Thermal field in the Romanian Carpathian bend and some aspects of its interpretation     

Marius Visarion  Serban Veliciu  Mihai StefĂnescu  Reviewer V. Čermák 《Studia Geophysica et Geodaetica》1978,22(2):196-200

Summary Using heat flow and heat generation measurements together with deep seismic sounding and gravity data, a reasonable geothermal model has been constructed for the Romanian Carpathian Bend. At the level of the MOHO discontinuity the calculated temperatures exhibit conspicuous differences between inner and outer border of the Carpathian Bend and a horizontal gradient of 200–300 °C/100 km in the region is not to be excluded.Paper presented at the KAPG Symposium on Geothermics in Liblice, November 1976.  相似文献   

Classical Scattering and Block Regularization for the Homogeneous Central Field Problem     

Cristina Stoica 《Celestial Mechanics and Dynamical Astronomy》2002,84(3):223-229

The present paper offers an alternative point of view of block regularization for the motion of a particle in a central potential field of the form –x ^–, where x is the distance between the particle and the source and some positive real number.Working in the physical space, we consider the scattering angle determined by the path of the particle as a function of angular momentum. We prove that a particle flow is passing over the collision singularity preserving differentiability with respect to initial data if and only if = 2(1–1/n), n positive integer, n 2.This result coincides with the outcome of block regularization applied by McGehee to the same dynamical problem. We discuss that this identity was to expect since both methods target the same physical constraint over the flow.  相似文献   

The content of some microelements in mineral waters from Covasna and Harghita Romanian districts     

Gabriela-Raluca Babaua  Anca-Iulia Stoica  Petre Capota  George-Emil Baiulescu 《Environmental Geology》2003,45(1):58-64

Using two analytical techniques, CSV/ASV and ICP–AES, the concentration of some microelements (lead, zinc, manganese) in mineral waters from the Covasna and Harghita districts of Romania were determined. The optimum parameters for the voltammetric determination of manganese, copper, zinc and lead were established (electrolyte, deposition time, pulse duration, pulse amplitude, etc.) and then the content of these elements in twelve samples of mineral water were determined. The results obtained by both techniques led to the conclusion that the concentration of microelements in mineral waters from Covasna and Harghita districts is connected to the mineral content underground.  相似文献   

Bacterioplankton community composition in nearshore waters of the NW Black Sea during consecutive diatom and coccolithophorid blooms     

Elena Stoica  Gerhard J. Herndl 《Aquatic Sciences - Research Across Boundaries》2007,69(3):413-418

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Speciation and role of iron in cloud droplets at the puy de Dôme station     

Marius Parazols  Angela Marinoni  Pierre Amato  Otman Abida  Paolo Laj  Gilles Mailhot  Anne-Marie Delort  Zappoli Sergio 《Journal of Atmospheric Chemistry》2007,57(3):299-300

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Late Pleistocene to Holocene paleoenvironmental changes in the NW Black Sea     

Andrei Briceag  Anastasia Yanchilina  William B. F. Ryan  Marius Stoica  Mihaela C. Melinte‐Dobrinescu 《第四纪科学杂志》2019,34(2):87-100

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An experimental investigation of spin-up from rest of a stratified fluid     

Jan Bert Flor  John W.M. Bush  Marius Ungarish 《地球物理与天体物理流体动力学》2013,107(4):277-296

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Small-scale modelling of the physiochemical impacts of CO₂ leaked from sub-seabed reservoirs or pipelines within the North Sea and surrounding waters     

Marius Dewar  Wei Wei  David McNeil  Baixin Chen 《Marine pollution bulletin》2013

A two-fluid, small scale numerical ocean model was developed to simulate plume dynamics and increases in water acidity due to leakages of CO₂ from potential sub-seabed reservoirs erupting, or pipeline breaching into the North Sea. The location of a leak of such magnitude is unpredictable; therefore, multiple scenarios are modelled with the physiochemical impact measured in terms of the movement and dissolution of the leaked CO₂. A correlation for the drag coefficient of bubbles/droplets free rising in seawater is presented and a sub-model to predict the initial bubble/droplet size forming on the seafloor is proposed. With the case studies investigated, the leaked bubbles/droplets fully dissolve before reaching the water surface, where the solution will be dispersed into the larger scale ocean waters. The tools developed can be extended to various locations to model the sudden eruption, which is vital in determining the fate of the CO₂ within the local waters.  相似文献   

