Origin of organic sulphur compounds and sulphur-containing high molecular weight substances in sediments and immature crude oils     

Jaap S. Sinninghe Damst  W. Irene  C. Rijpstra  Jan W. de Leeuw  P.A. Schenck 《Organic Geochemistry》1988,13(4-6)

The distribution patterns of Organic Sulphur Compounds (OSC), occurring in certain sediments and immature crude oils, were compared with those of the corresponding hydrocarbons. Because of the complexity of the OSC mixtures, they were desulphurized to hydrocarbons (n-alkanes, isoprenoid alkanes, steranes, triterpanes and branched alkanes). The hydrocarbons produced by desulphurization of the OSC exhibited distribution patterns different from those of the hydrocarbons originally present. Therefore reaction of elemental sulphur with these hydrocarbons at elevated temperatures must be considered as an unlikely origin for these OSC. Sulphur incorporation reactions on an intramolecular basis with suitable functionalized precursors at the early stages of diagenesis are probably the major origin for these OSc. Desulphurization of high molecular weight fractions also produced hydrocarbons, dominated by n-alkanes up to C₄₀. Therefore it is assumed that these substances contain n-alkanes, 2,5-dialkyl-thiophenes and -thiolanes linked to each other by sulphur briddges. These findings stronly suggest that sulphur-containing high molecular weight substances are formed by the same sulphur incorporation reactions as OSC, but in an intermolecular fashion.  相似文献   

Application of the TEX₈₆ temperature proxy to the southern North Sea     

Lydie Herfort  Stefan Schouten  Jan P. Boon  Jaap S. Sinninghe Damst 《Organic Geochemistry》2006,37(12):1715

A novel temperature proxy, the tetraether index of lipids with 86 carbon atoms (TEX₈₆), was applied to the suspended particulate organic matter (POM) and sediment core tops from eight sites in the southern North Sea in different seasons. The TEX₈₆-derived temperatures in many samples did not correlate with mean annual sea surface temperature (SST), but were shifted toward winter SST, apparently because Crenarchaeota are more abundant and metabolically active during periods of low primary production. This indicates that TEX₈₆-derived SST estimates do not necessarily reflect annual mean SST and may provide essential information about seasonal SST palaeoreconstruction. High TEX₈₆-derived SSTs were measured in the water of the river Rhine and in the sediment core tops and seawater from several stations in the southern North Sea. These sites were all characterised by important input of organic matter from soil and peat, as revealed by the relatively high values obtained with the new terrestrial proxy, the branched and isoprenoid tetraether (BIT) index. These data demonstrate that to reconstruct palaeotemperatures it is essential to estimate both TEX₈₆ and BIT indices to check that TEX₈₆ temperatures are not biased as a result of large terrestrial input. Important seasonal variations in TEX₈₆-derived SST were also evident for the surface sediments of several stations characterised by extremely low sedimentation rates, indicating temporary settlement of laterally transported organic matter with a warmer temperature signal. This implies that sediment core top correlations between TEX₈₆ and mean annual SST should not be carried out in areas characterised by transient sediment deposition.  相似文献   

Lithotype discrimination within a gridded model by inverting gravity data     

Tim van Zon  Pavel Ditmar  Kabir Roy Chowdhury  Jaap Mondt 《Geophysical Journal International》2007,170(2):481-491

In this paper we present a method which allows delineation of geologic structures in a bi-modal lithotype setting. We propose to use gravity data in combination with a priori information about the density contrast between the two lithotypes. The iterative method uses an objective function with five tunable parameters which need to be set. Using an efficient parameter search, suitable ranges of these are investigated to determine their optimal values, respectively, which in turn, ensures good inversion results.
The approach produces structural images of the subsurface, without the need of an a priori density model; the depth to the top of the inhomogeneity is also retrieved.
Besides synthetic simulations, the methodology has also been applied to a small gravity data set, acquired by the industry over a basinal structure. A consistent, bi-modal image of the bedrock depression is obtained from the data, which, in this case, was the goal. Other potential areas of application include delineation of salt structures and ore deposits.  相似文献   

Estudos do Quaternario. Revista de Associação Portuguesa para o Estudio do Quaternario (Quaternary Studies. Journal of the Portuguese Association for Quaternary Research) Price in EU is US$ 17.50, outside EU it is US$ 20.     

