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931.
The importance of the diet as a source of tributyltin (TBT) in Nucella lapillus was studied using [14C]tributyltin chloride. In N. lapillus provided with prelabelled mussels, Mytilus edulis, in labelled water (mean 20·5 ng/litre TBT) the rate of accumulation of total 14C was 2–3 times that in unfed animals. Owing to its degradation in the tissues of both fed and unfed animals, concentrations of [14C]TBT tended to reach a plateau after only 28 days. However, total concentrations of 14C were still increasing after 49 days. Under experimental conditions (15°C, ample food, no disturbance) the diet accounted for about 50% of the body burden of TBT in N. lapillus after 49 days exposure: concentration factors (dry tissue/water) for [14C]TBT in both male and female N. lapillus were similar at about 60 000 in fed and 30 000 in unfed animals. It is concluded that the diet may contribute less than half of the body burden of TBT found in natural populations subjected to life-long exposure. 相似文献
932.
Sand ridges on the inner Atlantic shelf of North America: Morphometric comparisons with Huthnance stability model 总被引:1,自引:0,他引:1
A. G. Figueiredo Jr. D. J. P. Swift Stubblefield T. L. Clarke 《Geo-Marine Letters》1981,1(3-4):187-191
Sand ridge fields on the inner shelf of the Middle Atlantic Bight are generally thought to have formed in response to northeasterly
storm flows as the shoreface underwent erosional retreat with postglacial sea-level rise. However, the hydrodynamic mechanism
is poorly unerstood. Coastal boundary models see the ridges as responses of the seafloor to distortions in the flow induced
by the coastal boundary. Stability models propose that an irregular initial topography will evolve toward an ordered array
of bedforms in response to repeated flow events. The two classes of models are not mutually exclusive, nor are members within
each class mutually exclusive. Results of measurements of ridge spacing on the inner Atlantic shelf of North America agree
with the predictions of stability models. 相似文献
933.
Robert D. Moore Leroy M. Dorman Chin-Yen Huang David L. Berliner 《Marine Geophysical Researches》1981,4(4):451-477
We describe the design and construction of an ocean bottom seismometer configured as a computer, based on an Intersil IM6100 microprocessor plus appropriate peripheral devices. The sensors consist of triaxial 1 Hz seismometers and a hydrophone, each sensor channel being filtered prior to digitizing so that typical noise spectra are whitened. Digital data are recorded serially on magnetic tape. The instrument is placed on the ocean bottom by allowing it to fall freely from just below the surface. An acoustic system allows precise determination of instrument position, acoustic recall, and transmission of operational information to the surface. Release from an expendable anchor is accomplished by redundant pyrotechnic bolts which can be fired by acoustic command or by precision timers.The operational flexibility provided by the micro-computer, which executes the DEC PDP8/E instruction set, enables optimum use of the 6-hr recording capacity (at 128 samples/second/channel) in the context of the particular experiment being performed.
相似文献
相似文献
934.
A submersible structural study of Tamayo transform fault, the second field study of an oceanic transform, was conducted with the diving saucer CYANA as part of the international project RITA. On the basis of the surface ship surveys and deep-tow traverses made prior to the diving program, the four successful dives of CYANA established the geometry of the presently active shear zones and demonstrated that the median ridge of the Tamayo transform is tectonically inactive. The dive results require the presence, in an area marked by diapir-like bodies, of an extensional relay zone linking the two offset shear zones which trend about 110°.P. CHOUKROUNE, Laboratoire de Géologie structurale, Université de Rennes I, avenue du Général-Leclerc, 35042-Rennes Cédex, France; P. J. FOX, State University of New York at Alban, Albany, New York, 12222, USA; M. SEGURET, Laboratoire de Géologie structurale Université des Sciences et Techniques du Languedoc, Place Eugéne-Bataillon, 34060, Montpellier Cédex, France; J. FRANCHETEAU, H. D. NEEDHAM, Centre Océanologique de Bretagne, B. P. 337, 29273, Brest Cédex, France; T. JUTEAU, Laboratoire de Minéralogie-Pétrographie, Université Louis-Pasteur, 1 rue Blessig, 67084, Strasbourg, Cédex, France; R. D. BALLARD, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543, USA; W. NORMARK, United States Geological Survey, Pacific-Arctic Branch of Marine Geology, Menlo Park, California, 94025, USA; A. CARRANZA, Centro de Ciencias del Mar y Limnologia, Ciudad Universitaria, Mexico 20 DF, Mexico; D. CORDOBA, J. GUERRERO, Instituto de Geologia, UNAM, Ciudad Universitaria, Mexico 20 DF Mexico; C. RANGIN, UNAM,now at Université de Paris VI, France. 相似文献
935.
