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

an effect of dissolved nutrient concentrations on alkenone based temperature estimates the ratio of 37 carbon diunsaturated to diunsaturated and triunsaturated alkenones uk 37 produced by some haptophytes is widely used as a proxy for past sea surface temperatures however our isothermal culturing experiments with emiliania huxleyi clone ccmp372 show uk 37 values to also vary with nutrient availability and cell division rate these results provide a reasonable explanation for large isothermal variation in uk 37 values of single coccolithophorid strains grown in culture they also suggest that alkenone based estimates of past sea surface temperatures may have been influenced by dissolved nutrient concentrations as well as by temperature

statistics of geomagnetic storms and ionospheric storms at low and mid latitudes in two solar cycles 1 the statistics of occurrence of the geomagnetic storms and ionospheric storms at kokubunji 35 7 n 139 5 e 26 8 n magnetic latitude in japan and boulder 40 0 n 254 7 e 47 4 n in america are presented using the dst and peak electron density nmax data in 1985 2005 covering two solar cycles 22 23 when 584 geomagnetic storms dst 50 nt occurred in addition to the known solar cycle and seasonal dependence of the storms the statistics reveal some new aspects 1 the geomagnetic storms show a preference for main phase mp onset at around ut midnight especially for major storms dst 100 nt over 100 excess mp onsets at ut midnight compared to a uniform distribution 2 the number of positive ionospheric storms at kokubunji about 250 is more than double that at boulder and 3 the occurrence of the positive storms at both stations shows a preference for the morning noon onset of the geomagnetic storms as expected from a physical mechanism of the positive storms 4 the occurrence of negative ionospheric storms at both stations follows the solar cycle phases most frequent at solar maximum better than the occurrence of positive storms which agrees with the mechanism of the negative storms

seasonal variability of the long chain alkenone flux and the effect on the u37k index in the norwegian sea a seasonally varying sedimentation pattern was observed for the alkenone flux measured with sediment traps in the northern north atlantic in the norwegian sea traps were set at 500 1000 and 3000 m the alkenone flux varied between 0 1 and 7 1 g m 2 d 1 and followed the seasonal pattern of the bulk parameters maximum fluxes occurred from mid october until mid november and were also high in may a surprising result was that considerably higher particle fluxes were observed at 3000 m for the alkenone flux the highest additional input of 250 was observed during the period when sediment resuspension was greatest in summer at the barents sea continental margin traps at 1840 and 1950 m the alkenone fluxes follow the sedimentation pattern of the bulk parameters with a less visible signal of distinct seasonality observed in the 1950 m trap the sedimentation of total alkenones varied between 0 8 and 144 g m 2 d 1 at 1840 m and between 0 5 and 31 0 g m 2 d 1 at 1950 m resuspension and lateral advection contributed significantly to measured fluxes in the two near bottom traps alkenone concentrations were determined in faecal pellets of appendicularia ostracods and euphausids from selected samples at the barents sea site the alkenone flux in pellets 4 to 24 of total was 5 to 6 times higher at 1950 m depth than at 1840 m and the major part 77 78 of the total flux of c37 3 reaching the near bottom trap at 1950 m was associated with faecal pellets of the meso zooplankton spatial and temporal variations of the u37k signals were observed indicating that the imprint in the alkenone signal depends on the origin and transport pathway of the organic material strong deviations occur in areas where nepheloid layers contribute particles of long residence times to the primary flux

diploptene in antarctic sediments abstract the presence of diploptene 17 h 21 h hop 22 29 ene in sediment cores from bransfield strait and mcmurdo sound antarctica is reported the organic geochemical data for these sediments provide evidence for the authigenic marine origin of this hopene

well preserved palaeogene and cretaceous biomarkers from the kilwa area tanzania we have investigated the biomarker composition of sediments ranging in age from 30 to 70 ma from the kilwa area of tanzania they are dominated by material of terrestrial n alkanols n alkanoic acids n alkanes and triterpenoids and bacterial hopanoids and a dipentadecyl glycerol diether dgd origin with only a minor contribution of marine origin crenarchaeol and some algal steroids this indicates a marine setting dominated by higher plant input which most likely stimulated sedimentary microbial activity including sulfate reduction the lipid composition specifically the presence of bacteriohopanepolyols bhps and the stereochemistry of hopanoids suggests a low degree of thermal maturity many biomarkers have still retained functionality even after 30 70 million years this is in good agreement with the exceptional preservation of foraminifera and nannofossils and can probably be attributed to the very low sediment permeability and burial depth there is a clear distinction in the biomarker distributions between the oligocene age sediments collected at the end of the peninsula near kilwa masoko and the older sediments collected from elsewhere indicating differences in depositional environment sediments from the end of the peninsula have higher branched and isoprenoid tetraether index values indicating a relatively higher terrestrial input they also contain two tentatively assigned c28 hopenes 28 30 dinorneohop 13 18 ene and 28 30 dinorhop 17 21 ene aromatic des a triterpenes des e hopenes aromatic pentacyclic triterpenoids c33 dgd archaeol and bhps which are absent from or only present in small amounts in the other sediments these differences likely reflect an evolution of the depositional area from a relative open shelf environment with substantial water depth to a shallower setting during the early oligocene

depth ranges of alkenone production in the central pacific ocean we report analytical results of long chain c 37 c 39 alkenones in the surface sediments taken along a latitudinal transect at 175 e from 48 n to 15 s unsaturation degree of c 37 alkenones u k 37 indicated that alkenone temperature is the highest about 28 3 c in the tropical pacific and decreases toward 48 n about 10 1 c although the latitudinal trend of the alkenone temperature is generally similar to that of the observed sea surface temperature of the surface mixed layer the former exhibits markedly lower values than the latter does in the midlatitude 35 19 n on the basis of the comparisons between water column temperatures and alkenone temperatures in the surface sediments we estimated that in the midlatitudes alkenones are produced in the thermocline waters whereas in the high 48 40 n and low 10 n 2 s latitudes they are produced in the surface mixed layer this result is supported by the depth distribution of emiliania huxleyi and gephyrocapsa oceanica along a 155 w transect in the central pacific the latitudinal distribution of the alkenone production layers estimated from u k 37 is found to be consistent with that of the nitrate suggesting that the depth of alkenone production is mainly controlled by the nutrient supply from deeper waters alkenones in the sediments exhibited relatively large abundances in 43 27 n with a maximum at 30 n which may be explained by high productivity of haptophyte algae in kuroshio extension

long chain alkenones and alkyl alkenoates as palaeotemperature indicators their production flux and early sedimentary diagenesis in the eastern north atlantic the production and fate of long chain alkenones and alkenoates was examined with regard to their use as palaeotemperature indicators alkenoate abundances were higher than previously reported for other regions and more strongly correlated with temperature than was alkenone unsaturation u37k suggesting biogeographical variability in alkenone and alkenoate production in surface waters we define the aa36 ratio to parameterize alkenoate abundance and present an empirical temperature calibration derived from our euphotic zone samples for use in the north atlantic t 17 35 25 12 u37k 26 73 aa36 93 90 u37k aa36 significant diagenetic losses of alkenones and alkenoates were found within the water column and near surface sediments in spite of diagenetic losses the temperature signal recorded by these compounds in the sediments remains largely unaltered and corresponds to the euphotic zone water temperature during the springtime period of maximum coccolithophorid production and flux rather than the average annual sea surface temperature

recent sedimentary hopanoids in the northwestern pacific alongside the japanese islands their concentrations and carbon isotopic compositions two hopanoids 17b h 21b h hop 22 29 ene diploptene and 17b h 21b h bishomohopanoic acid bbc32ha are the most abundant among the pentacyclic triterpenoids found in recent sediments of the pacific ocean alongside the japanese islands the concentration of diploptene normalized to organic carbon content is higher in sediments where c37 polyunsaturated alkene a biomarker of haptophytes is in high concentration suggesting that the diploptene may be associated with the accumulation of marine organic matter in open marine settings d 13 c values of bbc32 ha range from 23 8 to 19 4 relative to pdb being enriched in 13 c relative to diploptene 31 6 to 26 3 by 5 9 the isotopic diaerence indicates the presence of at least partially diaerent sources for the two hopanoids while diploptene is derived from cyanobacteria and chemotrophic bacteria in the water column or sediment bishomohopanoic acid may be produced mainly by heterotrophs in the sediment using marine organic matter in contrast the d 13 c values of the two hopanoids from river and bay sediments are similar 31 to 29 indicating a common source derived from soil components terrestrial plants or bacteria in soils 2000 elsevier science ltd all rights reserved

equatorial and low latitude ionosphere thermosphere system response to the space weather event of august 2005 1 the response of the equatorial and low latitude ionosphere thermosphere system to the geomagnetic storm during 23 26 august 2005 is investigated the study is carried out using the vertical total electron content vtec measured by gps receivers along the 77 78 e longitude and the o n2 ratio obtained from the global ultraviolet imager instrument on board the timed satellite the equatorial ionization anomaly eia shows a poleward latitudinal expansion on 24 august probably associated with an eastward prompt penetration electric field the equatorial and low latitudes show an increase in vtec during the main phase of the storm on 24 august the prompt penetration eastward electric field along with an increase in the o n2 ratio could be responsible for this observed positive phase the vtec variations on 24 august also reveal the signature of a large scale acoustic gravity wave traveling atmospheric disturbance propagating with a horizontal velocity of 750 m s suppression of the eia is observed during the storm recovery phase on 25 august which probably is associated with the westward disturbance dynamo electric field and the equatorward expansion of the neutral composition changes o n2 depletion

