ALBERT

Description: Many of the difficulties of staining plastic embedded tissues for light and electron microscopy derive from physical exclusion of hydrophilic staining reagents by hydrophobic embedding media. Structures which stain most intensely with hydrophilic reagents usually contain less hydrophobic plastic than do non-staining structures. Such incomplete infiltration is apparently caused by exclusion of viscous, hydrophobic monomers by physically dense and/or well hydrated tissue elements. In keeping with this, generalized staining of tissues embedded in hydrophobic media does occur when hydrophobic reagents are used. Staining of plastic-free structures with single hydrophilic reagents or with sequences of such reagents, is, however, largely rate-controlled. The surprising similarity of hydrophilic and hydrophobic plastic embedding media is discussed. Limits of this simple model are explored, with a consideration of the roles of fixative and of monomer-tissue reactions

Description: Volcanic ash layers, which represent the products of volcanic activity within the ocean basins, are common in sedimentary cores taken near Cobb Seamount and on the actively spreading Gorda and Juan de Fuca Ridges. Petrographic and chemical analyses of the glass shards from these deposits have revealed that they are unaltered and are as chemically representative of local volcanic events as are the glassy margins of fresh pillow basalts recovered from the same areas. The presence of unhydrated glass shards in samples as old as 3.8 my is in direct conflict with published hydration rates of both terrestrial and submarine volcanic glasses. A study of a sequence of ash layers from Cobb Seamount, which spans in time much of the Seamount's history, indicates that the volcanic products from Cobb Seamount have had alkaline affinities and that its eruptions have been becoming progressively enriched in Al2O3. Recent experimental petrological evidence and the data on the chemical compositions of Cobb Seamount and the adjacent Juan de Fuca Ridge magmas are in agreement with the hypothesis that magmas are being generated at progressively greater depths beneath Cobb Seamount as it migrates away from the Juan de Fuca Ridge.

Description: Pairs of individually recognizable male Octopus vulgaris were observed in a large seawater tank containing two suitable homes (brick pots or plastic buckets). None of the animals established exclusive occupancy of one home and for much of the time both animals were associated together at the same site. Usually one of the two homes was preferred and its occupant was most likely to be the larger animal, or the earlier resident if they were of equal size. Large animals were observed to take food forcefully from smaller octopus. An arm alignment interaction is described which, it is suggested, may be a means by which two octopuses establish their relative sizes.

Description: A general method for simulating aerosol size distribution dynamics is developed. The method, based on dividing the particle size domain into sections and dealing only with one integral quantity in each section (e.g., number, surface area, or volume), has the advantages that the integral quantity is conserved within the computational domain and coagulations between all particle sizes are properly accounted for. To demonstrate the simplicity and accuracy of the method for a practical problem, the evolution of a power plant plume aerosol undergoing coagulation is simulated.

Description: The exchange of inorganic nutrients; ammonium, nitrate and reactive phosphate between burrows of the infaunal polychaete Nereis virens Sars and the overlying water was assessed using V-shaped sediment cores. Exchange was determined by monitoring ventilation current and nutrient concentration of in- and excurrent water. Ammonium supply appeared independent of overlying water concentrations, showing a constant release of 0.5 μmol·h−1 (for a 2-g individual + burrow system) at concentrations from 2 to 87 μM. Of this release ≈40% originated from worm excretion, and the rest from microbial mineralization. Nitrate and phosphate exchange appeared very sensitive to overlying water concentrations, having equilibrium (zero flux) at 10–15 and 3 μM, respectively. Below these concentrations nitrate showed a slight release (due to nitrification), whereas phosphate was released at a rate of 3.2 × 10−2 μmol·h−1 at 1 μM (mineralization and desorption). Above equilibrium they both were removed during water passage through worm burrows, reaching 0.4 μmol·h−1 for nitrate at 107 μM (nitrate reduction) and 3.7 × 10−2 μmol·h−1 for phosphate at 5.6 μM (adsorption processes). The burrow system apparently acted as a buffer for phosphate and, to some degree, nitrate in the overlying water. At the study site (Norsminde Fjord estuary) nereid burrows were estimated to increase the sediment-water interface 150%. About 17% of the water column was cycled through the sediment by Nereis each day. The worm + burrow system was estimated to release 95 μmol· m−2·h−1 ammonium to the overlying water, which was ≈76–90% of the total release of ammonium from the sediment (30–36% was worm excretion).

