Diurnal photometric conditions at Teide observatory and long-term solar irradiance variations     

B. Andersen  V. Domingo  A. Jiménez  A. Jones  S. Korzennik  P. L. Pallé  F. Pérez Hernández  C. Régulo  T. Roca Cortés  L. L. Tomás 《Solar physics》1988,116(2):391-399

Monochromatic extinction coefficients at four wavelengths have been obtained over a period of more than two years at the Observatorio del Teide (Izaña Tenerife) using a full disc, direct sunlight, quadruple photometer devoted to the detection of integral luminosity oscillations of the Sun. The mean extinction coefficients (0.13 at 500 nm) show a seasonal variation of about 15%, the best atmospheric conditions being in winter and autumn. Moreover, in anyone day the extinction coefficient in the afternoon is always lower than the one in the morning by 7%. A one-year period fluctuation, with an amplitude of 0.035 mag, has been identified in the instrumental magnitudes outside the atmosphere, and is interpreted as the variation produced by the different Sun-Earth distance from winter to summer. Finally, the study made to detect periodic time fluctuations in both, Sun's magnitude and extinction coefficients, has given null results at levels of 0.04 and 1.8%, respectively.  相似文献   

Emission features in the solar corona after the perihelion passage of Comet 1979 XI     

D. Chochol  V. Rušín  L. Kulčár  V. Vanýsek 《Astrophysics and Space Science》1983,91(1):71-77

On the coronograph spectrophotographic records taken on 31.372 UT, August 1979, some faint emission features were found which can be ascribed to Siii and Niii. These emissions were obviously a transient phenomena which were detected only 10 hr after the supposed fall of Comet 1979 XI in the Sun's photosphere. It cannot be excluded that the appearance of Si and Ni lines was triggered by the evaporation of dust particles with a high abundance of heavier elements in the solar corona. This assumption is also supported by intensity distribution of the Fex coronal line around the Sun's limb. The maximum coincide with the position angle of the projected path of the comet.  相似文献   

Anthropogenic influence on trace element geochemistry of healing mud (peloid) from Makirina Cove (Croatia)     

S. Miko  G. Koch  S. Mesić  M. Šparica-Miko  M. Šparica  R. Čepelak  A. Bačani  P. Vreča  T. Dolenec  S. Bergant 《Environmental Geology》2008,55(3):517-537

Due to their balneotherapeutic features, the organic-rich sediments in Makirina Cove are an important source of healing mud. An environmental geochemistry approach using normalization techniques was applied to evaluate the anthropogenic contribution of trace metals to sediments used as healing mud. Sediment geochemistry was found to be associated with land-use change and storm events, as well as with proximity of a road with heavy traffic in the summer months. Local valley topography preferentially channels lithogenic and pollutant transport to the cove. Concentrations and distribution of trace metals indicate lithogenic (Ni, Cr, Co) and anthropogenic (Pb, Cu, Zn and Se) contributions to the sediments. The calculation of enrichment factors indicates a moderate (EFs between 2–3.5) input of anthropogenic Cu and Pb in surficial sediments to a depth of 10 cm. Patients using the Makirina Cove sediments as healing mud could be to some extent exposed to enhanced uptake of metals from anthropogenic sources via dermal contact.  相似文献   

Biomarker distributions as indicators for the depositional environment of lacustrine sediments in the Valjevo-Mionica basin (Serbia)     

Aleksandra Šajnović  Ksenija Stojanović  Branimir Jovančićević  Olga Cvetković 《Chemie der Erde / Geochemistry》2008,68(4):395-411

In this study, the molecular composition and biomarker distribution of lacustrine sediments from Val-1 drillhole in the central zone of the western part of the Valjevo-Mionica basin were investigated at depth interval of 0–400 m. Former investigations have shown that the core material can be separated into six depth intervals based on bulk geochemical, mineralogical and sedimentological characteristics. Concerning the quality of organic matter, presence of specific minerals, and high salinity and anoxicity, or alkalinity, three zones are of highest interest, defined at depth intervals of 15–75 m (A), 75–200 m (B) and 360–400 m (F). The first aim of the study was to identify which biomarkers characterize these specific intervals. The second aim, addressing the transitions zones of these intervals, was to extend the changes in the characteristics of the organic substance, to reflect the changes of conditions in the depositional environment as well as to define biomarker parameters which are the most sensitive sedimentological indicators.The sediments from the hypersaline anoxic and alkaline environment show high contribution of algal precursor biomass, what is in accordance with the good quality of organic substances in the sediments from these zones. High squalane content and low content of regular isoprenoid C₂₅ are typical for hypersaline anoxic environment, whereas sediments from alkaline environment have high regular isoprenoid C₂₅ content.Transition to specific sedimentation zones is characterized by change in total organic matter content, and of both free and pyrolysis-derived, and change in hydrogen index value. In the biomarker distributions, more significant changes were detected in distributions of n-alkanes and isoprenoids, compared to polycyclic alkanes. The most intensive changes in alkane distribution are reflected in changes in n-C₁₇ content compared to n-C₂₇, and phytane compared to n-C₁₈. In addition, significant sensitivity was seen in ratios between squalane and n-alkane C₂₆ (hypersaline depositional environment), or isoprenoid C₂₅ and n-alkane C₂₂ for high alkalinity environment.This study showed that Sq/n-C₂₆ ratio can be used to assess the quality of organic substance in immature lacustrine sediments.  相似文献   

Leaching mechanisms of oxyanionic metalloid and metal species in alkaline solid wastes: A review     

