Benthic Metabolism and Standing Stock in the Central and Northern Deep Red Sea     

H. Thiel    O. Pfannkuche    R. Theeg  G. Schriever 《Marine Ecology》1987,8(1):1-20

Abstract. Benthic metabolism and standing stocks were investigated in the deep Red Sea between 21^o and 27^oN, Activity was assessed by the determination of respiration rates with a shipboard method and by calculating oxygen consumption from the activity in the electron transport system. We attempted to compare results from different latitudes within the warm Red Sea and with data from cold Atlantic environments. Our investigations were part of an environmental risk assessment to evaluate future mining of metalliferous sediments from the Atlantis II Deep.  相似文献   

Influence of structural flexibility and wave interference on dynamic behavior of idealized offshore platform     

A.G. Abul-Azm  A.N. Williams  S.T. Mau 《Ocean Engineering》1987,14(3)

An approximate method is presented to estimate the hydrodynamic loading and structural response of an idealized offshore platform subjected to a regular train of linear surface waves. The platform is taken to consist of four bottom-mounted, flexible, circular cylinders supporting a rigid deck and is assumed to be aligned parallel to the incident wave direction. The response of each column is assumed to be one-dimensional and to be governed by linear beam theory. The solution technique for the fluid velocity potential involves replacing scattered waves by equivalent plane waves together with non-planar, first-correction terms, and can be shown to be a large spacing approximation.Numerical results are presented which show the effect of hydrodynamic interference and structural flexibility on the platform response.  相似文献   

Formation of chemogenic calcite in super-anoxic seawater — Framvaren, southern Norway     

Leif G. Anderson  David Dyrssen  Jens Skei   《Marine Chemistry》1987,20(4)

Framvaren, a super-anoxic fjord in southern Norway, contains 7–8 mmoll⁻¹ of sulphide and a total carbonate concentration of 18.5 mmol kg⁻¹ in the bottom water. The chemistry of calcium has been studied, considering sources, biogenic and chemical processes and sedimentary sinks. Calcium associated with the bacteria biomass at the redox interface (18m depth) appears to be the primary source of dissolved calcium in the deep, anoxic water. Excess calcium and high total carbonate cause supersaturation of calcite, which is precipitated chemogenically. Calcite (and presumably some aragonite) is identified both in sediment trap material and the bottom sediments below the depth of supersaturation.  相似文献   

Basement imaging with Side-Looking Seismics     

A. Peter Slootweg 《Marine Geophysical Researches》1986,8(2):149-174

The multistreamer Side-Looking Seismic system presented in this paper makes a sonograph of uncovered or buried crustal topography, thus revealing the structural fabric of the oceanic basement, even when this is covered with a sedimentary layer. Major elements of the system are an airgun as a sound source, five single-channel parallel streamers and two minicomputers for signal capture and processing.The system is used simultaneously for enhanced single-channel seismic profiling and for side-looking seismics. A vertical section with an improved signal-to-noise ratio and a suppression of side-echoes is produced on a digital seismic recorder. Primary side-looking seismic output in the form of 5 profiles with different angles of incidence is obtained within 10 seconds. This part of the processing can be done in real time.In sediment-covered areas the low frequencies used cause the slanted profiles (the side beams in the primary output) to be side-looking sonar images of buried topography. The projection process yielding final side-looking output corrects for slant range deformation caused by the water column and, if necessary, for deformation caused by refraction within the sedimentary column. The result approaches a conformal map of the structure of the traversed basement. Swath width is mainly determined by water depth and refraction effects in the sediment. In Madeira abyssal plain a swath width of 8000 m was attained in a water depth of 5000 m.Within the swath, oceanic basement structures are recognized in the form of elongate more or less parallel reflectors. They are interpreted as buried spreading topography. The lack of side-echoes within fracture zones combined with typical wall signatures can be used to trace fracture zones. These features are demonstrated for an area in Madeira abyssal plain.  相似文献   