carbon isotope signatures of bacterial 28 norhopanoic acids in miocene pliocene diatomaceous and phosphatic sediments abstract a series of c 29 c 31 28 norhopanoic acids occur in neogene marine sediments of the onnagawa funakawa and tentokuji formations northeastern japan and in the monterey formation of california usa the 28 norhopanoic acids exist mainly as free acids but are partly bound to kerogen and the polar fraction of the solvent extract via an ester bond the 13 c depletions of c 29 and c 31 28 norhopanoic acids compared with those of c 30 and c 32 regular hopanoic acids indicate that these 28 demethylated and regular hopanoic acids are derived from different precursor organisms the upper onnagawa formation contains abundant 28 norhopanoic acids and is characterized by the occurrence of calyptogena sp bivalvia which lives in a specific chemoautrophic ecosystem that utilizes chemical substrates from hydrothermal vents or cold seeps the depletion of 28 norhopanoic acids in 13 c compared with kerogen suggests that the 28 norhopanoic acids have been derived from bacteria that utilized 13 c depleted co 2 as their carbon source

biogeochemical assessment of sources of organic matter and paleoproductivity during the early aptian oceanic anoxic event at shatsky rise odp leg 198 this study investigates organic rich sedimentary sequences deposited during the early aptian oceanic anoxic event oae1a at sites 1207 and 1213 on shatsky rise odp leg 198 in the west central pacific biomarker analyses provide evidence of the algal and bacterial origin of organic matter om in these sediments where the abundance of steroidal components particularly sterenes and sterones suggests that the om includes major contributions from eukaryotic sources in an environment characterized by high phytoplankton productivity the presence of alkenones at site 1213b is diagnostic of om derived from representatives of haptophyte algae among the calcareous nannoplankton and their 13c values average 31 6 are consistent with those expected during elevated pco2 the occurrence and prominence of 2 methylhopanes and 2 methylhopanones indicates significant contributions to the om from cyanobacteria which are also likely contributors of hopanoids based on their 13c compositions these biomarker data suggest that oceanic conditions perhaps nitrate or iron limited were conducive to cyanobacteria production during oae1a which appears to distinguish this event from other cretaceous oae

aliphatic hydrocarbons and triterpenes of the congo deep sea fan abstract hydrocarbons were analyzed in sediments from the congo river deep sea fan from the congo river and in sinking particles collected by sediment traps 40 m above the sediment studied sites encompassed three lobes of decreasing age of formation along the canyon sites a f and c and a another lobe system disconnected from the active channel since 4 ka site e terrestrial long chain odd n alkanes were dominant in all sediments of the lobe system unsaturated terpenoids sourced by higher plants such as gammacerene lupene ursene and oleanene were also detected at site c characterized by high accumulation rates 10 20 cm yr 1 the organic matter spends less time in the oxic layer than at other sites and high phytadiene concentrations 10 17 g g oc 1 evidenced recent terrestrial and phytoplanktonic remains reworked in anaerobic conditions in these sediments organic carbon normalized concentrations of terrestrial alkanes and terpenoids were several fold higher than in the lobe sediments with lower accumulation rates sites a and f arguing for a more rapid degradation of terrestrial hydrocarbons than bulk organic carbon in the first steps of pre diagenesis ample variations in the contributions of biomarkers from higher plants ferns bacteria and angiosperms indicate an heterogeneous contribution of the soil and vegetation detritus delivered to the congo lobe sediments lower concentrations in terrestrial hydrocarbons at site e 45 km away from the active canyon indicated that river particles are still admixed to the dominant marine organic matter diploptene and hop 7 21 ene have a dual origin from terrestrial and marine microorganisms scatter in their relationship to gammacerene argues for a contribution of marine microorganisms in addition to soils sourced microorganisms the close distribution patterns of diploptene hop 21 ene hop 7 21 ene and neohop 13 18 ene is in line with the hypothesis of sequential clay catalyzed isomerisation of bacterial hopenes terrestrial biomarker accumulation fluxes at site c are one order of magnitude higher than vertical pelagic flux demonstrating the magnitude of the inputs delivered through turbiditic transport in the submarine canyon crude oil contamination was evidenced at the disconnected site e ucm c 21 to c 26 tricyclic diterpanes cpi and in smaller amounts in some sediments from sites a and c it may be related to marine crude oil extraction and transport a short chain mode of alkanes with an even predominance is evidenced in sediments of the lobe complex and likely sources crude oil microorganisms and ferns are discussed

empirical models of storm time equatorial zonal electric fields ionospheric plasma drifts often show highly complex and variable signatures during geomagnetically active periods due to the effects of different disturbance processes we describe initially a methodology for the study of storm time dependent ionospheric electric fields we present empirical models of equatorial disturbance zonal electric fields obtained using extensive f region vertical plasma drift measurements from the jicamarca observatory and auroral electrojet indices these models determine the plasma drift perturbations due to the combined effects of short lived prompt penetration and longer lasting disturbance dynamo electric fields we show that the prompt penetration drifts obtained from a high time resolution empirical model are in excellent agreement with results from the rice convection model for comparable changes in the polar cap potential drop we also present several case studies comparing observations with results obtained by adding model disturbance drifts and season and solar cycle dependent average quiet time drift patterns when the disturbance drifts are largely due to changes in magnetospheric convection and to disturbance dynamo effects the measured and modeled drift velocities are generally in good agreement however our results indicate that the equatorial disturbance electric field pattern can be strongly affected by variations in the shielding efficiency and in the high latitude potential and energy deposition patterns which are not accounted for in the model these case studies and earlier results also suggest the possible importance of additional sources of plasmaspheric disturbance electric fields

molecular records of twentieth century el nino events in laminated sediments from the santa barbara basin organic molecules preserved in sediments especially long chain alkenones can preserve and record evidence of past climate variations1 5 a dependence of alkenone distributions on temperature has been recognized in cultures of the unicellular coccolithophorid alga emiliania huxleyi1 6 which survives in sediments and water column participates6 through this dependence stratigraphic profiles of the degree of alkenone unsaturation expressed asuk37 values1 have been shown in several oceanic settings to reflect long term changes in sea surface temperatures associated with glacial interglacial cycles1 5 here we show that annual variations in alkenone unsaturation in laminated sediments from the santa barbara basin off the shore of california reveal increases in water temperatures which can be linked directly to the observed sequence of el nino events in the twentieth century7 the range and variations in water temperatures calculated from uk37 values 12 8 15 2 c using the relationship established from culture experiments6 8 broadly correspond to the annually averaged temperatures 11 3 15 2 c measured intermittently by the calcofi programme at 20 m depth between 1953 and 1984 these results show that in favourable settings alkenone unsaturation profiles can provide an annually resolved record of oceanic temperaturechanges and may constitute a valuable tool for describing and evaluating the history of global climate variability and change

methylhopanoids molecular indicators of ancient bacteria and a petroleum correlation tool abstract methylhopanoids are organic compounds synthesized by certain bacteria that when preserved in sediments act as molecular fossils or biomarkers for organic matter inputs from specific bacterial sources two series of methylhopanoids occur each mainly deriving from a distinct bacterial source cyanobacteria 2 methyl and methanotrophic bacteria 3 methyl the abundance and composition of methylhopanoids within sediments of modern depositional environments varies widely apparently due to different bacterial communities contributing to the sedimentary organic matter comparable molecular characteristics are found in oils and their source rocks consequently methylhopanoids are valuable in oil oil and oil source rock correlations distinguishing between samples related to different depositional environments in particular abundant 3 methylhopanoids from methanotrophic bacteria or an additional unknown bacterial source are characteristic of some modern alkaline saline lake environments comparable compositional features in the methylhopanes of oils allow the assignment of lacustrine oils offshore west africa to two distinct lacustrine source rock facies and to distinguish between different marine source facies thus refining oil source rock correlation

status of alkenone paleothermometer calibration report from working group 3 1 the alkenone unsaturation index u37k has now proven its worth as a tool for paleothermometry u37k measured in most modern sediments throughout the world ocean can be translated using established calibrations into realistic seemingly reliable estimates of mean annual temperature at the sea surface sst however it remains mysterious why water temperature estimates based on this biotic index correspond to mean annual sst and whether such estimates apply back in geological time solving these mysteries is imperative and will require thoughtful concerted research effort by the biological chemical and geological oceanographic community this report summarizes what is now known about alkenones in particular their use in estimating the growth temperature of specific haptophyte algae that synthesize and export these compounds to the marine sediment record it highlights future field and laboratory research directions that should be taken to clarify and bolster utility of alkenones as a generally valued paleoceanographic tool

triterpenols from sediments of santa monica basin southern california bight u s a the triterpenol geochemistry of the santa monica basin from the southern california borderland off the u s a is described from the study of two sets of trap deployments five box cores 30 cm and a hydroplastic core 1 m the biogenic sources and diagenetic stability of the triterpenols are discussed the 17 h 21 h hopanols 22r isomer occur in the carbon number range from 30 to 32 and their abundance is nearly uniform in the shallow sediment sections however the three hopanols follow the order of abundance c32 c31 c30 in deeper sections their concentrations spans from trace levels to 156 g g organic carbon 15 ng to 7 g g dry sediment tetrahymanol gammaceran 3 ol has been identified in all the samples except in one set of trap particles collected at 100 m water depth from trace level 1 g to 215 g g organic carbon 20 ng to 9 g g dry sediment diplopterol is also detected in trace amounts in some samples the triterpenols in the trap material generally increase with the water column depth and decrease with the subbottom depth in the sediment cores the extended hopanols are either degradation products of polyhydroxybacteriohopanes or are biosynthesized by bacteria tetrahymanol is probably the only suggested biological precursor of gammacerane the reduced counterpart of tetrahymanol which has been recognized in numerous crude oils and lithified sediments although it has been reported earlier from green river shale and from a residual pleistocene lake sediment tetrahymanol has so far been positively identified from recent marine sediments only in two recent studies the decreasing content of tetrahymanol in sedimentary depth profiles in the santa monica basin would favor an origin for this compound in the water column or at the sediment surface the ubiquitous occurrence of this compound throughout the study area suggests that this triterpenol most probably originates from primitive organisms protozoa bacteria hitherto not identified or more likely not yet analyzed for their lipid composition

