Evaporative weathering of petroleum residues: The age of pelagic tar     

James N. Butler 《Marine Chemistry》1975,3(1):9-21

The rate of evaporative weathering of a component of crude oil residue is assumed to be proportional to its equilibrium vapor pressure and to the amount remaining in the sample. This model is tested using literature data on normal paraffin profiles of crude oil weathered artificially and gas chromatographic data on crude oil residues weathered on rocky shores. Semiquantitative agreement over the time range from 1 to 400 days is demonstrated. Application of the model to gas chromatograms of pelagic tar lumps collected at Station S near Bermuda in 1972 implies that most of these lumps were formed by fragmentation of much larger and older masses, some within less than one day of the time they were collected. The weathering of pelagic tar thus involves a great deal more physical fragmentation than was previously supposed.  相似文献   

The influence of the gulf’s geometry on seiche oscillations in an enclosed basin     

Yu. V. Manilyuk  L. V. Cherkesov 《Physical Oceanography》1997,8(4):217-227

The finite-elements technique is applied to study the effect of a basin’s geometry (bays, harbours) and location of the characteristics of seiche oscillations in the basin and in the gulf proper. An increase of the length of the bay is shown to contribute to the periods of natural oscillations and to cause their restructuring. Translated by Vladimir A. Puchkin.  相似文献   

A pockmark field in the Patras Gulf (Greece) and its activation during the 14/7/93 seismic event     

T. Hasiotis  G. Papatheodorou  N. Kastanos  G. Ferentinos 《Marine Geology》1996,130(3-4):333-344

During a recent oceanographical-geophysical survey carried out in the southeastern part of the Gulf of Patras in Western Greece for the construction of an outfall, an active pockmark field was found. The pockmark field was formed in soft layered Holocene silts. The pockmarks are associated with acoustic anomalies attributed to gas-charged sediments. The pockmarks vary in size and shape from 25 to 250 m in diameter and from 0.5 to 15 m in depth and are among the largest and deepest observed in the world.

On July 14th, 1993, during the survey, a major earthquake of magnitude 5.4 on the Richter scale occurred in the area. During the 24 hour period prior to the earthquake the bottom water temperature anomalously increased on three occasions, whilst for a few days after the earthquake it was noted that the majority of the pockmarks were venting gas bublles.

It is considered that the three abrupt sea-water temperature increases were probably the result of upward migrating high-temperature gas bubbles in the water column. It is further suggested that the earthquake was the triggering mechanism and that the gas expulsion was caused by the reduction in the pore volume in the sediments resulting from changes in the stress regime prior to the earthquake. Therefore, it can be suggested that in seismic areas adjacent to pockmark fields, earthquake prediction may be achieved by monitoring the water temperature and/or the rate of gas venting in the pockmark field.

Our analysis indicates that the pockmark field in the Patras Gulf has formed slowly during the Holocene by continuous gas venting, which is periodically being interrupted by short-duration events of enhanced gas seepage triggered by earthquakes.  相似文献   

Transverse vibrations of a rectangular cantilever plate with thickness varying in a discontinuous fashion     

R.E. Rossi  P.M. Belles  P.A.A. Laura  S. La Malfa  L. Ercoli  D. Pasqua 《Ocean Engineering》1996,23(3):271-276

A numerical solution is obtained for the title problem by means of the popular finite element method. An experimental investigation of the problem is also presented for plates of square planform. The agreement between theoretical and experimental values is very good in the case of the fundamental frequency, and reasonably good when the second and third normal modes of transverse vibration are considered. It is concluded that beneficial effects are obtained in the sense that one generates a lighter structural element with higher fundamental frequency of transverse vibration. Hence, dynamic stiffening is achieved.  相似文献   

Experimental investigation of the combustive sound source   总被引：3，自引：0，他引：3  

Wilson  P.S. Ellzey  J.L. Muir  T.G. 《Oceanic Engineering, IEEE Journal of》1995,20(4):311-320

