Comparative study of epiphytic algal communities on Typha latifolia L. and Phragmites australis (Cav.) Trin. ex Steud in the shallow Gala Lake (European Part of Turkey)     

Burak  Öterler 《中国海洋湖沼学报》2018,36(5):1615-1628

Journal of Oceanology and Limnology - The aim of this study was to determine the species composition, biodiversity and, relative abundance of epiphytic algae and their relationship with...  相似文献   

Cosmological Parameters from Cosmic Microwave Background Anisotropies: Status and Prospects     

Alessandro Melchiorri  Carolina J. Ödman 《Astrophysics and Space Science》2003,283(4):457-468

A survey is made of the present constraints on cosmological parameters from Cosmic Microwave Background Anisotropies. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Karst hydrogeology of Kusluk-Dilmetas karst springs, Van-Eastern Turkey     

Murat H. Özler 《Environmental Geology》2001,41(3-4):257-268

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Main sequence for rotating stars of intermediate mass     

D. Eryurt-Ezer  H. Kirbiyik  N. Özkara 《Astrophysics and Space Science》1986,126(1):29-50

We have investigated the evolutionary behaviour of intermediate mass (2, 3, 4, 5, and 7M ) Population I stars, assuming two different rates of rotation at the threshold of stability.In the first part of the study, stars are assumed to start with a critical rotation (fast rotation model) and to progress to the point of rotational instability. The stars evolve by losing mass and become rotationally unstable before they reach the zero-age Main Sequence. It is argued that multiple star systems might be formed through the evolution of rapidly rotating stars. An expression for the rotational mass loss rate is derived as a function of the physical parameters of stars.In the second part of the study, stars are assumed to rotate at a rate below the critical value (slow rotation model). The evolution of slowly rotating stars is followed as far as zero-age Main Sequence on the theoretical Hertzsprung-Russell diagram and compared with that of normal stars. The evolutionary paths are found to be more or less similar to those of normal stars; but their positions on the Main Sequence are characterized by effective temperatures and luminosities lower than those of normal stars. The zero-age Main-Sequence times of these stars are longer than those of normal stars. The rotational rates obtained for the zero-age Main Sequence are in good agreement with observed values.  相似文献   

A geological and geotechnical investigation of the settlement area of Zümrüt Building (Konya, Turkey) which caused 92 fatalities due to its collapse     

Adnan Özdemir 《Environmental Geology》2008,53(8):1695-1710

This study examines the local geological conditions and soil structure as possible causes of the collapse of the Zümrüt Building 2 February 2004. This catastrophe resulted in 92 fatalities and 35 injuries. This study also examines other views which claim weak soil structure, elastic and consolidation settlement of soil and excessive groundwater extraction as well as subsidence resulting from the underground silt erosion as possible factors. Zümrüt Building was constructed on normally consolidated, low plasticity clay. The underground water table was 30 m in depth. The internal friction angle of soil was 8°–30°, its cohesion was between 34 and 127 kN/m² and standard penetration test numbers varied between 11 and 50. The underground water level beneath Zümrüt Building had risen 4.5 m since its construction. Therefore the claim that subsidence resulting from the decrease of underground water level contributed to the collapse is incorrect. Secondly the settlement, resulting from the filling up of the pores created by the silt receding with the underground water, was 4.4 mm in total, and attributing this as the primary cause of the collapse is also incorrect. Soil properties, in situ and laboratory test results showed that the existing and/or expected settlement and the differential ground settlement in the Zümrüt building vicinity had the potential to cause structural damage. The tensile stresses caused by differential settlements recorded here are thought to be an indicator, but not the main cause contributing to the collapse of the building. The Zümrüt Building collapse was due to several compounding mistakes during the construction phase. These were geotechnical and other project faults and the use of low quality construction materials. The resulting catastrophe caused 92 fatalities, 35 injuries and a material loss of approximately US$7 million.  相似文献   

Can cod farming affect cod fishing? A system evaluation of sustainability     

Dag Standal  Ingrid Bouwer Utne 《Marine Policy》2007

The cod resources in the Barents Sea constitute the most important fisheries in Norway. In order to reduce resource allocation conflicts among different gear and vessel groups and to ensure profit for all participants throughout the value chain, the sector is thoroughly organized. The institutions established to ensure long-term sustainability, have been developed within the framework of a joint Norwegian–Russian fisheries management regime. However, due to a very high fishing mortality, the cod stock is now under severe pressure. In addition, a major part of the cod fisheries is highly seasonal and unable to be a stable supplier to neither the land-based industry nor demanding international markets. In parallel, cod farming is expected to become a new emerging industry, with potential to copy the success of farmed Atlantic salmon. Many actors within the cod fisheries fear the future competition from the growing cod farming sector. With reference to important attributes that characterize the cod fisheries and cod farming, this paper discusses how a future farming industry may affect the traditional cod fisheries. Moreover, we discuss how the fisheries may be forced to organize in the future to encounter the expected competition from cod farming.  相似文献   

