The dynamics of phytoplankton, bacteria and heterotrophic flagellates at two Banks near Magdeburg in the River Elbe (Germany)     

Bernhard Karrasch  Maren Mehrens  Yvonne Rosenlcher  Karla Peters 《Limnologica》2001,31(2)

The main objectives of this study were to describe the seasonal standing stock dynamics of phytoplankton, bacterioplankton and heterotrophic flagellates in the highly eutrophic River Elbe (Germany), and to compare the seasonal patterns observed with other streams. Emphasis was placed on examining and assessing abiotic and biotic controlling factors influencing the structure and dynamics of the riverine plankton. All the physico-chemical and biological parameters determined were within the range or somewhat higher (in the case of phytoplankton abundance and biomass) than reported for other large streams. The underwater light conditions resulting from atypically short phytoplankton growth periods of about 6 months per year and the low phytoplankton carbon to chl a ratio of 23 were identified as a major limiting factor for phytoplankton development in the River Elbe. The seasonal distribution pattern of bacterioplankton indicated probable tight trophodynamical coupling both with phytoplankton and with heterotrophic flagellates, whereas heterotrophic flagellates showed a more trophic link with bacterial densities. Although approximately constant DOC and DON levels throughout the year sustained bacterial growth rates, during the phytoplankton growing season an increase of bacterial standing stocks was observed. Although the left-bank sampling site of the Elbe is strongly influenced by the tributaries Mulde and Saale containing higher concentrations of chloride, nitrogen nutrients, heavy metals and organic pollutants, no clear differences were observed between the two sides of the river concerning the biological parameters measured. Possible reasons and the slightly higher phytoplankton abundance and diversity at the right bank are discussed.  相似文献   

vii + 252 S. mit 133 Abb. u. 24 TabY.I. Sorokin, Aquatic Microbial Ecology Preis: Hfl 128,-, A Textbook for Students in Environmental Sciences, Backhuys Publishers, Leiden (NL) (1999) ISBN 90-5782-027-7.     

C.-J. Schulz 《Limnologica》2001,31(2)

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Modeling ocean–atmosphere carbon budgets during the Last Glacial Maximum–Heinrich 1 meltwater event–Bølling transition     

M. Schulz  D. Seidov  M. Sarnthein  K. Stattegger 《International Journal of Earth Sciences》2001,90(2):412-425

Benthic carbon isotope data indicate that the rate of North Atlantic Deep Water (NADW) formation and the mode of oceanic thermohaline circulation (THC) varied considerably across the transition from the Last Glacial Maximum (LGM) to the Heinrich 1 meltwater event (MWE) and, subsequently, to the Bølling warm period. We simulate changes in the Ocean-atmosphere carbon cycle induced by and linked to these oceanic fluctuations by means of a carbon cycle box model which resolves the major oceanic basins. The output from an ocean general circulation model (OGCM), which is forced by observed or reconstructed boundary conditions at its surface, serves to constrain the physical parameters of the carbon cycle model. The OGCM depicts three modes of Atlantic THC: an interglacial mode with vigorous NADW formation; a glacial mode with active, although weaker (-65%) NADW formation; and an MWE mode characterized by the complete lack of NADW formation. The carbon cycle model is forced from the LGM scenario into the MWE and finally into the Bølling interstadial. The glacial circulation mode accounts for approximately half (i.e., 37Dž µatm, depending on parameterization of biological productivity) of the observed glacial reduction in atmospheric CO₂ partial pressure (pCO₂). Approximately 70% of this pCO₂ decline is linked to changes in sea-surface temperature and salinity. The MWE circulation mode has only a small effect on atmospheric pCO₂ (ǃ µatm) but goes along with a massive redistribution of carbon from the Indo-Pacific and Southern oceans to the Atlantic Ocean, which stores 85NJ Gt (gigatons) excess carbon during the MWE. The onset of NADW formation after a meltwater event, has the potential to release 81Lj Gt carbon from the model ocean to the atmosphere, corresponding to an atmospheric pCO₂ increase by 38Dž µatm, equivalent to approximately half of the modern, man-made pCO₂ load.  相似文献   

The DAV and Periadriatic fault systems in the Eastern Alps south of the Tauern window     

Neil S. Mancktelow  Daniel F. Stöckli  Balz Grollimund  Wolfgang Müller  Bernhard Fügenschuh  Giulio Viola  Diane Seward  Igor M. Villa 《International Journal of Earth Sciences》2001,90(3):593-622

