Statistische Bearbeitung der Parameter des geomagnetischen Feldes und der Säkularvariation

Zusammenfassung Es werden Möglichkeiten zur statistischen Bearbeitung der Parameter geomagnetischer Potentialberechnungen dargestellt und bezüglich der Potsdamer Potentialberechnung zur Epoche 1945.0 praktisch erprobt. Die Ergebnisse werden in zusammengefasster Form vorgelegt und diskutiert.

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Summary The possibilities of a statistical analysis of the parameters of geomagnetic field are presented, and with reference to the spherical harmonical analysis of the Geomagnetic Institute in Potsdam practical tested. The results are presented and discussed in a summarized manner.

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Mitteilung aus dem Geomagnetischen Institut der DAW, Potsdam, Nr. 199.     

Isotope paleontology: growth and composition of extant calcareous species

Isotope paleontology uses the isotopic composition of fossil remains of organisms to make inferences about the physical surroundings of growth of the organisms (especially temperature), and to obtain clues about life history and modes of growth. In calcareous fossils, oxygen isotopes are mainly used in the former, and carbon isotopes in the latter. However, since physical surroundings and organism response are intimately associated, both types of information are contained in each of the isotopic signals. To explore the potential of isotope paleontology, and to provide a basis for reconstruction, a broad range of extant organisms has been studied, taking the pioneering work of Epstein and associates as a starting point. Results are summarized for a representative sampling of these studies, with emphasis on work at the laboratories of the authors, from the mid-seventies to the present. The organisms considered are nannoplankton, benthic algae, planktonic and benthic deep-sea foraminifera, “larger” foraminifera, sponges, corals, bryozoans, polychaetes, arthropods, bivalves, gastropods, cephalopods, and vertebrates (fish otoliths). The survey broadly suggests that, regarding oxygen isotopes, materials tend to be precipitated close to equilibrium with the surrounding seawater (as postulated by Urey), and that for carbon isotopes disequilibrium is the rule. Life spans, growth rates, differential seasonal growth, and age of reproductive activity can be extracted under favorable circumstances from individual shells and skeletal parts. In detail, the interpretation of isotope records of individual shells is quite complicated, and simple models will fail to give satisfactory results in many or most cases.     

Sedimentation of planktonic foraminifera

Fossil assemblages of planktonic Foraminifera contain many valuable clues to paleoclimate and paleo-oceanography. Unfortunately, our understanding of production, dissolution, redeposition, and other processes of foraminiferal sedimentation is but rudimentary. Lacking direct observations, information largely rests on comparisons between abundance and composition patterns of life-, death-, and sediment-assemblages.     

Bioaccumulation and depuration of Zn and Cd in mangrove oysters (Crassostrea rhizophorae, Guilding, 1828) transplanted to and from a contaminated tropical coastal lagoon

In order to study Zn and Cd accumulation and depuration, a set of oysters, Crassostrea rhizophorae, were transplanted to a metal contaminated coastal lagoon and another one was harvested there and transplanted to a non-polluted site. C. rhizophorae oysters and Perna perna mussels native from both sites were collected in order to monitor variability of metal concentration in resident populations. After three months exposure, oysters transplanted to the polluted site accumulated fourfold Zn (307-1319 microgg(-1)) without reaching the concentration level of resident oysters (9770 microgg(-1)). Cadmium concentrations had a slight but significant decrease during the same period (1.25-0.54 microgg(-1)). Oysters transplanted to the non-polluted site, showed threefold Zn depuration (6727-2404 microgg(-1)), while Cd had no significant variation (0.90-1.45 microgg(-1)). Results showed that transplanted oysters do not reach heavy metal concentrations in indigenous populations suggesting transplanted organisms would be better used to evaluate bioavailability instead of environmental concentrations.     

