Effects of scallop dredging on macrobenthic communities in west Iceland   总被引：1，自引：1，他引：1  

Guijarro Garcia  Elena; Ragnarsson  Stefan Aki; Eiriksson  Hrafnkell 《ICES Journal of Marine Science》2006,63(3):434-443

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Significance of vertical flux as a sink for surface water DMSP and as a source for the sediment surface in coastal zones of northern Europe     

Sauveur Belviso  Grard Thouzeau  Sabine Schmidt  Marit Reigstad  Paul Wassmann  Elena Arashkevich  Jacqueline Stefels 《Estuarine, Coastal and Shelf Science》2006,68(3-4):473

In April 1997 and 1998 the significance of sedimentation as a sink for epipelagic dimethylsulphoniopropionate (DMSP) production and as a source for marine sediments was reassessed using a newly designed sediment trap. The behaviour of the traps in immersion was monitored continuously and the collection efficiency was evaluated with ²³⁴Th measurements. Net DMS(P) fluxes were corrected for some physical and biological losses during the whole sedimentation process providing reliable estimates of gross DMSP fluxes. It is shown that daily losses by sedimentation account for between 0.1% and 16% of seawater particulate DMSP (DMSPp) standing stocks, and between 3% and 75% of daily DMSPp production. In the Malangen fjord we observed temporal increases of DMSP production and standing stocks which resulted also in increases of DMSP vertical fluxes and DMS(P) concentrations at the sediment surface. This result illustrates how tight the coupling can be between pelagos and benthos, and confirms that DMS(P) concentration in the sediment was a reliable diagnostic indicator of vertical export from overlying waters in Malangen fjord. In Ullsfjord, however, DMS(P) concentrations in the sediment were poorly indicators of Phaeocystis pouchetii export during the early stage of growth of a bloom. The high load of DMS(P) in Balsfjord's sediments could neither be attributed to local vertical sedimentation nor to short-term lateral advection of fresh DMSP-containing phytoplanktonic material, and provides indication that this tracer sometimes also can be misleading. The highest loads of DMS(P) in sediments and the fastest rates of sedimentation occurred in the Southern Bight of the North Sea.  相似文献   

Corrigendum to microstructure measurements in natural waters: Methodology and applications [Progress in Oceanography 70 (2006) 126-148]     

Elena Roget  Iossif Lozovatsky  Xavier Sanchez 《Progress in Oceanography》2007,72(1):114

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Hydrogen and Helium under high pressure: A case for a classical theory of dense matter     

Vladan čelebonović 《Earth, Moon, and Planets》1989,45(3):291-298

When subject to high pressure, H₂ and ³He are expected to undergo phase transitions, and to become metallic at a sufficiently high pressure. Using a semiclassical theory of dense matter proposed by Savi and Kaanin, calculations of phase transition and metallisation pressure have been performed for these two materials. In hydrogen, metallisation occurs at p _M= (3.0 ± 0.2) Mbar, while for helium the corresponding value is p _M= (106 ± 1) Mbar. A phase transition occurs in helium at p _tr= (10.0 ± 0.4) Mbar. These values are close to the results obtainable by more rigorous methods. Possibilities of experimental verification of the calculations are briefly discussed.  相似文献   

The ionization balance of the Fe in the solar corona for a non-Maxwellian electron distribution function     

Elena Dzifčáková 《Solar physics》1992,140(2):247-267

The ionization equilibrium of the Fe in the solar corona for a non-Maxwellian electron distribution with an enhanced number of particles in the high-energy tail is presented. A parametric form of the distribution function is used to demonstrate the changes in the ionization equilibrium with changes in the shape of the distribution. The results over the range of temperature 10⁵ K T 10⁸ K for different deviations of the distribution from a Maxwellian are given in tabular form. The results can be used for specific applications in the solar corona, especially in the active corona, where deviations from the Maxwellian distribution can be significant.  相似文献   

Submarine slump folds and gravitational normal faults in Quaternary sediments on the northern slope of the Derbent Basin (Caspian Sea)     

L. I. Lobkovskii  V. E. Verzhbitskii  L. R. Merklin  A. G. Roslyakov  A. S. Polyakov  O. V. Levchenko  S. A. Kovachev  A. S. Zverev  A. D. Mutovkin  V. A. Putans  N. V. Libina  V. Yu. Slobodyan  G. N. Mar  S. V. Gontarev 《Doklady Earth Sciences》2008,420(1):681-685

