Climatic change and design criteria in water resources management a regional case study     

Gerd Frch  Friedhelm Garbe  Jürgen Jensen 《Atmospheric Research》1996,42(1-4)

As a result of the anthropogenic greenhouse effect there is fear of alterations of the world climate, which also may result in hydrological changes and consequently in water resources management. In a case study it was investigated if such changes could be identified for a regional catchment area. Summarized it may be said that the regional analysis of hydro-meteorological data in the catchment area of the Sieg showed the expected effects of the anthropogenic climate change on the regional water cycle. Rises in annual mean temperature and precipitation could be observed over a period from 1892 until 1993. However, a significant relation between evident changes and greenhouse effect could not be stated. Changes in discharge do not show consistent behavior. Especially apparent contradictions show that additional examinations are necessary in order to make the complex natural inter-relationships between climate and regional water cycle with the impacts of existing anthropogenetic interferences visible and applicable for practical engineering tasks.  相似文献   

Decadal variability on the northwest european shelf     

Jürgen Sündermann  Gerd Becker  Peter Damm  Dries van den Eynde  Alexander Frohse  Remi Laane  Wim van Leussen  Thomas Pohlmann  Wim van Raaphorst  Günther Radach  Helga Schultz  Marijke Visser 《Ocean Dynamics》1996,48(3-4):365-400

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Die Kreide in der Zentralkordillere östlich von Lima (Peru,Südamerika)     

Prof. Dr. Axel Von Hillebrandt 《International Journal of Earth Sciences》1970,59(3):1180-1203

Lower and Upper Cretaceous sediments were investigated in the Peruvian Central Cordillera. As in the western facies of Central and Northern Peru, the Goyllarisquisga Group is subdivided into several lithologically different formations, in which sediments were transported from east to west. The area of investigation is situated west of the facies boundary between Marañon geanticline and West Peruvian trough; this indicates that the boundary continues south and does not follow the line Celendin-Rio Palanga as suggested byWilson. The limestones and dolomites of the Santa Formation were deposited in shallow water, possibly with intermittent subaerial exposure. The sandstone of the Farrat Formation are interpreted to be sediments of a west-east transgression; vertically they grade into the limestones of the Pariahuanca-Formation. Facies and thickness of the Chulec and Pariahuanca-Formation are little different from those in neighbouring areas. During deposition of the thick Jumasha Formation, the differences are much more significant, and only comparison with Northwest Peru shows some agreement.  相似文献   

Search for exoelectrons in apollo 12 materials     

Richard B. GammageKlaus Becker 《Earth and Planetary Science Letters》1971

The search for exoelectron emission from Apollo 12 materials usually produced negative results, suggesting that the concentration of naturally occurring traps is very low. Weak exoelectron activity was found scattered inhomogeneously within a pigeonite basalt rock and in a deep core tube sample. Its erratic appearance and intensity makes any interpretation of radiation history most difficult and is attributed to the activity being carried by only a few scattered crystals. The thermally stimulated emission of exoelectrons is judged an unsuitable technique for tracing the radiation histories of these samples.  相似文献   

Schwefel-, Kohlenstoff- und Sauerstoff-Isotopenuntersuchungen am Kupferschiefer als Beitrag zur genetischen Deutung     

