons especially the c23n alkane a major compound in certain sphagnum spp the d values of the c29 and c33n alkanes correlated mainly with plant composition and were relatively insensitive to climatic change in contrast the c23n alkane displayed variation that correlated strongly with recorded temperature for the period represented by the monolith agreeing with previously reported deuterium records in tree ring cellulose spanning the same period in scotland germany and the usa with more negative values occurring during the second part of little ice age these biomarker characteristics including the compound specific 13c and d records provide a new set of proxies of climatic change potentially independent of preserved macrofossils which will be of value in deeper sections of the bog where the documentary records of climate are unavailable and humification is well advanced

postglacial climate change record in biomarker lipid compositions of the hani peat sequence northeastern china abstract the peat sequence at hani in northeastern china accumulated over the past 16 cal kyr in a percolation mire in which rain water and ground water seeped through the peat system the molecular compositions of n alkanes n alkanols and n alkanoic acids extracted from the hani peat sequence reveal different responses to the progressive evolution of climate and changes in the nature of the peat forming vegetation long chain length components that originate from the waxy coatings of subaerial vascular plants dominate the n alkane distributions throughout the hani peat sequence the paleoclimate integrity of these biomarker molecules appears to be well preserved most of the n alkanol distributions are similarly dominated by long chain components that indicate their origins from subaerial plants in contrast n alkanoic acid distributions are dominated by secondary components that record the importance of post depositional microbial activity in this peat sequence which evidently can be extensive in a percolation mire elevated n alkane paq values and c23 c29 ratios which are both molecular proxies for water loving plants record an especially moist local climate in the bolling allerod 14 5 to 12 9 ka younger dryas 12 9 to 11 5 ka and pre boreal 11 5 to 10 5 ka portions of the hani peat sequence depressed paq values and c23 c29 ratios and larger n alkane average chain length values indicate that the holocene climatic optimum 10 5 to 6 ka was a period of warmer climate with lower effective precipitation which contrasts with evidence of wetter climates in most of east asia

n alkane distribution in ombrotrophic peatlands from the northeastern alberta canada and its paleoclimatic implications abstract in this paper the stratigraphic occurrence of n alkanes cn is investigated in three peat cores mildred jph4 and mcmurray from the ombrotrophic peatlands in northeastern alberta canada to determine their origin biomass input and paleoclimatic significance the molecular composition of n alkanes is dominated by the c21 medium to long chain homologues with a strong odd over even predominance a number of n alkane based indices e g predominant n alkane c23 c29 c23 c27 c31 paq acl and cpi show changing conditions in the organic matter om input from sphagnum species or terrestrial vascular plants which increasingly contributed upwards in the peat profiles and through time paq and c23 c27 c31 proxies are similar in the three cores and allow us to infer vegetation variations that coincide with the climate alternations of the medieval warm period mwp little ice age lia and modern recent warming rw the utilization of acl ket and c23 c25 c27 c29 c31 ket proxies performed in comparison with n alkane proxies further support the biomarker based reconstructions of paleoclimate variations over recent centuries this study suggests that n alkane homologues are sensitive to vegetation and climate changes and thus are reliable biomarkers for tracking past shifts in vegetation and climate variations in peat archives

multiple plant wax compounds record differential sources and ecosystem structure in large river catchments abstract the concentrations distributions and stable carbon isotopes 13c of plant waxes carried by fluvial suspended sediments contain valuable information about terrestrial ecosystem characteristics to properly interpret past changes recorded in sedimentary archives it is crucial to understand the sources and variability of exported plant waxes in modern systems on seasonal to inter annual timescales to determine such variability we present concentrations and 13c compositions of three compound classes n alkanes n alcohols n alkanoic acids in a 34 month time series of suspended sediments from the outflow of the congo river we show that exported plant dominated n alkanes c25 c35 represent a mixture of c3 and c4 end members each with distinct molecular distributions as evidenced by an 8 1 0 7 1 standard deviation spread in 13c values across chain lengths and weak correlations between individual homologue concentrations r 0 52 0 94 in contrast plant dominated n alcohols c26 c36 and n alkanoic acids c26 c36 exhibit stronger positive correlations r 0 70 0 99 between homologue concentrations and depleted 13c values individual homologues average 31 3 and 30 8 respectively with lower 13c variability across chain lengths 2 6 0 6 and 2 0 1 1 respectively all individual plant wax lipids show little temporal 13c variability throughout the time series 1 0 9 indicating that their stable carbon isotopes are not a sensitive tracer for temporal changes in plant wax source in the congo basin on seasonal to inter annual timescales carbon normalized concentrations and relative abundances of n alcohols 19 58 of total plant wax lipids and n alkanoic acids 26 76 respond rapidly to seasonal changes in runoff indicating that they are mostly derived from a recently entrained local source in contrast a lack of correlation with discharge and low stable relative abundances 5 16 indicate that n alkanes better represent a catchment integrated signal with minimal response to discharge seasonality comparison to published data on other large watersheds indicates that this phenomenon is not limited to the congo river and that analysis of multiple plant wax lipid classes and chain lengths can be used to better resolve local vs distal ecosystem structure in river catchments

the n alkanol paleoclimate records in two peat deposits a comparative study of the northeastern margin of the tibetan plateau and northeast china a number of studies have revealed that the climate in the eastern margin of the tibetan plateau and northeast china is sensitive to postglacial changes unfortunately the link of the past climate evolution between the two regions is not well understood in this study two cores are analyzed to determine this link directly the high resolution n alkanol distribution patterns from two typical peat sequences covering the past 16 000 cal years in the northeastern margin of the tibetan plateau and northeast china respectively are closely examined by gas chromatograph mass spectrometry analysis in combination with other palaeoclimatic proxies it is proposed that the n alkanol average chain length and c22 c24 c26 c28 ratio could reflect past climate changes in the two peat sequences the n alkanol proxies reveal several climatic intervals in the period from the last deglaciation through the holocene a comparison of n alkanol records between the northeastern margin of the tibetan plateau and northeast china indicates that the start and end of the warm holocene optimum differed at the two locations the spatially asynchronous pattern of climatic change is possibly a result of different responses to change in solar radiation the evolution of the holocene paleoclimate is more consistent with changes in northern hemisphere solar radiation in northeast china than on the tibetan plateau the holocene optimum began and terminated earlier in northeast china than in the northeastern margin of the tibetan plateau thus the two n alkanol proxies provide valuable insights into the regional holocene climate and local environmental conditions

paleoenvironmental implications of molecular and carbon isotopic distributions of n alkanes in the hominoid bearing upper miocene sediments from the zhaotong basin southwestern china abstract it is crucial to understand the relationship between hominoid primates and their living environment located at the southeastern margin of the tibetan plateau the shuitangba stb outcrop from the zhaotong basin is famous for bearing the remains of the youngest known ape fossil in the terminal miocene 6 2 ma in this study the molecular and carbon isotope compositions of n alkanes together with the loss on ignition and the bulk carbon isotope composition of total organic matter were investigated in the stb outcrop to infer the paleoenvironmental conditions in this uppermost miocene sedimentary sequence with the emphasis on the habitat of the stb hominoid in the hominoid bearing peaty clay layer and the surrounding lignite layers the n alkane molecular and carbon isotope compositions support a primary contribution from terrestrial higher plants in contrast n alkanes in the upper shallow lake sediments are derived from multiple origins mainly from aquatic plants and bacteria both carbon preference index cpi and average chain length acl vary closely with the lithology but the cpi record shows the larger amplitude of change than the acl and varies sharply during the lithological boundary it is notable that the changes of the molecular and carbon isotope compositions of long chain n alkanes do not parallel with the abrupt increase of poaceae pollen percentage during the stb hominoid appearing stage such an inconsistency between herb pollen percentage and n alkane ratios may result from the different sources our results clearly support that these organic matter based ratios have the potential to record the paleoenvironmental changes in ancient lacustrine sediments

