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Integrating Cavity Absorption Meter measurements of dissolved substances and suspended particles in ocean water

We have developed a new device to measure the separate contributions to the spectral absorption coefficient due to a pure liquid, due to the particles suspended in it, and due to the substances dissolved in it. This device, the Integrating Cavity Absorption Meter (ICAM), is essentially independent of scattering effects in the sample. In April 1993, a prototype of the ICAM was field tested on board the research vessel USNS Bartlett. A major part of the cruise track included criss-crossing the area where the Mississippi flows into the Gulf of Mexico at various ranges from the mouth of the river; thus samples were collected from areas of blue, green, and brown/black water. We evaluated 35 seawater samples collected with 5-l Niskin bottles from 22 locations to determine absorption spectra (380–700 nm) of suspended particles and dissolved substances (gelbstoff). Results validate the ICAM as a viable tool for marine optical absorption research. Gelbstoff absorption at 432.5 nm ranged from 0.024 to 0.603 m⁻¹. Over the spectral region 380→560 nm, gelbstoff absorption by each of the samples could be accurately fit to a decaying exponential. The particle absorption spectra are generally characteristic of those of phytoplankton and exhibit a local maximum at 430–440 nm. Absorption values at 432.5 nm ranged from zero to 1.0 m⁻¹. Some samples with moderate particulate absorption, however, did not show the characteristic local maximum of phytoplankton in the blue and instead resembled the characteristic decaying exponential of detritus with a shape similar to that observed in the gelbstoff. The ratio of gelbstoff to particulate absorption at 432.5 nm ranged from 0.46 to 152.     

Multi-stage emplacement of the G?temar Pluton, SE Sweden: new evidence inferred from field observations and microfabric analysis, including cathodoluminescence microscopy

The emplacement of the Mesoproterozoic G?temar Pluton into Paleoproterozoic granitoid host rocks of the Transscandinavian Igneous Belt is re-examined by microfabric analysis, including cathodoluminescence microscopy. Field data on the pluton-host rock system are used to strengthen the model. The G?temar Pluton, situated on the Baltic Shield of SE Sweden, is a horizontally zoned tabular structure that was constructed by the intrusion of successive pulses of magma with different crystal/melt ratios, at an estimated crustal depth of 4–8?km. Initial pluton formation involved magma ascent along a vertical dike, which was arrested at a mechanical discontinuity within the granitoid host rocks; this led to the formation of an initial sill. Subsequent sill stacking and their constant inflation resulted in deformation and reheating of existing magma bodies, which also raised the pluton roof. This multi-stage emplacement scenario is indicated by complex dike relationships and the occurrence of several generations of quartz (Si-metasomatism). The sills were charged by different domains of a heterogeneous magma chamber with varying crystal/melt ratios. Ascent or emplacement of magma with a high crystal/melt ratio is indicated by syn-magmatic deformation of phenocrysts. Complex crystallization fabrics (e.g. oscillatory growth zoning caused by high crystal defect density, overgrowth and replacement features, resorbed and corroded crystal cores, rapakivi structure) are mostly related to processes within the main chamber, that is repeated magma mixing or water influx.     

Recognition of micro‐scale deformation structures in glacial sediments – pattern perception,observer bias and the influence of experience

It is a scientist's mission to try to remain unbiased. However, certain factors play a role in scientific analyses that are not controlled by conscious thought. These factors are potentially very important in areas of science where interpretations are based on a scientist's ability to identify patterns or structures. One such area is the micromorphology of glacial sediments. In this paper we investigate the role of an analyst's experience in relation to pattern perception with specific reference to turbate microstructures in glacial diamictons. An experiment was conducted on 52 participants, which demonstrated that, as may be expected, more experienced (glacial) micromorphologists tend to exhibit a higher sensitivity‐to‐signal, but that complete novices, if given clear instructions, can reach levels of sensitivity similar to those of experts. It also showed, perhaps more surprisingly, that response bias does not decrease with experience. We discuss psychological factors, such as the drive for success and consistency, that may have contributed to these results and investigate their possible implications in the micromorphological analysis and interpretation of glacial sediments.     

