The origin of ozone-rich air in the middle stratosphere observed over Europe at the end of January 1979     

W. Braun  H. U. Dütsch 《Journal of Atmospheric Chemistry》1984,2(2):163-173

Daily ozone soundings over Switzerland in the winter of 1979 showed, at the end of January some extremely high values of the ozone mixing ration around the 10 mb level-9 to 10 ppm compared with a climatological mean of 6 ppm. At the same time, the temperature and ozone mixing ratio was measured by the LIMS experiment (Limb Infrared Monitor of the Stratosphere) on Nimbus 7. The single LIMS ozone profiles, as well as the LIMS 10 mb ozone maps, also showed extreme ozone maxima. Ozone transport was investigated by trajectory computations based on the LIMS geopotential height fields. Displacements and deformations of air parcel chains in 48 h were used to construct ozone maps, using the distribution on a previous day. The correspondence of such kinematically-constructed ozone maps using the actual LIMS maps is striking. This method is, thus, a strong indication of the self-consistency of the different LIMS products (ozone, temperature, geopotential) and explains the unusual ozone observations.  相似文献   

Helium,neon, and argon in the iron meteorites Dongling,Nantan and Ningbo   总被引：1，自引：0，他引：1  

H. W. Weber  O. Braun  F. Begemann 《中国地球化学学报》1986,5(4):320-330

The light noble gases He, Ne and Ar have been measured in the iron meteorites Dongling, Nantan and Ningbo. Dongling and Ningbo show a deficit of cosmic-ray that produced³He of ca. 30% and 10%, respectively, which is argued to be caused by the loss of³H (tritium) from the meteoroids during the time of their exposure to the cosmic radiation. Nantan has the lowest content of noble gases as yet reported for any iron meteorite. Cosmogenic³He and³⁸Ar are only about 1/5000 of those in Dongling which has particularly interesting implications if the two meteorites belong to the same fall^[2]. In addition, Nantan contains nonspallogenic⁴He which we believe to be of radiogenic origin. This radiogenic⁴He, together with a U-content of 2.6×10⁻¹¹ g/g^[20] yields a⁴He retention age close to the cosmic-ray exposure age of Dongling. If Dongling and Nantan were part of the same meteoroid^[2], this result would indicate that He retention in the meteoroid age were 4,500 Ma, a U-content of less than 7.2×10⁻¹³ g/g is required to explain the non-cosmogenic₄He present. An upper limit to the number of transuranium or superheavy-element atoms which have decayed by α-emission in Nantan since onset of He retention is 2×10¹⁰ per gram.  相似文献   

Mikrosondenuntersuchungen von Saussuriten in Abhängigkeit vom Metamorphosegrad und vom geochemischen Milieu     