biomarker temperature estimates for modern and last glacial surface waters of the california current system between 33 and 42 n sea surface temperature sst estimates were made using data for c37 39 alkenones analyzed in modern and glacial age intervals of sediment cores collected along an east west 42 n from 125 to 132 w and a north south 41 33 n transect of the california current system ccs the prymnesiophyte biomarker results suggest that surface waters warmed significantly throughout this region since the last glacial maximum lgm but the magnitude of warming varied spatially stratigraphic profiles from four sediment cores along the north south transect indicate the warming period was confined to the glacial interglacial transition 15 10 ka with sst reaching a maximum value at 10 ka and maintaining a uniformly high value throughout the holocene comparison of estimates derived from analysis of modern and lgm sediment intervals indicates the magnitude of the sst change was minimal for locations south of about 36 n 1 2 c and increased significantly 3 5 c north of this latitude using a simple heat balance model we calculate from the latitudinal gradient in sst that southward flow in the california current system during the lgm was about 60 of that measured today at 36 n our findings support the conclusion of others based on pollen data that coastal upwelling in the region of the northeast pacific off northern california was significantly reduced or even completely shutdown during the lgm

euphotic zone bacterioplankton sources major sedimentary bacteriohopanepolyols in the holocene black sea abstract bacteriohopanepolyols bhps are lipid constituents of many bacterial groups geohopanoids the diagenetic products are therefore ubiquitous in organic matter of the geosphere to examine the potential of bhps as environmental markers in marine sediments we investigated a holocene sediment core from the black sea the concentrations of bhps mirror the environmental shift from a well mixed lake to a stratified marine environment by a strong and gradual increase from low values 30 g g 1 toc in the oldest sediments to 170 g g 1 toc in sediments representing the onset of a permanently anoxic water body at about 7500 years before present bp this increase in bhp concentrations was most likely caused by a strong increase in bacterioplanktonic paleoproductivity brought about by several ingressions of mediterranean sea waters at the end of the lacustrine stage 9500 years bp 15n values coevally decreasing with increasing bhp concentrations may indicate a shift from a phosphorus to a nitrogen limited setting supporting growth of n2 fixing bhp producing bacteria in sediments of the last 3000 years bhp concentrations have remained relatively stable at about 50 g g 1 toc the distributions of major bhps did not change significantly during the shift from lacustrine or oligohaline to marine conditions tetrafunctionalized bhps prevailed throughout the entire sediment core with the common bacteriohopanetetrol and 35 aminobacteriohopanetriol and the rare 35 aminobacteriohopenetriol so far only known from a purple non sulfur proteobacterium being the main components other bhps specific to cyanobacteria and pelagic methanotrophic bacteria were also found but only in much smaller amounts our results demonstrate that bhps from microorganisms living in deeper biogeochemical zones of marine water columns are underrepresented or even absent in the sediment compared to the bhps of bacteria present in the euphotic zone obviously the assemblage of molecular fossils in the sediments does not represent an integrated image of the entire community living in the water column remnants of organisms living in zones where effective transport mechanisms such as the fecal pellet express exist are accumulated while those of others are underrepresented our work shows a high stability of bhps over geological time scales largely uniform distributions and only minor changes in structures like an increasing prevalence of saturated over unsaturated bhps with time were observed consequently sedimentary bhp distributions are less suitable as markers for in situ living bacteria but are useful for paleoreconstructions of bacterioplanktonic communities and productivity changes

c32 and c34 hopanoids in recent sediments of european lakes novel intermediates in the early diagenesis of biohopanoids a study of hopanoids in the sediments of five european lakes has identified bacteriohopane 32 33 34 35 tetrol 35 methoxybacteriohopane 32 33 34 triol and two new hopanoids with shorter side chains 35 norbacteriohopane 32 33 34 triol and 33 34 35 trinorbacteriohopane 31 32 diol their structures have been revealed by mass spectrometry polyfunctionalised hopanoids with shortened side chains are not often reported in sediments mainly due to the analytical procedures used their systematic investigation could shed further light upon the early diagenesis of biohopanoids

common origin of positive ionospheric storms at middle latitudes and the geomagnetic activity effect at low latitudes anomalous increases of the ionization density at middle latitudes positive ionospheric storms and anomalous increases of the neutral gas density at low latitudes the geomagnetic activity effect are prominent features of upper atmospheric storms the present study investigates the idea that both phenomena are caused by traveling atmospheric disturbances tads according to theory such tads are generated during magnetic substorm activity and propagate with high velocity from polar to equatorial latitudes to examine the above hypothesis magnetic ionospheric and neutral atmospheric data are compared for five different disturbance events these case studies demonstrate that 1 there is a good temporal correlation between magnetic substorm activity at high latitudes daytime positive ionospheric storms at middle latitudes and the geomagnetic activity effect at low latitudes 2 the initial phase of positive ionospheric storms propagates with high velocity toward lower latitudes 3 this velocity is roughly consistent with the time lag of the geomagnetic activity effect at low latitudes 4 the ionospheric disturbance is a conjugate phenomenon of global extent and 5 it cannot be explained as an electric field effect in summary our data are fully consistent with the idea that tads are responsible for both positive ionospheric storms at middle latitudes and the geomagnetic activity effect at low latitudes

ionospheric responses to the october 2003 superstorm longitude local time effects over equatorial low and middle latitudes 1 ionospheric responses to the major magnetic storm disturbances of october 2003 are investigated using database selected in the brazilian and japanese asian longitude sectors data obtained from latitudinally spaced digisondes in the equatorial and low latitude sites in brazil and from the asian and japanese ionosonde network the total electron content data from the extensive japanese gps receiver chain and magnetometer data from the pacific equatorial electrojet stations are analyzed during the period 28 31 october prompt penetrating pp dawn dusk polar cap electric fields produce large f region plasma uplift on the dayside and eveningside while the associated westward electric field on the nightside produces large downdraft of the f region plasma and causes development of westward electrojet current observed for the first time episodes of pp electric field effects appear to be of larger intensity over brazil than over asian longitudes equatorial anomaly development due to undershielding as well as overshielding electric fields was observed in the brazilian and in the asian sectors disturbance dynamo electric field causes large nighttime f layer uplifts that are modulated by strong meridional winds in both sectors the disturbance electric field local time variation patterns are compared with the results of recent global model mtiegcm simulation by richmond et al 2003 and validated in some cases transients of transequatorial winds flipping direction from southward to northward in the widely separated longitude sectors were diagnosed to be present toward the final recovery phase of the storm these results are presented and discussed in this paper

variability in aerobic methane oxidation over the past 1 2 myrs recorded in microbial biomarker signatures from congo fan sediments methane ch4 is a strong greenhouse gas known to have perturbed global climate in the past especially when released in large quantities over short time periods from continental or marine sources it is therefore crucial to understand and if possible quantify the individual and combined response of these variable methane sources to natural climate variability however past changes in the stability of greenhouse gas reservoirs remain uncertain and poorly constrained by geological evidence here we present a record from the congo fan of a highly specific bacteriohopanepolyol bhp biomarker for aerobic methane oxidation amo 35 aminobacteriohopane 30 31 32 33 34 pentol aminopentol that identifies discrete periods of increased amo as far back as 1 2 ma fluctuations in the concentration of aminopentol and other 35 aminobhps follow a pattern that correlates with late quaternary glacial interglacial climate cycles with highest concentrations during warm periods we discuss possible sources of aminopentol and the methane consumed by the precursor methanotrophs within the context of the congo river setting including supply of methane oxidation markers from terrestrial watersheds and or marine sources gas hydrate and or deep subsurface gas reservoir compound specific carbon isotope values of 30 to 40 for bhps in odp 1075 and strong similarities between the bhp signature of the core and surface sediments from the congo estuary and floodplain wetlands from the interior of the congo river basin support a methanotrophic and likely terrigenous origin of the 35 aminobhps found in the fan sediments this new evidence supports a causal connection between marine sediment bhp records of tropical deep sea fans and wetland settings in the feeding river catchments and thus tropical continental hydrology further research is needed to better constrain the different sources and pathways of methane emission however this study identifies the large potential of aminobhps in particular aminopentol to trace and once better calibrated and understood quantify past methane sources and fluxes from terrestrial and potentially also marine sources

long chain alkenones in qinghai lake sediments abstract long chain methyl and ethyl alkenones c 37 c 40 containing two to four double bonds have been detected in sediments from qinghai lake china this is the first report of the alkenones in lake sediments deposited under a variety of salinity conditions where the lake has not encountered any marine incursions the presence of the alkenones suggests the presence of prymnesiophyceae in the lake which may have reached the lake via eolian transportation or seabirds sediment samples from the more saline areas of the lake contained higher concentrations of the more highly unsaturated compounds widespread use of these compounds as paleotemperature indicators in marine sediments introduces the possibility of extrapolating this approach to lacustrine environments if appropriate calibrations can be undertaken

