Calcite Dissolution Kinetics     

Rolf?S.?ArvidsonEmail author  Cornelius?Fischer  Andreas?Luttge 《Aquatic Geochemistry》2015,21(5):415-422

We compare the canonical treatment of calcite’s dissolution rate from the literature in a closed system, particle batch reactor, with the alternative approach suggested by Truesdale (Aquat Geochem, 2015). We show that the decay of rate over time can be understood in terms of the evolution and distribution of reactive sites on the surface of these particles. We also emphasize that interpretation of observed rates must not exclude the fundamental role of crystal defects, whose importance is already implicitly reflected in the common form of rate laws in geochemistry. The empirical behavior of overall rate in closed systems, such as those described by Truesdale, may thus reflect relationships between defect centers and the generation of steps over the calcite surface (previously documented for silicates), such that below a critical free energy limit, there is insufficient driving force to open hollow cores and thus a loss of reaction mechanism. Dissolution in this very-near-equilibrium regime will be dependent on the distribution of extant steps and the energetics of new kink site nucleation. However, these sensitivities are complicated in the case of particle systems by grain boundaries, edges, corners, and other terminations. Such discontinuities constitute a defect class whose overall kinetic importance will be strongly tied to particle diameter and which can act independently of the internal strain field imposed by screw and edge dislocations.  相似文献   

Coeval Lower Miocene subsidence of the Eisenstadt Basin and relative updoming of its Austroalpine frame: implications from high-resolution geophysics at the Oslip section (Northern Burgenland,Austria)     

Hermann Häusler  Jürgen Scheibz  Werner Chwatal  Franz Kohlbeck 《International Journal of Earth Sciences》2015,104(2):475-493

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Climatic teleconnections with the equatorial pacific and the role of ocean/atmosphere coupling     

Hermann Flohn  Heribert Fleer 《大气与海洋》2013,51(3):96-109

Starting from the occurrence of a zonal Walker circulation supplementing the meridional Hadley cell, the concept of ultralong waves with diagonal upper troughs extending far into the Tropics is stressed. The model of equatorial upwelling with air‐sea coupling is critically discussed and a modification proposed. An intensification of the subtropical jet at the peak of the 1972 El Niño (as suggested by Rowntree's model calculations) has been verified.

Empirical studies deal with the large interannual and interdecadal variations of the energy fluxes at the air‐sea interface; time variations of the oceanic evaporation and sensible heat flux are greater than expected. Using spectrum analysis, the occurrence of a 5‐year periodicity in equatorial rainfall of the Pacific and Indonesia is demonstrated, together with a marked phase shift along the NE coast of New Guinea.  相似文献   

Theoretical density distribution of plasma streaming around a cylinder     

R. Grabowski  T. Fischer 《Planetary and Space Science》1975,23(2):287-304

The distribution of plasma density around a metallic cylinder in a collisionfree plasma is determined by the system of Vlassov equations and the Poisson equation. The plasma may have a streaming velocity perpendicular to the cylinder axis producing a wake behind the cylinder. In the region outside a thin double layer at the cylinder surface the problem allows some simplification. Then numerical solutions become possible-even if the streaming velocity is low. Some numerical solutions are presented. A magnetic field produces an asymmetric shape of the wake, if the gyration radius of the ion becomes comparable to the cylinder radius.  相似文献   

The design of the Central-Axis Reflector (ZAS)     

Hermann Hügenell 《Astrophysics and Space Science》1989,160(1-2):231-239

The Central-Axis Reflector, the design principle which is presented below is a segmented-mirror telescope. The inventions relate mainly to the optical system and to the tracking apparatus.A large number of small individual mirror bodies, ground off-axis (hexagonal/polygonal) produce one primary mirror with closed circular aperture when joined together.The overall design of the tracking apperatus results directly —and thus without unnecessary adornment — from the two planes of to aminimum but which are required for tracking of the telescope.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.  相似文献   

Is there a black hole among the black-hole candidates?     

Wolfgang Kundt  Daniel Fischer 《Journal of Astrophysics and Astronomy》1989,10(1):119-138

None of the tentative black-hole identifications has remained without serious difficulties. As a class, the black-hole candidates differ in no obvious property from neutron-star binaries other than in their estimated high mass. We favour an interpretation of the black-hole candidates as binary neutron stars surrounded by a more or less massive accretion disc  相似文献   

Topography and minimization of the standard deviation in one-dimensional magnetotelluric modelling     

Gaston Fischer  B. V. Le  Quang 《Geophysical Journal International》1981,67(2):279-292

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VOCs in Ground Water Influenced by Large Scale Withdrawals   总被引：1，自引：0，他引：1  

Alex J. Fischer  Elizabeth A. Rowan  Roy F. Spalding 《Ground water》1987,25(4):407-414

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Über den Einfluß von Meeresspiegelschwankungen auf Flachwassersedimente im Schwäbischen Jura     

Hermann Aldinger 《Mineralogy and Petrology》1965,10(1-4):61-68

Zusammenfassung Im Ablagerungsbecken des Unteren Lias und Dogger dürften, wenn nicht Ebbe und Flut, so doch aperiodische Schwankungen des Meeresspiegels um mehrer Meter aufgetreten sein. Durch die Spiegelschwankungen wird das Sedimentgefüge in von Ort zu Ort wechselndem Ausmaß geändert, austretendes Porenwasser trägt außerdem zur Sedimentbildung bei.

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Summary Aperiodic fluctuations of sea level, caused by wind, during some periods of Lower and Middle Jurassic in Southern Germany should have had similar effects as tides in Watten today, altering the fabric of sediments and bringing pore water low in pH and eH to the surface. Glauconite and Chamosite may have been formed by mixing of normal sea water with pore water.

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Herrn Professor Dr.F. Machatschki zum 70. Geburtstag gewidmet.  相似文献   

Escape models of the Alpine-Carpathian-Pannonian region in the light of palaeomagnetic observations     

Hermann J. Mauritsch  Emö Márton 《地学学报》1995,7(1):44-50

Recent tectonic models of the Alpine-Carpatho-Pannonian region (ALCAPA) assume a large eastward shift of the Transdanubian Range domain, in the Cenozoic. Since palaeomagnetism is one of the most powerful tools in solving geodynamic processes, the authors present an approach to the escape problem by using all available and relevant palaeomagnetic data. This data set demonstrates consistency with models put forward by geologists for Jurassic and older ages. From the mid-Jurassic on the Northern Calcareous Alps (NCA) did not share the rotations of the Transdanubian Range domain and of the Southern Alps. After individual movements from Neocomian to Miocene, the Transdanubian Range domain must have drifted northward in the mid-Miocene up to the Southern margin of the Northern Calcareous Alps, before starting the escape in the geologists' definition.  相似文献