Abstract. The shell-boring gastropod Ocinebrina edwardsi (PAYR.) lives associated with Mytilus galloprovincialis LMK on which it preys. Predation is preferentially directed towards small (< 15 mm long) mussels. The predation rate (number of mussels eaten per gastropod per day) for medium sized mussels (16–25 mm long) during a year ranges from 0.03 to 0.11. The predation rate is directly influenced by the sea-water temperature. Predation follows a seasonal cycle reaching a maximum in July and a minimum in January. O. edwardsi drills selectively the median anterior region of the mussel valve, close to the dorsal edge. 相似文献
936.
Walter H Pearson Stephen E Miller J.W Blaylock Bori L Olla 《Marine environmental research》1981,5(1):3-11
The ability of the blue crab, Callinectes sapidus, to detect petroleum hydrocarbons was measured with behavioural techniques. When presented with a water-soluble fraction of Prudhoe Bay crude oil, blue crabs abruptly changed antennular orientation, began rhythmic beating of the maxillipedal flagellae, and increased antennular flicking rate. The threshold concentration at which 50% of the crabs detected the water-soluble fraction was 2 × 10?6 mg/litre. The blue crab apparently can readily detect petroleum hydrocarbons at concentrations found in chronically polluted areas as well as oil spill situations. 相似文献
937.
A submerged apparatus, which consists of a buoy, several horizontal contraction and expansion tubes (Venturi-type tubes) and a long pipe, is expected to be used to pump the subsurface sea-water (200–300 meter depth) containing abundant nutrients to surface layer (50–100 m) by the dynamic of ocean currents. i.e. an artificial upwelling without energy cost. A preliminary experiment and analysis are undertaken and shows that the capacity of pumping the nutrient-rich sea-water is worth to build a pilot prototype model. 相似文献
938.
In recent years many fuller ship hull forms have been designed and constructed in various shipbuilding countries, but the data available for the development of the fuller forms are inadequate from the point of view of preliminary ship design. In this paper the authors describe how they have systematically tested vessel forms of block coefficients ranging from 0.80 to 0.90. The analysis and presentation of the test results have been made in such a manner that designers can produce hull forms like those of tankers and other bulk carriers quickly and reliably. 相似文献
939.
The chemical and mineralogical composition of suspended particle suites has been used to assess off-shelf transport on the West African shelves of Liberia and Sierra Leone. Using the ratios of Si/Al, Fe/Al, Mg/Al and Mn/Al as tracers, it was possible to detect shelf-derived materials in slope waters. In the majority of cases, these inputs could not have been detected using particle mass or light scattering measurements and could only be measured by using the chemical signatures of the particulate matter. At the time of sampling, the suspensate which had been moved seaward over the slope was detected adjacent to submarine canyons and highly turbid areas on the outer shelf. The chemical and mineralogical composition of the suspensates, and sediments in the adjacent eastern Atlantic basin are similar to those found in the water column seaward of the West African continental shelves and yet distinct from the Sahelian dust which is considered the major source of sedimentary material for the tropical and semi-tropical areas of the deep eastern basin. These findings suggest that materials from this shelf area could be a more important input to the deep sea than was previously realised. 相似文献
940.
A simulation of a chronic input of petroleum into an estuarine environment was investigated using the facilities at the Marine Ecosystems Research Laboratory at the University of Rhode Island. An oil-water dispersion of No. 2 fuel oil was added to the system (twice weekly for 24 weeks) and the saturated hydrocarbons from this oil were measured in suspended material and sediments. After the initial chronic oil addition, trace amounts of hydrocarbons were detected in the sediments within two weeks, but substantial accumulation was not detected for approximately 135 days. The oil appeared to enter the sediment via the suspended material, with most of the saturated hydrocarbons associated with smaller size sediment particles (< 45 μm to > 0·3 μm). With time, the fuel oil saturated hydrocarbons in the sediments were mixed to a depth of 3 to 4 cm. Although only 12% of the total saturated hydrocarbons added to the system were found in the sediments, these hydrocarbons appear to be relatively stable and were still detectable in these sediments for at least six months after the last oil addition. 相似文献