on the significant impact of the moderate geomagnetic disturbance of march 2008 on the equatorial ionization anomaly region over indian longitudes 1 the response of the equatorial and low latitude ionosphere plasmasphere system to the moderate geomagnetic disturbance of march 2008 is the subject of this paper this study for the first time reports large plasmaspheric electron content modulation at equatorial and low latitude regions over india during a moderate geomagnetic disturbance this paper also presents for the first time five station tomograms encompassing the entire eia region and unequivocally demonstrates the effectiveness of tomographic technique in investigating storm induced modulations of the equatorial ionization anomaly the present study has been carried out using the total electron content values derived from gps and coherent radio beacon experiment crabex data over indian longitudes ionosonde data at trivandrum 8 5 n 77 e and delhi 28 n 78 e and the geomagnetic field data from trivandrum and alibag

biomarkers for aerobic methanotrophy in the water column of the stratified gotland deep baltic sea filter samples from the oxic zone and suboxic zone of the physically stratified water column and sediment samples of the gotland deep baltic sea were analyzed for bacteriohopanepolyol bhp and phospholipid fatty acid plfa concentrations in total eight bhps were identified with the greatest diversity in the suboxic zone there 35 aminobacteriohopane 31 32 33 34 tetrol aminotetrol and 35 aminobacteriohopane 30 31 32 33 34 pentol aminopentol whose concentrations decreased concurrently from the lower to the upper suboxic zone indicated type i methanotrophic bacteria and thus aerobic oxidation of methane the presence and activity of type i aerobic methanotrophic bacteria was further supported by the presence of 13c depleted plfas specifically 16 1 8c and 16 1 5c 13c as low as 41 2 however the relative amount of methanotroph specific compounds was low aminopentol 0 2 of total bhps 16 1 8c ca 0 5 of total plfas suggesting a minor contribution of aerobic methanotrophic bacteria to the particulate organic matter the distinctive bhp pattern in the suboxic zone including aerobic methanotroph biomarkers and a tentative marker for a pelagic redoxcline putative 22s isomer of the ubiquitous 22r bacteriohopanetetrol bht was mirrored in the sediment samples our data indicate that a major portion of the sedimentary hopanoids of the gotland deep is sourced from the suboxic part of the water column via an effective but unknown transport mechanism

occurrence of a tetraaromatic hopane in the late holocene peat deposit central china abstract hopanoids are important cell membrane components of many prokaryotes these compounds are commonly found in sediments and are used as biomarkers for bacteria during the diagenesis biological hopanoids can be transformed into geological hopanoids including aromatic hopanoids our understanding of the processes active in the aromatization of hopanoids in young sediments and their paleoenvironmental implications however remains somewhat limited in this study we report the occurrence of a c 25 tetraaromatic hopane in the late holocene peat horizons at dajiuhu central china similar fluctuations of a c 25 tetraaromatic hopane and diploptene suggest that the latter may be an important precursor for the aromatic hopane in this peat sequence the concentration of the c 25 tetraaromatic hopane is greater in peats deposited between 2 2 and 1 6 ka when other proxies record a wetter climate and the peat water would have been less acidic than in other intervals the possible mechanisms underlying the relationship between aromatic hopanes and hydrological settings in immature sediments should be considered further in the future

hopane derived triterpenoids in soils the occurrence distribution and degradation pathways of hopanoid triterpenes have been studied in thirteen soil samples with varying degrees of biological activity hopanoids were shown to occur in all samples suggesting that they are not only ubiquitous in subaquatic sediments but also in soils hop 22 29 ene was generally predominant in the hydrocarbons whereas the 17 h 21 h bishomohopanoic acid c32 was the major component in the acids the concentrations of hopanes were usually rather low except in acidic peat the distribution in carbon number of hopanes and hopanoic acids showed great similarities with those of moderately oxic subaquatic sediments intact bacteriohopane tetrol widespread in microorganisms and the main precursor of geohopanoids was identified in substantial amounts in a peat exposed to groundwater oscillations

is there evidence for a substantial contribution of prokaryotic biomass to organic carbon in phanerozoic carbonaceous sediments the role of prokaryotes bacteria and archaea in producing biomass and reworking settling and buried organic matter is of paramount importance since it exerts a major impact on the composition of sedimentary organic matter and ultimately petroleum this key role of prokaryotes in combination with a biomarker fingerprint often dominated by prokaryotic molecular fossils e g hopanoids has led to the assumption that prokaryotic biomass is a substantial source for organic carbon in carbonaceous sediments however biosynthesising and reworking organic matter does not necessarily imply sourcing organic matter by the prokaryotes and the abundance of biomarkers does not always reflect relative contributions to sedimentary organic matter in this paper the existing evidence for a substantial prokaryotic biomass contribution to sedimentary organic carbon oc is critically evaluated this shows that despite the often prominent presence of prokaryotic biomarkers in sediments evidence for a substantial prokaryotic contribution to sedimentary oc is generally lacking this is demonstrated by i the application of the carbon isotopic mass balance principle in various sedimentary settings ii an alternative explanation for the proposed dominant role of heterotrophic reworking in the oxford clay iii a summary of the effects of bacterial oxidation in organic matter rich turbidites and iv recent data showing that the evidence for recalcitrant carbon in prokaryotes is scant although these observations do not rule out substantial contributions of prokaryotic carbon to oc in phanerozoic carbonaceous sediments this remains to be demonstrated and the final answer awaits the development of new technologies to full characterise sedimentary oc

a natural pyrolysis experiment hopanes from hopanoic acids abstract the formation or generation of hopanes are important processes during both the natural heating of organic rich sediments and laboratory pyrolysis experiments molecular maturity parameters as well as the amounts ng g rock of the c31 hopanes and c30 c32 hopanoic acids were quantified in a jurassic silty shale horizon isle of skye scotland as a function of distance from an igneous intrusion the maturity profiles of the homohopanes and the hopanoic acids are comparable there is also a correlation between the decreasing amounts of c30 c32 hopanoic acids and concomitant increases in c29 c31 hopanes suggesting that free hopanoic acids could be one potential source of hopanes in this particular horizon other possible sources could include hopanoic acids that are bound into the macromolecular fraction

local time dependent response of postsunset esf during geomagnetic storms 1 development or inhibition of esf during magnetically active periods has been an important space weather topic of interest during the recent past in view of its applications in the satellite based navigational systems particularly the postsunset period exhibits significant variability for storm time development of esf versus longitude in this paper we report the results of a multi instrumental ground based and space borne and multistation study on the development inhibition of postsunset esf during five moderate to intense geomagnetic storms occurred during the low and descending phase of the solar activity period 2004 2006 it has been observed that the prompt penetration of eastward electric fields into low latitudes and subsequent development of esf occurred in all longitudinal sectors where the local time corresponds to postsunset hours during the entire main phase of the storm in this paper we show the development of plasma bubble irregularities over a wide longitudinal extent of 92 owing to the dusk time penetration of eastward electric fields into low latitudes either the sudden increase in ae index and or a marked decrease in sym h index may be used as proxies to determine the occurrence as well as the time of penetration of electric fields into equatorial and low latitudes however in such cases where the ae index does not represent any sudden increase the dsymh dt seems to be the better index to determine the time of penetration in this paper is also presented an interesting case where the prompt penetration eastward electric fields dominated the existing strong westward electric fields and subsequently caused the onset of spread f and scintillations at both vhf 244 mhz as well as l band 1 5 ghz frequencies

environmental influence on the biohopanoid composition of recent sediments abstract bacteriohopanepolyols are the biological precursors of extended hopane biomarkers which are ubiquitous in the geosphere the abundance and composition of these biohopanoids were determined for modern sediments from eight depositional environments by gc ms analysis of hopanols derived from a side chain cleavage reaction periodic acid and sodium borohydride of the bacteriohopanepolyols we report quantitative data for bacteriohopanetetrol bht composite tetrafunctionalised biohopanoids pentafunctionalised biohopanoids and hexafunctionalised biohopanoids bht was found in concentrations higher than previously reported up to ca 1500 g g toc but comprised only a relatively small proportion 0 26 of the total biohopanoids in all except one sample composite tetrafunctionalised biohopanoids were the dominant group of bacteriohopanepolyols in all other sediments and are likely to be a major source of the geologically occurring extended hopanes hexafunctionalised biohopanoids were most abundant in lake sediments particularly two small highly productive stratified lakes where they comprised 20 40 of total biohopanoids this feature is interpreted to be due to greater contribution to the organic matter of these sediments from type i methanotrophic bacteria which produce dominantly hexafunctionalised biohopanoids consistent with the environmental settings in the marine environments where sulphate reduction is dominant hexafunctionalised biohopanoids are relatively minor constituents 2 6 of total biohopanoids these data comprise the first clear demonstration that bacteriohopanepolyols vary in composition between depositional environments and have the potential to preserve specific bacterial source information in sedimentary organic matter

hopanoic acids in mesozoic sedimentary rocks their origin and relationship with hopanes abstract hopanoic acids were found in all but the two most mature of a suite of 30 triassic to cretaceous sedimentary rocks their carbon number distributions generally maximise at c 32 consistent with hopanoic acids found in modern sediments the extent of isomerisation measured by and 22s parameters is less for the acids than for associated hopanes possibly due to increased isomerisation of hopanes in association with their generation from macromolecules and functionalised precursors in immature samples the hopane carbon number distributions are consistent with an origin from defunctionalisation of hopanoic acids and other early diagenetically formed hopanoids whilst hopanes in more mature samples exhibit broader carbon number distributions indicative of side chain cleavage during generation of macromolecularly bound hopanoids