Jaap J. M. Van Der Meer 《第四纪科学杂志》1999,14(5):471-471

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Tetraether membrane lipid distributions in water-column particulate matter and sediments: a study of 47 European lakes along a north–south transect     

Cornelia Iulia Blaga  Gert-Jan Reichart  Oliver Heiri  Jaap S. Sinninghe Damsté 《Journal of Paleolimnology》2009,41(3):523-540

We studied the distribution of glycerol dialkyl glycerol tetraethers (GDGTs) in water-column particulate matter and the top 5 cm of sediment from 47 lakes along a transect from southern Italy to the northern part of Scandinavia. Our objective was to investigate the biological sources and potential palaeoenvironmental applications of GDGTs in lacustrine sediments. Both archaea-derived isoprenoid and bacteria-derived branched GDGTs, produced by yet unknown soil bacteria, were identified in all lake sediments. GDGT distributions varied substantially. Crenarchaeotal GDGTs, including the characteristic GDGT crenarchaeol, were found in varying relative concentrations, and were more dominant in lakes from the Alps and some of the lakes from the more southern part of the latitudinal transect. In some lakes, we observed high amounts of the GDGT with no cyclopentane moieties relative to crenarchaeol. As methanogenic Euryarchaeota are known to biosynthesise this GDGT predominantly, these Archaea, rather than Crenarchaeota, may be its dominant biological source. In most of the lakes, high amounts of soil-bacteria-derived, branched GDGTs (>40% of total GDGTs) indicated a substantial contribution from soil erosion. Branched GDGTs dominated, especially in the northern lakes, possibly related to high soil-erosion rates. In many of the lakes, soil input affects the distribution of isoprenoidal GDGTs and prevents the reliable application of the TEX₈₆ temperature proxy for lake water temperature, which is based on in situ crenarchaeotal GDGTs production. In 9 out of the 47 lakes studied, the TEX₈₆ temperature proxy could be used reliably. When we compared the TEX₈₆ correlation with annual and winter lake-surface temperature, respectively, the relationship between TEX₈₆ and winter temperature was slightly stronger. This may indicate the season in which these GDGT-producing organisms have their peak production.  相似文献   

Predictive land value modelling in Guatemala City using a geostatistical approach and Space Syntax     

Jose Morales  Alfred Stein  Johannes Flacke  Jaap Zevenbergen 《International journal of geographical information science》2020,34(7):1451-1474

ABSTRACT

Spatial information of land values is fundamental for planners and policy makers. Individual appraisals are costly, explaining the need for predictive modelling. Recent work has investigated using Space Syntax to analyse urban access and explain land values. However, the spatial dependence of urban land markets has not been addressed in such studies. Further, the selection of meaningful variables is commonly conducted under non-spatialized modelling conditions. The objective of this paper is to construct a land value map using a geostatistical approach using Space Syntax and a spatialized variable selection. The methodology is applied in Guatemala City. We used an existing dataset of residential land value appraisals and accessibility metrics. Regression-kriging was used to conduct variable selection and derive a model for spatial prediction. The prediction accuracy is compared with a multivariate regression. The results show that a spatialized variable selection yields a more parsimonious model with higher prediction accuracy. New insights were found on how Space Syntax explains land value variability when also modelling the spatial dependence. Space Syntax can contribute with relevant spatialized information for predictive land value modelling purposes. Finally, the spatial modelling framework facilitates the production of spatial information of land values that is relevant for planning practice.  相似文献   

A new ‘microstructural mapping’ methodology for the identification,analysis and interpretation of polyphase deformation within subglacial sediments     

