Bestimmung sehr kleiner Verteilungskoeffizienten von Cs,Na und Ba zwischen Lösung und KCl-Einkristallen mit Hilfe radioaktiver Isotope     

Hans Hartmut Schock 《Contributions to Mineralogy and Petrology》1966,13(2):161-180

Distribution of Cs, Na, and Ba between great monocrystals of KCl and water solution was investigated. Impurity was either labelled by long-lived radioactive isotopes or was activated after growth of the crystals by neutrons in a nuclear reactor. No influence on partition coefficients was caused by using radioactive tracers, e.g. due to raised inclusion of mother liquor. Between impurity concentrations from 3·10^–4 to 10^–1 in the solution the partition coefficients were nearly constant and about 10^–3 for Na, about 10^–4 for Cs, and <5·10^–5 for Ba in KCl at temperatures of 40° C. If different impurity ions were built in simultaneously, the partition coefficients were independent of composition of solution. In case of Cs in KCl capture of Cs increased with increasing temperature.

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Meinem hoehverehrten Lehrer, Herrn Prof. Dr. W. von Engelhart, danke ieh für die freundliehe Überlassung des interessanten Themas. Für die stete Förderung und die zahlreichen fruehtbaren Diskussionen und Anregungen bin ich ihm und Herrn Dr. H. Puchelt zu großem Dank verpflichtet.Dem Bundesnlinisterium für wissensehaftliehe Forsehung danke ieh ffir die großzügige Unterstützung der Arbeit.Herrn Prof. Dr. W. Seelmann-Eggebert und Herrn Dr. V. Schneider vom Kernforsehungszentrum Karlsruhe und Herrn Dr. Bartel von der Kernforsehungsanlage Jülich danke ich für die Unterstützung bei der Neutronenaktivierung und Herrn Dr. J. Ottemann vom Mineralogischen Instigut der Universität Heidelberg für die Untersuchung mit der Elektronenmikrosonde.  相似文献   

Benthic mineralization rates at two locations in the southern North Sea     

Ronald Osinga  Arjen J. Kop  Gerard C. A. Duineveld  Rudolf A. Prins  Fleur C. Van Duyl 《Journal of Sea Research》1996,36(3-4)

Benthic oxygen uptake, sulphate reduction and benthic bacterial production were measured at two contrasting locations in the southern North Sea: the shallow and turbulent Broad Fourteens area in the Southern Bight, and the deeper Oyster Grounds, a deposition area, where thermohaline stratification occurs during summer. Oxygen uptake and sulphate reduction showed a clear seasonal pattern in the Broad Fourteens area, indicating a supply of carbon to the benthic system that is closely related to the standing stock of carbon in the water column. This close benthic-pelagic coupling is probably due to the influence of the tide in this part of the North Sea, which keeps the water column permanently mixed. At the Oyster Grounds, no seasonal pattern was observed. Peaks in oxygen uptake and sulphate reduction were found in winter. Irregularly occurring events, such as storms and fishery-related activities, are likely to affect the benthic mineralization patterns in this area. Annual benthic carbon mineralization rates estimated from oxygen uptake rates were 44 gC·m⁻² at the Broad Fourteens, and 131 gC·m⁻² at the Oyster Grounds, of which 26 and 28%, respectively, could be attributed to sulphate reduction (assuming an annual sulphide reoxidation rate of 100%). Although sulphate reduction rates in the southern North Sea are higher than previously suggested, aerobic respiration is the most important pathway for benthic carbon mineralization at the stations visited. Production rates of benthic bacterial carbon measured with labelled leucine were much higher than carbon mineralization rates based on oxygen uptake or sulphate reduction. This may either imply a very high bacterial carbon conversion efficiency, or point to shortcomings in the accuracy of the techniques. A critical evaluation of the techniques is recommended.  相似文献   

A simple method for comparing age-length keys reveals significant regional differences within a single stock of haddock (Melanogrammus aeglefinus)     

Gerritsen  Hans D.; McGrath  David; Lordan  Colm 《ICES Journal of Marine Science》2006,63(6):1096-1100

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A meta-analysis of the status of ICES fish stocks during the past half century   总被引：2，自引：0，他引：2  

Sparholt  Henrik; Bertelsen  Mette; Lassen  Hans 《ICES Journal of Marine Science》2007,64(4):707-713

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Estimating Deep Seafloor Interface and Volume Roughness Parameters Using the Multibeam-Hydrosweep System     

Bishwajit Chakraborty  Hans Werner Schenke  Vijay Kodagali  Rick Hagen 《Marine Geodesy》2002,25(1):19-26

Utilizing a hull-mounted, multinarrow beam echosounder onboard RV Polarstern, we measured variation of acoustic backscatter with incidence angles at two different sites in the Southern Oceans (Agulhas Plateau and the Riiser Larsen Sea). We modeled the data, using a composite roughness model, including water-sediment interface roughness and sediment volume roughness parameters. The model effectively uses the near normal incidence angle backscatter to determine the seafloor interface roughness parameters employing Helmholtz-Kirchhoff theory. Beyond 20° incidence angles, an application of Rayleigh-Rice theory is made by using a necessary splicing technique (combining both of the theories at 20° incidence angle). The estimated interface and volume roughness parameters are found to be in accordance with the known area geology.  相似文献   

