Wave climate in a groin field     

V. Sundar  H. Noethel  K. P. Holz 《Ocean Engineering》1992,19(5)

Wave records at seven different locations within a groin field have been analysed by both statistical and spectral approaches to study the general wave climate. The wave heights and periods from the wave records were obtained by both upcross and downcross methods for the statistical approach. The variation of different wave height and wave period parameters with respect to the time of measurement at a particular location and its variation at different locations within the groin field at a particular instant of time are presented and discussed in detail in this paper. It is generally found that the wave heights follow the Weibull distribution.  相似文献   

Facets of modern biogeochemistry: Festschrift for E. T. Degens: V. Ittekkot, S. Kempe, W. Michaelis and A. Spitzy (Eds.) Springer Verlag; 1990; ISBN 3 540 50145 2 and 0 387 50145 2; 427 pp     

V. Ittekkot  S. Kempe  W. Michaelis  A. Spitzy 《Marine and Petroleum Geology》1992,9(6)

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The role of organic coatings in the enrichment of marine particles with selenium. The fixation of selenite on an adsorbed amino acid     

R. Cohen  D. Schuhmann  F. Sinan  P. Vanel 《Marine Chemistry》1992,40(3-4)

The enrichment of marine particles with selenium cannot be explained as that with metals present in cationic form by complexation with anionic functional groups of adsorbed organic matter. Physicochemical data obtained using a model system are reported. The surface of the particles is modelized by a mercury electrode whose surface charge density can be easily changed, covered by a layer of adsorbed polymers. Studies with different kinds of macromolecules and salts show a specific interaction between adsorbed polyalanine and selenite. The results can be explained by the concordance of the distances between two oxygen atoms in this oxyanion and between two amine groups of the adsorbed polypeptide. A similar mechanism could occur in marine aggregates whatever their nature, as long as they contain amine groups at their surface which result in this concordance. Some prospects derived from the results are discussed.  相似文献   

Interaction of internal waves with a horizontally inhomogeneous density field area overlying a ridge     

N. M. Stashchuk  L. V. Cherkesov 《Physical Oceanography》1990,1(6):495-500

In the context of the general linear theory, we consider the propagation of an internal tide across a frontal zone overyling an oceanic ridge. For a uniformly stratified ocean, the solution was derived using Riemann's technique. The dependences of the generated internal wave amplitudes on the stratification parameters and bottom topography were determined. We have found that wave disturbances of high intensity inside and in the neighbourhood of the ridge may be concentrated in raytype areas. An increase of the horizontal density gradient in the frontal zone results in a perceptible deformation of these areas.Translated by Vladimir A. Puchkin.  相似文献   

Sea-floor observations in the tongue of the ocean,Bahamas: An Argo/SeaMARC survey     

William C. Schwab  Elazar Uchupi  Robert D. Ballard  Thomas K. Dettweiler 《Geo-Marine Letters》1989,9(3):171-178

SeaMARC side-scan sonographs and Argo video and photographic data suggest that the recent sedimentary environment of the floor of the Tongue of the Ocean is controlled by an interplay of turbidity current flow from the south, sediment spill-over from the carbonate platform to the east (windward side), and rock falls from the west carbonate escarpment (lee side). The spill-over forms a sandy sedimentary deposit that acts as a topographic obstruction to the turbidity current flow from the south. This obstruction is expressed by the westward migration of a northwest-southeast oriented turbidity-current-cut channel.  相似文献   

Letter to Editor: Comments on: “Semi-analytical quasi-static formulation for three-dimensional partially grounded mooring systems problems” by Y.T. Chai, K.S. Varyani and N.D.P. Barltrop, 2002. Ocean Engineering 29, 627-649.     