Emrys Phillips  Jaap J.M. van der Meer  Amanda Ferguson 《Quaternary Science Reviews》2011,30(19-20):2570-2596

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Seasonal changes in glycerol dialkyl glycerol tetraether concentrations and fluxes in a perialpine lake: Implications for the use of the TEX₈₆ and BIT proxies     

Cornelia I. Blaga  Gert-Jan Reichart  André F. Lotter  Jaap S. Sinninghe Damsté 《Geochimica et cosmochimica acta》2011,75(21):6416-6428

To determine where and when glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in lakes are produced, we collected descending particles in Lake Lucerne (Switzerland) using two sediment traps (at 42 and 72 m water depth) with a monthly resolution from January 2008 to late March 2009. Suspended particulate matter (SPM) was monthly filtered from the water column at three different depths. The potential application of GDGTs in palaeoenvironmental and palaeoclimatic reconstructions was investigated by comparing core lipids and their relative GDGT distribution, with lake water temperatures throughout the year. Fluxes of GDGTs and their concentrations in the water column vary according to a seasonal pattern, showing a similar trend in the SPM and sediment traps. Fluxes and concentrations of isoprenoid GDGTs increase with depth, maximum values being observed in the deeper part of the water column, indicating production of isoprenoid GDGTs by Thaumarchaeota in the deep (∼50 m), aphotic zone of Lake Lucerne. The flux-weighted averages of the proxies TEX₈₆ (0.27) and BIT (0.03) based on the total extracted GDGTs are similar at both trap depths. A sediment core from the same location showed that in the first few centimetres of the core TEX₈₆ and BIT values of 0.29 and 0.07, respectively, are similar to those recorded for descending particles and SPM, indicating that the sedimentary TEX₈₆ records the annual mean temperature of deeper waters in Lake Lucerne. TEX₈₆ values are slightly higher below 20 cm in the core. This offset is interpreted to be caused by the present-day trophic state of the lake, which probably resulted in a deeper niche of the Thaumarchaeota. Branched GDGTs represent only a minor fraction of the total GDGTs in the lake and their origin remains unclear. Our data reveal that GDGTs in lakes have a large potential for palaeoclimatic studies but indicate that knowledge of the system is important for accurate interpretation.  相似文献   

System Optimisation Of Multi-Beam Aperture Synthesis Arrays For Survey Performance     

Jaap D. Bregman 《Experimental Astronomy》2004,17(1-3):365-380

Investigating the requirements for an aperture synthesis array that optimise the performance for surveying shows that, next to collecting area and system temperature, the field-of-view (FoV) is key parameter. However, the effective sensitivity not only depends on bandwidth and integration time but could be seriously limited by side lobe confusion and by gain errors that determine the effective dynamic range. From the basic sensitivity equation for a radiometric system we derive an optimum cost ratio between collecting area and processing electronics, where the latter should be less than a third of the total cost. For an instrument that has to cover a fraction of sky larger than its field-of-view, the FoV enters the equation for survey sensitivity and we identify the number of independent feed systems per unit collecting area as a key parameter. Then the optimum cost distribution allows the electronics to account for up to half the total cost. Further analysis of the sensitivity formula shows that there is an optimum design frequency for a survey instrument below 1 GHz. We discuss the impact of station size and array configuration on self-calibration, side lobe confusion and effective sensitivity and conclude that a minimum station size of 20 m diameter is required at 0.3 GHz as long as multi-patch self-calibration procedures need, per baseline, a signal-to-noise ratio of more than two for each ionospheric coherence patch.  相似文献   

Encyclopedia of Antarctica and the Southern Oceans,B. Stonehouse (ed.). John Wiley & Sons,Ltd., Chichester, 2002 (391 pp) £245.00/US$375.00/€367.50. ISBN 0‐471‐98665‐8     

Jaap J. M. van der Meer 《第四纪科学杂志》2004,19(8):836-836

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