In this paper, we describe a unique low frequency underwater sound source called the combustive sound source (CSS). In this device, a combustible gas mixture is captured in a combustion chamber and ignited with a spark. The ensuing combustion produces expanding gases which in turn produce high intensity, low frequency acoustic pulses. With high-speed motion pictures of the CSS event, we relate the motion of the bubble to the acoustic waveform. We also compare the measured first bubble period in the CSS pressure signature with the predictions of the Rayleigh-Willis equation, including the dependence of the radiated acoustic waveform on the volume and depth of the bubble. Measurements of the first bubble period agree with Rayleigh-Willis theory in trend, but not in absolute value. In addition, we discuss the variation of the acoustic output with the fuel/oxygen mixture. Finally, several other factors that affect the acoustic output of CSS are discussed. These include the shape of the CSS combustion chamber, the type of oxidizer and fuel, and the ignition source  相似文献   

Joint Soviet-Turkish expedition in the Black Sea     

A. A. Bezborodov  S. L. Gokchen  V. N. Eremeev  I. T. Konuk  A. K. Saidam  E. M. Tirasin 《Physical Oceanography》1991,2(3):227-231

The hydrological and hydrochemical structures of the upper 300 m water column of the Black Sea in autumn 1988 have been studied. Regularities in the distribution of the physico-chemical characteristics in the zone of interaction between aerobic and anaerobic waters as well as the topography of the H₂S zone boundary and its connection with a certain density gradient have been found.Translated by Mikhail M. Trufanov.  相似文献   

Digital preprocessing techniques for GLORIA II sonar images     

Richard L. Miller  Fa S. Dwan  Chiu-Fu Cheng 《Geo-Marine Letters》1991,11(1):23-31

Image processing techniques are discussed that correct distortions in GLORIA II side scan sonar imagery including water column offset, slant-range distortion, multiple returns, aspect ratio, speckle noise, striping, and cross-track power drop-off. The software operates within NASA's ELAS image processing system and is applied to the original 12-bit GLORIA II data. Procedures are discussed for generating large scale mosaics and three-dimensional overlays with sea floor bathymetry. The results are shown in four sonographs acquired off the southern coast of California.  相似文献   

Reproductive variability in North Sea plaice, sole, and cod   总被引：4，自引：1，他引：4  

Rijnsdorp  A. D.; Daan  N.; van Beek  F. A.; Heessen  H. J. L. 《ICES Journal of Marine Science》1991,47(3):352-375

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Bioavailability: the organism as sensor     

Peter J. Wangersky  Regine L. Maass 《Marine Chemistry》1991,36(1-4)

The use of a system of continuous culture of phytoplankton at constant population density, the ‘cage-culture’ turbidostat, as a monitor of the bioavailability of pollutant materials, is illustrated. In the case of proposed dredge spoils from two polluted areas, it is shown that bulk analyses for scheduled materials cannot be equated with bioavailability. Monitoring for the effect of the whole pollutant mixture on a properly chosen test population could obviate the necessity for chemical analyses for each component.  相似文献   

Hypothesis for a submarine landslide and cohesionless sediment flows resulting from a 17th century earthquake-triggered landslide in Quebec,Canada     

C. T. Schafer  John N. Smith 《Geo-Marine Letters》1987,7(1):31-37

Textural isotopic and microfossil data from two gravity cores obtained in Saguenay Fjord, Quebec, suggest that a distinctive sandy clay bed was deposited as the result of a major landslide in the Saguenay River basin. Pb-210 dating of the cores indicate that the bed is of similar age to the magnitude 7 earthquake of February 5, 1663. The slide involved sensitive marine clays and may have occurred in two stages. Slide sediments carried into the Saguenay River channel were probably reworked and subsequently transported down the Fjord basin as two distinct cohesionless mass flows. Fine clay laminae that overlie the older mass flow bed record the modulation of depositional processes by tidal currents for several weeks after this event.  相似文献