Buchbesprechungen     

Peter Perret  F. Stössel 《Aquatic Sciences - Research Across Boundaries》1978,40(1):209-210

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Die Bedeutung der vertikalen Durchmischung für die phytoplanktische Sauerstoffproduktion in einem gestauten Fliessgewässer     

Joachim Von Löhr 《Aquatic Sciences - Research Across Boundaries》1985,47(2):179-196

Measured oxygen concentrations over the depth in an impounded river showed considerable vertical gradients. Their numerical calculation based on concepts to be found in the literature was yet not possible. For assessing the signification of the mixing over the depth for the phytoplanktic oxygen production a mathematical concept will be developped. This enables the quantification of the influence of the turbulence dependent permanent light-dark changes upon the phytoplanktic production. The results lead to the conclusion that the mixing processes may have a stimulating effect upon the algae which rises their photosynthetic production by a factor from about 2 up to 4.  相似文献   

Variation in mercury content of Guillemot feathers over 150 years     

Helge Appelquist  Iver Drabæk  Sten Asbirk 《Marine pollution bulletin》1985,16(6):244-248

The feathers of 277 Black, Common and Brünnich's Guillemot from the Baltic, Kattegat, Faroe Islands and Greenland were analysed for mercury. The levels were found to be higher in the Baltic and the Kattegat compared to the Faroe Islands and Greenland. While the levels were almost constant for the last two areas a substantial increase during this century was found for the Baltic and the Kattegat. In Common Guillemots from the Baltic a decrease was indicated after 1969. In general the mercury levels were higher for Black Guillemots living close to the coast compared to the Uria sp. living off-shore. The inhomogeniety of the mercury load near the shore was indicated by a large individual variation within a colony of Black Guillemots. This variation was reinforced by differences in migration and feeding habits. It has been shown by analysis of individuals recaptured during successive years that the year to year variation of one individual is considerably smaller.It is concluded that chronological series based on feathers from sea birds and museum collections may contribute to the elucidation of the long term trend of mercury pollution at sea.  相似文献   

Preliminary results from a dataset collected with the towed system “Delphin” during FLEX '76     

Marion Stössel 《Ocean Dynamics》1986,39(4):169-177

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Geography in school     

Maria Stănescu  Aurel Popescu 《Geoforum》1975,6(1):74-76

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Three-component spectral analysis of geomagnetic pulsations     

Jaroslav Střeštík  Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1980,24(2):163-172

nua m¶rt; nma aaua a, umua m nma, m n¶rt;um umau nuau un nmam. m¶rt; annua aaum nauu Pi2 u Pc3 u amu u u ¶rt;. ¶rt;a ma m ¶rt; nmam nuau aamumu u u auum m aum amumu.  相似文献   

The Kelly chondrite: A parent body surface metabreccia     

T. E. Bunch  Dieter Stöffler 《Contributions to Mineralogy and Petrology》1974,44(2):157-171

The Kelly brecciated chondrite, originally classified as a polymict breccia, is actually a monomict breccia, based on conclusions from this study. Microprobe analyses of differently textured clasts are very similar to each other and also to well-known LL-type chondrites. Clast and matrix olivine compositions range between Fa_27–31, well within the range of LL-chondrite olivine. A correlation was found between the degree of recrystallization and plagioclase composition; least recrystallized plagioclase is more Ca-rich than fully recrystallized plagioclase. Petrographic observations of shocked, annealed, and unshocked clasts coupled with particle size distribution measurements strongly indicate that Kelly is similar to lunar metabreccias in mode of formation, i.e., repeated mixing and accumulation of disaggregated surface rocks and impacting debris followed by partial annealing under moderate temperatures. At least three breccia generations are indicated. We propose that Kelly is an LL-chondrite parent body metabreccia that represents the final accumulation phase of the parent body. Only LL-type fragments were found in Kelly, which suggests that the parent body consisted of only LL-chondrites and was not a multi-shelled body of H-, L-, and LL-chondrites.  相似文献   

Later stages of evolution of an epithermal system: Au–Ag mineralizations at Apigania Bay, Tinos Island, Cyclades, Hellas, Greece     

