North Atlantic climate impact on early late‐glacial climate oscillations in the south‐eastern Alps inferred from a multi‐proxy lake sediment record     

Roland Schmidt  Kaarina Weckström  Stefan Lauterbach  Richard Tessadri  Kerstin Huber 《第四纪科学杂志》2012,27(1):40-50

High‐resolution multi‐proxy analyses of a sediment core section from Lake Jeserzersee (Saissersee) in the piedmont lobe of the Würmian Drau glacier (Carinthia, Austria) reveal pronounced climatic oscillations during the early late glacial (ca. 18.5–16.0k cal a BP). Diatom‐inferred epilimnetic summer water temperatures show a close correspondence with temperature reconstructions from the adjacent Lake Längsee record and, on a hemispheric scale, with fluctuations of ice‐rafted debris in the North Atlantic. This suggests that North Atlantic climate triggered summer climate variability in the Alps during the early late glacial. The expansion of pine (mainly dwarf pine) between ca. 18.5 and 18.1k cal a BP indicates warming during the so‐called ‘Längsee oscillation’. The subsequent stepwise climate deterioration between ca. 18.1 and 17.6k cal a BP culminated in a tripartite cold period between ca. 17.6 and 16.9k cal a BP with diatom‐inferred summer water temperatures 8.5–10 °C below modern values and a shift from wet to dry conditions. This period probably coincides with a major Alpine glacier advance termed the Gschnitz stadial. A warmer interval between ca. 16.9 and 16.4k cal a BP separates this cold phase from a second, shorter and less pronounced cold phase between ca. 16.4 and 16.0k cal a BP, which is thought to correlate with the Clavadel/Senders glacier advance in the Alps. The following temperature increase, coupled with wet (probably snow‐rich) conditions, caused the expansion of birch during the transition period to the late glacial interstadial. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

ESR dating of palaeolithic calcite: A comparison between powder and monocrystal spectra with thermal annealing     

Yuji Yokoyama  Roland Bibron  Concle Leger 《Quaternary Science Reviews》1988,7(3-4)

Evolution of ESR spectra with thermal annealing at different temperatures is studied for a monocrystal calcite taken in the Orgnac III site. Up to 20 ESR lines are recognized from the angular dependence of these lines. These lines are compared with the ESR lines observed for powder and rotating monocrystal calcites.The h1 line (g = 2.0057) and h3 line (g = 2.0007) are isotropic or nearly isotropic and are due to the electrons trapped in the amorphous region formed by fission tracks or alpha-ray recoil nuclei. The h2 line (g = 2.0021) is a composite of several different lines.  相似文献   

Electron microscopic examination of hydrothermally treated bentonite clay     

Roland Pusch  Necip Gü  ven 《Engineering Geology》1990,28(3-4):303-314

Water-saturated Na bentonite clay with a bulk density of 2 g/cm³ was autoclaved at 150 and 200°C for up to 0.5 years and then left to rest under confined conditions at room temperature for several weeks. Transmission electron microscopy with elemental micro-analysis was applied to study hydrothermally induced changes, which were found to have the form of particle reorganization and, at 200°C, release and precipitation of silica. The precipitations are suspected to be hydrated amorphous silica gels. The microstructural alteration, which was more obvious at 200°C than at 150°C, involved regrouping of previously dispersed and expanded stacks of montmorillonite flakes to yield dense branches of interwoven, contracted stacks separated by large voids.  相似文献   

Remote sensing of substances in water     

Heinz van der Piepen Dr.  Roland Doerffer Dr. 《GeoJournal》1991,24(1):27-48

Remote sensing of water colour and its application to the mapping of pigments, suspended matter and other substances by means of airborne and spaceborne sensors is discussed. After an introduction to the physical process involved, the methods for a quantitative interpretation especially of CZCS data are indicated. Applications towards the monitoring of coastal pollution, of algae blooms and of dynamic processes are shown by means of selected examples. Multispectral scanner and imaging spectrometer technologies are discussed with special reference to NASA's Earth Observation System and ESA's Earth Observation Programme.  相似文献   

Diatomeen-, pollen- und sedimentmikrostratigraphische Untersuchungen zur anthropogenen Beeinflussung des Höllerer Sees (Oberösterreich)     

Roland Schmidt  Heikki Simola 《Aquatic Sciences - Research Across Boundaries》1991,53(1):74-89

A profundal sediment core from Höllerer See frozen in situ was studied by means of diatom, microstratigraphical tape peel and pollen analyses. Varved sequences reflect eutrophication during mediaeval settlement and according to varve counts a recent eutrophic phase since the 1970's. Mesotrophication in-between coincides with regrowth of forests near the lake.