organic matter biomarker analysis as a potential chemostratigraphic tool for late pleistocene tills from the hudson bay lowlands canada abstract during the last glacial maximum approximately 22 000 years ago the hudson bay lowlands hbl lay at the center of the 3 km thick laurentide ice sheet during the course of the last glacial cycle hbl was crossed by ice from the west the keewatin sector and from the east labrador sector but the relative influence of the outflow centers is debateable because of continuing uncertainty surrounding the age and stratigraphic position of lithologically similar tills in different areas this study examines the use of organic matter om biomarkers to analyze om sources in hbl tills these tills are believed to be of late wisconsin age sachigo severn and an older possibly early wisconsin deposit rocksand till and biomarkers may provide insights into source materials and degree of diagenesis solvent extraction base hydrolysis and cupric oxide oxidation were performed to isolate and quantify free lipids bound lipids and lignin derived phenols respectively lipid biomarker patterns indicate higher sphagnum derived om to the severn and rocksand tills relative to the sachigo till consistent with subglacial reworking and incorporation of peat om within the severn till is dominated by om derived from non woody gymnosperms and non woody angiosperms whereas sachigo and rocksand tills have both woody and non woody gymnosperms and angiosperms derived om furthermore the severn till contained the most suberin derived om while the sachigo till had the least acid to aldehyde ratios of lignin derived phenols suggest that the severn till has undergone less diagenesis in comparison to sachigo and rocksand confirming that it is likely the youngest of the three tills this study highlights that biomarker analysis is an important chemostratigraphic tool that may distinguish till deposits and provides insight into paleovegetation and paleoclimate in the hbl prior to glacial incorporation of om into till this information facilitates paleoenvironmental analyses to be extended into preglacial and interstadial episodes where no stratigraphic record exists

carbon isotopic compositions of prokaryotic lipids as tracers of carbon cycling in diverse settings recent work has highlighted the ubiquity of bacteria and archaea and continues to affirm their significance in diverse biogeochemical processes the 13c values and distributions of diagnostic lipids derived from such microorganisms can provide insights into prokaryotic processes in modern settings and are one of the few means by which past prokaryotic processes in depositional settings can be elucidated here we present a brief review of prokaryotic lipids commonly observed in sediments and the controls on their carbon isotopic compositions we then present two case studies one of mediterranean cold seeps at which anaerobic oxidation of methane occurs and one of a holocene peat deposit in which a variety of aerobic and anaerobic microorganisms govern the degradation of organic matter these two studies illustrate the potential utility of compound specific carbon isotope analyses to deconvolute pathways of carbon flow in microbial communities

biomarkers aromatic hydrocarbons and polar compounds in the neogene lignites and gangue sediments of the konin and turoszow brown coal basins poland abstract this paper presents geochemical characteristics of 35 samples of miocene lignites and gangue sediments clays sampled in the konin and turoszow brown coal basins poland lignites belonged to xylitic detro xylitic detritic and fusitic lithotypes organic geochemistry of them were investigated using such methods as rock eval pyrolysis gas chromatography mass spectrometry of separated aliphatic hydrocarbons compounds of medium polarity and methyl esters of fatty acids flash pyrolysis gc ms was applied for investigation of macromolecular organic matter of the samples reflected light microscopy was used to find maceral composition and huminite reflectance all samples organic matter show immature features well corresponding to its values of huminite reflectance 0 17 0 35 rock eval t max values were exceptionally low in all cases on average 387 c and they show high differentiation according to the lignite lithotypes with lowest values for xylites also other geochemical features of organic matter are lithotype dependant such as n alkanes and fatty acids distributions many biomarkers presence and distribution types and chemical composition of lignite macromolecular fraction it was possible to asses dominating sources of organic matter using relative concentrations of three groups of compounds with diterpene hopane and oleanane molecular structures most of miocene detritic lignites come from monocotyledonic material with some of them containing coniferal detritus like needle leaves xylitic lignites come from podocarpaceae pinaceae cupressaceae and taxodiaceae families what is indicated by diterpenoids and sesquitenoids distribution detro xylitic lignites show intermediate geochemical features between detritic and xylitic lignites

vertical evolution of petrographic and organic geochemical parameters in las duenas mire cantabrian coast north spain abstract las duenas mire has developed on a flat siliceous substrate over the holocene the sedimentary cover has a thickness of around 50 cm and the mire comprises a surface area of 27 ha a core sample obtained using a manual probe was split into sub samples of around 3 4 cm thickness for petrographic and organic geochemical analysis the fen originated by minerogenesis and contains a high concentration of mineral matter throughout its profile which decreases towards the top the present day vegetation is dominated by sphagnum a variety of transparent textinite with intense fluorescence is evidence of the low maturity of the profile which is also confirmed by the presence of low reflecting huminite of the a variety hr 0 15 the fluorescence spectra of sporinite and cutinite are similar and compared with those of transparent textinite they have a lower intensity and are shifted to higher wavelengths the low maturity of the organic matter is also confirmed by the presence of unstable hopane configurations the abundance of hopene and the presence of functionalized hopanoids steroids and other triterpenoids the evolution of the geochemical parameters in the peat profile indicates the presence of more humid conditions in the top 4 cm and at a depth of 11 15 cm these periods are characterized by a high sphagnum higher plant contribution as deduced from the n alkane ratios the low reflectance of huminite at the depth of 11 15 cm could also support less oxidizing condition the sediment at a depth of 22 cm where peaty matter starts to accumulate has been dated as 9603 cal bc whereas the plant fraction at the same depth dates back to a maximum of 200 years sediment reworking derived from radiocarbon dates indicates that this fen is not suitable for palaeoenvironmental studies

terpenoids in surface soils from different ecosystems on the tibetan plateau abstract realizing the potential of terpenoid biomarkers as an unequivocal land ecosystem and floral diversity indicator calls for work to establish a direct link between the terpenoids extracted from the plants and those found in the underlying soils to this end we have characterized the triterpenoid profile of soils and vegetation along two altitudinal transects representing very different ecosystems the first transect comprising 31 sample sites was on the eastern slopes of mt gongga eastern tibetan plateau rising from 1230 m to 4500 m above sea level an area with a temperate monsoonal climate the second transect sampling 29 sites was on the northern slopes of mt west kunlun a region characterized by montane desert meadow and alpine steppe located between 1300 m and 5050 m above sea level the dominant terpenoid biomarkers polycyclic triterpenoids of the taraxerane oleanane friedelane ursane lupane glutinane and lanostane series identified in the soils were found to be consistent with the overlying vegetation however the discovery of some unusual triterpenoids including the pentacyclic triterpene 3 methyl ethers ptmes d a friedo 2 3 secoolean 2 3 dioic acid methyl 3 acetoxylup 20 29 en 28 oate 24 methylenecycloartan 3 one 9 19 cyclolanostan 3 yl 24 methylene acetate 3 methoxy 9 lanosta 7 24 dien 26 23 olide and 3 methoxy 9 lanost 7 en 26 23 olide in the gongga soils does not match the current vegetation and may be indicative of a long vanished forest type vegetation thus soil biomarkers may be a useful tool in the reconstruction of palaeo vegetation

lipid biomarkers in the zoige hongyuan peat deposit indicators of holocene climate changes in west china 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

replicability and variability of the recent macrofossil and proxy climate record from raised bogs field stratigraphy and macrofossil data from bolton fell moss and walton moss cumbria england replication of results is a basic tenet of science but in palaeoecology this is very time consuming and the signal is subject to noise the derivation of proxy climate signals from ombrotrophic peat was carried out originally using samples from open peat faces where the stratigraphic relationships could be easily observed now that such sections are rare and often degraded there is a need to demonstrate that data can be replicated from core profiles ten short cores taken from two adjacent bogs have been analysed for macrofossils and show a coherent series of changes which are also similar to previous profiles from the same sites it is concluded that variation between profiles is slight and less than observations of present vegetation mosaics might suggest recommendations for a standard approach to fieldwork on raised bogs that emphasises the utility of subfossil pool layers are proposed and the need for a secure chronology is stressed 1998 john wiley sons ltd

moisture conditions during the younger dryas and the early holocene in the middle reaches of the yangtze river central china the last glacial interglacial climate transition in east asia was characterized by an intensified monsoon but knowledge about hydrological responses at a regional scale during this transitional period is limited here we provide a novel lipid based paleohydrological record for this period from the dajiuhu peat deposit central china high water levels and persistent wet conditions during the younger dryas 12 5 11 6 ka and the early holocene 10 5 9 9 ka were inferred on the basis of enrichments of sterenes a group of unstable intermediate diagenetic products derived from biogenic sterols that are most likely preserved under a waterlogged peatland surface these two wet intervals were accompanied by temperature decreases indicated by an increase in pollen abundance from cold favoring conifer trees and a decrease in total hardwood tree pollen this cold and wet climate pattern which is different from the concordant cold dry pattern documented in north china was probably caused by the regional influen