storm time dependence of equatorial disturbance dynamo zonal electric fields we use jicamarca radar observations of f region vertical plasma drifts and auroral electrojet indices during 1968 1988 to study the characteristics and temporal evolution of equatorial disturbance dynamo zonal electric fields these electric fields result from the dynamo action of storm time winds and or thermospheric composition changes driven by enhanced energy deposition into the high latitude ionosphere during geomagnetically active conditions the equatorial vertical drift perturbations last for periods of up to 30 hours after large increases in the high latitude currents on the average this process can be described by two basic components with time delays of about 1 12 hours and 22 28 hours between the high latitude current enhancements and the equatorial velocity perturbations our data indicate strong coupling between dynamo processes with different timescales the short term disturbance dynamo drives upward equatorial drifts eastward electric fields at night with largest amplitudes near sunrise and small downward drifts during the day these perturbation drifts are in good agreement with results from the blanc richmond disturbance dynamo theory the dynamo process with time delays of about a day drives upward drift velocities at night with largest values near midnight and downward drifts in the sunrise noon sector in this case the amplitudes of the disturbance drifts maximize during geomagnetically quiet times preceded by strongly disturbed conditions we also present results of a new equatorial storm time dependent empirical model which illustrate the characteristics of the vertical disturbance dynamo drifts

extended hopanoids in peat environments abstract detailed results are presented for the distributions of triterpenoid alkanes acids and alcohols of the hopane family in ten samples of peat from three environments and of contributing organisms in the case of lyne of skene scotland extended hopanoids of the and configuration appear at the very earliest stage of diagenesis such environments appear to be characterised by particular distributions of c 32 hopanoid acids and alcohols and a high preponderance of the c 31 hopane

atlantic core top calibration of the u37k index as a sea surface palaeotemperature indicator abstract a field calibration of the uk index with sea surface temperature is discussed through analysis of an extensive suite of surface sediments n 109 from the northeastern atlantic 2 s 75 n values of u 37 k are compared with sea surface temperatures for overlying waters measured at different depths and seasons to obtain a correlation suitable for palaeotemperature reconstructions the best fit is obtained using surface 0 m temperatures corresponding to caloric winter and autumn months however the annual average spring and summer surface temperature equations also have high correlation coefficients and are also appropriate for climatic studies the results further validate the general applicability of the u 37 k as a climatic proxy because the calibration equations are valid over a wide range of surface water temperatures 0 28 c for different algal populations and are representative of the average contribution of alkenones to sediments as found in sediment cores

release of kerogen bound hopanoids by hydropyrolysis hydropyrolysis was used to determine the concentrations of kerogen bound hopanoid hydro carbons the samples characterized were a recent sediment priest pot english lake district and three source rock kerogens green river shale draupne shale and jet rock shale the hydropyroly zate of a hopanoid producing bacterium methylobacterium organophilum showed that this procedure does not overly obscure the original isomer compositions of the samples characterized although signifi cant side chain cleavage does occur which is inevitable with any pyrolysis method notable diaerences are observed between the composition of pyrolyzates and bitumen extracts for each of the source rock kerogens the overall level of hopane isomerization within the pyrolyzate is significantly lower than in the corresponding extracts this is particularly the case for the draupne sample the pyrolyzate of which contains 17b 21b hopanes though these are absent in the bitumen diaerences in isomeric com position of the pyrolyzates are in line with the isomer contents of the bitumen extracts the abundance of kerogen derived hopanes is highly variable both in terms of absolute concentration and also relative to the concentration of hopanes in the bitumen this is in part due to maturity diaerences but deposi tional environment and diagenetic conditions may also exert a control on kerogen bound hopane con centration these results show that hydropyrolysis provides valuable data on the concentration of kerogen bound hopanes whilst largely preserving their original isomeric composition 1998 elsevier science ltd all rights reserved

depth and seasonality of alkenone production along the california margin inferred from a core top transect alkenone unsaturation indices uk 37 of marine sediment could prove particularly useful on organic rich continental margins where carbonate dissolution hampers the use of other paleoclimatic proxies mccaffrey et al 1990 kennedy and brassell 1992 forty core top samples of recent sediment from a latitudinal transect 23 40 n along the california margin yield uk 37 values that correlate linearly with modern mean annual sea surface temperatures ssts in the range of 12 23 c reproducibility of the unsaturation value in closely spaced cores is near analytical error uk 37 data define a relationship to temperature nearly identical to the prahl et al 1988 laboratory cultures of emiliania huxleyi the close agreement is particularly significant in light of the nannofossil composition of the sediments where the abundance of the coccolith taxon gephyrocapsa oceanica known to synthesize alkenones equals or exceeds that of e huxleyi comparison with seasonal temperature variations at different depths indicates that little if any alkenone production occurs at depths 30 m along the continental margin water depths 2 km sediments in more pelagic locations exhibit small but consistent biases toward winter and or subsurface production similar to previously reported sediment trap and core top data from the oregon margin prahl et al 1993 doose et al 1997

equatorial plasma fountain and its effects over three locations evidence for an additional layer the f 3 layer the equatorial plasma fountain and equatorial anomaly in the ionospheres over jicamarca 77 w trivandrum 77 e and fortaleza 38 w are presented using the sheffield university plasmasphere ionosphere model under magnetically quiet equinoctial conditions at high solar activity the daytime plasma fountain and its effects in the regions outside the fountain lead to the formation of an additional layer the f3 layer at latitudes within about plus or minus 10 of the magnetic equator in each ionosphere the maximum plasma concentration of the f3 layer which occurs at about 550 km altitude becomes greater than that of the f2 layer for a short period of time before noon when the vertical e b drift is large within the f3 layer the plasma temperature decreases by as much as 100 k the ionograms recorded at fortaleza on january 15 1995 provide observational evidence for the development and decay of an f3 layer before noon the neutral wind which causes large north south asymmetries in the plasma fountain in each ionosphere during both daytime and nighttime becomes least effective during the prereversal strengthening of the upward drift during this time the plasma fountain is symmetrical with respect to the magnetic equator and rises to over 1200 km altitude at the equator with accompanying plasma density depletions in the bottomside of the underlying f region the north south asymmetries of the equatorial plasma fountain and equatorial anomaly are more strongly dependent upon the displacement of the geomagnetic and geographic equators jicamarca and trivandrum than on the magnetic declination angle fortaleza

variations of total electron content during geomagnetic disturbances a model observation comparison this paper studies the ionospheric response to the major geomagnetic storm of october 18 19 1995 using the ncar tie gcm simulations and the global ionospheric maps gim of total electron content tec observations from the worldwide network of global positioning system gps receivers the tie gcm results show a good agreement with the gps gim in terms of simulating storm time tec disturbances over the polar regions the model indicates that the increase of electron density in the high latitude e and lower f regions below 200 km is directly related to the magnetospheric energy input through auroral precipitation to the ionosphere while the decrease of tec is mainly due to the increase in o2 and n2 densities in the upper f region above 200 km during the recovery phase both the tie gcm and gps gim reveal a distinct hemispheric asymmetry in the tec integrated above 50 magnetic latitude with a 20 decrease in the southern summer like hemisphere and a 30 increase in the northern winter like hemisphere

lipid biomarkers preserved in hydrate associated authigenic carbonate rocks of the gulf of mexico anaerobic oxidation of methane aom is common in ocean margin sediments where it is mediated by consortia of archaea and bacteria and can result in the formation of authigenic carbonate including extensive carbonate crusts previous work indicates that aom is associated with gulf of mexico hydrocarbon seeps and is mediated by similar organisms as identified in other settings however biological investigations have not been done on the associated 13c depleted carbonates here we show that 13c depleted archaeal and bacterial biomarkers are abundant in gulf of mexico authigenic carbonate rocks revealing that aom mediating organisms are closely associated with carbonate authigenesis moreover the rocks share general characteristics of the background soft sedimentary archaeal and bacterial community inferred from biomarker analysis suggesting that the organisms associated with carbonate authigenesis are the same as those that live elsewhere in the hydrocarbon seep environment this provides further evidence that aom by archaea and sulfate reducing bacteria can result in the sequestration of significant quantities of methane derived carbon in carbonate rocks

lipid biomarker patterns of methane seep microbialites from the mesozoic convergent margin of california abstract in order to reconstruct biogeochemical pathways at mesozoic methane seeps a set of late jurassic tithonian to early cretaceous aptian albian 13 c depleted seep limestones from forearc strata in western california were subjected to detailed molecular isotopic biomarker analyses two of the microbial carbonate deposits are turbidite hosted fault related whereas one is hosted in serpentinite in a diapir related setting the limestones contain 13 c depleted archaeal lipid biomarkers such as crocetane 13 c 80 and pmi 100 indicative of an involvement of anaerobic oxidation of methane aom in carbonate precipitation isotopically depleted crocetane in the tithonian sample represents the oldest reported occurrence of this compound at methane seeps in the set of samples a series of strongly 13 c depleted regular c 21 to c 24 isoprenoids possibly results from diagenetic alteration of archaeal sesterterpanylglycerol diethers as suggested by the presence of the putative intermediate 3 7 11 15 19 pentamethylicosanoic acid 13 c depleted 17 h 21 h and 17 h 21 h hopanes c 30 c 34 with 22 s and 22 r isomer couplets c 31 are present in all samples in distributions indicative of a moderate thermal maturity low 13 c values 78 to 60 suggest that these are derived from anaerobic bacteria involved in aom notably 22 s isomers are consistently enriched in 13 c relative to their 22 r counterparts our samples represent 70 myr of seepage activity and aom along the mesozoic margin of western california filling the gap between the currently oldest methane seep biomarker record from the oxfordian late jurassic and the more widely recognised cenozoic examples