Eckart Braun 《Contributions to Mineralogy and Petrology》1974,46(4):301-327

Zusammenfassung In einem Profil ansteigender Metamorphose werden im Stavanger-Gebiet/SW-Norwegen zwei Gesteinstypen, repräsentiert durch 17 Meta-Arkosen und Quarz-Feldspat-Gneise, sowie 19 metamorphe Tuffe und Tuffite, modellhaft auf ihre Saussuritparagenesen hin analysiert.Mikroskopische und mikroanalytische Untersuchungen zeigen eine weitestgehende Eduktabhängigkeit der Saussuritparagenesen. In calcitarmen granitoiden Edukten bilden sich schon im sehr schwach-metamorphen Stadium folgende mit Ab-reichem Plagioklas koexistierende Saussuritmineralien: 4 An-reicher Plagioklas+K-Feldspat+4 Eisenhydroxid + H₂O 2 Fe(III)Al₂-Epidot+Muskovit+Hämatit+2 Quarz. In calcitführenden Meta-Arkosen gewinnt die Mineralreaktion: An-Plagioklas+K-Feldspat+2 Eisenhydroxid+CO₂Calcit+Muskovit+ Hämatit+Quarz an Bedeutung. Im reduzierenden geochemischen Milieu der Meta-Tuffe und -Tuffite tritt in diesem metamorphen Bereich als charakteristische Neubildung Biotit neben Muskovit auf. Auch in den calcitreichen tuffitischen Proben koexistieren die Saussuritkomponenten Calcit, Muskovit, Hämatit, Quarz und Biotit.Die mikroanalytisch untersuchten Saussuritmineralien Plagioklas und Epidot zeigen anhand von annähernd 800 chemischen Vollanalysen in der Entwicklung ihrer Chemismen während der Metamorphose für beide Sedimente gleiche Trends. Im niedrigtemperierten Bildungsstadium der Saussurite können die An-Gehalte der Feldspäte in Abhängigkeit vom Edukt und aufgrund unterschiedlich intensiver Rekristallisation der Sedimente relativ stark schwanken. Die Epidote sind je nach primärem Fe(III)-Angebot mehr oder weniger eisenreich. In Richtung ansteigender Metamorphose stellen sich in den Epidoten beim Übergang zu oligoklasführenden Paragenesen maximale Fe(III)-Gehalte ein, die in Form eines rhythmischen Zonarbaus die wechselnden -Bedingungen im Verlauf der Metamorphose widerspiegeln. Bereits hier setzt der retrograde Saussuritisierungsprozeß ein: es reagieren Fe(III)Al₂-Epidot, Muskovit, Quarz, Hämatit und Albit/Oligoklas zu anorthitreicherem Plagioklas, Biotit und Wasser. Zusätzlich bildet sich durch die Zersetzung des Al-reichen Epidots Mikroklin.Die Untersuchung zur Wechselbeziehung zwischen dem Eisengehalt des Eduktes und dem der Epidote ergibt, daß die Fe(III)-Einbaurate der Epidote in keiner Weise von den Fe(III)-Konzentrationen der Meta-Sedimente beeinflußt wird, vielmehr können eduktspezifische Intervalle für die Eisenanreicherung der Epidote nachgewiesen werden.

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Electron microprobe investigations of saussurites dependent on metamorphic stage and geochemical environment

In a profile of ascending metamorphism, the saussuritic parageneses of two characteristic rock types, 17 acid meta-arkoses and 19 basic meta-tuffs and meta-tuffites, were investigated by microscopical and microanalytical methods.Microscopic studies reveal that the specific saussurite mineral association is dependent on the petrographic substratum. In very low stage metamorphism, granitic rocks show the following saussurite minerals coexisting with albite-rich plagioclase: 4 An-rich plagioclase+K-feldspar +4 ironhydroxide+H₂O2 Fe (III) Al₂-epidote + muscovite + hematite + 2 quartz. Phyllitic and calciferous meta-arkoses exhibit predominantly the following saussurite reaction: An-plagioclase + K-feldspar + 2 ironhydroxide + CO₂ calcite + muscovite + hematite + quartz. In the reducing environment of the meta-tuffs and meta-tuffites, biotite is formed in addition to muscovite.The changing chemical composition of the saussurite minerals (plagioclase and epidote) at different stages of metamorphism was determined by 800 quantitative electron microprobe analyses. The changes found in both rock types are nearly the same. During low metamorphic stage, the An-content of the plagioclases depends on the substratum and the variable intensity of recrystallization. The Fe-content of the epidotes is dependent on the amount of iron available.The epidotes are enriched in Fe toward the transition to oligoclase-bearing parageneses. These Fe-contents cause rhythmical zoning, representing varying conditions during metamorphism. With increasing metamorphic grade the retrograde process of saussuritization is initiated. The reactants are Fe (III) Al₂-epidote, muscovite, quartz, hematite, and albite/ oligoclase. The decomposition of these minerals leads to An-rich plagioclase, biotite, microcline, and H₂O.

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Herrn Prof. Dr. G. Müller, Clausthal, danke ich für viele anregende Diskussionen sowie für die kritische Durchsicht des Manuskriptes.

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Mein Dank gilt auch Herrn Dr. A. Schneider, Geochemisches Institut der Universität Göttingen, der mir freundlicherweise das Rucklidge-Korrekturprogramm für Silikatanalysen zur Verfügung stellte. Zu danken habe ich auch Herrn Dr. F. Wurm, Geologisches Landesamt Baden-Württemberg, für sein großzügiges Entgegenkommen und die tatkräftige Unterstützung bei der ergänzenden Probennahme im Gebiet der nordwestlichen Inseln des Boknfjords.