Detection of DNA damage in mussels and sea urchins exposed to crude oil using comet assay     

Taban IC  Bechmann RK  Torgrimsen S  Baussant T  Sanni S 《Marine environmental research》2004,58(2-5):701-705

The single-cell microgel electrophoresis assay or the comet assay was used to evaluate DNA damage of dispersed crude oil on sea urchins (Strongylocentrotus droebachiensis) and mussels (Mytilus edulis L.). Sea urchins were exposed to 0.06 and 0.25 mg/L dispersed crude oil in a continuous flow system, while the mussels were exposed to 0.015, 0.06 and 0.25 mg/L dispersed crude oil. Sea urchin coelomocytes and mussel haemocytes were sampled after 4 and 5 weeks exposure, respectively. In the sea urchin coelomocytes, there was a significant concentration-related increase in the percentage of DNA in comet tail. In mussel haemocytes, there was a significantly higher percentage of DNA in comet tail for all treatments compared to the control. The responses were concentration-related up to 0.06 mg/L oil. The two highest exposure concentrations of mussels were not significantly different from each other. These results indicate that the comet assay can be used for biomonitoring of DNA damage in marine invertebrates following oil contamination.  相似文献   

Macrofauna Communities in the Eastern Mediterranean Deep Sea   总被引：1，自引：0，他引：1  

Ingrid Kröncke  Michael Türkay  & Dieter Fiege 《Marine Ecology》2003,24(3):193-216

Abstract. During two expeditions with RV ‘Meteor’ in summer 1993 and winter 1997/98 the structural and functional diversity of the benthic system of the highly oligotrophic eastern Mediterranean deep sea was investigated. The macrofauna communities were dominated by polychaetes even at the deepest stations. The fauna at shallow stations was dominated by surface deposit feeders, whereas subsurface deposit feeders and predators generally increased with depth. A high percentage of suspension‐feeding Porifera was found in the Levantine Basin. Mean abundance and number of taxa of both expeditions were significantly correlated to depth and distance to the nearest coast as well as to the total organic carbon (TOC) content in sediments. Numbers of taxa and abundance decreased generally with depth, although lowest numbers were not found at the deepest stations but in the extremely oligotrophic Levantine and Ierapetra Basin. Biomass measured during the second cruise was extremely low in the Ierapetra Basin and comparable to other extreme oligotrophic seas. The significant correlations found for TOC contents and macrofauna with distance to coast during both expeditions apparently reflect the role of hydrographically governed transport of organic matter produced in coastal regions into greater and extreme depths of the Mediterranean Sea. Seasonal differences in macrofauna communities due to seasonal differences in food supply were not found. However, recent large‐scale hydrographic changes (Eastern Mediterranean Transient, EMT) might change the oligotrophy and, thus, the structure of the benthic communities in the Eastern Mediterranean deep sea.  相似文献   

On the longitudinal distribution of the solar surges     

Atίla Özgüç 《Solar physics》1989,123(2):381-383

After re-examination of data presented by Verma (1984), some misuse of solar parameteres published in Solar Geophysical Data is presented. Consequently some conclusions made by Verma (1984, 1986) on about the longitudinal distribution of cool solar surges based on these misuses are discussed.  相似文献   

Retrograde fluid infiltration in the high-grade Modum Complex South Norway: evidence for age,source and REE mobility   总被引：1，自引：1，他引：0  

Ingrid Anne Munz  David Wayne  Håkon Austrheim 《Contributions to Mineralogy and Petrology》1994,116(1-2):32-46

The high-grade metamorphic basement of the Modum Complex, South Norway,exhibits retrogradation and alteration due to late stage fluid infiltration.Extensive alteration zones of albite-and calcite-rich veining occur especiallywithin and around numerous metagabbros. The gabbros, intruded at 1224±15Ma, are now partly altered to amphibolites due to the subsequent high-grade metamorphism.Two generations of albite-rich rocks have been recognized: (1) a fine-grained, foliated type;(2) a coarse-grained, crosscutting type. Both types show a typical greenschist facies mineralassemblage; albite ± actinolite ± chlorite ± talc. The calcite veins/dykesrepresent a younger generation of veins than both albite-rich types. U–Pb data for spheneof type (1) yielded an age of 1080±3 Ma, determining a point on the retrogradeP-T-t path of the Modum Complex. Increasing albitisation of themetagabbros leads to a decrease in(¹⁴³ND/¹⁴⁴Nd)_oand an increase in (⁸⁷Sr/⁸⁶)_o.Albite- and calcite-rich samples show negative _Nd and positive _Sr, suggesting that fluids which interacted with the metagabbros originated from a crustal reservoir. The Nd and Sr isotopic data show disequilibrium at the microscale as well as at the macroscale. Negative Sm–Nd model ages of the albite-rich rocks demonstrate that rare-earth elements (REEs) were mobile and fractionated during albitisation.  相似文献