protection of organic matter by mineral matrix in a cenomanian black shale abstract three types of pathways degradation recondensation natural sulphurization and selective preservation are commonly considered for the formation of kerogen dispersed in sedimentary rocks a fourth pathway has been recently put forward however from studies on recent marine sediments the so called sorptive protection mechanism this pathway is based on the adsorption of otherwise labile organic compounds onto minerals thus preventing their diagenetic degradation and promoting their subsequent condensation into kerogen the main results of the present study are derived from a combination of microscopic and pyrolytic methods applied on a cenomanian kerogen they provide i evidence on an ancient material for a crucial role of the mineral matrix both in organic matter om preservation during kerogen formation and in kerogen stability once formed ii indications that the dominant protective process likely involves physical protection by minerals resulting from alternation of organic and clay nanolayers of approximately 100 nm in thickness rather than om adsorption as molecular monolayers and iii observations of the relatively poor stability of an isolated kerogen contrary to the inertness commonly assumed for fossil macromolecular organic matter

distributions and sources of hopanes hopanoic acids and hopanols in miocene to recent sediments from odp leg 190 nankai trough the distributions and origins of hopanes hopenes hopanoic acids and hopanols in marine sediments from sites 1175 1176 and 1178 ocean drilling program odp leg 190 nankai trough were investigated the high concentrations of hopanoic acids and anhydrobacteriohopanetetrol in the sediments correspond well with a terrestrial contribution as indicated by the abundance of higher plant derived lipids and turbidite layers suggesting that they are mainly transported from land bacteriohopanetetrol and hopanepolyols with short side chains were commonly detected down to about 400 m below sea floor diagenetic transformation from biohopanoids to geohopanoids can take place quickly after the death of bacteria the presence of intact bacteriohopanetetrol in geological sediments tends to suggest an origin from in situ living bacteria so bacteriohopanetetrol might be a potential life marker for deep sub surface bacteria

the disappearance of sphagnum imbricatum from butterburn flow uk the disappearance of the previously abundant moss species sphagnum imbricatum has been investigated at butterburn flow northern england using organic geochemical elemental macrofossil pollen and testate amoebae analyses variations in the assemblage of peat forming plants were tracked using the macrofossil distributions as well as the relative chain lengths of n alkanes and concentrations of 5 n alkylresorcinols and triterpenols no significant changes to the vegetation assemblage could be detected prior to the loss of s imbricatum variations in water depth were reconstructed using a testate amoebae transfer function and inferred qualitatively using bulk elemental composition and biomarkers for changing redox conditions in the bog subsurface the degree of isomerization in the c31 hopanes and the concentrations of bishomohopanol and archaeol pollen analysis reconstructed the landscape surrounding the mire and revealed evidence for human disturbance the results suggest that bog surface wetness increased with the transition from sphagnum imbricatum to sphagnum magellanicum but the increase was not large and s imbricatum had previously survived similar periods of wetness however the loss of s imbricatum coincides with increasing human disturbance surrounding the bog which may have altered nutrient inputs to the bog surface from agriculturally derived dust to the detriment of s imbricatum but to the benefit of s magellanicum and eriophorum vaginatum it is proposed here that the stresses imposed by the combination of changing nutrient inputs and a rapidly rising water table drove the disappearance of s imbricatum from butterburn flow at c cal ad 1300

novel polyfunctionalised geohopanoids in a recent lacustrine sediment priest pot uk abstract the sediment of a highly productive lake priest pot uk contains the biosynthesised hopanoid bacteriohopanetetrol bht and a series of hopanediols and triols these polyols represent intermediate stages in the conversion of biologically produced hopanoids to the diagenetic products hopanes two of these geohopanoids assigned as trishomohopane 32 33 diol and bishomohopane 30 31 32 triol have not been previously reported in recent sediments and their identification in addition to that of tetrakishomohopane 32 33 34 triol and a bishomohopanediol gives valuable information on the original composition and subsequent diagenesis of bacteriohopanepolyols within recent sediments

diverse biohopanoid compositions of non marine sediments abstract biohopanoid compositions were determined for modern sediments from 27 lacustrine environments and 1 near coastal lagoon gc ms analysis of existing hopanols and those produced by a side chain cleavage reaction periodic acid and sodium borohydride of the bacteriohopanepolyols provided quantitative data for bacteriohopanetetrol bht bacteriohopanepentol and composite tetra penta and hexafunctionalised biohopanoids additional analysis of acetylated total extracts by hplc apci ms has allowed us to identify up to seven intact bacteriohopanepolyols in these environments including the first direct observation of 35 aminobacteriohopanepentol in environmental samples this method is complementary to the periodic acid approach in providing more specific compositional information the lacustrine environments exhibit a wide range of compositions many with high inputs of hexafunctionalised biohopanoids up to 60 of total tetra penta and hexafunctionalised biohopanoids indicative of major contributions to the sediment from type i methanotrophic bacteria several methylated biohopanoids were also detected in most of the samples with 2 as the dominant configuration of the methyl group 2 methylbacteriohopanetetrol was by far the most abundant and most commonly occurring compound of this type and comprised the most abundant bacteriohopanepolyol in one saline lake laguna grande spain such compounds are believed to be derived from cyanobacteria currently the only known quantitatively significant source of 2 methylated biohopanoids biohopanoids containing a methyl group at c 3 were also detected in a limited number of environments these data demonstrate the wide variability in bacteriohopanepolyol compositions among depositional environments and the potential of these compounds to preserve bacterial source information and thereby to record environmental change

decoupling of bio and geohopanoids in sediments of the benguela upwelling system bus abstract geohopanoids derive from bacteriohopanepolyol bhp precursors however knowledge of the specific sources and diagenetic fate of both compound classes in marine sediments is fragmentary we studied the relationship between bhps and geohopanoids in a sediment core from the central benguela upwelling system bus including deposits over the last 75 ka the bus is a palaeo oceanographically stable setting where primary production is largely controlled by variation in upwelling intensity and therefore nutrient supply marine production in the bus was generally higher during glacial than during interglacial times as reflected in the levels of sedimentary total organic carbon geohopanoids at the study site consisted mainly of extractable hopanes and hopanols and occurred in the highest amounts during glacial periods a minor but still considerable fraction of geohopanoids was sulfur linked to geomacromolecular organic matter among these s bound hopane moieties 17 h 21 h trishomohopane c33 was the predominant compound suggesting a diagenetic overprint of bhps before linkage among the bhps a rare bacteriohopanetetrol with likely 22s configuration was observed this structural feature was lacking in the geohopanoids which all had the 22r configuration different behaviour of bhp and geohopanoid concentrations as well as 13c discrepancies indicate a decoupling of bio and geohopanoids geohopanoids most likely reflect laterally transported fossil organic matter whereas bhps are indigenous to the upper water column of the study site and may relate to past upwelling intensity nutrient levels hence care has to be taken using geohopanoids and other biomarkers for palaeoreconstruction in settings where sedimentation processes are not fully understood

holocene land cover dynamics in the curuai floodplain inferred from lacustrine biomarkers this study on curuai floodplain central amazonia sediments last 5600 cal yr bp focused in rock eval re hydrogen hi and oxygen oi indices tmax s2 curve and tps2 organic petrography and molecular biomarkers n alkanes hopanes pentacyclic triterpene methyl ethers ptmes and derivatives of pentacyclic triterpenes such as des a lupane and aromatic derivatives analyses between 5600 and 5100 cal yr bp the environment was waterlogged and dominated by emersed plants paq 0 27 0 38 the influence of the amazon river was low terrestrial vs aquatic ratio t a 0 8 cpi values 3 4 and high contents of ptme 0 22 1 54 g g sed and aromatics 21 53 g g sed indicated a strong contribution of terrestrial material and anoxic om deposition conditions between 5100 and 5000 cal yr bp more humid conditions due to heavier rainfalls were observed early in this period terrestrial biomarker contents 253 g g sed of aromatics paq 0 17 increased due to input of watershed erosion material this provoked a rapid burial and good preservation of terrestrial om cpi 3 4 5 from 5000 cal yr bp a strong sedimentation of carbonate minerals oi 1600 mg co2 g 1 masked the om signal and affecting re parameters paq 0 18 t a ratio 0 4 and the decrease of c31 c31 hopanes 1 18 indicate increasing aquatic conditions up to 2700 cal yr bp cpi ratio 1 2 and degraded phytoclasts suggest intense degradation during transport to the sedimentation location the ptmes results showed that from 3000 yr cal bp the poaceae genuses were different from those found at the bottom middle holocene suggesting a change of vegetation the last 600 cal yr bp were marked by the seasonal influence of the amazon river during periods of low water level the organic petrography and cpi values 1 0 evidenced om degradation and the return of rather drier conditions

origin of variations in organic matter abundance and composition in a lithologically homogeneous maar type oil shale deposit gerce pliocene hungary despite having an homogeneous lithology the largest hungarian maar type deposit gerce oil shale pliocene has previously been shown to exhibit substantial variations in organic matter quantity and quality with depth this het erogeneity is also reflected in the present study by large variations in bitumen abundance and composition for 23 samples from gerce well 6 core based on the above bitumen data four samples were selected that were representative of the whole set which exhibit contrasting features scanning and transmission electron microscopy showed the occurrence of extensively altered botryococcus colonies in this deposit gc ms and gc c ir ms of the saturated hydrocarbon fractions of the bitumen of these samples reveal a predominant algal contribution along with a variable bacterial input the relative abundance of these two contributions in the four selected samples is also reflected by dif ferences in ftir and solid state 13 c nmr spectra of the isolated kerogens curie point pyrolysis gc ms of these kerogens revealed a relatively high terrestrial contribution in one sample and confirmed the variable input of algae and bacteria the above diaerences in relative contributions account for the variations in organic matter quantity and quality observed along the core 2000 elsevier science ltd all rights reserved

