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1.
Granulometric and chemical composition of the Sava River sediments upstream and downstream of the Krsko nuclear power plant 总被引：2，自引：2，他引：0
Visnja?OrescaninEmail author Stipe?Lulic Gordana?Pavlovic Luka?Mikelic 《Environmental Geology》2004,46(5):605-614
Total concentrations of 13 elements (K, Ca, Ti, Cr, Mn, Fe, Cu, Zn, Rb, Sr, Y, Zr, Pb) in the size-fractionated Sava River sediments upstream and downstream of the Krsko nuclear power plant together with metal speciation within bulk sediment have been investigated. Trace metals generally increase with decreasing particle size, however, because of entrapment of organic matter in the 0.63–1 mm fraction, concentrations in the coarser sediment fraction are higher than expected. Exchangeable Pb, Zn, Cu, Mn, Cr and Fe are generally found to represent a negligible fraction of the total metal concentration of the bulk sediment. Seasonal variations of the Pb, Zn and Cu concentrations in the <0.5 mm fraction reflect decreased values during the spring period. Heavy metal concentrations in the 2003 waste water discharges from the Krsko nuclear power plant released into the Sava River were much lower than their maximum allowed values. Combined rubidium and organic matter normalization of the Zn, Pb and Cu concentrations, which was applied on the minus 0.063 mm fraction, indicated three potential sources of contaminants. 相似文献
2.
Luka Č. Popović 《New Astronomy Reviews》2012,56(2-3):74-91
It is now agreed that mergers play an essential role in the evolution of galaxies and therefore that mergers of supermassive black holes (SMBHs) must have been common. We see the consequences of past supermassive binary black holes (SMBs) in the light profiles of so-called ‘core ellipticals’ and a small number of SMBs have been detected. However, the evolution of SMBs is poorly understood. Theory predicts that SMBs should spend a substantial amount of time orbiting at velocities of a few thousand kilometers per second. If the SMBs are surrounded by gas observational effects might be expected from accretion onto one or both of the SMBHs. This could result in a binary Active Galactic Nucleus (AGN) system. Like a single AGN, such a system would emit a broad band electromagnetic spectrum and broad and narrow emission lines.The broad emission spectral lines emitted from AGNs are our main probe of the geometry and physics of the broad line region (BLR) close to the SMBH. There is a group of AGNs that emit very broad and complex line profiles, showing two displaced peaks, one blueshifted and one redshifted from the systemic velocity defined by the narrow lines, or a single such peak. It has been proposed that such line shapes could indicate an SMB system. We discuss here how the presence of an SMB will affect the BLRs of AGNs and what the observational consequences might be.We review previous claims of SMBs based on broad line profiles and find that they may have non-SMB explanations as a consequence of a complex BLR structure. Because of these effects it is very hard to put limits on the number of SMBs from broad line profiles. It is still possible, however, that unusual broad line profiles in combination with other observational effects (line ratios, quasi-periodical oscillations, spectropolarimetry, etc.) could be used for SMBs detection.Some narrow lines (e.g., [O III]) in some AGNs show a double-peaked profile. Such profiles can be caused by streams in the Narrow Line Region (NLR), but may also indicate the presence of a kilo-parsec scale mergers. A few objects indicated as double-peaked narrow line emitters are confirmed as kpc-scale margers, but double-peaked narrow line profiles are mostly caused by the complex NLR geometry.We briefly discuss the expected line profile of broad Fe Kα that probably originated in the accretion disk(s) around SMBs. This line may also be very complex and indicate the complex disk geometry or/and an SMB presence.Finally we consider rare configurations where a SMB system might be gravitationally lensed by a foreground galaxy, and discuss the expected line profiles in these systems. 相似文献
3.
Luka Gale Tea Kolar-Jurkov?ek Andrej ?muc Bo?tjan Ro?i? 《Swiss Journal of Geoscience》2012,105(3):435-462
Conodonts and re-deposited shallow-water benthic foraminifera co-occur in the Upper Norian-Rhaetian Slatnik Formation of the Slovenian Basin (Southern Alps). The Mt. Kobla and Mt. Slatnik sections were investigated in order to give the first direct correlation between these two groups. The Norian-Rhaetian boundary (NRB) is placed at the First Appearance Datum of the conodont Misikella posthernsteini and is approached with the First Occurrence of the foraminifer Involutina turgida. An association of Trocholina turris with duostominids is a good marker for the Rhaetian. Careful revision of literature combined with our data culminated in reambulation of stratigraphical ranges for several foraminiferal species. The foraminiferal Triassic-Jurassic boundary (TJB) can be defined with the Last Occurrence of Galeanella tollmanni, ??Sigmoilina?? schaeferae or duostominids. The absence of the uppermost Rhaetian Misikella ultima conodont zone and the close coincidence of foraminiferal and conodont TJB could point to the presence of hiati in the upper part of the Slatnik Formation. Consequently, the exact pattern of disappearance of Late Triassic foraminifera at the boundary could not be observed. It is clear, however, that the foraminiferal assemblage was decimated for reef-dwelling foraminifera, duostominids and most of the platform-dwelling foraminifera. Biotic changes at the TJB are best explained as a result of a biocalcification crisis. 相似文献
4.