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Strömungsuntersuchungen im Fehmarnsund (Ostsee)

Zusammenfassung Im ersten Abschnitt werden mehrere Strommessungen, die vom verankerten Forschungskutter Südfall im Fehmarnsund gewonnen wurden, in ihrer Beziehung zu Wind und Wasserstandsdifferenzen qualitativ diskutiert. Ein Beispiel für Strom bei ruhiger Wetterlage zeigt deutlich vorwiegend Gezeiten. Ein anderes Beispiel für die Verhältnisse bei stürmischen Winden läßt extreme Wasserstandsschwankungen erkennen, die die Gezeitenwelle zum Verschwinden bringen.Im zweiten Abschnitt wird mit Hilfe hydraulischer Formeln für turbulente Strömungen (S. 93) das Oberflächengefälle in Richtung des Fehmarnsundes ermittelt. Ferner wird eine Beziehung zwischen dem Absolutbetrag des Gefälles und der mittleren Stromgeschwindigkeit eines bestimmten Stromprofils abgeleitet, die durch die Messungen befriedigend bestätigt wird.Zum Schluß wird, ebenfalls unter Benutzung von Ansätzen aus der Hydraulik (S. 97), die Verteilung der Oberflächenströmung im Fehmarnsund berechnet, die durch weitere Strommessungen auf verschiedenen Positionen bestätigt wird. Das benutzte Verfahren ist geeignet, die Auswirkungen vorauszuberechnen, die wasserbauliche Änderungen im Fehmarnsund zur Folge haben werden. Die Grenzen dieser Methode werden anhand von mehreren Beispielen aufgezeigt.

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On current investigations in the Fehmarn Sound

Summary The first paragraph deals with several current measurements obtained on board the anchored research cutter Südfall in the Fehmarn Sound and discusses their relation to wind and variations in sea level in a qualitative way. An example of current measurements in calm weather clearly shows the effect of the tides whilst in case of stormy weather, extreme variations in sea level cause the tidal wave to vanish.In the second paragraph, the surface gradient oriented in the axis of the Fehmarn Sound is ascertained with the aid of hydraulic formulae for turbulent currents (see page 93). Besides, a relation between the absolute value of the gradient and the mean current velocity of a certain current profile is derived; this relation is satisfactorily confirmed by the current measurements.At last, hydraulic formulae (see page 97) serve again for calculating the distribution of surface currents in the Fehmarn Sound. Their results are confirmed by a number of current measurements from various stations. The applied method is a suitable aid in predicting the effects of planned hydraulic constructions on the conditions in the Fehmarn Sound. Several examples show the utmost limit of application of this method.

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Sur des recherches de courant dans le Sund de Fehmarn

Résumé Le premier chapitre traite plusieurs mesures du courant effectuées dans le Sund de Fehmarn par le bateau mouillé de recherche Südfall et expose qualitativement leurs rapports avec le vent et avec les différences du niveau de la mer. On donne deux exemples dont l'un se réfère à des mesures du courant prises par un temps calme et l'autre à des mesures ducourant effectuées par un temps orageux. Le premier exemple nous montre nettement la prépondérance de la marée, le deuxième exemple fait voir que les extrêmes variations du niveau de la mer font disparaître l'onde de marée.Dans le deuxième chapitre on calcule, à l'aide des formules hydrauliques pour des courants turbulents (voir page 93), le gradient superficiel incliné dans la direction du Sund de Fehmarn. En outre, on dérive un rapport entre la valeur absolue du gradient et la vitesse moyenne du courant d'une certaine coupe transversale; des mesures du courant vérifient satisfaisamment l'existence d'un tel rapport.A la fin, on calcule, également à l'aide de formules hydrauliques (voir page 97), la distribution des courants superficiels dans le Sund de Fehmarn; ce calcul correspond aux mesures spéciales du courant effectuées à diverses stations. Le procédé y employé est un moyen convenable permettant de prévoir des effets qui pourraient être produits dans le Sund de Fehmarn par des constructions hydrauliques projetées. Plusieurs exemples montrent les limites de cette méthode.

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Herrn Prof. Dr. G. Wüst, meinem verehrten Lehrer, zum 65. Geburtstage gewidmet.