Gerd Marowsky 《Contributions to Mineralogy and Petrology》1969,22(4):290-334

The isotopic composition of sulfur, carbon and oxygen was determined in 106 samples mainly from profiles of Kupferschiefer occurences in N.W. Germany and N. Holland. From the bulk samples pyrite, non-pyritic sulfides and gypsum have been concentrated for isotopical analysis. C¹³/C¹²-ratios were measured in carbonates and in organic carbon and O¹⁸/O¹⁶-ratios in carbonates and in sulfates. Analytical data on CO₂, C, S in all samples and on Fe, Cu, Zn and Pb in a part of the profile samples are presented.Primary sulfates can be distinguished from sulfates formed from oxydized sulfides by their sulfur and oxygen isotopic composition. The abundance of light carbon and sulfur as well as the correlation between the S- and C-values are strong indications for bacterial sulfate reduction. Highly S³²-enriched metal sulfides (S³⁴ averages –30 to –35) have fixed the H₂S from bacterial production at its starting conditions. A large variation of the sulfide-S-values (–4 to –44) and the occurence of S³⁴-enriched residue-sulfates from closed systems (+11 to +26) support the above mentioned theory. A systematic fractionation of sulfur between the sulfur minerals as observed in hydrothermal deposits (increasing S³⁴ in the sequence: pyrite>sphalerite>chalcopyrite>galena) has not been detected. In our case the regular difference in S³⁴ between the sulfides is consistent with the idea of a successive precipitation of the metals due to their different solubility with increasing bacterial H₂S production. In such a sequence the increase of S³⁴ is due to the consumption of light sulfate by bacterial reduction after the transition from an open to a closed system.It is alternately discussed, whether bacterial reduction and metal precipitation took place in bodies of stagnant sea water above or within the sediment. Presuming a precipitation of metals in a closed water-reservoir observations of other authors concerning the vertical sequence of metals and of the present author regarding the accumulation of S³⁴ in the sequence of precipitated sulfides can be easily explained.Evidence from isotope fractionation in sediment sequences favours the assumption of a precipitation of metals in the sediment: light carbon above the zone rich in carbonates (with a marine carbon composition) and metals. This characteristic change in the C¹³/C¹²-ratio is due to the increasing influence of light carbon dioxide of biogenic origin. Assuming the production of H₂S as restricted to the sediment, the transition from the open to the closed system as a result of growing thickness of the sediment (with lowered permeability for sulfate- and metalbearing water) controls the sequence of carbon composition. The restriction of metal precipitation in the sediment causes difficulties in interpreting regular zoning of metals and the metal supply. Especially the numerous exchanges of pore water required for the supply of sulfate and metals in the bituminous sediment with very low permeability cannot be explained.The assumption of a syngenetic sulfide precipitation is confirmed by the results of the carbon isotope analysis. The trend to heavy carbonates in the sequence of the profiles can be interpreted as due to rising marine influence with time in the early Zechstein basin. This trend is only interrupted several times in the Kupferschiefer-sediment by the occurence of light carbonates of biogenic origin above zones of sulfide accumulation. A model of epigenetic metal supply forming this regular pattern of correlated sulfur and carbon distribution and composition cannot be constructed. The evidence from our data favours the assumption of concurring processes of carbon fixation in carbonates and in organic substances and sulfur precipitation as sulfides during the formation of the sediment.

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Herrn Prof. Dr. K. H. Wedepohl danke ich für die Stellung des Themas, Überlassung des Probenmaterials und für sein reges Interesse am Fortgang der Arbeit. Meinen Dank möchte ich auch allen Mitarbeitern der mineralogischen Anstalten und des Zentrallabors aussprechen, die mich durch vielerlei Anregungen und Diskussionsbereitschaft unterstützt haben. Die massenspektrometrischen Untersuchungen wurden von der Deutschen Forschungsgemeinschaft durch die Einrichtung des Zentrallabors für Geochemie der Isotope an der Universität Göttingen ermöglicht.  相似文献   

Entwurf von Photoelektrischen Rückkopplungsverstärkern mit Vorgeschriebenen Übertragungseigenschaften     

Axel Plešinger 《Studia Geophysica et Geodaetica》1968,12(1):50-55

Приводится описание фотокомпенсационного усилителя на полупроводниках, предназначенного для усиления слабых выходных сигналов пассивных преобразователей геофизических величин. Шумовые помехи отнесенные к входу усилителя порядка 10^?8 в или 10^?10 а в диапазоне частот 0,01–20Гц. Описывается новый метод, который позволяет создать фотокомпенсационные усилители напряжения или тока с заранее заданными передаточными свойствами (заданной амплитудной или фазовой частотной характеристкой, заданным быстродействием и т.п.). Возможности использования этого метода демонстрируются на двух практических примерах.  相似文献   

Anwendung Elektronischer Filtersysteme zur Identifizierung von Schwachen Seismischen Signalen     

Axel Plešinger 《Studia Geophysica et Geodaetica》1967,11(4):460-464

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The monosaccharide spectra of natural waters     

Kenneth Mopper  Rodger Dawson  Gerd Liebezeit  Venu Ittekkot 《Marine Chemistry》1980,10(1):55-66