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Der Deutschen Forschungsgemeinschaft schulde ich Dank für die finanzielle Unterstützung dieser Arbeit.  相似文献   

Buchbesprechungen     

Rudolf Braun 《Aquatic Sciences - Research Across Boundaries》1955,17(1):170-172

Ohne Zusammenfassung  相似文献   

Computerdarstellung von Achsenverteilunganalysen     

Dr. Günter Braun 《International Journal of Earth Sciences》1972,61(3):849-871

Zusammenfassung Ein wichtiges Verfahren der Gefügeanalyse ist die Achsenverteilungsanalyse. Dieses zeitaufwendige Verfahren wird besser und schneller mit Hilfe eines Computers durchgeführt. Ein selbstentwickeltes Programmsystem in ALGOL, das besonders im Hinblick auf die Durchführung von Achsenverteilungsanalysen entworfen wurde, beherrscht sowohl die traditionellen Verfahren zur Auswertung des Makro- und Mikrogefüges als auch neuere Methoden zur Darstellung von Achsenverteilungsanalysen.Nach einer schematischen Darstellung des angewendeten Verfahrens wird als Beispiel ein 9×9 mm großer Bereich eines Chlorit-Biotit-Gneises analysiert und abschließend die Anwendung des Verfahrens im Makrobereich diskutiert.

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The axial-distribution analysis is an important method for the investigation of petrofabrics. The analytical procedure is very time-consuming and can be more exactly and rapidly performed by means of a computer. The program system which was developed by the author is written in ALGOL language and has been worked out with special respect to the performance of axial-distribution analyses. The program masters the traditional procedures of treating the macro-, meso-, and microscopic fabrics as well as new representation methods of axial-distribution analysis.The method is described by a sequence of graphs illustrating the proceeding of the analytical process. It is applied to the analysis of a 9×9 mm area of a chlorite-biotitegneiss. Finally, the application of the method to the investigation of macroscopic areas is discussed.

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Résumé L'analyse de la distribution des axes est une méthode très importante de l'analyse structurelle. Cette méthode, qui consomme beaucoup de temps, est mieux et plus vite réalisée à l'aide d'une calculatrice électronique. Un système de programmes en langue ALGOL, qui a été développé par l'auteur spécialement pour l'exécution des analyses de distribution des axes, traite aussi bien les méthodes traditionnelles de l'évaluation des macroet microstructures que les méthodes nouvelles pour la représentation des analyses de distribution d'axes. La méthode employée est appliquée à l'analyse d'une surface de 9×9 mm d'un gneiss à chlorite et biotite et est finalement discutée aux échelles supérieures.

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. . ALGOL, , , , . , , , -- 9×9 ; .

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Die Diagramme wurden mit der aus Mitteln der DFG betriebenen Rechenanlage Electrologica X8/X1 berechnet.Mein besonderer Dank gilt Herrn Prof. Dr. F.Karl für das Verständnis, das er den langwierigen Programmierarbeiten entgegenbrachte, sowie die hilfreichen Diskussionen der gefügekundlichen Probleme. Dank schulde ich ferner Herrn F.Pina Mendes für einige Diskussionen sowie das Einmessen des untersuchten Dünnschliffes.  相似文献   

Debate articles: have changes in Quaternary climate affected erosion?          下载免费PDF全文

Jean Braun  Max Coleman  Georges Calas  Carlo Doglioni  Klaus Mezger  Jason Phipps Morgan 《地学学报》2016,28(1):1-1

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The production of circumstellar26Al by massive stars     

N. Langer  H. Braun  J. Fliegner 《Astrophysics and Space Science》1995,224(1-2):275-278

We investigate the production of²⁶Al during hydrogen burning and its ejection by massive single and binary stars. Effects of convection and rotation are studied. We discuss the importance of RSGs, LBVs and WR stars to the total Galactic²⁶Al production, and the detection probability of the²⁶Al decay in individual objects as P Cygni, Velorum and Carinae.  相似文献   

Anthropogenic organic matter inputs indicated by sedimentary fecal steroids in a large South American tropical estuary (Paranaguá estuarine system, Brazil)     

César C. Martins  Juliana A.F. Braun  Eunice C. Machado 《Marine pollution bulletin》2010,60(11):2137-2143

