Coulometric total carbon dioxide analysis for marine studies: maximizing the performance of an automated gas extraction system and coulometric detector

A global survey of the distribution of dissolved CO₂ taking advantage of sampling opportunities provided by the World Ocean Circulation Experiment: World Hydrographic Program (WOCE-WHP) is being carried out through 1995. Goals include the measurement of oceanic inorganic carbon transport and the development of a data base from which future fossil-fuel CO₂ build-up can be monitored. The analytical method selected for total carbon dioxide (C_T) is gas extraction of acidified seawater with coulometric titration of the acid formed by the resultant carbon dioxide and monoethanolamine. To combine high accuracy and precision (± 1.5 μmol/kg for C_T ≥ 2000 μmol/kg) with a high rate of analysis, we have modified an automated single-parameter system. Following prototype development between 1987 and 1990, an instrument emerged with the acronym Somma standing for single-operator multiparameter metabolic analyzer. Improved functional and operating procedures have integrated electronic calibration, CO₂ gas calibration, and sample analysis with automated pressure, temperature, and conductivity (salinity) sensing into a single convenient transportable package.     

Radioecological studies of activation products released from a nuclear power plant into the marine environment

The seaweeds Fucus vesiculosus, Fucus serratus, Ascophyllum nodosum and Cladophora glomerata and crustaceans of the Idothea and Gammarus families have proven to be excellent bioindicators for radioactive corrosion products released from a nuclear power plant into the marine environment. These bioindicators have been used to map the spatial and temporal distribution of the released radioactivity. The activity has been followed up to 150 km from the power plant, and the decrease in activity concentration C(z) in the bioindicators with distance z can be expressed by a power function C(z) = α. z^?1·4 where α is a constant.The variation with time of activity concentration very well reflects the amount of activity discharged from the power plant, with surprisingly good resolution in time.The bioindicators exhibit different uptake patterns of the radionuclides detected, and variations from summer to winter for the crustaceans Idothea, when compared to Fucus, has been found.     

Time-domain simulation of large-amplitude response of floating platforms

Two numerical simulation models to predict large-amplitude motions of floating platforms are presented. The first method is based on the application of the relative-velocity formulation of Morison's equation for force calculations. The second method developed in this work uses the three-dimensional potential theory in time domain. In this method, both the Froude-Krylov and scattering forces are calculated by considering finite wave amplitude effects in random waves. The effect of various nonlinearities on the low-frequency motions and high-frequency tether-tension response of a tension leg platform are studied using these simulation models in conjunction with power spectral methods. The presence of current and the nonlinear drag force are observed to have a significant effect on the low-frequency motions and tether tensions.     

The mysid Siriella armata as a test organism in toxicology: Effects of cadmium

A shrimp-like crustacean of the coastal Zooplankton in the north-western Mediterranean Sea, the mysid Siriella armata, offers a test organism whose life cycle is entirely controllable under laboratory conditions. The effects of the heavy metal cadmium were studied on adults and juveniles cultured in the laboratory including acute toxicity, bioaccumulation and effects on growth, ingestion and moult cycle.     

On the vertical distribution of

The aim of this paper is to present an analytical expression for the vertical distribution of the correlation between the horizontal ( ) and vertical ( ) wave velocity components. This quantity, , which appears explicitly in the time-averaged momentum balance equations, has been shown to play an important role in the vertical distribution of wave-induced currents.The proposed formulation for is based on an identity that relates the effective (wave) shear stress to the effective (wave) normal stresses ( ² and ²) and to the vorticity of the oscillatory flow gw. This general expression has been applied to simplified situations and has been shown to degenerate into other existing formulations with comparable simplifying assumptions, viz. irrotational waves in shallow water over an arbitrary bottom topography and breaking waves over a horizontal bottom.The model has also been applied to the case of waves interacting with a depth-varying current over a horizontal bottom, in which preliminary results have been obtained for a simplified situation invoking linear (small-amplitude) wave theory.     

Wave forces on, and water-surface fluctuations around a vertical cylinder encircled by a perforated square caisson

The wave forces and moments on and the water surface fluctuations around a vertical circular cylinder encircled by a perforated square caisson were experimentally investigated. The porosity of the outer square caisson was varied from 4.24 to 14.58%. The in-line wave forces on the inner vertical cylinder are influenced by changing the porosity of the outer caisson, whereas the variations in the water surface fluctuations are less influenced in this porosity range. The in-line moment on the vertical cylinder is relatively less sensitive when the porosity is increased from 4.24 to 8.75%, but varies substantially when it is increased from 8.75 to 14.58%. The force and moment ratio (i.e. the ratio of the force or moment on the vertical cylinder, when it is encircled by the perforated caisson to the force or moment on the cylinder without any protection around it) reduces with increased wave height, H, and wave length, L, whereas the wave height ratio (ratio of the wave height at a point in the vicinity of the structure to the incident wave height) is less sensitive for the varying H and L. A new non-dimensional parameter, p^1.5 (D/L)/(H/d), is introduced to predict the in-line force and moment on the inner vertical cylinder, where d is local water depth, D is the diameter of the inner cylinder and p is the porosity of the outer caisson in percentage. Simple predictive equations for forces, moments and water surface fluctuations are provided.     