abnormal evening vertical plasma drift and effects on esf and eia over brazil south atlantic sector during the 30 october 2003 superstorm 1 equatorial f region vertical plasma drifts spread f and anomaly responses in the south american longitude sector during the superstorm of 30 october 2003 are analyzed using data from an array of instruments consisting of digisondes a vhf radar gps tec and scintillation receivers in brazil and a digisonde and a magnetometer in jicamarca peru prompt penetrating eastward electric field of abnormally large intensity drove the f layer plasma up at a velocity 1200 ms 1 during post dusk hours in the eastern sector over brazil the equatorial anomaly was intensified and expanded poleward while the development of spread f plasma bubble irregularities and gps signal scintillations were weaker than their quiet time intensity significantly weaker f region response over jicamarca presented a striking difference in the intensity of prompt penetration electric field between peru and eastern longitudes of brazil the enhanced post dusk sector vertical drift over brazil is attributed to electro dynamics effects arising energetic particle precipitation in the south atlantic magnetic anomaly sama these extraordinary results and their longitudinal differences are presented and discussed in this paper

early diagenesis of bacteriohopanoids in recent sediments of lake pollen norway abstract the distribution of free bio and geohopanoids were studied in a short 46 cm core from recent sediments of lake pollen norway bacteriohopanepolyols are abundant components of the sediments totalling up to 321 g g dry sediment 7485 g g toc being dominated by c 32 33 34 35 tetrafunctionalised hopanoids significantly bacteriohopanetetrol only accounts for between 7 to 62 of these 24 on average indicating that composite bacteriohopanoids are more abundant sedimentary constituents and thus more important precursors of geohopanoids than previously recognised downcore profiles of bio and geohopanoid abundance show maxima at ca 25 to 30 cm with a marked decrease in abundance above this depth which coincides with a well documented change in environment from fjord to isolated lake a second maximum in biohopanoid abundance occurs at ca 5 to 12 cm depth specific biohopanoids were affected to different extents by the change in environment suggesting that they have at least partly different sources our data thus indicate that biohopanoids and their geohopanoid products may be sensitive to changes in depositional environment and that they have potential to act as markers for environmental conditions

lipids of aquatic organisms as potential contributors to lacustrine sediments ii abstract the relationship between the lipid composition of organisms in the water column of an eutrophic lake and the lipid composition of underlying sediments previously examined for n alkanols and steroids is now reported for hydrocarbons ketones and carboxylic acids the n c7 alkane and alkenoic acids from two primary sources are rapidly metabolized in the water column and surficial sediment bacterial biomarkers including hopenes and i ai branched fatty acids were detected in the photosynthetic bacterial layer occurring just above the sediment water interface within the sediment the apparent conversion of free n alkanes alkan 2 ones and hydroxy acids to the corresponding bound form is noted microbiological oxidation of n alkanes to alkan 2 ones is supported by the detection of the intermediate alkan 2 ols with a distribution similar to that of the ketones the geochemistry of sediment deposited c 1900 prior to biological study of the site was interpreted from stable biomarkers and the diagenetic changes recognised in the study of contemporary deposition a qualitative difference in algal input to the older sediment is inferred from the low 7 sterol content and presence of 2 6 10 trimethyl 7 3 methylbutyl dodecane however there was still significant dinoflagellate input as indicated by the presence of 4 methylsterols a difference in higher plant input to the older sediment indicated from the n alkane alkene and triterpenoid ketone distributions is consistent with the recent development of tree cover

molecular record of secular sea surface temperature changes on 100 year timescales for glacial terminations i ii and iv high resolution palaeoclimate records based on oxygen isotope data have provided important insights into climate variability and rates of natural climate change on about a thousand year timescale1 3 little is known4 however about the variation of climate and of palaeoceanographic conditions throughout the quaternary on timescales of less than 1 000 years at frequencies far greater than those of the milankovitch orbital cycles here we show that such high time resolution is possible from molecular stratigraphic studies based on biomarker organic molecules alkenones we have sampled alkenone stratigraphic records at 70 to 200 yr intervals across glacial terminations i ii and iv in sediment cores from oop site 658 off northwest africa5 sea surface temperatures ssts derived from the alkenone uk37 index6 8vary rapidly beyond the range of analytical noise by up to 2 5 c in 300 yr showing hitherto unknown cycles with about 600 yr periodicities some of the changes parallel similar events in the oxygen isotope stratigraphy sst oscillations may be linked in part to abrupt breakdowns in atlantic deep water ventilation resulting from meltwater events of quaternary glacial terminations3 9 10

lipid geochemistry of lake kinneret lake kinneret a relict lake from the neogene is characterised by the dominance among its phytoplankton of the dinoflagellate peridinium cinctum the lipid geochemistry of lake kinneret is discussed herein in terms of the biology chemistry and hydrology of the lake lipids isolated from two sediment sections surface and 15 cm deep obtained from the deepest point of lake kinneret include 1 4 methyl 5 h stanols and related derivatives characteristic of p cinctum the novel sterol 4a methylgorgosterol and peridinosterol and 4 methylgorgostanol not previously reported to occur in lacustrine sediments 2 c30 and c32 alkane 1 15 diols not previously reported to occur in contemporary lacustrine deposits and 3 products of early diagenesis many similarities were observed with the more widely studied marine dinoflagellates and marine sediments with dinoflagellate input

bacterial hopanoids as tracers of organic carbon sources and processing across the western arctic continental shelf tracing the inputs of bacterial organic carbon to marine systems has been constrained by the lack of distinguishing geochemical tracers and limited contribution in sediments compared to other sources of organic matter bacteriohopanepolyols bhps provide a direct means to identify bacterial inputs which also reflect potential bacterial groups and their activities in aquatic systems we applied recent analytical approaches to identify and quantify bacterial derived carbon contributions to surface sediments from the western arctic ocean using bhps the abundance and distribution of bhps resemble trends of water column primary production and suggest active heterotrophic recycling of in situ production with some component of long term preservation bhps proposed as terrestrial derived signatures i e adenosylhopanes were also abundant in western arctic sediments and reflect offshore trends of other terrigenous lipid signatures with a fraction representing their degradative products analysis of bhps in organic rich peat and surface sediments from two arctic rivers showed the highest inputs of adenosylhopanes implying active bacterial recycling of recalcitrant terrigenous material bhps observed in western arctic surface sediments reveal significant contributions of bacteria associated with organic carbon from multiple sources

biomarkers as environmental indicators in a carbonate complex example from the middle to upper devonian holy cross mountains poland abstract autochthonous biomarker distributions were studied in an array of different subfacies of a devonian carbonate complex represented in platform reef and off platform shelf basinal systems it revealed that biomarkers are sensitive indicators of depositional environments and may serve to refine palaeoenvironmental interpretations of carbonate complexes based on classical sedimentological facies analyses the contrasting biomarker composition of the carbonate platform and reef complex versus shelf basin deposits is here interpreted as the effect of both more diverse biotic sources of a primary organic matter in the former environments highly scattered results of sterane distribution and contrasting styles of decay and bacterial reworking of the primary biomass peritidal dolostones deposited under anoxic to suboxic conditions and with scarce sedimentological evidence of elevated salinity reveal the highest potential of organic matter preservation among other platform reefal facies their biomarker composition includes several compounds indicating hypersaline conditions and anoxia whereas others in particular gammacerane indicate that the water column was stratified during sedimentation this observation constrains environmental interpretation of these deposits pointing to shallow subtidal lagoons with elevated salinity and low oxygen near bottom waters most probably originating from a salinity controlled stratification of the water column biomarkers diagnostic of green sulphur bacteria were found in both peritidal lagoonal dolostones and shelf basinal facies this indicates the existence of photic zone anoxia in the latter environment thus suggesting a shallow position of the redoxcline the frasnian famennian mass extinction event s apparently had no impact on the biomarker distribution in the shelf basinal system continuous across the stage boundary

preservation and diagenesis of hopanoids in recent lacustrine sediments of priest pot england abstract absolute concentrations of various bio and geohopanoids have been determined in a 24 cm long core from anoxic recent sediments of priest pot a small highly productive lake in the english lake district samples were soxtherm extracted derivatised by methods targeted at specific hopanoid groups and quantified by gc ms periodic acid sodium borohydride treatment was used to cleave the side chains of highly functionalised hopanoids producing products more amenable to our detection methods biohopanoids are extremely abundant totalling up to 3000 g g dry sediment particularly those with composite or highly penta and hexa functionalised side chains suggesting that these are important precursors to sedimentary hopanoids in priest pot downcore biohopanoid abundance profiles show a general diagenetic decline with a marked dip at 5 8 cm which we interpret as a change in bacterial input since this is most marked in the composite hopanoids rather than bacteriohopanetetrol we suggest that these two hopanoid groups have at least partly different sources and may thus have potential as environmental markers the geohopanoids are also abundant totalling up to 1700 g g dry sediment being dominated by the and bishomohopanoic acids and bishomohopanol and hop 17 21 ene downcore plots show no apparent conversion of free bio to geohopanoids with depth which suggests that incorporation into kerogen may be commencing at an early diagenetic stage in the sediments

stable carbon isotopic correlation of individual biolipids in aquatic organisms and a lake bottom sediment abstract isotope ratio monitoring gc ms irm gcms analyses of individual hydrocarbons isolated from the surface sediment of a small eutrophic lake priest pot u k and a phytoplankton tow sample from the upper water column have been undertaken in order to assign sources of sedimentary lipids the 13c values for the sedimentary n alkanes showed no clear distinction between lower molecular weight components c17 c19 of presumed algal origin and higher members c23 c33 of presumed higher plant origin thus indicating a limitation to the use of compound specific isotope analysis in the freshwater system studied in contrast the 13c values of sedimentary hopenes were markedly depleted by over 20 compared with those in the phytoplankton sample from the upper water column hop 22 29 ene in the surficial sediment had a 13c value of 55 2 which contrasts witht he value of the phytoplankton component 32 7 attributed to cyanobacteria these values indicate that a highly 13c depleted source provides a major contribution to the sedimentary component it is proposed that the sedimentary hopenes originate in part from methanotrophic bacteria demonstrating the presence of a bacterial methane cycle in this environment