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Der Quality Status Report (QSR) für Region 7a     

Dr. Roland Salchow 《Ocean Dynamics》1991,44(5-6):363-382

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The physical state of pore water of na smectite used as barrier component     

Roland Pusch  Torbjrn Carlsson 《Engineering Geology》1985,21(3-4):257-265

The molecules constituting the first hydrate layers on montmorillonite crystal platelets appear to be characterized by preferred orientation and, depending on the exchangeable cation, by an ice-like configuration. Such organized interlamellar water is concluded to contribute to the high swelling pressure and shear resistance, as well as to the very low hydraulic conductivity at high clay bulk densities. At low densities the parallel arrangement of the lamellae alters to edge-to-face associations and the fraction of free water increases. However, even at very low densities the homogeneity of the clay gel still offers very tortuous passages to flowing water, which is manifested by a very low hydraulic conductivity.  相似文献   

Creep in rock as a stochastic process     

Roland Pusch 《Engineering Geology》1984,20(4):301-310

The heterogeneous character of rock suggests the use of statistical mechanics for the formulation of models of plasticity and creep. A stochastic creep model which allows for large variations in strength and size of the involved rock mass is outlined. The model, which is analogous to a previously developed concept for clastic materials, is shown to account rather well for typical creep behaviour of rock at moderate stresses and temperatures. Thus, it yields the often observed linear relation between the creep strain and the logarithm of time.  相似文献   

Vertical column abundances of HCN deduced from ground-based infrared solar spectra: Long-term trend and variability     

E. Mahieu  C. P. Rinsland  R. Zander  P. Demoulin  L. Delbouille  G. Roland 《Journal of Atmospheric Chemistry》1995,20(3):299-310

A set of high-resolution IR solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, from 84/06 to 93/06, and at the National Solar Observatory McMath-Pierce solar telescope facility on Kitt Peak, Arizona, U.S.A. from 78/05 to 92/07 have been analyzed to determine the vertical column abundances of hydrogen cyanide, HCN, above the two stations. The analysis was based on least-squares curve fitting of calculated spectra to the observations encompassing the P4 and the P8 lines of HCN respectively located at 3299.5273 and 3287.2483 cm^–1. The results obtained for the two stations indicate that no significant long-term trend affects either of the two databases; however, this analysis reveals variable increases during springtime of up to a factor of 2 in the HCN total column above the Jungfraujoch and even up to 3 above Kitt Peak. The calculated mean vertical column abundances, excluding the spring observations, are equal to (2.55±0.30)×10¹⁵ molec./cm² (S.D.) and (2.75±0.30)×10¹⁵ molec./cm² respectively above the Jungfraujoch and the Kitt Peak observatories. Based on a realistic volume mixing ratio profile, these columns translate into mean volume mixing ratios equal to 190×10^–12 ppv at the respective altitudes of the stations.  相似文献   

Cyclotella-taxa (Bacillariophyceae) in lakes of the Alpine region and their relationship to environmental variables     

Sybille Wunsam  Roland Schmidt  Rolf Klee 《Aquatic Sciences - Research Across Boundaries》1995,57(4):360-386

Surface sediment diatom assemblages for 86 Alpine lakes were analysed focusing on the dominant genusCyclotella and corresponding environmental data. The range of morphological variability of theCyclotella bodanica/radiosa, C. distinguenda, C. ocellata, C. comensis andC. stelligera complexes was documented. Significance tests included in the canonical correspondence analysis (CCA) indicated that total phosphorus, conductivity and surface water temperature were significantly correlated withCyclotella taxa assemblage distribution. Numerical species optima and tolerances were calculated in respect to these significant variables using weighted averaging (WA) regression and calibration. CCA and WA were able to provide information about the environmental preferences of the various morphotypes observed.  相似文献