Lysosomal injury and MFO activity in the liver of flounder (Platichthys flesus L.) in relation to histopathology of hepatic degeneration and carcinogenesis     

Angela Khler  Hans Jürgen Pluta 《Marine environmental research》1995,39(1-4)

Flounder (Platichthys flesus L.), 18–48 cm total length were sampled in the mouth of the Elbe River during a 3-year interdisciplinary project ‘Fish Diseases in the Wadden Sea’. Lysosomal changes (lysosomal membrane stability) and the activity of biotransforming enzymes (MFOs/EROD) were measured parallel to investigations of ultrastructural changes in liver cells, tissue pathologies and macroscopically visible changes. The aim of the study was to investigate if these cyto- and biochemical parameters were able to reflect contaminant induced biological effects. Interlinking of the results of the MFO activity to the pathological alterations observed at the electron- and light-microscopic levels as well as during macroscopic inspection of identical individuals evidenced that the activity of the biotransformation enzymes (EROD) was not induced in healthy livers, increased considerably with the onset of liver changes and dropped again in those livers with degenerative, preneoplastic and neoplastic lesions. In contrast, concurrent studies of lysosomal membrane stability measured in parallel showed a decrease with the onset and progression of liver lesions from reversible to irreversible, neoplastic change.  相似文献   

Should total landings be used to correct estimated catch in numbers or mean weight-at-age?     

Lewy  Peter; Lassen  Hans 《ICES Journal of Marine Science》1997,54(3):462-470

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Development of fouling communities on vertical structures in the Baltic Sea   总被引：6，自引：2，他引：6  

Susanne Qvarfordt  Hans Kautsky  Torleif Malm 《Estuarine, Coastal and Shelf Science》2006,67(4):618-628

The pillars of the bridge connecting the Island of Öland with the Swedish mainland were rebuilt between 1990 and 2000. The renovation produced pristine vertical concrete substrates, which became submerged in known years and seasons. The fouling communities on the pillars were examined in 2001 to determine whether the community structure could be explained in terms of either orderly successional development or of seasonal variation in the settlement of benthic organisms. As well, the communities on the pillars were compared to communities on the vertical surfaces of boulders in the area. The results indicated that an annual species composition is the final stage in the succession on the observed, vertical constructions. The few perennial species add to the variation between pillars as they increase in biomass (Polysiphonia fucoides) or become out-competed (Balanus improvisus). Also, observed seasonal differences in the biomass of these perennial species indicated that the time of year free space becomes available might be an important determinant of the future structure of the community. Comparison between the pillar and boulder communities showed that the artificial structures were not surrogates for the natural hard substrate: pillar communities differed in that they lacked most perennial algal species and had a high biomass of B. improvisus.  相似文献   

Benthic photosynthesis in submerged Wadden Sea intertidal flats   总被引：3，自引：1，他引：3  

Markus Billerbeck  Hans Ry  Katja Bosselmann  Markus Huettel 《Estuarine, Coastal and Shelf Science》2007,71(3-4):704-716

In this study we compare benthic photosynthesis during inundation in coarse sand, fine sand, and mixed sediment (sand/mud) intertidal flats in the German Wadden Sea. In situ determinations of oxygen-, DIC- and nutrient fluxes in stirred benthic chamber incubations were combined with measurements of sedimentary chlorophyll, incident light intensity at the sediment surface and scalar irradiance within the sediment. During submergence, microphytobenthos was light limited at all study sites as indicated by rapid response of gross photosynthesis to increasing incident light at the sea floor. However, depth integrated scalar irradiance was 2 to 3 times higher in the sands than in the mud. Consequently, gross photosynthesis in the net autotrophic fine sand and coarse sand flats during inundation was on average 4 and 11 times higher than in the net heterotrophic mud flat, despite higher total chlorophyll concentration in mud. Benthic photosynthesis may be enhanced in intertidal sands during inundation due to: (1) higher light availability to the microphytobenthos in the sands compared to muds, (2) more efficient transport of photosynthesis-limiting solutes to the microalgae with pore water flows in the permeable sands, and (3) more active metabolic state and different life strategies of microphytobenthos inhabiting sands.  相似文献   

A giant three-stage submarine slide off Norway   总被引：8，自引：0，他引：8  

Tom Bugge  Stein Befring  Robert H. Belderson  Tor Eidvin  Eystein Jansen  Neil H. Kenyon  Hans Holtedahl  Hans Petter Sejrup 《Geo-Marine Letters》1987,7(4):191-198

One of the largest submarine slides known, The Storegga Slide, is located on the Norwegian continental margin. The slide is up to 450 m thick and has a total volume of about 5,600 km3. The headwall of the slide scar is 290 km long and the total run-out distance is about 800 km. The slide involved sediments of Quaternary to Early Tertiary age and occurred in three stages. Earthquakes combined with decomposition of gas hydrates are believed to be the main triggering agents for the slides. The first slide event is tentatively dated to be about 30,000 to 50,000 years B.P. and the two last major events are dated to be at 6,000 to 8,000 years B.P.  相似文献