An assessment of the use of stabilized coal and oil ash for construction of artificial fishing reefs: Comparison of fishes observed on small ash and concrete reefs   总被引：2，自引：0，他引：2  

Frederic E. Vose  Walter G. Nelson   《Marine pollution bulletin》1998,36(12):980-988

Fishes present on small artificial reefs located 2 km off the central east coast of Florida (USA) were surveyed to determine the acceptability of using stabilized oil and coal ash residue as a component material in construction of artificial fishing reefs. Species richness was not significantly different over 2.5 yr on stabilized oil and coal ash reefs compared to concrete control reefs. Of 19 species tested for significant differences in mean abundance, lane snapper was observed at significantly higher mean abundances on fossil-fuel ash reefs (stabilized oil ash/coal fly ash), while three reef species (hairy blenny, porkfish and gray snapper) were significantly more common on concrete control reefs. Further study is needed to determine whether contaminants (Cu, V, Ni and Zn) from stabilized ash blocks can cause abundance differences for some fishes. Plausible alternate explanations for the differences in mean abundance include both interspecific interactions (competition and predation) and differences in the attraction or retention of fish among reef replicates due to slight variations in reef dimensions.  相似文献   

The Bayesian approach to an internally consistent thermodynamic database: theory, database, and generation of phase diagrams     

Niranjan D. Chatterjee  Ralf Krüger  Gerd Haller  Walter Olbricht 《Contributions to Mineralogy and Petrology》1998,133(1-2):149-168

An internally consistent thermodynamic dataset has been derived for 148 endmember phases (145 solids and 3 fluids) comprising the elements Li, Na, K, Be, Mg, Ca, Ti, Cr, Mn, Fe, Zn, Al, Si, C, H, and O. This has been achieved by simultaneous treatment of phase property (like standard enthalpy of formation, standard entropy, molar heat capacity, molar volume, thermal expansivity, bulk modulus etc.) and reaction reversal data by the Bayesian method. The theory underlying the approach, and the computational methods involved, are briefly outlined. (For the benefit of readers unfamiliar with inference statistics, the basic concepts of the Bayes method are also presented in such a way that they can be grasped intuitively.) Although not yet addressed, this method can be extended to refine the thermodynamic mixing properties of crystalline solutions. The sources of the input data, culled from the literature, are summarized in the Appendix. The resulting database is succinctly documented in this paper. It includes the enthalpies of formation and entropies, their uncertainties, and the correlation among them. The database allows calculation of P-T, T-X _CO2, P-X _CO2, and T-f _O2 sections, with error propagation into the computed phase diagrams on a routine basis. A user-friendly computer program has been written to generate such phase diagrams. It is public domain software. The software and the thermodynamic database (which includes a complete documentation of the thermodynamic data above and beyond those listed (Table 2, here) may be downloaded from the web site http://homepage.ruhr-uni-bochum.de/niranjan.chatterjee/Index.htm. Examples of computed phase diagrams are given to illustrate the quality of the data and the capabilities of the software. Received: 11 March 1998 / Accepted: 11 June 1998  相似文献   

Mass models of the Milky Way     

Walter Dehnen  & James Binney 《Monthly notices of the Royal Astronomical Society》1998,294(3):429-438

A parametrized model of the mass distribution within the Milky Way is fitted to the available observational constraints. The most important single parameter is the ratio of the scalelength R _d* of the stellar disc to R ₀. The disc and bulge dominate v _c( R ) at R ≲ R ₀ only for R _d,*/ R ₀≲0.3. Since the only knowledge we have of the halo derives from studies like the present one, we allow it to contribute to the density at all radii. When allowed this freedom, however, the halo causes changes in assumptions relating to R  ≪  R ₀ to affect profoundly the structure of the best-fitting model at R  ≫  R ₀. For example, changing the disc slightly from an exponential surface-density profile significantly changes the form of v _c( R ) at R  ≫  R ₀, where the disc makes a negligible contribution to v _c. Moreover, minor changes in the constraints can cause the halo to develop a deep hole at its centre that is not physically plausible. These problems call into question the proposition that flat rotation curves arise because galaxies have physically distinct haloes rather than outwards-increasing mass-to-light ratios.   The mass distribution of the Galaxy and the relative importance of its various components will remain very uncertain until more observational data can be used to constrain mass models. Data that constrain the Galactic force field at z ≳ R and at R  >  R ₀ are especially important.  相似文献   

Local stellar kinematics from Hipparcos data   总被引：1，自引：0，他引：1  

Walter Dehnen  & James J. Binney 《Monthly notices of the Royal Astronomical Society》1998,298(2):387-394

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Tracing the exhumation of the Eclogite Zone (Tauern Window,Eastern Alps) by <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dating of white mica in eclogites     

Walter Kurz  Robert Handler  Christian Bertoldi 《Swiss Journal of Geoscience》2008,101(1):191-206