an overview of the early november 1993 geomagnetic storm this paper describes the development of a major space storm during november 2 11 1993 we discuss the history of the contributing high speed stream the powerful combination of solar wind transients and a corotating interaction region which initiated the storm the high speed flow which prolonged the storm and the near earth manifestations of the storm the 8 day storm period was unusually long the result of a high speed stream maximum speed 800 km s emanating from a distended coronal hole storm onset was accompanied by a compression of the entire dayside magnetopause to within geosynchronous earth orbit geo for nearly 12 hours the near earth environment was in a state of tumult a super dense plasma sheet was observed at geo and severe spacecraft charging was reported the effects of electrons precipitating into the atmosphere penetrated into the stratosphere subauroral electron content varied by 100 and f layer heights oscillated by 200 km equatorial plasma irregularities extended in plumes to heights of 1400 km later energetic particle fluxes at geo recovered and rose by more than an order of magnitude a satellite anomaly was reported during the interval of high energetic electron flux model results indicate an upper atmospheric temperature increase of 200 k within 24 hours of storm onset joule heating for the first 24 hours of the storm was more than 3 times that for typical active geomagnetic conditions we estimate that total global ionospheric heating for the full storm interval was 190 pj with 30 of that generated within 24 hours of storm onset

physical mechanisms of the ionospheric storms at equatorial and higher latitudes during the recovery phase of geomagnetic storms 1 the paper studies the physical mechanisms of the ionospheric storms at equatorial and higher latitudes which are generally opposite both during the main phase mp and recovery phase rp of geomagnetic storms the mechanisms are based on the natural tendency of physical systems to occupy minimum energy state which is most stable the paper first illustrates the recent developments in the understanding of the mechanisms during daytime mps when generally negative ionospheric storms in nmax and tec develop at equatorial latitudes and positive storms occur at higher latitudes including why the storms are severe only in some cases the paper then investigates the relative importance of the physical mechanisms of the positive ionospheric storms observed at equatorial latitudes within 15 during daytime rps when negative storms occur at higher latitudes using champ ne and gps tec data and sheffield university plasmasphere ionosphere model the results indicate that the mechanical effect of the storm time equatorward neutral winds that causes plasma convergence at equatorial f region could be a major source for the positive storms with the downwelling effect of the winds and zero or westward electric field if present acting as minor sources

long chain alkenones in baltic sea surface sediments new insights abstract c 37 alkenones produced by certain haptophytes of the isochrysidales are valuable sedimentary biomarkers used to estimate sea surface temperature sst in the open ocean however in coastal seas the role of salinity gradients on alkenone producing species and sst estimates is poorly known alkenones were analyzed in surface sediments from the marine skagerrak region and the entire brackish baltic sea three types of alkenone distribution patterns were identified type a distribution which resembles the distribution in emiliania huxleyi type b distribution which is similar to ruttnera lamellosa isochrysis galbana and pseudoisochrysis paradoxa distributions although these haptophytes are absent from the baltic sea and type c distribution which is also found in worldwide lake sediments these types of distribution are apparent in the percentage of c 37 4 alkenone c 37 4 which is significantly negatively correlated to sea surface salinity sss the distribution of alkenones very likely results from distinct alkenone producing haptophytes whose spatial distribution is ultimately related to sss as supported by the hydrogen isotope fractionation between alkenones and water u 37 k and u 37 k correlate more significantly than u 37 k with both sst and sss probably due to the superimposed effect of changing alkenone producing species the application of u 37 k and u 37 k as sst proxies results in unrealistic holocene temperature records for the southern baltic sea but c 37 4 as a sss proxy reveals reasonable salinity changes interestingly a c 32 hopanoic acid was found abundantly as the methyl ester in the ketone fractions and may represent a marker for cyano bacterial biomass in the baltic sea

biomarker features of sabkha associated microbialites from the zechstein platy dolomite upper permian of northern poland abstract the zechstein upper permian platy dolomite deposits of the eba elevation n poland formed a shallow water carbonate platform developed in hypersaline peritidal arid system dominated by various microbialite lithofacies extractable hydrocarbons from the platy dolomite microbialite carbonate deposits from the eba elevation n poland show a predominance of even carbon numbered n alkanes within the range of c 20 to c 30 maximum at n c 24 hopanes are represented by the 17 h 21 h and 17 h 21 h series with carbon numbers ranging from c 29 to c 35 plus minor amounts of 17 h 22 29 30 trisnorhopane 17 h 22 29 30 trisnorhopane and gammacerane despite the absence of 17 h 21 h hopanes an anomalously high content of c 29 c 30 17 h 21 h hopanes and the extent of epimerization at c 22 below the value of the equilibrium value for the c 31 c 35 compounds of both 17 h 21 h and 17 h 21 h hopane series indicate the immaturity of the organic matter organic geochemistry data confirm that the organic matter originated from degraded cyanobacterial and bacterial remains

response of the equatorial and low latitude ionosphere in the indian sector to the geomagnetic storms of january 2005 1 the equatorial and low latitude ionospheric response to three moderate geomagnetic storms 17 18 and 22 january during the period from 16 to 23 january 2005 is investigated in the context of development inhibition of the equatorial ionization anomaly eia and the subsequent occurrence nonoccurrence of equatorial spread f esf irregularities on these days the study is carried out using the total electron content tec measured with the gps receivers along the 80 e longitude sector and the f layer bottom height obtained from the ionosonde located over the dip equatorial location of trivandrum 8 5 n 77 e dip latitude 0 5 n in india it is observed that for the storms on days 17 and 22 the development of the anomaly was inhibited probably due to the westward disturbance dynamo electric fields subsequently the post sunset enhancement in the vertical drift of the equatorial f region was also inhibited significantly compared to the quiet day pattern and as anticipated no esf was observed on these days a large vertical drift of the equatorial f region followed by nearly simultaneous onset of weak esf was observed on day 18 the late development of the eia on this day could be due to the eastward prompt penetration electric field associated with the southward turning of the interplanetary magnetic field also strong and distinct f3 layer appeared for a short time in the morning reappeared later in the noon time and then quickly ascended to the topside ionosphere during the main phase of the storm on day 18

molecular and stable carbon isotopic compositions of hopanoids in seep carbonates from the south china sea continental slope abstract the lipid biomarkers of hopanoids in cold seep carbonates from the south china sea continental slope were investigated by gas chromatography mass spectrometer gc ms and gas chromatography isotope ratio mass spectrometer gc ir ms the distribution of hopanes hopenes shows a preference for the biological 17 h 21 h over the geological 17 h 21 h configuration this interpretation is in agreement with the strong odd even preference of long chain n alkanes in those samples suggesting that the hopanes may be the early diagenetic products of biohopanoids and the configurations of hopanes were mainly derived from allochthonous sources contributing to the organic matter of the carbonates in terms of hopanoid acids the c30 to c33 17 h 21 h hopanoid acids were detected with c32 17 h 21 h hopanoid acid being the most abundant however there is a significant difference in stable carbon isotopic compostions of the c32 17 h 21 h hopanoic acid among samples 30 7 to 69 8 the 13c values match well with the carbon isotopic compositions of srb derived iso anteiso c15 0 fatty acids in the samples which strongly depend on the carbon utilization types by microbe the most abundant compound of hopanols detected in the samples c30 17 h 21 h hopanol may be a good indicator of diagenetic product of type i methanotrophs the molecular and carbon isotopic compositions of hopanoids demonstrate clearly that there is a combination contribution of both srb and type i or type x methanotrophs to the source organism in the seep carbonates from the south china sea continental slope

unusual distributions of long chain alkenones and tetrahymanol from the highly alkaline lake van turkey long chain c37 to c40 alkenones with di tri and tetra unsaturation are very abundant in sediment trap material and holocene to late pleistocene core samples from the earth s largest soda lake lake van turkey thus the known distribution range of these typical biomarkers for haptophyte microalgae is extended to highly alkaline environments the observed unsaturation patterns differ strikingly from those found in open marine haptophytes and sediments by an enhanced relative abundance of the tetra unsaturated compounds especially the c37 4 methyl ketone their preponderance is suggested to be a facies marker pattern for lacustrine and marginal marine areas of sedimentation using published u37k calibrations no reliable absolute temperatures were obtained for the lake van samples accordingly marine sea surface temperature determinations based on long chain alkenones should be applied with caution when a contribution of these compounds from coastal or nonmarine sources can not be excluded the presence of tetrahymanol and gammacer 3 one in the lake van materials is attributed to organic matter contributions of ciliates the relative abundance of long chain alkenones and of tetrahymanol gammacer 3 one is considered to reflect changes in the environmental conditions in particular in the hydrological setting we suggest that times of pronounced stagnation are recognised by very high tetrahymanol gammacer 3 one concentrations together with drastically increased stanol stenol ratios and intervals of enhanced convection or of high freshwater input are characterised by high alkenone contributions

bacteriohopanepolyols in hydrothermal vent biogenic silicates abstract biogenic silicates from the taupo volcanic zone north island new zealand are shown to contain a number of unusual polyfunctionalised bacteriohopanepolyols hopanoid fractions isolated from the rotokawa hot spring 80 82 c contained significant amounts of 32 35 anhydrobacteriohopanetetrol and two isomers of a related trihydroxylated compound the origin of these unusual hopanoid side chains is unclear and they may result either from novel biosynthetic or diagenetic transformation pathways of known biohopanoid precursors such as bacteriohopanetetrol via cyclisation or reductive removal of adenine from adenosylhopane

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