Oceanography and marine biology, 10: Harold Barnes (editor). George Allen and Unwin,London, 1972, 565 pp., £10.50

A bathymetric survey of the Gilliss Seamount, in the northwest Atlantic Basin, using a multi-beam sonar array system reveals an extremely complex morphologic character of this feature. A new chart provides the most detailed topographic presentation of an Atlantic seamount published to date and highlights the similarity of the Gilliss Seamount with terrestrial strata-volcanoes. Bottom photographs and samples reveal pillow-Iava formation. Seismic profiles show that the volcanic basement is irregularly covered by acoustically transparent deposits that are as much as 668 m thick. Volcanic debris and sediments locally are displaced down the flanks of the seamount. Bottom photographs and cores indicate that the transparent layer has accumulated slowly by deposition from suspensate-rich (mostly clay and planktonic foraminifera) water masses that flow around the mid to lower sectors of this submarine volcano. Bottom-current activity also modifies the abyssal plain turbidite-hemipelagic sequence surrounding the seamount.     

Factor analysis of trends in energy and metals production and consumption in developed and developing countries

This paper presents a methodology used to combine energy and mineral market variables between Less Developed Countries (LDCs) and Developed Countries (OECD) over the past 24 years (1966–1990). LDCs include all countries, except OECD and central planned economies (CIS) and other countries in Eastern Europe. This period permits a comprehensive view of the impact of the energy crisis and the changes in economic growth patterns, correlated with changes in trends of production and consumption of energy and metals in both country blocs. This complex relationship was evaluated by a factor model of consumption and production variables using the aluminum, copper, lead, and zinc industries. The following variables are used in the factor model: export dependence, geographic concentration of mining production, geographic concentration of refined demand, geographic concentration of refined production, import dependence, refined demand growth, stability of demand, income elasticity of refined demand, price stability, intensity of use, and intensity of energy. The model for all commodities shows that the factor scores projections for LDCs and OECD blocs depicted a clearly divergent trend after the two oil shocks (1973–1979), when the intensity of energy variable presents high loading in the factor. The results are in substantial agreement with findings that the demand for energy, as well as for metals, is growing more rapidly in LDCs than OECD.     

Magnetic braking of Ap/Bp stars: application to compact black-hole X-ray binaries

We examine the proposal that the subset of neutron-star and black-hole X-ray binaries that form with Ap or Bp star companions will experience systemic angular-momentum losses due to magnetic braking, not otherwise operative with intermediate-mass companion stars. We suggest that for donor stars possessing the anomalously high magnetic fields associated with Ap and Bp stars, a magnetically coupled, irradiation-driven stellar wind can lead to substantial systemic loss of angular momentum. Hence, these systems, which would otherwise not be expected to experience 'magnetic braking', evolve to shorter orbital periods during mass transfer. In this paper, we detail how such a magnetic braking scenario operates. We apply it to a specific astrophysics problem involving the formation of compact black-hole binaries with low-mass donor stars. At present, it is not understood how these systems form, given that low-mass companion stars are not likely to provide sufficient gravitational potential to unbind the envelope of the massive progenitor of the black hole during a prior 'common-envelope' phase. On the other hand, intermediate-mass companions, such as Ap and Bp stars, could more readily eject the common envelope. However, in the absence of magnetic braking, such systems tend to evolve to long orbital periods. We show that, with the proposed magnetic braking properties afforded by Ap and Bp companions, such a scenario can lead to the formation of compact black-hole binaries with orbital periods, donor masses, lifetimes and production rates that are in accord with the observations. In spite of these successes, our models reveal a significant discrepancy between the calculated effective temperatures and the observed spectral types of the donor stars. Finally, we show that this temperature discrepancy would still exist for other scenarios invoking initially intermediate-mass donor stars, and this presents a substantial unresolved mystery.     

