Perylene in sediments from the Namibian Shelf     

Stuart G. Wakeham  Christian Schaffner  Walter Giger  Jaap J. Boon  J.W. De Leeuw 《Geochimica et cosmochimica acta》1979,43(7):1141-1144

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Organic geochemistry of Walvis Bay diatomaceous ooze—I. Occurrence and significance of the fatty acids     

Jaap J. Boon  J.W. De Leeuw  P.A. Schenck 《Geochimica et cosmochimica acta》1975,39(11):1559-1565

Diatomaceous ooze of the shelf off Walvis Bay (S.W. Africa) was analysed for lipid material. The lipids from the sediment consist of a mixture of hydrocarbons, alcohols, ketones, fatty acids, sterols, carotenoid pigments and chlorophylls. The total fatty acid mixture has been analysed by capillary gas chromatography mass spectrometry and shown to consist of straight chain, iso-, anteiso- and isoprenoid acids. The environmental setting of the S.W. African shelf (Walvis Bay) makes it possible to discuss these fatty acids as markers for the fate of organic matter. The acids in the sediment point to a generation during passage of algal lipids through levels of microbial activity either on or slightly above the burial surface.  相似文献   

Effect of artificial maturation on carbazole distributions, as revealed by the hydrous pyrolysis of an organic-sulphur-rich source rock (Ghareb Formation, Jordan)     

Heather Clegg  Brian Horsfield  Heinz Wilkes  Jaap Sinninghe Damst  Martin P. Koopmans 《Organic Geochemistry》1998,29(8):1953-1960

Hydrous pyrolysis experiments were performed on the Ghareb Formation (Upper Cretaceous, Jordan), a carbonate- and organic-rich (TOC 19.6%) source rock, using a temperature range of 200 to 360°C (72 h). The original sediment contains only low amounts of carbazoles, (maximum 2.2 μg/g bitumen for 1-methylcarbazole). With increasing thermal maturation, intense generation begins at temperatures only in excess of 300°C, reaching a maximum at 360°C. Likewise, during natural maturation, generation occurs at later stages of maturity (e.g. for Tithonian source rocks at >0.81% R_r and for Posidonia Shale at >0.88% R_r). Some isomeric changes during hydrous pyrolysis do not resemble those in nature whereas others do. The relative abundances of selected C₁- and C₂-alkylcarbazoles on ternary diagrams reveal differences, whereas the benzo[a]carbazole/benzo[a]carbazole+benzo[c]carbazole ratio is closely similar. The latter result supports the contention that maturation plays a key role in controlling carbazole distributions in source rocks. However, the results for alkylcarbazoles, especially the C₂-carbazoles, are not easy to interpret.  相似文献   

Release of sulfur- and oxygen-bound components from a sulfur-rich kerogen during simulated maturation by hydrous pyrolysis     

Anke Putschew  Christine Schaeffer-Reiss  Philippe Schaeffer  Martin P Koopmans  Jan W de Leeuw  Michael D Lewan  Jaap S Sinninghe Damsté  James R Maxwell 《Organic Geochemistry》1998,29(8):1875-1890

An immature sulfur-rich marl from the Gessosso-solfifera Formation of the Vena del Gesso Basin (Messinian, Italy) has been subjected to hydrous pyrolysis (160 to 330°C) to simulate maturation under natural conditions. The kerogen of the unheated and heated samples was isolated and the hydrocarbons released by selective chemical degradation (Li/EtNH₂ and HI/LiAlH₄) were analysed to allow a study of the fate of sulfur- and oxygen-bound species with increasing temperature. The residues from the chemical treatments were also subjected to pyrolysis–GC to follow structural changes in the kerogens. In general, with increasing hydrous pyrolysis temperature, the amounts of sulfide- and ether-bound components in the kerogen decreased significantly. At the temperature at which the generation of expelled oil began (260°C), almost all of the bound components initially present in the unheated sample were released from the kerogen. Comparison with an earlier study of the extractable organic matter using a similar approach and the same samples provides molecular evidence that, with increasing maturation, solvent-soluble macromolecular material was initially released from the kerogen, notably as a result of thermal cleavage of weak carbon–heteroatom bonds (sulfide, ester, ether) even at temperatures as low as 220°C. This solvent-soluble macromolecular material then underwent thermal cleavage to generate hydrocarbons at higher temperatures. This early generation of bitumen may explain the presence of unusually high amounts of extractable organic matter of macromolecular nature in very immature S-rich sediments.  相似文献   

Origin of low-molecular-weight alkylthiophenes in pyrolysates of sulphur-rich kerogens as revealed by micro-scale sealed vessel pyrolysis     

Jaap S. Sinninghe Damst  Math E. L. Kohnen  Brian Horsfield 《Organic Geochemistry》1998,29(8):1891-1903