Alpine deformation of Austroalpine units south of the Tauern window is dominated by two kinematic regimes. Prior to intrusion of the main Periadriatic plutons at ~30 Ma, the shear sense was sinistral in the current orientation, with a minor north-side-up component. Sinistral shearing locally overprints contact metamorphic porphyroblasts and early Periadriatic dykes. Direct Rb-Sr dating of microsampled synkinematic muscovite gave ages in the range 33-30 Ma, whereas pseudotachylyte locally crosscutting the mylonitic foliation gave an interpreted ⁴⁰Ar-³⁹Ar age of ~46 Ma. The transition from sinistral to dextral (transpressive) kinematics related to the Periadriatic fault occurred rapidly, between solidification of the earlier dykes and of the main plutons. Subsequent brittle-ductile to brittle faults are compatible with N-S to NNW-SSE shortening and orogen-parallel extension. Antithetic Riedel shears are distinguished from the previous sinistral fabric by their fine-grained quartz microstructures, with local pseudotachylyte formation. One such pseudotachylyte from Speikboden gave a ⁴⁰Ar-³⁹Ar age of 20 Ma, consistent with pseudotachylyte ages related to the Periadriatic fault. The magnitude of dextral offset on the Periadriatic fault cannot be directly estimated. However, the jump in zircon and apatite fission-track ages establishes that the relative vertical displacement was ~4-5 km since 24 Ma, and that movement continued until at least 13 Ma.  相似文献   

Evidence for the trapped liquid shift effect in the Mount Ayliff Intrusion,South Africa   总被引：1，自引：2，他引：1  

R. Grant Cawthorn  Bernhard K. Sander  Ian M. Jones 《Contributions to Mineralogy and Petrology》1992,111(2):194-202

Postcumulus trapped liquid shift in layered complexes produces cumulate minerals with more fractionated compositions than the original primary phases. This effect is shown by olivine compositions from the base of the Mount Ayliff Intrusion, where varying proportions of olivine to interstitial liquid produce a suite of rocks which define a tight linear trend on a binary whole-rock plot of MgO versus FeO. Extrapolation of this trend constrains the composition of the primary cumulus olivine to the range Fo_84–86, whereas olivine actually present have compositions Fo_77–83. The magnitude of the discrepancy between the theoretical and observed olivine compositions correlates directly with the weight fraction of interstitial liquid. These observations are quantitatively predicted by the trapped liquid shift model. They also argue against significant migration of residual liquid. Trapped liquid shift is documented over a vertical interval of 60 m. It occurred in rocks lying only 1 m above the basal contact of the intrusion and hence must be a comparatively rapid process.  相似文献   

Editorial     

Gerhard Furrer  Bernhard Wehrli  Heinz Gamsjäger 《Aquatic Sciences - Research Across Boundaries》1993,55(4):229-229

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Das erdmagnetische Feld im Jahr 1992 nach Messungen des Erdmagnetischen Observatoriums Wingst     

Günter Schulz 《Ocean Dynamics》1993,45(3):215-218

Ohne Zusammenfassung  相似文献   

Unterwasserbeobachtungen im sublitoralen Solfatarenfeld von Vulcano (Äolische Inseln,Italien)     

Oskar Schulz 《Mineralium Deposita》1970,5(3):315-319

Zusammenfassung Unterwasserbeobachtungen im sublitoralen Solfatarenfeld von Vulcano brachten Einzelheiten über die verschiedene Gestaltung des Meeresbodenreliefs im Bereich der Gasaustritte und über die Anlagerung von kolloidalem Schwefel. Die Befunde werden anhand mehrerer Unterwasserphotographien erläutert und es wird auf die Ähnlichkeit der rezenten Bodengestaltung mit gewissen aus triadischen Pb-Zn-Erzlagerstätten bekannten Gefügen hingewiesen. Hinweise auf Flora und Fauna im Bereich der submarinen Vulkanexhalationen ergänzen die Untersuchungen.

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Underwater studies in the sublitoral field of solfataras of Vulcano revealed details on the relief of the sea bottom in areas with volcanic exhalations and on the deposition of colloidal sulphur. The observations made are illustrated by several underwater photographs. The similarity between the recent shape of the ground and certain fabrics known from Triassic Pb-Zn- ore deposits is pointed out. These studies are supplemented by short data on the abundant flora and fauna in the area of the submarine volcanic exhalations.

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Quasi-exospheric heat flux of solar-wind electrons     

Aharon Eviatar  Michael Schulz 《Astrophysics and Space Science》1976,39(1):65-73

Density, bulk-velocity, and heat-flow moments are calculated for truncated maxwellian distributions representing the cool and hot populations of solar-wind electrons, as realized at the base of a hypothetical exosphere. The electrostatic potential is thus calculated by requiring charge quasineutrality and the absence of electrical current. Plasma-kinetic coupling of the cool-electron and proton bulk velocities leads to an increase in the electrostatic potential and a decrease in the heat-flow moment. If the velocities differ by the Alfvén speed along the magnetic field, for example, the potential rises to 72.6 V and the heat flux falls to 2.72×10^–2 erg cm^–2 s^–1. In each case the heat flux is carried mainly by the quasi-exospherichot electrons.  相似文献   

ADS40航空数码摄影相机的校准     

李月锋 《测绘技术装备》2006,8(3):41-44

高性能的航摄相机需要高分辨率几何校准、光谱校准和辐射线测量校准。LH系统公司和德国宇航中心(DLR)拥有符合这些严格规范的仪器。本文论述了LH系统公司新的ADS40数码摄影相机的基本操作原理,并给出了第一次交叉测量的结果。  相似文献