Seasonal trends in Romanian streamflow          下载免费PDF全文

Marius‐Victor Birsan  Liliana Zaharia  Viorel Chendes  Emilia Branescu 《水文研究》2014,28(15):4496-4505

Mean daily streamflow records from 44 river basins in Romania with an undisturbed runoff regime have been analyzed for trends with the nonparametric Mann‐Kendall test for two periods of study: 1961–2009 (25 stations) and 1975–2009 (44 stations). The statistical significance of trends was tested for each station on an annual and seasonal basis, for different streamflow quantiles. In order to account for the presence of serial correlation that might lead to an erroneous rejection of the null hypothesis, a trend‐free prewhitening was applied to the original data series. The regional field significance of trends is tested by a bootstrap procedure. Changes in the streamflow regime in Romania are demonstrated. The main identified trends are an increase in winter and autumn streamflow since 1961 and a decrease in summer flow since 1975. The streamflow trends are well explained by recent changes in temperature and precipitation that occurred in the last 50 years. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Response of the coccolithophores Emiliania huxleyi and Coccolithus braarudii to changing seawater Mg and Ca concentrations: Mg/Ca, Sr/Ca ratios and δCa, δMg of coccolith calcite     

Marius N. Müller  Ba?ak K?sakürek  Ruth Gutperlet  Ulf Riebesell  Anton Eisenhauer 《Geochimica et cosmochimica acta》2011,75(8):2088-5818

Calcium and magnesium concentrations in seawater have varied over geological time scales. On short time scales, variations in the major ion composition of seawater influences coccolithophorid physiology and the chemistry of biogenically produced coccoliths. Validation of those changes via controlled laboratory experiments is a crucial step in applying coccolithophorid based paleoproxies for the reconstruction of past environmental conditions. Therefore, we examined the response of two species of coccolithophores, Emiliania huxleyi and Coccolithus braarudii, to changes in the seawater Mg/Ca ratio (≈0.5 to 10 mol/mol) by either manipulating the magnesium or calcium concentration under controlled laboratory conditions. Concurrently, seawater Sr/Ca ratios were also modified (≈2 to 40 mmol/mol), while keeping salinity constant at 35. The physiological response was monitored by measurements of the cell growth rate as well as the production rates of particulate inorganic and organic carbon, and chlorophyll a. Additionally, coccolithophorid calcite was analyzed for its elemental composition (Sr/Ca and Mg/Ca) as well as isotope fractionation of calcium and magnesium (Δ^44/40Ca and Δ^26/24Mg). Our results reveal that physiological rates were substantially influenced by changes in seawater calcium rather than magnesium concentration within the range estimated to have occurred over the past 250 million years when coccolithophores appear in the fossil record. All physiological rates of E. huxleyi decreased at a calcium concentration above 25 mmol L⁻¹, whereas C. braarudii displayed a higher tolerance to increased seawater calcium concentrations. Partition coefficient of Sr was calculated as 0.36 ± 0.04 (±2σ) independent of species. Partition coefficient of Mg²⁺ increased with increasing seawater Ca²⁺ concentrations in both coccolithophore species. Calcium isotope fractionation was constant at 1.1 ± 0.1‰ (±2σ) and not altered by changes in seawater Mg/Ca ratio. There is a well-defined inverse linear relationship between calcium isotope fractionation and partition coefficient of Sr²⁺ in all experiments, suggesting similar controls on both proxies in the investigated species. Magnesium isotope ratios were relatively stable for seawater Mg/Ca ratios ranging from 1 to 5, with a higher degree of fractionation in Emiliania huxleyi (by ≈0.2‰ in Δ^26/24Mg). Although Mg/Ca ratios in the calcite of coccolithophores and foraminifera are similar, the former have considerably higher Δ^26/24Mg (by >+3‰), presumably due to differences in calcification mechanisms between the two taxa. These observations suggest, a physiological control over magnesium elemental and isotopic fractionation during the process of calcification in coccolithophores.  相似文献