Urban sewage is considered one of the most important sources of marine pollution in South America, because most coastal cities do not have proper facilities to treat and dispose of sewage. The Paranaguá estuarine system is an important estuarine environment of the South American coast where fishing, urban and tourist activities, industries and the main Brazilian grain shipping port are potential sources of pollution in this area. The anthropogenic input of sedimentary organic matter, represented by sewage contribution, was evaluated by fecal steroid concentrations. The coprostanol levels were comparatively low (<0.10 μg g⁻¹), except at the sites close to Paranaguá city, where the coprostanol concentration reached 2.22 μg g⁻¹ showing strong sewage contamination. Fecal steroid levels were comparable to the lower to midrange concentrations reported for coastal sediments worldwide. The results of this work demonstrated that sewage pollution can be considered a problem for a small part of the Paranaguá estuary.  相似文献   

Modeling ground water flow in alluvial mountainous catchments on a watershed scale   总被引：1，自引：0，他引：1  

Wolf J  Barthel R  Braun J 《Ground water》2008,46(5):695-705

In large mountainous catchments, shallow unconfined alluvial aquifers play an important role in conveying subsurface runoff to the foreland. Their relatively small extent poses a serious problem for ground water flow models on the river basin scale. River basin scale models describing the entire water cycle are necessary in integrated water resources management and to study the impact of global climate change on ground water resources. Integrated regional-scale models must use a coarse, fixed discretization to keep computational demands low and to facilitate model coupling. This can lead to discrepancies between model discretization and the geometrical properties of natural systems. Here, an approach to overcome this discrepancy is discussed using the example of the German-Austrian Upper Danube catchment, where a coarse ground water flow model was developed using MODFLOW. The method developed uses a modified concept from a hydrological catchment drainage analysis in order to adapt the aquifer geometry such that it respects the numerical requirements of the chosen discretization, that is, the width and the thickness of cells as well as gradients and connectivity of the catchment. In order to show the efficiency of the developed method, it was tested and compared to a finely discretized ground water model of the Ammer subcatchment. The results of the analysis prove the applicability of the new approach and contribute to the idea of using physically based ground water models in large catchments.  相似文献   

Biogeochemical and ecological functioning of the low-salinity water lenses in the region of the Rhone River freshwater influence,NW Mediterranean Sea     

Frédéric Diaz  Jean-Jacques Naudin  Claude Courties  Peggy Rimmelin  Louise Oriol 《Continental Shelf Research》2008

A quasi-synoptic survey of a eulerian small grid was carried out twice during mid-spring 2002 in the Gulf of Lions, NW Mediterranean Sea. Analysis of hydrological core parameters reveal for the first time, in the region of freshwater influence (ROFI) of the Rhone River, the presence of low-salinity water (LSW) lenses. The present work details the biogeochemical and ecological functioning of the two LSW lenses from a combined analysis of nutrients and organic matter content, taxonomic assemblages of phytoplankton, primary productivity measurements and nitrogen regeneration fluxes. During the first survey, the lens observed is only detached in part from the Rhone River plume and is considered as a juvenile lens. In contrast, the second lens is totally detached from the plume forming a confined 3D structure with a large vertical development and is considered as having a more advanced maturity. A second survey, 4 days later, provided the opportunity to propose a complete sequence of ecological functioning of the LSW lenses, from their formation to a late stage of maturity just before dispersion. Nitrate contents and dissolved organic matter remain in high concentrations during the juvenile stages while the little available phosphate is rapidly exhausted. In such, an unbalanced-nutrient environment picoplankton appear to out-compete bacterioplankton for phosphate and other resources such as ammonium. In turn, the dominance of such prokaryotic assemblages could have involved the rapid development of microzooplankton. The sudden increase in phosphate observed in a more advanced stage of lens maturity is attributed to intense P-regeneration driven by the large abundance of microzooplankton. This top-down control does not seem to enable the prokaryotic assemblages to bloom again but the high concentrations of phosphate and nitrate favour the development of larger phytoplankton. These autotrophic communities rapidly exhaust nutrients and then decline in the confined ecosystem of the LSW lens that subsequently evolves towards oligotrophic conditions. In the observed last stage, small-sized phytoplankton again dominates the microbial assemblages and the trophic regime is mainly based on regenerated production. The long lifetime of the LSW lens compared to that of the Rhone River plume enables a deep transformation of the initial characteristics of the Rhone River freshwaters both in terms of nutrients balance and microbial food webs, especially through trophic cascading effects. Hence, we show that the LSW lenses have the potential to transfer nutrients and organic matter offshore but the nature (inorganic vs. organic) of the dominant compound exported will depend on the maturity of the lens at the time of its dispersion.  相似文献