Oxygen-carbon dioxide-nutrients relationships in the Southeastern Region of the Bering Sea

The vertical distribution of density, salinity, temperature, dissolved oxygen, apparent oxygen utilization, nutrients, preformed phosphate, pH, alkalinity, alkalinity: chlorinity ratio, in situ partial pressure of carbon dioxide, and percent saturation of calcite and aragonite, for the Southeastern Bering Sea, is studied and explained in terms of biological and physical processes. Some hydrological interactions between the Bering Sea and the North Pacific Ocean are explained. The horizontal distribution of dissolved oxygen at 2000 and 2500 m depths, throughout the Bering Sea, indicates that deep water is flowing from the Pacific, through the Kamchatka Strait, and then northward and eastward in the Bering Sea. Based on the dissolved oxygen distribution we estimate roughly that it takes 20 years for the deep waters to move from the Kamchatka Strait to the Southeastern part of the eastern basin. The surface concentration of nutrients is higher in the Bering Sea than in the North Pacific Ocean, probably because of upwelling and intense vertical mixing in the Bering Sea. A multivariable regression analysis of dissolved oxygen as a function of phosphate concentration and potential temperature was applied for the region where the potential temperature-salinity diagram is straight, and the confidence interval of the PO₄ coefficient, at the 95% probability level, was found consistent with theRedfield biochemical oxidation model. The calcium carbonate saturation calculations show that the Bering Sea is supersaturated with aragonite in the upper 100 m, and with calcite in the upper 200 m. Below these depths seawater is undersaturated with respect to these two minerals.     

Nutrient Concentrations are High in the Turbid Waters of the Colorado River Delta

We studied the seasonal change of the spatial distribution of nitrite (NO^-₂), nitrate (NO^-₃), reactive phosphate (PO^3-₄), and silicate (SiO₂) in the Colorado River Delta. We also generated 24-h time series at one location to study their short-period variability. The delta is a negative estuary. During summer, salinity may be as high as 40. Amplitude of spring tides is as large as 9 m, and this causes great water turbidity by sediment resuspension. Nutrient concentrations were high throughout the whole year, with lower values towards the oceanic region. Maximum nutrient values in the river delta were 15, 53, 11·5 and 92 μM, for NO^-₂, NO^-₃, PO^3-₄, and SiO₂, respectively. Most values were under 2, 40, 5, and 60 μM, for NO^-₂, NO^-₃, PO^3-₄, and SiO₂, respectively. Our nutrient data show no clear seasonal pattern. Possibly, high NO^-₃ values in the delta are due to groundwater input, mostly at the internal extreme, and high NO^-₂, PO^3-₄, and SiO₂ values are due to resuspension of sediments and mixing of porewaters with the water column, caused mainly during spring tides. In the case of NO^-₂, oxidation of NH⁺₄ in the water column would be part of the mechanism. This would explain the high negative correlation between NO^-₃ and sea-level, and the relatively low correlation between the other nutrients and sea-level, for the time series generated at a single location.     

Differences in the Crustal and Uppermost Mantle Structure of the Bohemian Massif from Teleseismic Receiver Functions

A target of our study was the Bohemian Massif in Central Europe that was emplaced during the Variscan orogeny. We used teleseismic records from ten broadband stations lying within and around the massif. Different techniques of receiver function interpretation were applied, including 1-D inversion of R- and Q-components, forward modelling of V _s velocity, and simultaneous determination of Moho depth and Poissons ratio in the crust. These results provide new, independent information about the distribution of S wave velocity down to about 60 km depth. In the area of Bohemian Massif, the crustal thickness varies from 29 km in the NW to 40 km in the SE. A relatively simple velocity structure with gradually increasing velocities in the crust and uppermost mantle is observed in the eastern part of the Bohemian Massif. The western part of the massif is characterized by more complicated structure with low S wave velocities in the upper crust, as well as in the uppermost mantle. This could be related to tectono-magmatic activity in the Eger rift that started in the uppermost Cretaceous and was active in the West Bohemia-Vogland area till the late Cenozoic.