characterizing carbon isotopic variability in sphagnum to understand more fully the nature of isotopic fractionation in mosses and to explore the potential of stable isotope analyses of selected peat constituents for palaeoenvironmental research we present results from a study of inter and intra plant 13c variability in sphagnum spp subdivisions of stem pendant and horizontal branch elements of modern sphagnum capillifolium plants revealed consistent and statistically significant differences in their isotopic composition sequential downstem analysis of a further cohort of four modern sphagnum capillifolium plants also reveals evidence of common forcing on the isotopic composition of sequentially formed stem and branch increments this relationship was tested further by analysis of a series of branch and stem samples manually recovered from sphagnum fuscum preserved within a late holocene ad 2003 1970 peat monolith from a european mire the high degree of isotopic coherence observed between plants supports the analysis of sphagnum in palaeoecological

molecular indicators of redox and marine photoautotroph composition in the late middle ordovician of iowa u s a abstract saturated and aromatic hydrocarbons were used to evaluate depositional redox conditions and marine photoautotroph contributions to middle caradocian strata of the central united states ia at the base of the spechts ferry member of the decorah formation 13c enriched aryl isoprenoids derivatives of green sulfur bacteria become abundant indicating the development of photic zone anoxia this is coincident with the disappearance of the organic walled microfossil gloeocapsomorpha prisca and a marked decrease in the relative abundances of cyanobacterial biomarkers the development of dysoxic to anoxic conditions and or associated changes in basin circulation potentially affected the distributions and abundances of these organisms in the overlying guttenberg member g prisca derived organic matter becomes dominant but relative cyanobacteria abundances remain low in addition the percentage total organic carbon is greater than 20 even though selected biomarker ratios pristane phytane ratios greater than 3 and homohopane indices less than 0 5 and the presence of bioturbation indicate that bottom waters were oxygenated it is suggested that deposition of g prisca affected both organic matter preservation and depositional redox conditions observed variations in redox indicators and marine photoautotroph contributions are associated with changes in siliciclastic deposition reported macrofauna turnover and with evidence for oceanic cooling and a change in circulation patterns documented in the eastern united states

bog burst in the eastern netherlands triggered by the 2 8 kyr bp climate event the nature and cause of the so called 2 8 kyr bp event have been a subject of much debate peat sequences have provided much of the evidence for this event but the process link between climate and peatland response is not well understood multiproxy high resolution analysis of a core from bargerveen in the eastern netherlands based on pollen non pollen palynomorphs testate amoebae and geochemistry identified an abrupt shift from relatively dry to extremely wet conditions radiocarbon based wiggle match dating wmd and biostratigraphy based on the pollen record show that this shift in local hydrology occurred around 2800 cal yr bp we interpret an erosional hiatus lasting up to 950 years immediately prior to this as the effect of a bog burst after excessive rainfall this phenomenon was not limited to our sampling location but occurred over a large part of the former bargerveen peat at the hiatus contains microfossils that reflect temporary eutrophication as a consequence of local fires and secondary decomposition because of increased drainage after the erosion event our data show how detailed multiproxy analyses can elucidate the past response of peatlands to changing climate and suggest that the climatic change in northwest europe at this time caused major non linear disruption to these ecosystems

biomarkers in coastal marshlands environmental characteristics of the mazarron basin during the middle pleistocene mis 7 and holocene mis 1 abstract we reconstructed the paleoenvironmental conditions of the mazarron basin during mis 7 and mis 1 based on their alkane and fatty acid contents their mineralogy and the fossil content of an amino acid dated sediment sequence the n alkane and fatty acid indices proved to be excellent paleoenvironmental proxies for studying the paleo hydrogeological and paleoclimatological evolution of this marshland three geochemical units gus were identified from the abundance of the c25 n alkane and the acl tarhc and paq values confirming the importance of phases with terrestrial plant input or aquatic macrophyte predominance these gus were used to define three paleoenvironmental episodes pes during mis 7 in pe7 1 the contribution of algal and aquatic macrophytes predominated in a temporarily flooded saline muddy plain in pe7 2 the major contribution was from aquatic macrophytes flooded marsh although it was marked by episodes of emersion with greater terrestrial contribution at the top of the mis 7 record pe7 3 there was a significant reduction in the water depth with the main input deriving from terrestrial plants in a muddy alluvial plain six pes were established during mis 1 holocene of which three predominately received organic matter derived from aquatic macrophytes while the major contribution in the other three came from terrestrial plants the two sets of pes were linked to episodes of increased and decreased water level respectively this interpretation is consistent with the characteristics of the sediment facies with pe1 1 1 3 and 1 5 corresponding to a marsh with deeper water and a greater input of detrital materials and pe1 2 1 4 and 1 6 to a shallow environment with carbonates and gypsum deposits direct marine influence was limited so the oscillations in the water level in the marsh were likely to be more related to climatic changes drier wetter phases and recent tectonics than to large changes in sea level emersion led to degradation of the organic matter and enrichment in short chain and branched saturated fatty acids

multi proxy study of soil organic matter dynamics in permafrost peat deposits reveal vulnerability to climate change in the european russian arctic soil organic carbon soc in permafrost terrain is vulnerable to climate change perennially frozen peat deposits store large amounts of soc but we know little about its chemical composition and l

evolution of organic matter indicators in response to major environmental changes the case of a formerly cut over peat bog le russey jura mountains france to assess whether the biochemical characteristics of peat can provide clues for past ecosystem changes or not a study was carried out combining elemental analysis micro morphological counts and neutral monosaccharide determination of peat organic matter om and the dominant living plants from a formerly cut over peat bog in the jura mountains peat profiles up to 50 cm depth from two distinctive zones bare peat fra and a regenerating stage frc were compared with the reference profile frd taken from an unexploited area of the bog the results show contrasting om composition along the profiles in the upper sections of the frd and frc profiles high c n ratios and sugar contents in the same range as in the source plants and the large predominance of well preserved plant tissues indicate good preservation of primary biological inputs in contrast in peat from the fra profile and deeper levels of the frc profile lower c n ratios lower amounts of sugars and a predominance of amorphous om and mucilage suggest more extensive om degradation these features delineate a clear threshold between an uppermost new regenerating peat section and an old catotelm peat below nevertheless even in the latter the sugar contents remain relatively high 80 mg g compared with other organic and mineral soils analysis of typical peat forming plants and of bulk peat and fine grained fractions allowed identification of the following source indicators xylose and arabinose for cyperaceae rhamnose galactose and mannose for mosses and ribose and to a lesser extent hemicellulosic glucose possibly for microbial synthesis

biomarkers as paleoclimate proxies in peatlands in coastal high plains in asturias n spain abstract this study represents an attempt to correlate wet and dry episodes as defined by biomarker parameters in peat profiles of asturias north spain the peats developed in a coastal location on high plains at heights ranging between 115 and 256 m above sea level the peat profiles which cover different holocene intervals exhibit growth rates ranging from 0 05 to 0 56 mm yr and so provide records of different resolution biomarkers have revealed the widespread occurrence of nonadecan 2 one k 19 a characteristic of cantabrian peatlands different periods of dominance by higher plants and bacterial triterpenoids and an alternance of humid and dry periods as reflected in the n alkane ratios a change from a more arboreous vegetation before 4000 cal yr bp in the relatively dry warm climate of the middle holocene to a sphagnum herbaceous dominant vegetation typical of cooler wetter conditions is observed the wet episode between 2200 and 3000 cal yr bp has a widespread occurrence in the studied profiles whereas other dry wet episodes are only recorded in some peat deposits and may be associated with local conditions