New radiometric ages from the Subpenninic nappes (Eclogite Zone and Rote Wand – Modereck Nappe, Tauern Window) show that phengites formed under eclogite-facies metamorphic conditions retain their initial isotopic signature, even when associated lithologies were overprinted by greenschist- to amphibolite-facies metamorphism. Different stages of the eclogite-facies evolution can be dated provided ⁴⁰Ar/³⁹Ar dating is combined with micro-structural analyses. An age of 39 Ma from the Rote Wand – Modereck Nappe is interpreted to be close to the burial age of this unit. Eclogite deformation within the Eclogite Zone started at the pressure peak along distinct shear zones, and prevailed along the exhumation path. An age of ca. 38 Ma is only observed for eclogites not affected by subsequent deformation and is interpreted as maximum age due to the possible influence of homogenously distributed excess argon. During exhumation deformation was localised along distinct mylonitic shear zones. This stage is mainly characterised by the formation of dynamically recrystallized omphacite2 and phengite. Deformation resulted in the resetting of the Ar isotopic system within the recrystallized white mica. Flat argon release spectra showing ages of 32 Ma within mylonites record the timing of cooling along the exhumation path, and the emplacement onto the Venediger Nappe. Ar-release patterns and ³⁶Ar/⁴⁰Ar vs.³⁹Ar/⁴⁰Ar isotope correlation analyses indicate no significant ⁴⁰Ar-loss after initial closure, and only a negligible incorporation of excess argon. From the pressure peak onwards, eclogitic conditions prevailed for almost 8–10 Ma.  相似文献   

Neuere Veröffentlichungen     

Günter Dietrich  Walter Hansen  A. Schumacher  F. Errulat 《Ocean Dynamics》1952,5(2-3):153-156

Ohne Zusammenfassung  相似文献   

Zur Alpensynthese     

Walter Del-Negro 《International Journal of Earth Sciences》1929,20(4-5):341-342

Ohne Zusammenfassung  相似文献   

Bildung von Kondensationskernen durch UV-Strahlung in verschiedenen Gasen     

Walter Hoppe 《Pure and Applied Geophysics》1961,50(1):129-139

Zusammenfassung Die Erzeugung von Kondensationskernen durch UV-Licht wurde mittels eines automatischenPollakschen Kernzählers und einerWilsonkammer aus Glas untersucht. Da die UV-Kerne von einem Schwebstoffilter zurückgehalten werden, ließ sich durch Verwendung zweier Bestrahlungsgefäße mit dazwischengeschaltetem Filter die Spurengashypothese bestätigen. Bestrahlungsversuche in Luft, Stickstoff, Sauerstoff, Argon und Wasserstoff ergaben, daß durch längere Bestrahlung eines abgeschlossenen Gasvolumens die kernbildende Substanz allmählich verbraucht wird. Durch Zugabe definierter Mengen gasförmigen Ammoniaks in den Bestrahlungsraum zeigte sich, daß die von verschiedenen Autoren geäußerte Ansicht, gasförmiges Ammoniak sei die kernbildende Substanz, nicht haltbar ist. Die Untersuchung des Einflusses von Schwefelwasserstoff bzw. Schwefeldioxyd ergab, daß die atmosphärische Konzentration von H₂S zur Erklärung des UV-Effektes nicht ausreicht, während dies bei SO₂ der Fall ist. Das Ergebnis, daß SO₂ maßgebend an der Bildung der UV-Kerne in atmosphärischer Luft beteiligt ist, wird dadurch gestützt, daß der UV-Effekt einen ähnlichen Tagesgang zeigt wie das atmosphärische SO₂.

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Summary The production of condensation nuclei by UV light was investigated by means of an automaticPollak nucleus counter and aWilson glass-chamber. As the UV nuclei can be removed by an aerosol filter, the trace gas hypothesis could be confirmed by using two irradiation tubes separated by an aerosol filter. Irradiation experiments in air, nitrogen, oxygen, argon and hydrogen in a closed volume had the result that the nucleogenic substance gradually disappears after sufficiently long irradiation. By adding definite quantities of ammonia vapour into the irradiation tube it could be shown that ammonia is not the nucleogenic substance, as was supposed by some authors. The investigation of the influence of sulphur dioxide and hydrogen sulfide showed that the atmospheric concentration of H₂S is not sufficient to explain the UV effect in atmospheric air, whereas this is true with SO₂. The result that SO₂ takes part in the formation of the UV nuclei is supported by the fact that SO₂ and the UV effect show a similar diurnal variation.

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GEOGRAPHIC ACTIVITIES OF THE DIVISION OF EARTH SCIENCES,NATIONAL RESEARCH COUNCIL     

Walter H. Bailey 《The Professional geographer》1968,20(4):272-275

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CLEARANCE PROBLEMS IN AFRICAN RESEARCH     

Frank E. Bernard  Bobbie J. Walter 《The Professional geographer》1968,20(1):28-32

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