S. F. Tombros  K. St. Seymour  A. E. Williams-Jones  P. G. Spry 《Mineralogy and Petrology》2008,94(3-4):175-194

Precious metals accompany all types of epithermal deposits. In general, the largest of these deposits occur in intrusive or extrusive rocks of alkaline or calc-alkaline affinity. The Apigania Bay vein system and Au–Ag mineralization is hosted in Mesozoic marbles and schists, and is composed primarily of five nearly parallel, high-angle quartz veins that extend for at least 200 m. Gold–silver mineralization, in association with more than thirty ore and vein minerals, is developed in three stages and occurs at the contact of marbles and schists. Zones of epidote–chlorite–calcite and sericite–albite alteration are associated with precious metal-bearing milky and clear quartz veins. Fluid inclusion studies suggest that hydrothermal mineralization was deposited under hydrostatic pressures of ~100 bars, at temperature of 120–235°C, from low to moderate, calcium-bearing, saline fluids of 0.2 to 6.8 equiv. wt.% NaCl. Calculated isotope compositions (δ¹⁸O?=??4.7‰ to 1.7‰ and δD?=??120‰ to ?80‰) for waters in equilibrium with milky and clear quartz are consistent with mixing with dilute, low temperature meteoric ore fluids. Calculated δ ¹³C_CO2 (0.6‰ to 1.1‰) and δ ³⁴S_H2S (?7.3 to ?0.3‰) compositions of the ore fluids indicate exchange, in an open system, with a metasedimentary source. Gold and silver deposition was associated with degassing of hydrogen due to intense uplift of the mineralizing area. The physicochemical conditions of mineralization stages I to III range between 200°C and 150°C, $f_{{\text{S}}_2 } = 10^{ - 18.1} $ to 10^?16.8, $f_{{\text{O}}_2 } = 10^{ - 44.0} $ to 10^?41.5, pH?=?6.9 to7.6, $f_{{\text{H}}_{\text{2}} {\text{S}}} = 10^{ - 3.4} $ to 10^?2.6 and $a_{{\text{H}}_{\text{2}} {\text{S}}} = 10^{ - 2.7} $ to 10^?2.6. Apigania Bay could be possibly considered the latest evolutional phase of Tinos hydrothermal system.  相似文献   

Identifying drivers for fishing pressure. A multidisciplinary study of trawl and sea snail fisheries in Samsun,Black Sea coast of Turkey     

Ståle Knudsen  Mustafa Zengin  Mahmut Hakan Koçak 《Ocean & Coastal Management》2010,53(5-6):252-269

This study aims to investigate and model driving forces that lead to increased fishing pressure and an altered state of the environment in the coastal areas near Samsun on the Turkish Black Sea coast. We have applied a modified DPSIR model to structure our investigation and analysis and have investigated the drivers that generate fishing pressure in the Samsun fisheries. The overall health of the ecosystem is declining, and there is a consistent trend of deterioration in the condition of the three major species targeted by the trawl fisheries. Although introduced invasive species have brought significant changes to the Black Sea, it is clear that the state of the environment is significantly and negatively affected by the pressure exerted by fisheries. Fishing pressure has to a certain extent been redirected to pelagic trawling as bottom trawling has become less profitable and a rise in catch capacity has levelled off. This reduction is, however, offset by an increase in illegal trawling and dredging by a very rapidly growing sector of multi-purpose small boats, resulting in a considerable increase in the overall accumulated engine power of fishing boats in Samsun during 2000–2005. Fisheries in Samsun, in particular sea snail fisheries, have constituted a frontier of sorts open to the poorer populations of Samsun during the last 20 years, and, thereby, constitute one of the major drivers for fishing pressure. We identify eight drivers of importance for the period 2000–2005. Although the authorities can impact all or most of those drivers, most of them are beyond the scope of conventional ‘fisheries management’.  相似文献   

Zeitschriften- und Bücherschau     

St.  Sal. 《International Journal of Earth Sciences》1912,3(8):573-575

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