Description: Before making a critical evaluation of the crude oil and natural gas prospects for the years to the end of the century, it is necessary to review the geology and structure of the three German hydrocarbon-producing provinces. Furthermore, past exploration, production and reserves should be discussed. The three hydrocarbon-producing provinces are: the NW German Basin, the Upper Rhine Graben and the Molasse Basin, which together make up about 41% of West German territory (Fig. 1). The NW German Basin contains a sedimentary sequence over 8,000 m thick ranging in age from Permian to Quaternary. Gas and oil, the two natural hydrocarbons, are generally confined to separate lower and higher stratigraphic levels respectively (Fig. 2). The NW German Basin is the most important prospective area in West Germany. It extends into the North Sea. The tectonic rift feature of the Upper Rhine Graben originated in the Eocene. The Tertiary fill is over 4,000 m thick. Oil is found mainly in Mesozoic, Eocene and Oligocene rocks; the Miocene and Pliocene reservoir rocks contain natural gas almost exclusively (Fig. 3). The Molasse Basin is part of the foredeep north of the Alpine and Carpathian mountain ranges. The basin is filled with Upper Eocene to Pliocene and Quaternary sediments which, near the Alpine nappes, reach a thickness of over 5,000m (Fig. 4). During this century there were peaks in annual oil-production in 1910, 1940 and 1968 (see Fig. 5). The 1910 peak was the result of drilling activity in the Wietze oilfield. During the period 1934–1945, government financial aid was made available for drilling exploration wells. The success of this collaboration is demonstrated by the oil output in 1940 of 1 × 106 t. After World War II, many different types of oil-bearing structure were found, particularly by reflection seismic techniques in conjunction with detailed stratigraphical and palaeogeographical investigations. The success achieved can be seen by the peak of 8 × 106 t oil production for 1968 (Fig. 5) and in the growth of oil reserves (Fig. 7). Intensive exploration also enabled many new gasfields to be developed, especially in the deeper horizons of the NW German Basin. In 1971, estimated gas reserves reached 360 × 109 m3 (Fig. 11), and annual gas production in 1979 was 20.7 × 109 m3 (731 Bcf) (Fig. 9). There is, no doubt, still scope for the discovery and exploitation of oil and gas in Germany, especially in the NW German Basin where the best prospects for the future lie. This is borne out by two recent offshore oil discoveries and also by the successful application of enhanced recovery methods in the oilfields. The chances of finding more gas at the lower stratigraphic levels are promising now that gas has been discovered in the deeper parts of the Permian basin. The results of massive-hydraulic-fracturing tests in low-permeability pay-horizons are also encouraging. The deeper parts of oil- and gas-producing basins contain interesting prospects and have yet to be tested by ultra-deep wells. Provided that the economic climate remains favourable, there should be no difficulty in finding and supplying German oil and gas in the future. Geologically and technically possible reserves should be converted into proven and/or probable reserves. German crude oil will be available for several years beyond the year 2000, and German natural gas for a far longer time. A production rate of 19 to 20 × 109 m3 of gas per annum is feasible over the next twenty years, and oil production will probably not sink below 3 × 106 t/a in this period.

Description: Acoustic basement lies at an average of between 6.0 and 6.5 sec two-way time below sea level in the southern Rockall Trough and northern Porcupine Abyssal Plain. The overlying sedimentary succession reaches maximum thicknesses of at least 4.0 sec, and can be divided by 3 regionally-developed seismic reflecting horizons, which are used as a framework to establish an acoustic stratigraphy for the area by selecting three “type” seismic sections. These reflectors are named, in ascending order, Shackleton, Charcot and Challenger. The area is crossed by E—W basement high structures, the Clare Lineament (which may be an easterly extension of the Charlie Gibbs Fracture Zone), that separates the Porcupine Abyssal Plain from the eastern part of southern Rockall Trough. Under the latter, the post-Shackleton acoustic sequence is thickened, as if dammed to the north of the Clare Lineament, whilst a further thickening, above reflector Charcot, occurs along a NE—SW line somewhat farther north into the southern Rockall Trough. This can also be related to shallow-lying acoustic basement features. Pre-Shackleton sediments overlie a very irregular basement topography. The acoustic characters of the various sediment packages are described and it is speculated that major changes in the sedimentary environments took place across reflectors Shackleton and Challenger, the latter probably establishing the modern bottom current circulation patterns. No ages can be unequivocally assigned to the main reflectors, but previously published data suggest a late Eocene—Oligocene age for Challenger. Possible lavas or sills are identified in the succession between reflectors Shackleton and Charcot.

Description: Isopach asymmetry, and sediment component changes in DSDP cores from the SE Atlantic (Orange Basin) support the hypothesis of major drainage system changes in SW Africa during late Cretaceous—Cenozoic time. This involved alternations in the use of the 28°S (modern Orange River) and 31°S (modern Olifants River) exit points across the western escarpment by rivers carrying run-off from the Upper Orange/Vaal catchment areas, as well as radical re-organizations of internal drainage geometry. It is postulated that during late Cretaceous times the 28°S exit was used, with the Middle Orange River following a course in the interior well to the south (up to 150 km) of its modern channel. Sediment discharge rates from this river were relatively high (at least 10 × 106 m3 yr−1), and resulted in rapid advancement of the continental margin sediment prism west of the mouth by large-scale slumping. The Palaeogene Orange/Vaal river exit was via the 31°S escarpment crossing, and during the later part of this period, the Cape Canyon was cut across the continental shelf and slope. A significant reduction in sediment discharge (to 2.0 × 106 m3 yr−1) suggests that the Lower Tertiary climate for SW Africa was drier than that of late Cretaceous times. However, aridity did not commence until late Miocene times, when the Orange/Vaal discharge had switched back to the 28°S exit. Modern sediment discharge rates (6.5 × 106 m3 yr−1) are relatively high and reflect soil erosion caused by agricultural activity. The two major alterations in exit point of the Orange/Vaal (late Cretaceous—early Tertiary, and late Oligocene—early Miocene) are related to periods of low sea level, which promoted river capture adjacent to the western escarpment. An additional factor in the first course change may have been the disruption of the Middle Orange channel by late Cretaceous igneous intrusions. Less important internal reorganizations of the drainage system are postulated in late Miocene—Pleistocene times. Economic implications for offshore diamond distribution are briefly mentioned.

Description: Four palaeogeographical reconstructions are presented for the southern Cape covering the period Late Permian to Late Cretaceous. This time spans the commencement to an advanced stage of breakup of Gondwanaland, during which the area moved from a mid-continental, high latitude, to an ocean-dominated, middle latitude position. These movements can be traced in facies changes and erosional cycles associated with the rift between West Gondwana and Antarctica (proto southwest Indian Ocean) and the later rift between South America and Africa (proto southeast Atlantic Ocean).