On the analysis of catch and effort data   总被引：1，自引：0，他引：1  

Laurec  A; Shepherd  J. G. 《ICES Journal of Marine Science》1983,41(1):81-84

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The uptake and accumulation of Ni by Cerastoderma edule and its effect on mortality,body condition and respiration rate     

James G Wilson 《Marine environmental research》1983,8(3):129-148

The concentration of Ni in C. edule ranges from 17·8 μg/g to 53·82 μg/g with the highest concentration in the gills and mantle and the lowest in the foot and adductor muscles. The concentration does not change with either size or season.There is no significant increase in mortality even in the highest Ni concentration (100 μg/litre), nor is body condition correlated with experimental Ni concentrations. The rate of uptake of Ni (y) is described by the equation: where x₁ = Ni concentration (μg/litre) and x₂ = time (h).The respiration rates did not significantly change up to the highest Ni concentration used (1000 μg/litre).It is postulated that the main pathway for Ni uptake is through the gills, possibly through mucus sheet or transmembrane absorption, with a secondary uptake route via the viscera.C. edule may therefore be a suitable indicator species for Ni.  相似文献   

Petroleum hydrocarbons in sediments of Southampton water estuary     

Anthony H. Knap  Peter J. LeB. Williams  Elizabeth Lysiak 《Marine environmental research》1982,7(4):235-249

The sediments of Southampton Water were analysed for petroleum hydrocarbons to determine the fate of petrochemical refinery waste in the estuary. Much of the petroleum hydrocarbons appears to be removed by adsorption onto estuarine sediments close to source. Surface sediment concentrations range from 3·1mg/g dry weight near a refinery to 0·5 mg/g dry weight at locations distant from the refinery.The absence of any change with depth in total hydrocarbon concentrations from some sediment cores and the presence of distinct ‘oil’ horizons in others suggests that mixing of sediments in the area is very random. Sedimentation rates in areas where a distinct oil horizon was observed ranged from 1 to 3cm a year.  相似文献   

Ionic activity coefficients in aqueous mixtures of NaCl and MgCl₂     

R. A. Robinson  R. G. Bates 《Marine Chemistry》1978,6(4):327-333

Methods developed earlier, based on hydration numbers for individual ionic species, have been extended to the calculation of ionic activity coefficients in aqueous systems of two electrolytes MX and NX₂ with a common unhydrated anion (X⁻). The data required include the mean activity coefficients of MX and NX₂ in the mixtures, together with the osmotic coefficient. The procedure is illustrated by a calculation of γ_Na, γ_Mg, and γ_Cl in a mixture of NaCl and MgCl₂ closely approximating the composition of seawater with salinity of 35‰.  相似文献   

The role of damped equatorial waves in the oceanic response to winds     

Toshio Yamagata  S. G. H. Philander 《Journal of Oceanography》1985,41(5):345-357

In inviscid shallow water models currents generated by spatially uniform winds are transient and are eliminated by Rossby and equatorial Kelvin waves excited at the eastern and western coasts, respectively. The inclusion of mixing processes can lead to an entirely different steady state in which currents are present. It is shown that the mixing of heat affects the steady state more than does the mixing of momentum because the waves that are important in the oceanic adjustment are divergent.  相似文献   

Estimation of the leeway drift of small craft   总被引：1，自引：0，他引：1  

G.L. Hufford  S. Broida 《Ocean Engineering》1976,3(3):123-132

Small craft (<6·4 m) leeway is determined as a function of the wind speed in the range of 5–20 knots (3·6–10·3 m/sec). Leeway is calculated relative to the surface current by measurement of the separation distance of the small craft from a dyed patch of surface water at sea, using time-sequenced aerial photography. Leeway increases linearly with wind speed for small craft equipped with or without a sea anchor in the wind range studied. Leeway for small craft without sea anchor can be calculated from the equation U_L = 0.07 U_W + 0.04 where U_W is the wind speed at 2 m elevation. Leeway for small craft drifted off the be calculated from the equation U_LD = 0·05 U_W − 0·12. The small craft drifted off the downwind direction in about 80% of the experiments. The drift angle is variable and difficult to predict.  相似文献