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Contributions of boron isotopes to understanding the hydrogeochemistry of the coastal detritic aquifer of Castellón Plain,Spain   总被引：1，自引：0，他引：1  

Elena Giménez Forcada  Ignacio Morell Evangelista 《Hydrogeology Journal》2008,16(3):547-557

The Castellón Plain alluvial aquifer, Spain, is intensively exploited to meet the demand for agricultural irrigation and industrial water supply. The geochemistry of its groundwater shows complex salinization in the northern and southern parts of the aquifer, with significant pollution from human origin in the central portion. Boron content and B isotope geochemistry are useful for distinguishing between various sources of pollution and their relative importance in different parts of this aquifer. Boron concentrations in the groundwater vary between 0.01 and 0.85 mg/L. In the more saline groundwaters, found at the northern and southern ends of the study area, the presence of B is linked to inputs from seawater and water with a calcium-magnesium sulphate facies, which feed the aquifer and clearly influence the chemistry of its waters. Evidence of B adsorption processes in some samples is shown by the low B/Cl ratios and the high values of δ¹¹B. In the central portion of the aquifer, the high B/Cl ratios and the strongly negative δ¹¹B are related to pollution of human origin.  相似文献   

Croatia as a Danube country     

Ivan Crkvenčić Ph.D.  Adolf Malić Ph.D. 《GeoJournal》1996,38(4):455-462

Among the three principal regional units of Croatia, i.e. the elongated and spacious Adriatic littoral (with numerous islands), the relatively small and narrow mountainous belt (the Croatian transit doorway) and the Pannonian/peri-Pannonian region, the latter is the largest and accounts for 54 percent of the surface area and 66 percent of the population of Croatia (1991 census). It is part of the Pannonian (or Carpathian) basin, or the central Danube basin, so that Croatia is simply by its position a Danube country. Its Danube character is also highlighted by the fact that the Pannonian/peri-Pannonian region of Croatia through the Sava and Drava Rivers is directly linked to the navigable Danube, which is the historical and ethnic eastern boundary of Croatia. Croatia is an old historical Danube nation and country, although it has nominally appeared as a state after the break-up of Yugoslavia, and its international recognition as an independent state (1992).  相似文献   

Energy balance of simple elastodynamic sources     

Václav Vavryčuk 《Pure and Applied Geophysics》1994,143(4):563-586

Complete relations are derived for energy and energy flux of elastic waves generated by an isotropic and double-couple source in a perfectly elastic, homogeneous, isotropic, and unbounded medium. In the energy balance of elastodynamic sources near-field waves play an essential role, transforming static energy into wave energy, andvice versa. For explosive and dislocation sources, the sources surface radiates a positive wave energy that is partially distributed to the medium transforming into static energy. For implosive and antidislocation sources, the source surface generates elastic waves, but it does not necessarily imply that it also radiates a positive wave energy. The energy transported by waves can originate in gradual transformation of the static-to-wave energy during propagation of waves through a stressed medium.On leave from Geophysical Institute, Czech Academy of Sciences, Boní II/1401, 41 31, Praha 4 Czech Republic  相似文献   

Dynamics of the plasmasphere in the dusk sector as observed in the outer ionosphere     

J. Bošková  F. Jiříček  J. Šmilauer  P. Tříska 《Studia Geophysica et Geodaetica》1994,38(1):82-92

Summary Direct measurements of the thermal plasma parameters in the topside ionosphere reveal variations of the plasmasphere boundary in the dusk sector. The ACTIVE satellite's near-polar orbits at altitudes of 500 – 1800 km around winter solstice 1989 were used to study the bulge region of the plasmasphere during intervals with different levels of geomagnetic agitation. The narrow, sharply defined trough in electron concentration corresponding to the plasmapause under quiet conditions situated at L = 6 – 7 moved to lower L-values with increasing geomagnetic activity. This narrow trough can be found in all main ion constituents. During periods of moderate geomagnetic activity, following the onset of a weak magnetic storm, a portion of the plasmaspheric bulge region was separated from the main plasmaspheric body. This can be seen in the outer ionosphere as an inner narrow trough at lower L-value. Troughs in light ions need no longer coincide with this in electron concentration. He⁺ is the most sensitive constituent reflecting the dusk sector plasmaspheric situation at this altitude.Dedicated to the Memory of Professor Karel P  相似文献