Technical Issues and Recommendations Related to the Installation of Continuous GPS Stations at Tide Gauges

Geodesists around the world have begun installing continuous GPS (CGPS) stations at tide gauges in order to determine the exact position of these tide gauges and, in particular, the vertical velocity of the land or the seafloor underlying each tide gauge. The goal is to make these measurements in a well-defined global reference frame. The scientific applications of these measurements include the calibration of satellite altimeters and the removal of crustal motion signals from long time series of sea level change. In this article we focus on the technical issues associated with this agenda, including site selection, instrumentation, monumentation, ancillary measurements, and the tide gauge leveling program. There is no universally best approach to building CGPS stations at tide gauges. Therefore we emphasize the various trade-offs that typically occur, and give general recommendations and rules of thumb based on recent installations and experience. Additional information can be found at the CGPS@TG website.     

Arsenic in seawater and brown algae of the Baltic and the North Sea

A long-term study within the pilot environmental specimen bank programme of the Federal Republic of Germany on arsenic levels in coastal and open seawater and their reflection in the brown seaweed (Fucus vesiculosus) has been performed. Dissolved arsenic was on average 0.76 (range 0.45–1.11) μgl⁻¹ for 17 sampling stations in the Baltic Sea, whereas contents of dissolved arsenic are somewhat higher in shallow waters of the coastal zone of the North Sea. Total arsenic levels in algae ranged up to 40 mg kg⁻¹ (dry weight) and showed for the four locations studied obvious seasonal variations for comparatively nonpolluted or nondisturbed locations only. However, probably due to biological influences, the results obtained so far indicate that composite samples integrating a one year period are supposed to be the best strategy for future environmental specimen banking. Using a new efficient speciation technique the percentage of chemically stable organoarsenic compounds in the investigated algae has been found to be 95% of the total arsenic content and thus somewhat lower than in teleost fish. For comparison, typical data for a few other algae species from the Baltic and the Mediterranean Sea are also shown.     

Pulsar nebulae

Several of the exotic supernova remnants are re-interpreted as pulsar-illuminated former windzones. The class of supernova remnants thus splits into (i) (the usual) shell remnants and (ii) pulsar nebulae in which a (fairly young) pulsar blows its relativistic wind into its low-density environs.     

Stockert's chimney — A galactic fountain

A new type of galactic outflow phenomenon has been discovered and published under the name of thermal spur by Mülleret al. (1987). It is argued that this outflow consists of relativistic pair plasma with an admixture of partially ionized hydrogen and cosmic rays, escaping from a large Hii region. This chimney serves as a substantial leak for the cosmic rays, i.e., may be an essential part of the galactic foundtain.     

The critical state behaviour of barodesy compared with the Matsuoka–Nakai failure criterion

Barodesy is a new approach to constitutive modelling of soil. It is based on Goldscheider's principles and maps stretching directions onto corresponding stress directions with the help of a simple exponential function. This mapping also determines a critical state surface in principal stress space. The article investigates this surface and relates it to the well‐known Matsuoka–Nakai failure criterion. It turns out that the difference between these two surfaces is negligible for practical applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Paleontology,sedimentology and paleoenvironment of a new fossiliferous locality of the Jurassic Cañadón Asfalto Formation,Chubut Province,Argentina

A new Late Jurassic assemblage of “conchostracans”, ostracods, bivalves and caddisfly cases from the locality “Estancia La Sin Rumbo”, Chubut Province (Patagonia, Argentina) is recorded. The fossils occur in the upper part of an outcropping 45 m thick volcaniclastic lacustrine sequence of yellowish tuffs and tuffites of the Puesto Almada Member, which is the upper member of the Cañadón Asfalto Formation with U/Pb age of 161 ± 3 Ma. The sequence represents one sedimentary cycle composed of a (lower) hemicycle of expansion and a (higher) hemicycle of contraction of the water body. The invertebrates lived in small freshwater bodies during the periods of expansion of the lake. The occurrence of a great number of small spinicaudatans, associated with mud-cracks, is evidence of dry climatic conditions and suggests several local mortality events. The spinicaudatan record of the fushunograptid–orthestheriid (component of the Eosestheriopsis dianzhongensis fauna) and the presence of Congestheriella rauhuti Gallego and Shen, suggest a Late Jurassic (Oxfordian to Tithonian) age. Caddisfly cases are recorded for the first time in the Cañadón Asfalto Basin.