The study of intermittent hydrophysical fields in the vicinity of the frontal zone

CTD data provided by the MGI-4204 and MARK-III probes are used to study the quasistationary subpolar front structure in the north-western Sea of Japan. In order to provide further insights into the intermittent scalar hydrophysical fields, the method of inhomogeneity identification using temperature pulsations calculated by the moving interval is suggested. The experimentally-derived inhomogeneity distribution is satisfactorily approximated by the exponential law.Translated by V. Puchkin.     

Submersible observations of an iceberg pit and scour on the Grand Banks of Newfoundland

An elongated sea bed depression (pit), 80 by 125 m and 10 m deep located on the Grand Banks of Newfoundland was identified on high resolution surficial geophysical survey lines and investigated using a manned submersible. The pit occurs at the termination of a long (greater than 3 km) iceberg scour, 1.5 m deep, and 80 m wide in 91 m of water. It is similar to other depressions in the region that indent the sea bed up to seven times deeper than the surrounding deepest iceberg furrows. The pit is interpreted to be the sea bed response to impact and loading by a rolling and grounding iceberg. The iceberg scour and pit appear to be of recent origin.     

Dynamic response of dolos armor units to drop test impact loads

Dolos concrete units have been used extensively throughout the world for the protection of shorelines and rubble structures. A three-dimensional finite element model is used to determine the states of dynamic stress in dolosse with varying dimensions and concrete properties. An analytical procedure is developed which accurately predicts the tensile stress in the shank and horizontal fluke of dolosse subject to drop test loading conditions Numerical examples are presented which illustrate the application of prediction and iso-stress equations.     

Bioavailability: the organism as sensor

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.     

Interactions of cadmium with the reproductive cycle of Mytilus edulis L.

Sublethal effects of cadmium on reproduction can have detrimental consequences for the long-term survival, even of species with high LC₅₀ values. The sea mussel, Mytilus edulis, is well-known for its use in biomonitoring work due to its relatively low sensitivity towards many toxicants, including cadmium.¹ Because little is known on sublethal effects of this metal in invertebrates,^2–6 we have studied these effects, with emphasis on reproduction, by exposing mussels to 100 ppb cadmium in sea water. This concentration significantly inhibits follicle development in both male and female gonads, but has subsequently a stimulating effect on the spawning frequency. Due to these opposite effects the consequences of cadmium stress for gamete production are expected to be small, as the average number of gametes released by spawning animals was not significantly changed.     

Sea-level, sediment supply and coastal changes: Examples from the coast of Ireland

Sediment supply and pre-existing shoreline morphology are crucial factors in controlling coastal changes due to sea-level rise. Using examples from both southeast and northeast Ireland, it can be shown that sea-level change may trigger a sequence of events which leads to both static and dynamic shoreline equilibrium. Cliff erosion and longshore sediment movement in east Co. Wexford has led to injection of sediment onto the shelf, and the growth, under both wave and tide regimes, of linear offshore shoals. These shoals now control the pattern of shoreline erosion and provide a template for possible stepwise evolution of the coast under any future sea-level rise. In contrast, the nearby coast of south Co. Wexford comprises a series of coarse clastic barriers moving monotonously onshore, via overwash processes. Here the behavior of the barrier is conditioned by the antecedent morphology of both the beach face and stream outlet bedforms. Finally, the rock platform coast of Co. Antrim presents a far more resistant shoreline to incident marine processes, yet even here there is strong evidence of present process control over so-called ‘raised’ platforms and embayments. It is concluded that coastal sediment supply and dynamics, together with coastal morphology and its interaction with waves, present a far more complex variety of sea-level indicators than is normally acknowledged.     

Bioaccumulation of heavy metals by bivalves from Limski Kanal (North Adriatic Sea). II. Copper distribution between oysters, Ostrea edulis, and ambient water

Accumulation of copper was studied between June 1979 and June 1980 in the oyster Ostrea edulis Linnaeus, cultivated in the Limski Kanal, on the Istria Peninsula (Yugoslavia).The copper distribution in different organs of oysters of the same age was compared with concentrations of copper existing in different physicochemical forms in ambient sea water, i.e., dissolved Cu in labile complexes determined at the natural pH of 8; ‘total’ dissolved Cu determined after acidification to pH 2; and Cu bound to suspended particles with a diameter above 0.45 μm. Copper concentrations in the water were determined by differential pulse anodic stripping voltammetry (DPASV) and in analyses of biotic material, graphite furnace atomic absorption spectrometry (GFAAS) was applied.Significant correlations have been found between copper complexed with dissolved organic ligands and its concentration in the soft part of the oyster. Copper contents increase gradually with the weight of the organs until enhanced gametogenetic activity of the oysters occurs. Thereafter the correlation factor between copper contents and the size of body parts varied significantly with the season.