palaeohydrology fires and vegetation succession in the southern baltic during the last 7500 years reconstructed from a raised bog based on multi proxy data we present the first 7500 yr long multi proxy record from a raised bog located at the southern baltic coast poland testate amoebae plant macrofossils pollen and microscopic charcoal were used to reconstruct environmental changes in pomerania northern poland kaszuby lakeland from a 7 m thick peat archive of st zki bog dated 5500 bc ad 1250 we obtained a record of proxies representing different spatial scales regional vegetation changed simultaneously with local vegetation and testate amoebae showed a pattern of change similar to that of pollen and plant macrofossils on the basis of the combined proxies we distinguished three hydroclimatic stages moist conditions 5500 3450 bc drier conditions with regionally increased fires up to 600 bc and again moist conditions from 600 bc onward during the drier interval a first climatic shift to wetter conditions at 1700 bc is indicated by regional pollen as the replacement of corylus by carpinus and locally by e g the increase of hyalosphenia elegans and mire plants such as sphagnum sec cuspidata furthermore we observed a correlation since 600 bc among the re expansion of carpinus after a sudden decline ca 950 bc increased peat accumulation increase of hyalosphenia species and fewer fires suggesting lower evapotranspiration and a stable high water table in the bog fagus started to expand after ad 810 gradually replacing carpinus which was possibly due to a gradually more oceanic climate though we cannot exclude human impact on the forests peat accumulation determined by radiocarbon dating varied with bog surface wetness the hydroclimatic phases found in st zki peatland are similar to moisture changes recorded in other sites from poland and europe this is the first detailed record of hydroclimatic change during the holocene in the southern baltic region so it forms a reference site for further studies on other southern baltic bogs that are in progress

development and refinement of proxy climate indicators from peats peat especially from acidic mires bogs is a natural archive of past environmental change reconstructions of past climate from bogs commenced in the 19th century through examination of visible peat stratigraphy and later formed the basis for a postglacial climatic scheme widely used in northwest europe nevertheless misconceptions as to how bogs grow led to a 50 year lacuna in peat climate study before the concept of cyclic regeneration in bogs was refuted in recent decades research using proxy climate indicators from bogs has burgeoned a range of proxies for past hydrological change has been developed as well as use of pollen bog oaks and pines and other data to reconstruct past temperatures most of this proxy climate research has been carried out in northern europe but peat based research in parts of asia and north america has increased particularly during the last decade while research has also been conducted in australia new zealand and south america this paper reviews developments in proxy climate reconstructions from peatlands chronicles use of a range of palaeo proxies such as visible peat stratigraphy plant macrofossils peat humification testate amoebae and non pollen palynomorphs and explains the use of wiggle match radiocarbon dating and relationship to climate shifts it details other techniques being used increasingly such as biomarkers stable isotopes inorganic geochemistry and estimation of dust flux and points to new proxies under development although explicit protocols have been developed recently for research on ombrotrophic mires it must be recognised that not all proxies and techniques have universal applicability owing to differences in species assemblages mire formation topographic controls and geochemical characteristics

organic matter in upper albian marine sediments in the high tatric units central western carpathians related to oceanic anoxic event 1d geochemistry microfacies and palynology abstract a multidisciplinary study of upper albian hemipelagic sediments related to the oceanic anoxic event 1d oae1d from the high tatric units central western carpathians polish part of the tatra mountains was undertaken to characterize organic matter om and to investigate its origin microfacies and palynological records combined with mineralogical and geochemical data from these sediments show the occurrence of both marine and land derived om in the limestone and marl successions whose deposition corresponds to the parathalmanninella apenninica zone in the late albian both types of om were strongly degraded under the oxic conditions that prevailed during the entire time of their deposition the sedimentation of marls with low contents of total organic carbon

hydrogen isotopic ratios of plant wax n alkanes in a peat bog deposited in northeast china during the last 16 kyr abstract based on paleoclimatic reconstructions using various proxies the holocene climate optimum 10 5 6 ka has been characterized as a warmer and wetter period in most of east asia the summer monsoons associated with the east asian monsoon evidently intensified and extended further inland from the pacific ocean a source region of moisture a notable exception to this general pattern exists in northeast china where less wet conditions are recorded we determined molecular compositions of individual plant wax hydrocarbons and their hydrogen isotope compositions d values in a radiocarbon dated peat core recovered from the hani marsh in jilin province china and confirmed that the temperature dependent effective precipitation in northeast china decreased during the holocene climate optimum a combination of p aq an indicator of the relative contribution of aquatic to terrestrial plants and the difference in d between low c 23 c 25 and c 27 and high molecular weight c 31 n alkanes in the hani peat bog indicates a dramatic change in vegetation from the deglaciation to the holocene no significant differences were observed between the d values of low and high molecular weight n alkanes with relatively high d values and low p aq during the early holocene indicating that all n alkanes were produced by evapotranspiration sensitive terrestrial plants during that time however lower d values of mid chain n alkanes c 23 c 25 and c 27 relative to the long chain n alkane c 31 together with higher p aq values during the deglaciation 14 11 ka suggest an increase in the contribution of aquatic plants and a higher water level during the period the study demonstrates that northeast china was under a markedly wetter climate condition during the late deglaciation for the 16 kyr record in the hani peat sequence we infer that moisture delivery by the east asian monsoon was relatively invariable in northeast china but increased evaporation during the warmer holocene climate optimum reduced the effective precipitation defined by the balance between precipitation and evaporation

middle to late holocene environmental changes in the depositional system of the tropical brackish bolgoda lake coastal southwest sri lanka abstract the tropical bolgoda lake is one of the largest lagoonal estuaries in sri lanka organic constituents in this lake were investigated using 28 surface sediments three cores from the lake and four short cores from mangrove mud elemental and molecular compositions of sediments and living organic matter om were determined using cns elemental analysis and gas chromatography mass spectrometry respectively chronology of events was determined using accelerated mass spectrometry ams 14 c data for bulk oms woods and mollusk shells the history of bolgoda lake can be divided into two major chrono stratigraphic divisions namely a lower sedimentary succession from ca 7 0 cal ky b p to 2 5 cal ky b p and an upper sedimentary succession from ca 2 5 cal ky b p to the recent according to the sapropelic depositional system concentrations of the mangrove biomarker taraxone increased significantly at ca 7 0 cal ky b p the lower part of the sediment sequence had moderate productivity and was mainly deposited under marine terrestrial influence in oxygen poor anoxic conditions during mid holocene sea level highstands a drastic increase in total organic carbon toc content reaching 29 was found in one of the bolgoda cores this increase occurred because of sea level regression at about 2 5 cal ky b p this change was probably caused by development of a beach rock sandbar and the estuary system changed to a semi closed lake due to the sea level regression as a result aquatic vascular plants predominate in this depositional system after ca 2 5 cal ky b p toc content decreased slightly but relatively high toc contents were maintained in the muddy sediments in moderately sized and shallow 1 2 m tropical estuaries lagoons such as bolgoda lake drastic changes in toc contents may be the most sensitive indicator of sea level variations increase in higher plant om with higher n c 29 n c all and n c 37 n c all alkane ratios also suggest a climatic transition from wetter to somewhat drier after the middle holocene accumulations of pyrogenic polycyclic aromatic hydrocarbons pahs in the modern sediments record anthropogenic activity after european settlement in the 15th century

satellite thermal infrared observations of mt etna after the 17th march 1981 eruption abstract the aim of this study is to estimate the feasibility of monitoring the surface temperature of an active volcano using satellite thermal infrared data for this the data collected by a radiometer on board the noaa polar orbiting satellites over mt etna were processed geometrical and radiometric corrections and merged with a digital terrain model in order to correct for the variations of mean ground temperature and atmospheric absorption with altitude four pictures or scenes subsequent to the eruption of 17th march 1981 have been interpreted and they display two thermal anomalies one near the summit zone and the other on the nnw slope where lava flows took place some elementary models of thermal evolution are proposed

impact of early diagenesis on distributions of sphagnum n alkanes in peatlands of the monsoon region of china abstract sphagnum species are important peat forming plants in wetlands the world over their n alkane distributions are typically characterized by a predominance of mid chain c 23 and c 25 alkanes a property that has been employed in paleoclimatic reconstruction based on peat sequences however knowledge of the fate of sphagnum derived n alkanes during the very early stage of diagenesis remains limited this study compares the n alkane differences between samples of fresh plants and litter collected from four peatlands across the monsoon region of china the results clearly show that the distributions of sphagnum derived n alkanes differ between the plants and the litter with proportional decreases in c 23 and c 25 n alkanes and increases in c 29 and c 31 homologs in the litter other than the influence of species shifts changes in the n alkane distributions between the fresh plants and litter samples may be caused by preferential degradation of mid chain n alkanes c 23 and c 25 relative to their longer chain homologues c 29 and c 31 during the early diagenesis of sphagnum n alkanes this hypothesis is supported by decreases in cpi values and positive excursions of 13 c values of c 23 and c 29 n alkanes from the plant to the litter samples regardless of what the exact mechanisms for the changes may be the p aq ratio should be applied with caution as a paleoclimatic proxy in peat deposits especially those located in warmer climates or deposited during former warmer stages relatively low p aq values may result from elevated microbial degradation of sphagnum alkanes in such conditions and hence fail to record the former plant assemblages accurately