Tracking the last sea-level cycle: seafloor morphology and shallow stratigraphy of the latest Quaternary New Jersey middle continental shelf

Seafloor geomorphology and surficial stratigraphy of the New Jersey middle continental shelf provide a detailed record of sea-level change during the last advance and retreat of the Laurentide ice sheet (120 kyr B.P. to Present). A NW–SE-oriented corridor on the middle shelf between water depths of 40 m (the mid-shelf “paleo-shore”) and 100 m (the Franklin “paleo-shore”) encompasses 500 line-km of 2D Huntec boomer profiles (500–3500 Hz), an embedded 4.6 km² 3D volume, and a 490 km² swath bathymetry map. We use these data to develop a relative stratigraphy. Core samples from published studies also provide some chronological and sedimentological constraints on the upper <5 m of the stratigraphic succession.The following stratigraphic units and surfaces occur (from bottom to top): (1) “R”, a high-amplitude reflection that separates sediment >46.5 kyr old (by AMS ¹⁴C dating) from overlying sediment wedges; (2) the outer shelf wedge, a marine unit up to 50 m thick that onlaps “R”; (3) “Channels”, a reflection sub-parallel to the seafloor that incises “R”, and appears as a dendritic system of channels in map view; (4) “Channels” fill, the upper portion of which is sampled and known to represent deepening-upward marine sediments 12.3 kyr in age; (5) the “T” horizon, a seismically discontinuous surface that caps “Channels” fill; (6) oblique ridge deposits, coarse-grained shelly units comprised of km-scale, shallow shelf bedforms; and (7) ribbon-floored swales, bathymetric depressions parallel to modern shelf currents that truncate the oblique ridges and cut into surficial deposits.We interpret this succession of features in light of a global eustatic sea-level curve and the consequent migration of the coastline across the middle shelf during the last 120 kyr. The morphology of the New Jersey middle shelf shows a discrete sequence of stratigraphic elements, and reflects the pulsed episodicity of the last sea-level cycle. “R” is a complicated marine/non-marine erosional surface formed during the last regression, while the outer shelf wedge represents a shelf wedge emplaced during a minor glacial retreat before maximum Wisconsin lowstand (i.e., marine oxygen isotope stage 3.1). “Channels” is a widespread fluvial subarial erosion surface formed at the late Wisconsin glacial maximum 22 kyr B.P. The shoreline migrated back across the mid-shelf corridor non-uniformly during the period represented by “Channels” fill. Oblique ridges are relict features on the New Jersey middle shelf, while the ribbon-floored swales represent modern shelf erosion. There is no systematic relationship between modern seafloor morphology and the very shallowly buried stratigraphic succession.     

Spatial structure and variability of fields of currents, attenuation factor of light, and temperature in the surface layer of the northwest part of the Black Sea

On the basis of the results of simultaneous observations of parameters of currents, attenuation factor of light, and temperature performed aboard a moving vessel, we established the main characteristics and features of the circulation of waters and the structure of transparency and temperature fields in the surface layer of the northwest part of the Black Sea. We investigate the correlation between the variability of fluid dynamics and redistribution of transparency and temperature fields. The measured currents are compared with those calculated using the actual field of atmospheric pressure during the time of observation. It is shown that the results obtained in the areas of steady currents in the west and central regions are in good agreement. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Seasonal and spatial variability of the content of suspended organic substances in the active layer of the Black Sea

On the basis of the generalized data of multiannual observations (1985–1994), we analyze the seasonal variability of the vertical and spatial distributions and composition (C_sos, N_sos, C_sos/cha, and C/N) of suspended organic substances (SOS) in the shelf zone and in the upper active layer of the abyssal part of the Black Sea. The results of our analysis enable us to conclude that only a narrow coastal band of the shelf in the northwest and west parts of the sea suffers to an extremely pronounced anthropogenic impact, which manifests itself in a significant increase in the mass of suspended organic substances. The formation of new organic substances and, hence, the mass of suspended organic substances in these regions attain the level of eutrophic waters in the late-spring and summer periods. In the open-sea region, the anthropogenic impact is less pronounced and the spatial distribution of suspended organic substances is determined by the general dynamics of waters and the intensity of phytoplankton production. Translated by Peter V. Malyshev and Dmitry V. Malyshev