Monosaccharides were determined in waters and sediment pore waters from a wide variety of environments and locations. Desalting was performed by electrodialysis and concentrated extracts were analyzed by two forms of liquid chromatography. At least 12 sugars were identified. Glucose and fructose were the dominant monosaccharides in nearly all samples examined. Analyses of over 150 seawater and sediment pore water samples showed that fructose is highly significantly correlated (>0.99) with glucose concentrations. Laboratory kinetic experiments on the epimerization reaction, glucose ? fructose, in sterilized natural seawater in the dark, yielded a forward rate constant, k₁, of 1.2 × 10^?5 h^?1 at 25°C and 1.6 × 10^?7 h^?1 at 2°C. The approximate time required to attain equilibrium at 25°C was 1.1 y and at 2°C, 15.4 y; the measured equilibrium constant was in the range 0.3–0.4. The actual ratio of fructose to glucose in natural water samples was usually in the range 1.0–1.4/l, independent of the total monosaccharide concentrations, which varied in the samples by a factor of ～100. Several possible explanations for the apparent discrepancy in the determined and found ratios are discussed: the presence of universal, as yet, undiscovered major biological sources for fructose in marine environments; preferential utilization of glucose; preferential incorporation of fructose into or onto inorganic colloids; and preferential formation of fructose-transition metal ion associations.  相似文献   

Thermal modeling of Carboniferous to Triassic sediments of the Karawanken Range (Southern Alps) as a tool for paleogeographic reconstructions in the Alpine–Dinaridic–Pannonian realm     

Gerd?RantitschEmail author  Thomas?Rainer 《International Journal of Earth Sciences》2003,92(2):195-209

Vitrinite reflectance was measured in Late Carboniferous to Triassic shales, siltstones and marls of the Karawanken Range. Thermal models of the central South-Karawanken Range were calibrated on the basis of these data. They suggest an eroded overburden of more than 3,200 m of Jurassic to Cretaceous sediments and a heat flow in the range of 42 to 60 mW m^?2 during the time of maximum subsidence. Because the reconstructed thermal history of the South-Karawanken Range is very similar to the thermal history of the Generoso basin (western Southern Alps), these data provide strong evidence for a deep basinal position of the Southern Karawanken Range during Jurassic to Cretaceous times. A vitrinite reflectance anomaly at the northern margin of the South-Karawanken Range is explained by advective heat transport during the Oligocene. The heat source for the anomalies at the western margin of the Seeberg Rise and in the area between the Periadriatic Lineament and the Donat Fault Zone is unknown. Vitrinite reflectance in Late Triassic sediments indicates the South-Karawanken Range and the South-Zala Unit of the Pannonian basement as exotic blocks in the Sava Composite Unit. This is explained by Miocene displacement of structural units, which were derived from different paleogeographical segments of the Permo-Mesozoic western Tethyan margin.  相似文献   

Contaminant concentrations in sport fish from San Francisco Bay, 1997     

Davis JA  May MD  Greenfield BK  Fairey R  Roberts C  Ichikawa G  Stoelting MS  Becker JS  Tjeerdema RS 《Marine pollution bulletin》2002,44(10):1117-1129

In 1997, seven sport fish species were sampled from seven popular fishing areas in San Francisco Bay. Mercury exceeded a human health screening value in 44 of 84 (52%) samples. All collected samples of leopard shark and striped bass exceeded the mercury screening value of 0.23 microg/g wet weight. PCBs exceeded the screening value in 51 of 72 (71%) samples. DDT, chlordane, and dieldrin, had lower numbers of samples above screening values: 16 of 72 (22%) for DDT, 11 of 72 (15%) for chlordanes, and 27 of 72 (37%) for dieldrin. Concentrations of PCBs and other trace organics were highest in white croaker and shiner surfperch, the two species with the highest fat content in their muscle tissue. Fish from one location, Oakland Harbor, had significantly elevated wet weight concentrations of mercury, PCBs, DDTs, and chlordanes compared to other locations. Removal of skin from white croaker fillets reduced lipid concentrations by 27-49% and concentrations of trace organics by 33-40%.  相似文献