the last forests on antarctica reconstructing flora and temperature from the neogene sirius group transantarctic mountains abstract fossil bearing deposits in the transantarctic mountains antarctica indicate that despite the cold nature of the continent s climate a tundra ecosystem grew during periods of ice sheet retreat in the mid to late neogene 17 2 5 ma 480 km from the south pole to date palaeotemperature reconstruction has been based only on biological ranges thereby calling for a geochemical approach to understanding continental climate and environment there is contradictory evidence in the fossil record as to whether this flora was mixed angiosperm conifer vegetation or whether by this point conifers had disappeared from the continent in order to address these questions we have analysed for the first time in sediments of this age plant and bacterial biomarkers in terrestrial sediments from the transantarctic mountains to reconstruct past temperature and vegetation during a period of east antarctic ice sheet retreat from tetraether lipids mbt cbt palaeothermometer we conclude that the mean continental summer temperature was ca 5 c in agreement with previous reconstructions this was warm enough to have allowed woody vegetation to survive and reproduce even during the austral winter biomarkers from vascular plants indicate a low diversity and spatially variable flora consisting of higher plants moss and algal mats growing in microenvironments in a glacial outwash system abietane type compounds were abundant in some samples indicating that conifers most likely podocarpaceae grew on the antarctic continent well into the neogene this is supported by the palynological record but not the macrofossil record for the continent and has implications for the evolution of vegetation on antarctica

hydrological changes in eastern europe during the last 40 000 yr inferred from biomarkers in black sea sediments the black sea is connected to a large drainage area including the european russian plain part of the alps and southeastern europe to study the hydrological changes in this basin over the last 40 000 years we measured specific terrigenous biomarkers for wetland vegetation in well dated sediments from the northwestern black sea spanning the last glacial period lacustrine phase and the holocene marine phase low abundances of these biomarkers are observed during the north atlantic ice melting and cooling events known as heinrich events 4 to 2 the last glacial maximum and the younger dryas event increased biomarker inputs characterize the mild climate phases known as dansgaard oeschger interstadials the bolling allerod and preboreal warmings indicating increased erosion due to permafrost degradation higher primary productivity and or wetland extension in the drainage basin the final retreat of the fennoscandian ice sheet from the russian plain occurs during the early part of heinrich event 1 and is characterized by increased biomarker concentrations in a typical series of four deglacial clay layers for the last glacial period the correspondence in timing between the biomarker records and the atmospheric ch4 record from ice cores suggests an important ch4 contribution due to boreal permafrost thawing and wetland emission

dating raised bogs new aspects of ams 14c wiggle matching a reservoir effect and climatic change abstract high resolution ams dating of holocene raised bog deposits engbertsdijksvenen the netherlands shows natural 14c variations wiggles which can be matched with the dendrochronological calibration curve comparison of our results with other conventionally dated peat cores and the 14c record shows an unexpected and as yet unreported reservoir effect and a marked and sudden wetting of the bog surfaces coinciding with the advent of a sporer type solar minimum the homeric minimum the potential of ams dating to vastly improve the accuracy of holocene chronologies is demonstrated

a novel framework for quantifying past methane recycling by sphagnum methanotroph symbiosis using carbon and hydrogen isotope ratios of leaf wax biomarkers the concentration of atmospheric methane is strongly linked to variations in earth s climate currently we can directly reconstruct the total atmospheric concentration of methane but not individual terms of the methane cycle northern wetlands dominated by sphagnum are an important contributor of atmospheric methane and we seek to understand the methane cycle in these systems we present a novel method for quantifying the proportion of carbon sphagnum assimilates from its methanotrophic symbionts using stable isotope ratios of leaf wax biomarkers carbon isotope ratios of sphagnum compounds are determined by two competing influences water content and the isotope ratio of source carbon we disentangled these effects using a combined hydrogen and carbon isotope approach we constrained sphagnum water content using the contrast between the hydrogen isotope ratios of sphagnum and vascular plant biomarkers we then used sphagnum water content to calculate the carbon isotope ratio of sphagnum s carbon pool using a mass balance equation we calculated the proportion of recycled methane contributed to the sphagnum carbon pool prm we quantified prm in peat monoliths from three microhabitats in the mer bleue peatland complex modern studies have shown that water table depth and vegetation have strong influences on the peatland methane cycle on instrumental time scales with this new approach 13c of sphagnum compounds are now a useful tool for investigating the relationships among hydrology vegetation and methanotrophy in sphagnum peatlands over the time scales of entire peatland sediment records vital to our understanding of the global carbon cycle through the late glacial and holocene

coal related sources of organic contamination in sediments and water from the bierawka river poland abstract river sediments mixed with coaly material occur all along the length of the bierawka river poland to identify the origin of the coal in the sediment the coaly material was investigated by reflected light microscopy and rock eval pyrolysis and solvent extracts by gas chromatography mass spectrometry gc ms organic compounds dissolved in water were separated by solid phase extraction spe and analyzed by gc ms the results point to a kerogen iii source petrographic analyses confirm abundant coal charred and coked particles in the sediments vitrinite reflectance varied between 0 66 0 80 r r without any large spatial variation the coaly particles have different sources generally the primary origin of coal particles is from coal processing and the dumping the ash with unburned coal particles from a glass factory near the river source later this material was redeposited along the entire river course in addition hard coal processing crushing washing features are visible in larger coal pieces a second source of coaly organic matter is a coal waste dump at szczyglowice where intensive erosion of steep slopes has delivered copious amounts of organic matter into the river the mixing of this organic matter with that from the glass factory is clearly identified on a ternary diagram pah distributions also show differences between sections the coal particle input from the waste dump increased the relative content of naphthalene relative content downstream as in the coal waste 4 5 ring pahs predominate in the sediments the pyrogenic origin of pahs and aromatic compounds such as methylbiphenyls and dibenzofurane in the sediment is indicated by diagnostic pah ratios burned particles were identified petrographically the river water contains only 2 3 ring pahs possibly of industrial origin or leached from coal particles in the river sediments

multimolecular tracers of terrestrial carbon transfer across the pan arctic 14c characteristics of sedimentary carbon components and their environmental controls distinguishing the sources ages and fate of various terrestrial organic carbon oc pools mobilized from heterogeneous arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost through molecular 14c measurements including novel analyses of suberin and or cutin derived diacids das and hydroxy fatty acids fas we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers including plant wax lipids cutin suberin lignin and hydroxy phenols in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial oc pools across the pan arctic terrestrial lipids including suberin derived longer chain das c24 26 28 plant wax fas c24 26 28 and n alkanes c27 29 31 incorporated significant inputs of aged carbon presumably from deeper soil horizons mobilization and translocation of these old terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions by contrast shorter chain c16 18 das and lignin phenols as well as hydroxy phenols in rivers outside eastern eurasian arctic were much more enriched in 14c suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers furthermore the radiocarbon content of terrestrial markers is heavily influenced by specific oc sources and degradation status overall multitracer molecular 14c analysis sheds new light on the mobilization of terrestrial oc from arctic watersheds our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial oc pools in the face of increasing arctic permafrost thaw

contrasting lipid biomarker composition of terrestrial organic matter exported from across the eurasian arctic by the five great russian arctic rivers contrasting lipid biomarker composition of terrestrial organic matter exported from across the eurasian arctic by the five great russian arctic rivers