P. A. A. Laura  C. A. Rossit  D. V. Bambill 《Ocean Engineering》2003,30(7):949-950

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Heave compensation and formation strength evaluation from downhole acceleration measurements while coring   总被引：1，自引：0，他引：1  

G. Guerin  D. Goldberg 《Geo-Marine Letters》2002,22(3):133-141

In order to evaluate the efficiency of heave compensation in the Ocean Drilling Program, we developed a device measuring the acceleration of the core barrels. First results show that heave compensation limits bit motion to 10% of the surface heave. We also use the acceleration data to characterize the formation. On rotary corers, acceleration amplitudes decrease with increasing hardness of the formation. Comparison with geophysical logs shows that this relationship can resolve cm-scale features. On piston corers, the maximum acceleration is characteristic of the sediment shear strength. Easy and fast to deploy, this tool allows to characterize formations before any sample analysis.  相似文献   

Metal accumulation in mussels of the Kuril Islands, north-west Pacific Ocean   总被引：1，自引：0，他引：1  

Kavun VY  Shulkin VM  Khristoforova NK 《Marine environmental research》2002,53(3):219-226

Concentrations of cadmium, copper, iron, lead, manganese, nickel and zinc were investigated in two species of mussel from the Kuril Islands in the north-western Pacific Ocean: the short-lived mussel Mytilus trossulus and the much larger and longer-lived Crenomytilus grayanus. The concentrations of most elements were low, and these reported levels are believed to reflect background values for pristine locations. However, both iron and zinc concentrations were elevated in some samples taken from areas of hydrothermal vent activity, and these are believed to reflect the enrichment of the two metals in solution at such sites. Furthermore, the concentrations of cadmium were unusually elevated in both species of mussel, especially in the longer-lived C. grayanus. The high accumulation of cadmium in mussels from the Kuril Islands is believed to reflect regional upwelling, but it is also postulated that filtration rates of the mussels are high due to low levels of suspended matter, and this leads to a high assimilation efficiency for cadmium. The distribution of cadmium amongst the tissues of C. grayanus is also reported, and the need for further ecotoxicological studies in the area is proposed.  相似文献   

Investigating spatio-temporal change in spawning activity by Atlantic mackerel between 1977 and 1998 using generalized additive models   总被引：1，自引：3，他引：1  

Beare  D. J.; Reid  D. G. 《ICES Journal of Marine Science》2002,59(4):711-724

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Significance of pteropods in deciphering the late Quaternary sea-level history along the southwestern Indian shelf     

A. Singh  K. Ramachandran  M. Samsuddin  N. Nisha  V. Haneeshkumar 《Geo-Marine Letters》2001,20(4):243-252

The paper evaluates the usefulness of pteropods in palaeobathymetric synthesis along the southwestern continental shelf of India. Core samples collected from the shelf off north Kerala (SW coast of India) were studied for faunal assemblages (pteropods and foraminifers), calcium carbonate contents and lithological characteristics. A fundamental precept for considering any organism as a bathometer is that it should be highly sensitive to changing water depths. To ascertain this, the bathymetric distribution patterns of modern pteropods as well as planktonic and benthic foraminifers were recorded in core-top samples. The results reveal that certain pteropod species (Limacina inflata, Creseis acicula, Creseis virgula, and Creseis chierchiae) are highly depth sensitive. The response of these species to depth changes was assessed in terms of the L. inflata and Creseis spp. abundance ratio. A model for the relationship between water depths and the L. inflata/Creseis spp. ratio is proposed for the southwestern shelf of India. Variations of benthic/planktonic foraminifers (BF/PF) and pteropods/planktonic foraminifers (Pt/PF) in the modern sediments were also found to be depth controlled. Two sediment cores, representing the last 36,000 and 23,000 years, were collected to investigate past sea-level changes. These cores comprised two distinct lithological units, the upper unit corresponding to the Holocene, and the lower unit to the last glacial period. The L. inflata/Creseis spp. model was successfully applied to the fossil record for reconstructing the palaeobathymetry of the shelf study locations. Down-core variations in the BF/PF and Pt/PF ratios support these inferred sea-level changes. Major periods of sea-level oscillations were also found to have a strong influence on the calcium carbonate distribution. For both core sites, the palaeobathymetric curves reflect consistency in terms of changing sea level. The results suggest that the sea level stood around 100 m below the present mean sea level during the last glacial maximum. A rapid rise in sea level was documented between 15 and 10 ka B.P. The sea-level rise has been slower since 7 ka B.P.  相似文献