Geert Cornelis  C. Anette Johnson  Tom Van Gerven  Carlo Vandecasteele 《Applied Geochemistry》2008

An overview is presented on possible mechanisms that control the leaching behaviour of the oxyanion forming elements As, Cr, Mo, Sb, Se, V and W in cementituous systems and alkaline solid wastes, such as municipal solid waste incinerator bottom ash, fly ash and air pollution control residues, coal fly ash and metallurgical slags. Although the leachability of these elements generally depends on their redox state, speciation measurements are not common. Therefore, experimental observations available in the literature are combined with a summary of the thermal behaviour of these elements to assess possible redox states in freshly produced alkaline wastes, given their origin at high temperature. Possible redox reactions occurring at room temperature, on the other hand, are reviewed because these may alter the initial redox state in alkaline wastes and their leachates. In many cases, precipitation of oxyanions as a pure metalate cannot provide a satisfactory explanation for their leaching behaviour. It is therefore highly likely that adsorption and solid solution formation with common minerals in alkaline waste and cement reduce the leachate concentration of oxyanions below pure-phase solubility.  相似文献   

Deep-seated gravitational slope deformations and their influence on consequent mass movements (case studies from the highest part of the Czech Carpathians)   总被引：3，自引：0，他引：3  

Jan Hradecký  Tomáš Pánek 《Natural Hazards》2008,45(2):235-253

Gravitational spreading of mountain ridges displays primary disequilibrium of flysch mountain areas of the Czech Carpathians. The progression of various types of mass movements is a product of long-term ridge disintegration and is predisposed by the geological structure of the area and the upper Tertiary-Quaternary morphogenesis of the mountain area. Deep-seated slope deformations are spatially interconnected by the occurrence of some other types of slope deformations (e.g. debris flows, debris slides, slumps, rock avalanches, etc.), which pose a considerable risk for the existence of human society. An important causative factor in these dynamically developing hazardous processes is, among other factors, the way in which land has been used in the last three centuries. Therefore, the occurrence of various types of slope deformations is studied in terms of their relation to deep-seated gravitational deformations and in terms of other limiting factors (structural geological, morphological and climatic factors, manmade impacts, etc.). The paper presents several case studies of slope deformations (Velká Čantoryje Mt, Lysá hora Mt, Ropice Mt and Smrk Mt) in the area of the Outer Carpathians within the territory of the Czech Republic and also adverts to some consequences in terms of the socioeconomic structure of the landscape.  相似文献   

On the types and dispersions of whistlers as observed in czechoslovakia     

František Jiříček 《Studia Geophysica et Geodaetica》1962,6(1):98-101

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Astronomische Bestimmung der Relativen Lotabweichungen im Westlichen Tatragebiet     

Josef Kabeláč 《Studia Geophysica et Geodaetica》1962,6(1):1-13

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Метод трех направлений     

Karel Kučera 《Studia Geophysica et Geodaetica》1966,10(4):411-421

Summary In [1] the author has put forward a three-direction method, a general way of adjustment of angular observations in incomplete sets by the method of extending into angular combinations, and the definition of mean weightP ^*. In this article the question is dealt with as a whole. In the three-direction methods>3 triangulation directions are measured in direction triplets 123, 234, 345,… …,s12, while in the method of measuring single angles at the station they are measured in angles 12, 23, 34, 45, …,s1. The advantage of transition from angles to direction triplets rests, besides in saving 31% of pointings, above all in certain possibility of elimination of the horizontal refraction, which follows from this. The treatise of the relation between the method of measurement and the refraction is not included into this article, as it would go beyond its scope. The fact that adjusted directions, with the exception of the stations having four directions, are not of equal weight, is proper not only to the three-direction method. The non-equality of weights is even more conspicuous in the method of measuring single angles at the station, and it appears already at the stations having four directions. In author's view the homogeneity of observation elements is more important than the homogeneity of weights from the point of view of adjustment at the station; therefore the direction triplets ought not to exist abreast with the angles in one programme, and especially the number of observations ought to be constant at one station with adjusted direction of homogeneous mean weight in the net. This transition from angles to direction triplets could also provoke a comment that simultaneous visibility of three adjoining directions occurs less often than of two such directions. The author adds to this that nowadays the causes of this phenomenon, following from unsuitable technique, must be eliminated. It is just air limpidity that ought to define the visibility, not unsufficient or everywhere equal intensity of light of reflectors, or too long sides of the triangulation net. Recent approach to this problem requires simultaneous visibility of all directions during most of the days of observation. In connection with the out-of=date technique, the methods of angular observation often have one unfavourable character: they are the cause of the accumulation of observations of “always visible” directions. The supposed merit of angles thus turns into their imperfection.

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Адрес: Politickych vězňů 12, Praha 1-Nové Město  相似文献   

Lower Tertiary volcanic rocks off Kristiansund — Mid Norway     

Tom Bugge  Tore Prestvik  Kåre Rokoengen 《Marine Geology》1980,35(4):277-286

Grab samples from the Norwegian continental shelf show that diapiric structures occurring within a sequence of Mesozoic and Tertiary sediments represent volcanic rocks consisting of porphyritic olivine-nephelinite. The KAr age of 55.7 ± 0.9 m.y. shows that the area affected by Lower Tertiary magmatism in the North Atlantic region also included the continental shelf off Mid Norway. The highly undersaturated nature of these volcanic rocks, however, indicates that they are unlikely to be closely related to the widespread tuff horizons of the same age known from the North Sea.  相似文献