upper crustal structure of the western colombian basin caribbean sea multichannel seismic reflection profiles show that most of the western colombian basin is underlain by a large oceanic plateau the crust of this plateau has a smooth upper surface an oceanic velocity structure and a thickness at least twice that of typical oceanic crust locally well defined reflections within the plateau crust are related to layered basalt flows and interbedded sediments a mounded reflection pattern within acoustic basement at the crest of the plateau mono rise may represent volcanic knolls smooth surfaced basement of the western colombian basin is probably equivalent to the upper cretaceous basement complex below seismic reflection horizon b in the central venezuelan basin and resembles the basements of some cretaceous oceanic plateaus and aseismic rises in the western pacific an area of apparently typical oceanic crust lies adjacent to the colombian basin plateau and may represent relatively unmodified oceanic crust upon which the plateau was constructed reflections within the flank of the colombian basin plateau appear to overlap this crust indicating that the plateau is younger than the oceanic crust oceanic plateau crust extends to panama and costa rica without apparent structural break and may be continuous with the basement complex of southern central america

organic geochemical evidence of postglacial paleoenvironmental evolution of the comeya peatland asturias n spain abstract comeya peatland is located in picos de europa national park n spain at 851 m above sea level representing the continuous postglacial infill of a hollow growth rate 0 4 mm yr during the last 15 000 cal yr bp three intervals can be distinguished in the profile the bottom one with ash content close to 90 which is previous to the peatland installation in the area and is followed by an interval with oscillating ash content 30 60 probably related to alluvial fan sedimentation the uppermost one corresponds to the peat deposit with ash content generally close to 10 the present day vegetation consists of sphagnum species with herbaceous plants and heathers the study comprises the analysis of some biomarkers with potential as palaeoenvironmental proxies quantified by gas chromatography mass spectrometry supported by bulk 13 c and 15 n isotopic the biomarker assemblage is dominated by the n alkanes and methyl ketones with medium to high molecular weight and odd number of carbons the biomarker ratios indicate an enrichment in sphagnum characteristic compounds at 120 250 cm 3150 6350 cal yr bp reflecting more humid conditions this episode coincides with higher c n atomic ratio higher values of 13 c and lower of 15 n the wetter conditions of this interval are also shown by the depleted d values of the n alkane particularly those related with mosses as n c 23 and n c 25 and the enriched 13 c values of both n alkanes and methyl ketones segregation of 13 c values has been observed for homologues series in comeya peat with medium molecular weight n alkanes typical of mosses living in waterlogged environments being enriched in 13 c values compared with higher molecular weight n alkanes typical of woody and herbaceous plants of drier habitats this study has shown a slight enrichment of 13 c values of methyl ketones compared to n alkanes the differences being not conclusive to support a common or different origin for both compound classes

petrology and organic geochemistry of peat samples from a raised bog in kalimantan borneo abstract two peat cores from the margin and centre of a tropical raised bog from the sebangau river near palangkaraya in kalimantan indonesia were investigated to illustrate the changes during peatification using coal petrographic and organic geochemical techniques these methods included a maceral analysis on polished peat blocks under reflected white and blue light excitation using the brown coal maceral nomenclature soxhlet extraction was carried out and an estimate of the humic composition was undertaken on the residues gc and gc ms analysis of the alkane and aromatic fractions were also made to identify biomarkers present in the peat results of this study show that peats from the margin of the raised bog were more decomposed than peats from the centre tissue content extract yield and alkaline insoluble acid soluble humic acid fraction support these results not only were there differences between the two locations of the peat cores but also differences arose with respect to depth in both cores the basal peats were more decomposed than the peats from the upper layers this was a result of their differing environments of deposition i e the basal peats were deposited under relative mesotrophic conditions and a more seasonal climate whereas the peats from the upper layers were deposited under acidic and oligotrophic conditions the biomarker composition of the alkane fraction included long chain n alkanes from n c 23 to n c 35 with an odd over even predominance and interestingly n alkanes from n c 36 to n c 40 with an even over odd predominance peaking at n c 38 pentacyclic triterpenoids were mainly represented by 17 21 h homohopane and hop 17 21 ene biomarkers in the aromatic fraction included polyaromatic triterpenoids derived from and amyrin

early diagenetic transformation of higher plant triterpenoids in deep sea sediments from baffin bay abstract a sediment sequence of early miocene to holocene from ocean drilling program site 645 in central baffin bay was found to contain abundant triterpenoids of higher plant origin including monodesmethyl derivatives and other oxidative degradation products 24 nor triterpenoids of the oleanene ursene and lupane series were found in the nonaromatic hydrocarbon and alcohol fractions of the sediment extracts other diagenetic transformation products included 24 28 dinor olean 17 ene and 24 nor urs 12 en 1 1 one as well as their tentatively identified des a counterparts the identification of these novel degradation products was confirmed by synthesis of a suite of reference compounds the simple reaction sequence applied to obtain 24 nor urs 12 ene from 3 acetoxyurs 12 en 24 oic acid is likely to happen in a similar manner during early diagenesis of organic matter in nature these results have implications for the understanding of the diagenetic reaction sequence leading to the formation of other demethylated triterpenoids of terrigenous origin e g 24 28 dinor lupanes 28 30 dinor 17 hopane is sometimes the dominant hydrocarbon in the most deeply buried samples its co occurrence with higher plant triterpenoids and the low abundance of other regular hopanoids is not considered an indication however that 28 30 dinor 17 hopane is derived from a higher plant precursor molecule it is suggested that two independent sedimentary processes are responsible for the presence of the two types of demethylated triterpenoids observed in baffin bay sediments

petrological and organic geochemical investigation of recent peats with known environments of deposition abstract a series of recent peat samples from tropical sub tropical and temperate locations were investigated using coal petrographical and organic geochemical techniques maceral and biomarker compositions were examined to see if they correlated or diverged from the known environment of deposition of the peats the proportion of humotelinite was related to the water depth and the frequency of dry periods the ph and trophic level have a modifying influence on the preservation of tissues furthermore the proportions of sclerotinite in the peats seem to reflected the oxygen status in the mire which was also mirrored in the abundance of humic and fulvic acids a facies diagram was calculated for the peat samples to see how maceral indices would fare in interpreting their known environments of deposition the results proved to be generally unsuccessful as the herbaceous and woody peats did not always give the predicted high humodetrinite and humotelinite compositions respectively the aliphatic hydrocarbon fraction from the extracts of the peat samples show that mainly odd numbered n alkanes are present diterpenoids triterpenoids and hopanoids were found in most samples and were mainly unsaturated in nature the relative proportion of hopanoids in pears appears to be related to bacterial activity in acidic environments de a triterpenoids were also detected in the peat stage of diagenesis in an angiosperm dominated peat type mariscus polycyclic aromatic triterpenoids were present in the aromatic fraction of the extract their occurrence and proportion appears to be related to the degree of humification in a taxodium peat mono di and triaromatic diterpenoids were detected the presence of these aromatic biomarkers indicate the rapid formation of these compounds in the peat stage mainly mediated by microbial activity

the diagenetic fate of taraxer 14 ene and oleanene isomers abstract the extractable organic matter in holocene to early miocene deep sea sediments from site 645 odp leg 105 in baffin bay contains almost exclusively biological markers of terrigenous origin pentacyclic triterpenoids of the ursene and amyrin oleanene type often occur as the most abundant compounds in the aliphatic hydrocarbon ketone and alcohol fractions of the sediment extract a specific diagenetic reaction involves the conversion of taraxer 14 ene into olean 12 ene in the upper 700 metres of the sedimentary sequence the taraxerene to oleanene conversion is complete before the onset of isomerisation of diasterenes at c 20 in the sediment as well as in laboratory simulation experiments olean 12 ene further isomerises to olean 13 18 ene and olean 18 ene the latter of which may be the direct precursor of 18 h and 18 h oleanane found in sediments containing more mature organic matter and in crude oils the subsurface interconversion of these triterpenoid skeletons indicate that oleanane does not necessarily start life as an oleanoid