Visnja Orescanin Delko Barisic Ivanka Lovrencic Luka Mikelic Martina Rozmaric-Macefat Gordana Pavlovic Stipe Lulic 《Environmental Geology》2005,49(1):53-64
The objective of this study was chemical and radiological characterization of Kastela Bay sediments exposed to numerous anthropogenic sources like deposition of fly and bottom ash enriched in radionuclides and heavy metals, chemical plant, cement plant, iron plant, shipyard, electroplating facility, untreated industrial and domestic waste waters as well as heavy traffic. Totally, 33 samples of the mixture of fly and bottom ash, 12 sediment cores ranging from 0 to 40 cm and nine surface sediment samples were analyzed. Enrichment in heavy metals in the mixture of fly and bottom ash was ranging from 1.5 to 36 times compared to flysch soil while 226Ra and 238U were up to 50 times enriched compared to average activities characteristic for surrounding soils developed on the Middle and Upper Eocene flysch. Maximum 238U activity was approximately 32 times higher and 226Ra approximately 40 times higher in the Kastela Bay sediment compared to mean value determined for Adriatic sediments. The highest enrichment in sediment cores compared to background values were found for Zn (35.6 times), Pb (16 times), Cr (9.1 times) and Ni (4 times) 相似文献
5.
Igor Bogunovic Darija Bilandzija Zeljko Andabaka Domagoj Stupic Jesús Rodrigo Comino Marija Cacic Luka Brezinscak Edi Maletic Paulo Pereira 《Arabian Journal of Geosciences》2017,10(15):340
The use of machinery in vineyards is increasing soil compaction and erosion. However, there is a lack of information about the impacts of different management practices on soil conditions of vineyards. Therefore, the aim of this study was to assess soil compaction in Croatian vineyards under four different management systems: no-tillage (NT) system, conventional tillage (CT), yearly inversed grass covered (INV-GC) and tillage managed (INV-T) treatments. Four key top-soil (0–20 cm) parameters were assessed in the different land uses: bulk density (BD), penetration resistance (PR), soil water content (SWC) and carbon dioxide (CO2) fluxes. Tractor traffic increased the BD and PR in all treatments, with exception of CT treatment, as consequence of tillage. SWC showed higher values in INV-GC treatment during the dry period; meanwhile, it was similar during the wet season in every management type. Lower CO2 fluxes were found in INV-GC and NT than in the CT and INV-T treatments. 相似文献
6.
Josip Terzić Tamara Marković Jasmina Lukač Reberski 《Environmental Earth Sciences》2014,72(4):1129-1142
Miljacka is a karst spring situated in Dalmatia, Croatia. The interpretation of the Miljacka Spring catchment area boundary has repeatedly changed in the past, and the main conclusions of previous studies were that the spring, which is located in the Krka River canyon, receives all of its water from another karst river, Zrmanja. Here, we review a new hypothesis that the Miljacka Spring receives some of its water from the Krka River. It was not possible to verify the hypothesis by solely studying the geological composition, structural–tectonic relations and tracer test results. Therefore, a hydrochemical study was performed to confirm the hypothesis. By studying the geological composition, it was found that part of the catchment area of the Krka River is built of evaporites (gypsum and anhydrite), which are different in their mineral composition than carbonates, the usual rock mass of the Dinaric karst. The hydrochemical model was made using the NETPATH-WIN and PHREEQC software packages. The mixing model results confirmed the hypothesis that the Miljacka Spring waters come from both the Zrmanja (including smaller proportion of precipitation infiltrated directly in the karst aquifer) and Krka rivers. This case study shows the great importance of the application of hydrochemical investigations in karst hydrogeology, where research is often difficult due to the complexity of the groundwater system. 相似文献
7.
8.
Saša Simić Luka Č. Popović Michael I. Andersen Lise Christensen 《Astrophysics and Space Science》2007,309(1-4):173-177
In this paper we investigate the variability of the gamma ray burst light curve. It is generally known that this fluctuation
arise in the second phase of a GRB event, when two shock waves of different Lorentz factors collide. This is so called internal
shock scenario. We have developed a simple model which includes dynamical and radiating part, to simulate shock wave evolution
and collision. By specifying the model parameters, we show that this scenario could be used to describe variability of GRB
light curve. We then use the model to simulate peeks in several different long GRB events from the BATSE database, which show
us that some of the basic parameters have a very narrow range of values.
相似文献
9.
The compatibility of cosmologic principles and possible large-scale inhomogeneities of the Universe is discussed. It seems that the strongest symmetry principle compatible with reasonable inhomogeneities is full conformal symmetry in the three-space defined by the cosmological velocity field; but even then the standard model is isolated from inhomogeneous ones when the whole evolution is considered. 相似文献
10.
Vassiliki Kotroni Evangelos Floros Konstantinos Lagouvardos Goran Pejanovic Luka Ilic Momcilo Zivkovic 《Earth Science Informatics》2010,3(4):209-218
Weather forecasting is based on the use of numerical weather prediction (NWP) models that are able to perform the necessary
calculations that describe/predict the major atmospheric processes. One common problem in weather forecasting derives from
the uncertainty related to the chaotic behaviour of the atmosphere. A solution to that problem is to perform in addition to
“deterministic” forecasts, “stochastic” forecasts that provide an estimate of the prediction skill. A computationally feasible
approach towards this aim is to perform “ensemble forecasts”. Indeed, in the frame of SEE-GRID-SCI EU funded project a Regional
scale Multi-model, Multi-analysis ensemble forecasting system (REFS) was built and ported on the Grid infrastructure. REFS
is based on the use of four limited area models (namely BOLAM, MM5, ETA, and NMM) that are run using a multitude of initial
and boundary conditions over the Mediterranean. This paper presents the tools and procedures followed for developing this
application at a production level. 相似文献