Micro-scale sealed vessel (MSSV) pyrolysis experiments have been conducted at temperatures of 150, 200, 250, 300, 330 and 350°C for various times on a thermally immature Type II-S kerogen from the Maastrichtian Jurf ed Darawish Oil Shale (Jordan) in order to study the origin of low-molecular-weight (LMW) alkylthiophenes. These experiments indicated that the LMW alkylthiophenes usually encountered in the flash pyrolysates of sulphur-rich kerogens are also produced at much lower pyrolysis temperatures (i.e. as low as 150°C) as the major (apart from hydrogen sulfide) sulphur-containing pyrolysis products. MSSV pyrolysis of a long-chain alkylthiophene and an alkylbenzene indicated that at 300°C for 72 h no β-cleavage leading to generation of LMW alkylated thiophenes and benzene occurs. In combination with the substantial production of LMW alkylthiophenes with a linear carbon skeleton at these conditions, this indicated that these thiophenes are predominantly formed by thermal degradation of multiple (poly)sulfide-bound linear C₅–C₇ skeletons, which probably mainly originate from sulphurisation of carbohydrates during early diagenesis. LMW alkylthiophenes with linear carbon skeletons seem to be unstable at MSSV pyrolysis temperatures of ≥330°C either due to thermal degradation or to methyl transfer reactions. LMW alkylthiophenes with a branched carbon skeleton most likely derive from both multiple (poly)sulfide-bound branched C₅–C₇ skeletons and alkylthiophene units present in the kerogen.  相似文献   

Estimation of impact of climate change on the peak discharge probability of the river Rhine   总被引：2，自引：0，他引：2  

Jaap Kwadijk  Hans Middelkoop 《Climatic change》1994,27(2):199-224

RHINEFLOW is a GIS based water balance model that has been developed to study the changes in the water balance compartments of the river Rhine basin on a monthly time basis. The model has been designed to study the sensitivity of the Rhine discharge to a climate change. The calculated discharge has been calibrated and validated on the period 1956 to 1980. For this period the model efficiency of RHINEFLOW is between 0.74 and 0.81 both for the entire Rhine and for its tributaries. Also calculated values for variations in other compartments, e.g. snow storage and actual evapotranspiration, were in good agreement with the measured values.Since a high correlation between monthly discharge and peak discharge was found for the period 1900–1980 The RHINEFLOW model is used to assess the probability of exceedence for discharge peaks under possible future climate conditions.The probabilities of exceedence were calculated from the conditional probabilities of peak discharges for a series of 15 classes of monthly discharges. Comparison of a calculated frequency distribution of high discharge peaks with observed peaks in a test series showed that the method performs well.Scenarios for temperature changes between 0 °C and plus 4 °C and precipitation changes between plus 20% and minus 20% have been applied. Within this range flood frequencies are more sensitive for a precipitation change than for a temperature change. The present two-year return period peak flow (6500–7000 m³/s) decreases by about 6% due to a temperature rise of 4 °C; a precipitation decrease of 20% leads to 30% lower two-year peaks whilst 20% precipitation increase raises them by approximately 30%.Application of a Business As Usual (BAU) and an Accelerated Policy (AP) climate scenario resulted in a significant increase in probability of peak flows for the BAU scenario, while for the AP scenario no significant change could be found. Due to sampling errors, accurate estimations of recurrence times of discharge peaks7000 m³/s require a longer sampling time series than 90 years. For management purposes the method can be applied to estimate changes of probabilities of events with a relatively long recurrence time.  相似文献   

The influence of oxic degradation on the sedimentary biomarker record I: evidence from Madeira Abyssal Plain turbidites     

Marcel J.L. HoefsW.Irene C. Rijpstra  Jaap S. Sinninghe Damsté 《Geochimica et cosmochimica acta》2002,66(15):2719-2735

Free and ester-bound lipid biomarkers were analysed in oxidised and unoxidised parts of four distinct turbidites from the Madeira Abyssal Plain (MAP), which contained 1 to 2% organic carbon homogeneously distributed throughout the turbidites at the time they were deposited. These turbidites are well suited to study the effects of oxic degradation on lipid biomarkers without the complicating influence of varying organic matter sources, sedimentation rates, or bioturbation. One sample from the oxidised turbidite was compared with two samples from the unoxidised part of each turbidite. Postdepositional oxic degradation decreased concentrations of biomarkers by several orders of magnitude. The ester-bound lipids were degraded to a far lesser extent than their free counterparts were. The extent of degradation of different compounds differed substantially. Within a specific class of biomarkers, degradation also took place to a different extent, altering their distributions. This study shows that oxic degradation of the organic matter may have a profound effect on the biomarker fingerprint and may result in a severe bias in, for example, the interpretation of organic matter sources and the estimation of the palaeoproductivity of specific groups of phytoplankton.  相似文献   