reconstruction of late glacial and holocene climate evolution in southern china from geolipids and pollen in the dingnan peat sequence we have carried out a multi proxy analysis of a radiocarbon dated peat core that records the history of paleoclimate change dating from 18 ka in the dingnan region of southern china fatty acid and hydrocarbon distributions total organic carbon toc concentrations pollen assemblages and sediment lithology reveal a succession of three major paleoclimate intervals plant waxes are the predominant origin of the n alkanoic acid and n alkane compositions of this sedimentary sequence contributions of these geolipid components vary relative to toc and with changes in lithology and help to refine a pollen based reconstruction of local paleoclimate evolution a period of cool and fairly wet climate 15 630 10 450 cal abp follows accumulation of coarse fluvial sediments under relatively dry deglacial conditions the second period 10 450 6040 cal abp experienced the warmest climate and the highest precipitation indicated by a minimum c18 1 c18 0 ratio together with the low cpi values of n alkanes and high acl values the third time interval 6040 3800 cal abp was a moderately dry and cool period the climate record of the most recent period 3800 cal abp is obscured by agricultural disturbance the younger dryas 12 900 11 600 cal abp appears in this record as a period of variable and very wet climate during the interval 10 450 6040 cal abp both temperature and the precipitation evaporation ratio maximized therefore we consider this period to represent the holocene optimum which coincides with that of the northern hemisphere moreover our results do not fit the spatially asynchronous pattern of the east asian monsoon holocene optimum in china suggested by previous studies they instead parallel the pattern of global paleoclimate change and consequently show that the evolution of holocene paleoclimate in southern china is consistent with changes in northern hemisphere solar radiation

effect of climate change on delivery and degradation of lipid biomarkers in a holocene peat sequence in the eastern european russian arctic 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

a 220 ka palaeoenvironmental reconstruction of the fuentillejo maar lake record central spain using biomarker analysis abstract the sedimentary record of the volcanic lake known as the fuentillejo maar central spain offers the opportunity to determine the palaeoenvironmental evolution of the central southern part of the iberian peninsula during the middle and upper pleistocene a total of 439 samples from the upper 88 m of a ca 142 m long core spanning the last ca 355 ka were examined the interval corresponds to the last 220 ka of the record high n alkane cpi values and the presence of sulfur revealed that little diagenetic signal attenuation or modification had occurred a number of n alkane based indices e g predominant n alkane acl paq and tar hc ratios and the proportion of c 27 c 29 and c 31 n alkanes with respect to the summed c 27 c 29 c 31 alkanes showed changing conditions in the organic matter input to the maar lake over time with episodes involving a major input of terrestrial vegetation alternating with others in which algae or a mixed input of terrestrial plants aquatic macrophytes and algae occurred the proportions of c 27 c 29 and c 31 were useful for reconstructing the palaeoenvironmental evolution of the basin as they allowed assignment of several dry intervals during which grasses developed while during humid phases trees expanded at the expense of grasses in general we found good correspondence between these episodes and the climatic cycles observed in 18 o records from ices cores in greenland and antarctica as well as from marine cores thus we conclude that global palaeoclimatological changes were recorded in the maar record likewise heinrich events appeared to be reflected in the n alkane indices this was confirmed by single spectral analysis and cross spectral analysis with the insolation curve on 21 july at a latitude of 65 n the approach revealed that the cycles interpreted in the fuentillejo record 103 41 23 and 19 ka showed evidence of orbital influence related to the astronomical cycles of the eccentricity variation in the earth s orbit the earth s obliquity oscillation and the precession variation milankovitch theory

evidence from northwest european bogs shows little ice age climatic changes driven by variations in solar activity fluctuations in holocene atmospheric radiocarbon concentrations have been shown to be due to variations in solar activity analyses of both 10 be and 14 c nuclides cone rm that production ratechanges during

postglacial floral and climate changes in southeastern china recorded by distributions of n alkan 2 ones in the dahu sediment peat sequence abstract long chain n alkane 2 ones occur widely in lacustrine and peat depositional settings however their paleobotanical and paleoclimate implications are less understood compared with their n alkyl counterparts n alkanes n fatty acids in this study we have performed a molecular stratigraphic investigation of changes in the plant contributions and depositional conditions using n alkan 2 ones in the dahu lacustrine peat sequence spanning the last 17 kyr a series of n alkan 2 ones ranging from c23 to c33 with a maximum at c29 appears to be contributed by microbial oxidation of both n alkanes and n alkanoic acids the values of the average chain length acl and the ratios of mid to long chained n alkan 2 ones display a trend comparable with the abundance of trees relative to herbs and ferns in addition the carbon predominance index cpi of n alkan 2 ones varied in pace with lithology paleoenvironment with higher values seen in peat deposits the alternating layers represent a succession of shallow lakes and peatlands that filled the depositional basin in response to paleoclimate changes between wetter and less wet conditions the succession of paleohydrologic conditions is responsible for the variation of ketone cpi values in this peat sediment sequence

mid holocene climate change and landscape formation in ireland evidence from a geochemical investigation of a coastal peat bog following a period of unusually strong winds and high seas in the spring of 2014 a blanket peat bog formerly covered by a beach comprised of fine sand and large rocks was uncovered at a coastal site in spiddal co galway ireland the surface of the bog was littered with standing tree stumps the remnants of a holocene forest that had succumbed to a relatively sudden drowning a combination of inorganic and organic geochemical techniques was applied to determine the cause of this rapid submersion and to glean palaeoclimatic information from the preserved record within the peat the study represents the first use of a multiproxy lipid biomarker approach to investigate palaeoclimate conditions from a peat bog in ireland the results provide evidence of climatic variation throughout a ca 3400 yr timeframe during the mid holocene biomarker proxies displaying the relative contribution of sphagnum spp vs higher plants were used to show changes in precipitation and temperature during peat formation the data correlate with described events including the 4 2 ka event and the subboreal subatlantic transition and show the benefit of a lipid biomarker method for investigating ireland s peatland resources in particular the indication of colder wetter conditions coinciding with the 4 2 ka event implies the possibility that its effects were felt in ireland contrary to some reports the results suggest that a combination of warm and dry conditions followed by a rapid rise in sea level led to the growth and subsequent drowning of the ancient forest landscape

improved reconstruction of palaeo environments through unravelling of preserved vegetation biomarker patterns montane forest composition and specifically the position of the upper forest line ufl is very sensitive to climate change and human interference as a consequence reconstructions of past altitudinal ufl dynamics and forest species composition are crucial instruments to infer past climate change and assess the impact of pre historic human settlement one of the most detailed methods available to date to reconstruct past vegetation dynamics is the analysis of fossil pollen unfortunately fossil pollen analysis does not distinguish beyond family or generic level in most cases while its spatial resolution is limited amongst others by wind blown dispersal of pollen affecting the accuracy of pollen based reconstructions of ufl positions to overcome these limitations we developed a new method based on the analysis of plant specific groups of biomarkers preserved in suitable archives such as peat deposits that are unravelled into the plant species of origin by the newly developed verhib model here we present this new method of biomarker analysis and describe its first application in a peat sequence from a biodiversity hotspot of montane rainforest in the ecuadorian andes we show how a combination of the new biomarker application with conventional pollen analysis from the same peat sequence yields a reconstruction of past forest compositions including ufl dynamics with previously unattainable detail

a sensitive high resolution record of late holocene climatic change from a raised bog in northern england proxy climatic data in the form of plant macrofossils have been analysed from a 5 m core from bolton fell moss cumbria uk detailed analysis of peat from the upper 50 cm of this core is used to demonstrate a strong correlation between changes in the relative proportion of taxa and known climatic changes over the last 1000 years the record of changes in bog vegetation contained within the peat profile is used to reconstruct changes in bog surface wetness for the latter half of the holocene as bog surface wetness is directly controlled by the prevailing climatic conditions this reconstruction can be viewed as a proxy climate record twelve radiocarbon age estimates on the 5m core suggest that between 50 and 500 cm peat accumulated at a relatively constant rate of 12 4 yr cm 1 the regular sampling intervals thus provide a time series of past bog surface wetness spectral analyses of this series indicates that wetness changes are cyclic with a ca 800 year periodicity

organic proxies in speleothems new developments advantages and limitations abstract research into organic matter in speleothems has progressed recently to encompass new analytical approaches and applications which offer increased potential in areas such as palaeo temperature reconstruction and high resolution palaeo environmental records from the quaternary here we review three major areas of relevance for future work in the field the origin transport and transformation of the organic matter which is ultimately preserved in speleothems the types of proxies currently available for use or in development and their advantages and issues and the recently developed prospect of high resolution organic matter records derived from the analysis of organic trace elements complexes the continuing extension of work in these research areas offers excellent potential for organic speleothem proxies to grow as a valuable tool in palaeoenvironmental research

