Comparison of different systems of deflections of the vertical in the Czechoslovakian test area     

Miloš Pick  Ivana Jakubcová  Milada Kožíšková 《Studia Geophysica et Geodaetica》1970,14(2):186-190

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Adriatic seiche decay and energy loss to the Mediterranean     

Ivana Cerove?ki  Mirko Orli?  Myrl C. Hendershott 《Deep Sea Research Part I: Oceanographic Research Papers》1997,44(12):2007-2029

A salient feature of sea level records from the Adriatic Sea is the frequent occurrence of energetic seiches of period about 21 h. Once excited by a sudden wind event, such seiches often persist for days. They lose energy either to friction within the Adriatic, or by radiation through Otranto Strait into the Mediterranean.The free decay time of the dominant (lowest mode) seiche was determined from envelopes of handpassed sea level residuals from three locations (Bakar, Split and Dubrovnik) along the Croatian coast during twelve seiche episodes between 1963 and 1986 by taking into consideration only time intervals when the envelopes decreased exponentially in time, when the modelled effects of along-basin winds were smaller than the error of estimation of decay time from the envelopes and when across-basin winds were small. The free decay time thus obtained was 3.2±0.5 d. This value is consonant with the observed width of the spectral peak.The decay caused by both bottom friction and radiation was included in a one dimensional variable cross section shallow water model of the Adriatic. Bottom friction is parameterized by the coefficient k appearing in the linearized bottom stress term _ρ0u (where u is the along-basin velocity and ρ₀ the fluid density). The coefficient k is constrained by values obtained from linearization of the quadratic bottom stress law using estimates of near bottom currents associated with the seiche, with wind driven currents, with tides and with wind waves. Radiation is parameterized by the coefficient f appearing in the open strait boundary condition ζ =auh/c (where ζ is sea level, h is depth and c is phase speed). This parameterization of radiation provides results comparable to allowing the Adriatic to radiate into an unbounded half plane ocean. Repeated runs of the model delineate the dependence of model free seiche decay time on k and a, and these plus the estimates of k allow estimation of a.The principle conclusions of this work are as follows.

1. (1) Exponential decay of seiche amplitude with time does not necessarily guarantee that the observed decay is free of wind influence.

2. (2) Winds blowing across the Adriatic may be of comparable importance to winds blowing along the Adriatic in influencing apparent decay of seiches; across-basin winds are probably coupled to the longitudinal seiche on account of the strong along-basin variability of across-basin winds forced by Croatian coastal orography.

3. (3) The free decay time of the 21.2 h Adriatic seiche is 3.2±0.5 d.

4. (4) A one dimensional shallow water model of the seiche damped by bottom stress represented by Godin's (1988) approximation to the quadratic bottom friction law ρ₀C_Du|u| using the commonly accepted drag coefficient C_D = 0.0015 and quantitative estimates of bottom currents associated with wind driven currents, tides and wind waves, as well as with the seiche itself with no radiation gives a damping time of 9.46 d; radiation sufficient to give the observed damping time must then account for 66% of the energy loss per period. But independent estimates of bottom friction for Adriatic wind driven currents and inertial oscillations, as well as comparisons between quadratic law bottom stress and directly measured bottom stress, all suggest that the quadratic law with C_D=0.0015 substantially underestimates the bottom stress. Based on these studies, a more appropriate value of the drag coefficient is at least C_D=0. In this case, bottom friction with no radiation leads to a damping time of 4.73 d, radiation sufficient to give the observed damping time then accounts for 32% of the energy loss per period.

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Influence of atmospheric pressure variations on measurements made with Sharpe and Worden gravimeters     

Ladislav Gargalovič  Ludmila Kubáčková  Ivana Jakubcová  Reviewer Z. Šimon 《Studia Geophysica et Geodaetica》1978,22(1):93-98

Summary The paper deals with the influence of the atmospheric pressure variations on Sharpe gravimeters CG 2 No. 226 and 280 and on the Worden gravimeter No. 978, equipped with a thermostat.Dedicated to RNDr. Jan Pícha, CSc., on his 60th Birthday  相似文献   

Trypanosome infections of marine fish in the southern Barents Sea and the invasive red king crab Paralithodes camtschaticus     

Ivana Malovic  Willy Hemmingsen  Ken MacKenzie 《Marine pollution bulletin》2010,60(12):2257-2262

The red king crab Paralithodes camtschaticus was introduced to the Barents Sea from the North Pacific in the 1960s. A previous study concluded that it may be indirectly responsible for increased transmission of Trypanosoma murmanense to cod Gadus morhua in the southern Barents Sea by promoting an increase in the population of the leech vector Johanssonia arctica. Eleven species of fish, totalling 681 individuals, caught in October 2002 along the coast of Finnmark, were examined for trypanosome infections. The aims were to investigate changes in levels of infection in cod since 1999–2001, and to extend the sampling to other fish species. Relatively high infection levels were found in cod, haddock Melanogrammus aeglefinus and long rough dab Hippoglossoides platessoides, while other species were lightly infected or uninfected. In cod, no significant geographical differences in levels of infection were found, but haddock were significantly more heavily infected in western Finnmark.  相似文献   

The behavior of arsenic and antimony at Pezinok mining site,southwestern part of the Slovak Republic     

Renata Flakova  Zlatica Zenisova  Ondra Sracek  David Krcmar  Ivana Ondrejkova  Martin Chovan  Bronislava Lalinská  Miriam Fendekova 《Environmental Earth Sciences》2012,66(4):1043-1057

Arsenic and antimony contamination is found at the Pezinok mining site in the southwest of the Slovak Republic. Investigation of this site included sampling and analysis of water, mineralogical analyses, sequential extraction, in addition to flow and geochemical modeling. The highest dissolved arsenic concentrations correspond to mine tailings (up to 90,000 μg/L) and the arsenic is present predominately as As(V). The primary source of the arsenic is the dissolution of arsenopyrite. Concentration of antimony reaches 7,500 μg/L and its primary source is the dissolution of stibnite. Pore water in mine tailings is well-buffered by the dissolution of carbonates (pH values between 6.6 and 7.0) and arsenopyrite grains are surrounded by reaction rims composed of ferric iron minerals. Based on sequential extraction results, most solid phase arsenic is in the reducible fraction (i.e. ferric oxyhydroxides), sulfidic fraction, and residual fraction. Distribution of antimony in the solid phase is similar, but contents are lower. The principal attenuation mechanism for As(V) is adsorption to ferric oxide and hydroxides, but the adsorption seems to be limited by the competition with Sb(V) produced by the oxidation of stibnite for adsorption sites. Water in mine tailings is at equilibrium with gypsum and calcite, but far from equilibrium with any arsenic and antimony minerals. The concentrations of arsenic and antimony in the surrounding aquifer are much lower, with maximum values of 215 and 426 μg/L, respectively. Arsenic and antimony are transported by ground water flow towards the Blatina Creek, but their loading from ground water to the creek is much lower compared with the input from the mine adits. In the Blatina Creek, arsenic and antimony are attenuated by dilution and by adsorption on ferric iron minerals in stream sediments with resulting respective concentrations of 93 and 45 μg/L at the site boundary south of mine tailing ponds.  相似文献