First evidence for the Cenomanian–Turonian oceanic anoxic event (OAE2, ‘Bonarelli’ event) from the Ionian Zone,western continental Greece     

Vassilis Karakitsios  Harilaos Tsikos  Yvonne van Breugel  Lyda Koletti  Jaap S. Sinninghe Damsté  Hugh C. Jenkyns 《International Journal of Earth Sciences》2007,96(2):343-352

Integrated biostratigraphic (planktonic foraminifera, calcareous nannofossils), chemostratigraphic (bulk C and O isotopes) and compound-specific organic geochemical studies of a mid-Cretaceous pelagic carbonate—black shale succession of the Ionian Zone (western Greece), provide the first evidence for the Cenomanian–Turonian oceanic anoxic event (OAE2, ‘Bonarelli’ event) in mainland Greece. The event is manifested by the occurrence of a relatively thin (35 cm), yet exceptionally organic carbon-rich (44.5 wt% TOC), carbonate-free black shale, near the Cenomanian–Turonian boundary within the Vigla limestone formation (Berriasian–Turonian). Compared to the ‘Bonarelli’ black-shale interval from the type locality of OAE2 in Marche–Umbria, Italy, this black shale exhibits greatly reduced stratigraphic thickness, coupled with a considerable relative enrichment in TOC. Isotopically, enriched δ¹³C values for both bulk organic matter (−22.2‰) and specific organic compounds are up to 5‰ higher than those of underlying organic-rich strata of the Aptian-lower Albian Vigla Shale member, and thus compare very well with similar values of Cenomanian–Turonian black shale occurrences elsewhere. The relative predominance of bacterial hopanoids in the saturated, apolar lipid fraction of the OAE2 black shale of the Ionian Zone supports recent findings suggesting the abundance of N₂-fixing cyanobacteria in Cretaceous oceans during the Cenomanian–Turonian and early Aptian oceanic anoxic events.  相似文献   

Clionid sponge surveys on the Florida Reef Tract suggest land-based nutrient inputs   总被引：1，自引：0，他引：1  

Ward-Paige CA  Risk MJ  Sherwood OA  Jaap WC 《Marine pollution bulletin》2005,51(5-7):570-579

Bioerosion by Cliona delitrix and Cliona lampa was assessed at 43 sites along the Florida Reef Tract, USA, in the summer of 2001. Sponge abundances were estimated using rapid visual assessment. Tissue samples of sponges were taken for analysis of delta15N. Comparison samples were taken from Belize. Annual trends in sponge abundance were estimated from archived videos covering the period from 1996 to 2001. Sites with the greatest boring sponge size and cover were in the Backcountry and Lower Keys, where total nitrogen, ammonium, and delta15N levels were highest. The sites with the largest relative increase of C. delitrix and C. lampa over the 5 year period were in the Upper Keys, where the greatest relative decline in stony coral cover has occurred. Florida sponge delta15N values were 5.2(+/-0.1)%, suggesting the influence of human waste; in comparison, offshore Belize samples were 2.1(+/-0.1)%. These results suggest sewage contamination of the Florida Reef Tract, shifting the carbonate balance from construction to destruction.  相似文献   

The analysis of wax esters,very long mid-chain ketones and sterol ethers isolated from walvis bay diatomaceous ooze     

Jaap J. Boon  J.W. de Leeuw 《Marine Chemistry》1979,7(2):117-132

Wax esters (ranging from C₃₂ to C₄₄), very long mid-chain ketones (ranging from C₃₁ to C₄₃) and sterol ethers were isolated from Walvis Bay diatomaceous ooze and identified by glass capillary gas chromatography/mass spectrometry and direct probe high-resolution mass spectrometry.The wax ester compositions of co-eluting wax esters with the same molecular weight were determined from fragment ions characteristic for the alcohol and fatty acid moieties. Dominant wax esters are the C₃(16F-20A), C₃₆(18F-18A), C₃₈(16F-22A), C₃₈(18F-20A), C₄₀(18F-22A), C₄₀(20F-20A) and C₄₀(24F-16A).The presence of isoprenoid wax esters and the chain length distributions of alcohol and fatty acid moieties point to an origin from zooplankton. The position of the ketogroup in the mid-chain ketones is determined from characteristic fragment ions. Major ketones are the C₃₈(C₁₈H₃₇-CO-C₁₉H₃₉) and C₄₀(C₁₈H₃₇-CO-C₂₁H₄₃).The sterol ethers have C₈ and C₉ ether moieties and C₂₇, C₂₈, and C₂₉ steroid moieties. The origin and significance of the ketones and the sterol ethers is obscure.  相似文献