sequential fatty acid analysis of a peat core covering the last two millennia tritrivakely lake madagascar diagenesis appraisal and consequences for palaeoenvironmental reconstruction seven samples from a 1 m long peat core taken from the centre of the tritrivakely maar lake madagascar and covering the last 2300 yr were analysed for their fatty acid fa content solvent extraction followed by acid hydrolysis and saponification allowed successive release of free h labile and oh labile bound fas downcore variations in the concentration of individual compounds released by the different treatments allowed distinction between the following three major types of input i primary production ii secondary production that most certainly forms as a result of microbial degradation of primary products immediately underlying the sub surface iii a notable bacterial stock that appears later and slowly at depth the latter input is revealed by the regularly increasing concentration of several h labile compounds with depth sedimentary horizons that were sites for good preservation conditions are indicated by high relative amounts of nearly all the compounds especially those inherited from the primary as well as from the secondary producers including the primary consumers in contrast depth intervals that have been the site for intensive diagenetic alteration contain few compounds including those inherited from late consumers

molecular stratigraphy a new tool for climatic assessment variations in sea surface temperatures over the past 500 000 years are inferred from the relative abundance behaviour of two organic compounds c37 alkenones over the upper 8 metres of a sediment core from the eastern equatorial atlantic this molecular record ascribed to contributions from prymnesiophyte algae correlates well with the variations in the 18 signal for the calcareous skeletons of certain planktonic foraminifera thus providing the first demonstration of a new stratigraphical technique which may be especially valuable where methods based on carbonate 18 fail

lipid stratigraphy of a flandrian peat bed northumberland uk comparison with the pollen record a flandrian peat bed near low hauxley northumberland uk was studied both optically and geochemically to compare the pollen and lipid records of changing plant input during its accumulation a pr

reconstructing human landscape interactions in the ancient mediterranean harbour of cartagena spain here we sought to reconstruct the pleistocene and holocene evolution of cartagena bay therefore 16 borehole cores were analysed with the following aims 1 to define a chronological framework 2 to obtain data on the palaeoenvironment and 3 to establish the relationship with human activities especially focused on the reconstruction of the carthago nova also known as qart hadasht conquest a total of 147 samples were recovered for amino acid racemisation aar dating 32 for radiocarbon dating 14c and 159 for sedimentological palaeontological and biomarker determination these approaches allowed us to elucidate the evolutionary phases of the palaeolandscape in cartagena the simultaneous use of aar and 14c dating allowed the discrimination of spurious ages and the establishment of a chronological scale during the marine isotope stages mis 7 and 5 the sea level sl in cartagena bay was almost the same as today an alluvial plain developed in the northern area and a delta was formed by

differential hydrogen isotopic ratios of sphagnum and vascular plant biomarkers in ombrotrophic peatlands as a quantitative proxy for precipitation evaporation balance abstract we have developed a new approach to quantitatively reconstruct past changes in evaporation based on compound specific hydrogen isotope ratios of vascular plant and sphagnum biomarkers in ombrotrophic peatland sediments we show that the contrast in h isotopic ratios of water available to living sphagnum top 20 cm and in the rooting zone of peatland vascular plants can be used to estimate the fraction of water remaining after evaporation vascular plant leaf waxes record h isotopic ratios of acrotelm water which carries the d h ratio signature of precipitation and is little affected by evaporation whereas the sphagnum biomarker c 23 n alkane records h isotopic ratios of the water inside its cells and between its leaves which is strongly affected by evaporation at the bog surface evaporation changes can then be deduced by comparing h isotopic ratios of the two types of biomarkers we calibrated d h ratios of c 23 n alkane to source water with lab grown sphagnum we also tested our isotopic model using modern surface samples from 18 ombrotrophic peatlands in the midwestern united states finally we generated a 3000 year downcore reconstruction from minden bog michigan usa our new record is consistent with records of other parameters from the same peatland derived from different proxies and allows us to differentiate precipitation supply and evaporative loss

maceral composition and molecular markers of two condensed middle holocene peat profiles in n spain abstract this study deals with the palaeohydrological information obtained from lipids composition and vegetal tissue preservation of two peat cores from asturias north spain the two profiles differ in the type of peatland raised bog in la borbolla and blanket bog in buelna and the type of organic matter being more bryophytic in the raised bog and more herbaceous in the blanket bog the peatlands are located close to the coast on impermeable old flat erosion surfaces which favoured peat accumulation within a distance of 3 5 km from each other the accumulation rate varied between 0 05 and 0 07 mm yr and the records extend from around 9000 to 2500 cal yr bp the main differences between the two peat sites can be summarized as follows the raised bog has lower mineral matter content and h c atomic ratio and higher c n ratio and extraction yields compared to the blanket bog it has also a higher tissue preservation index for huminite macerals and increasing inertodetrinite index with depth regarding biomarkers the raised bog has a relatively higher concentration of n alkane 2 ones compared to the corresponding n alkane of similar carbon number higher concentration of medium vs high molecular weight methyl ketones and higher triterpenoids steroids ratio than the blanket bog alternating humid dry periods have been recorded in both profiles based on lipid concentrations indicating that the sphagnum rich intervals in the raised bog are more sensitive than the herbaceous blanket peat record to climatic variations the main humid intervals identified are dated as 5000 7500 cal yr bp in the blanket bog and as 6000 3500 cal yr bp and last 2500 cal yr bp in the raised bog and correlate with the humid periods traced in other peatlands locations in this region the transition middle to late holocene is characterized by humid conditions in the region which favoured the sphagnum growth in the peats the reflectance of huminite in these records appears to be more related with differences in the oxidative conditions than with variation of peat maturity it is higher in the layers with high mineral matter content at the beginning of organic matter accumulation and also in the upper part of the profile subjected to seasonal desiccation a more intense biochemical gelification coincides with higher concentration of hopanoids derived from bacteria in the upper part of the profile acrotelm high amount of nonadecan 2 one k 19 and high concentrations of triterpenyl acetates which are also determined in other peat profiles from northern spain are also detected in these profiles this indicates that the specific conditions required for the formation of these compounds probably associated to wet temperate climate dominated throughout the region

paleoenvironmental significance of compound specific δ13c variations in n alkanes in the hongyuan peat sequence from southwest china over the last 13 ka abstract compound specific 13c 12c ratios of the c23 c25 c27 c29 and c31 n alkanes in the hongyuan peat sequence from southwest china were measured to decipher paleoenvironmental information recorded in the 13c variations over the last 13 ka the 13c values of the n alkanes range between 35 4 and 30 5 falling within the range of those from modern c3 peat forming vegetation however the vertical trends do not match with those of the 13c value for the c3 peat forming plant cellulose such a discrepancy between the 13c profiles implies that the n alkane 13c values are unlikely to reflect signals from emerged aquatic plants in the bog because submerged floating aquatic plants are major contributors of mid chain c23 and c25 n alkanes in the sequence the decoupling between the c23 and c25 n alkanes and the peat cellulose likely reflects the situation that these mid chain homologues primarily record the isotopic signals of submerged floating aquatic plants the stratigraphic profile of 13c values of submerged floating aquatic plant n alkanes c23 and c25 reveals two prominent positive excursions 0 8 2 4 during the early to middle holocene the excursions coincide with peat accumulation maxima and stronger indian monsoon activity in southwest china indicating that the 13c variations in submerged floating aquatic plants are closely related to changes in bog primary productivity controlled by the asian monsoon activity

proxy records of climate change in the uk over the last two millennia documented change and sedimentary records from lakes and bogs this project of collaborative research project ha of the nerc tigger programme terrestrial initiative in global geological environmental research into the climatic history of the late holocene used a variety of techniques both tested and experimental on carefully chosen sites in lowland and upland environments to derive high quality proxy records of climatic change over the last 2000 years the methodology involved the use of high resolution analyses diatoms cladocera chironomids ostracods magnetics pollen macrofossils humification lipid biomarkers and stable isotopes of the stratigraphy of well dated ams and conventional 14 c 210 pb pollen tephra scp spheroidal carbonaceous particles cores from a remote montane lake and lowland lakes and from a montane blanket and a lowland raised bog linked to historical records of climate change this paper reviews some of the major results obtained both in the magnitude synchroneity and periodicity of change especially during the little ice age and in the evaluation of the various techniques used the fact that such techniques can be validated and calibrated against a known climatic signal in the recent past allows for better interpretation of changes in the more distant past