Ein einfaches Klein-Aräometer zur exakten Bestimmung des Salzgehaltes im Meerwasser

Zusammenfassung Im folgenden wird eine neuartige Aräometer-Apparatur zur Dichte- und Salzgehaltsbestimmung von Meerwasserproben beschrieben. Vor ähnlichen Apparaten zeichnet sie sich durch folgende Punkte aus:Sie ist besonders klein und kompakt gebaut und benötigt mit Vorspülen nur 60 bis 80 ccm Meerwasser. — Der Aräometer-Schwimmer selbst hat ein Volumen von nur 7 ccm. Dadurch, daß er an einem Härchen aufgehängt und die Oberflächenspannung durch Zugabe einiger Tropfen einer Detergenz-Lösung aufgehoben ist, wird ein reibungsloses Gleiten des Schwimmers ermöglicht. — Infolgedessen läßt sich der Auftrieb mit der großen Genauigkeit von 0,05 mg messen, was einer Empfindlichkeit von 0,01 S entspricht. — Als Meßinstrument dient eine kompakt gebaute Tor-sionswaage mit kreisförmiger Ableseskala, die sich in bequemer Höhe zum Auge befindet. Der Gesamtwägebereich umfaßt 200 mg, so daß der gesamte ozeanische Meßbereich von 0 bis 40 S ohne Schwimmerwechsel erfaßbar ist. — Gegenüber der Titration des Cl-Gehaltes hat die Methode den Vorteil, daß bei etwas erhöhter Empfindlichkeit und Arbeitsgeschwindigkeit im Serienbetrieb die Ablesung des Zeigers und des Thermometers wesentlich weniger ermüdend ist als die diffizile tropfenweise Zugabe der Silbernitratlösung und die Beobachtung des Indikatorumschlagpunktes. — Die Endberechnung des Salzgehaltes erfolgt über die beiden beobachteten Werte von Gewicht (an der Torsionswaage) und Temperatur (am Thermometer) und mit Hilfe einer bequem ablesbaren Fluchtentafel. — Der Meßvorgang selbst erfordert weder Chemikalien noch den Anschluß von Wasser oder elektrischem Strom.

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A simple small-type areometer for the precise determination of salinity and density in seawater

Summary The present paper describes a newly developed areometer for the determination of salinity and density of sea-water. The apparatus is distinguished by the following features:The areometer is extremely small, its construction is very compact; including preliminary rinsing, it requires only 60 to 80 cm³ of sea-water. The volume of the areometer float itself is 7 cm³ only. Besides, by suspending the float by a fine hair and suppressing surface tension by adding a few drops of detergent solution the float is enabled to slide without friction. Owing to these two operations, the weight can be determined with so high an accuracy as 0,05 mg, corresponding to a sensitivity of 0,01 S. — A compact torsion-balance which, at a convenient height, includes a circular reading scale, serves as a measuring instrument. The total weighing range of the balance amounts to 200 mg, thus enabling the entire oceanic measuring range from 0 to 40 S to be determined without having to change the float. — In comparison with chlorinity titration the new method offers the advantage of an increased sensitivity and a higher working speed, since in serial investigations reading of the indicator needle and of the thermometer is far less tiring than the troublesome addition of silver nitrate solution and the simultaneous observation of the equivalance point. — The definitive determination of salinity is carried out with the aid of the two observed values of weight (on the torsion balance) and temperature (on the thermometer) and a conveniently readable nomograph. — The measuring procedure requires neither the use of chemicals, nor water connection, nor power equipment.Résumé Le travail actuel décrit un nouvel aréomètre pour déterminer la salinité et la densité des échantillons d'eau de mer. Cet appareil est caractérisé par sa petitesse, par sa construction compacte, par la quantité insignifiante d'eau de mer de 60 à 80 cm³ qu'il demande, y compris l'eau pour le rincement préalable, et par le petit volume de seulement 7 cm³ de son flotteur. De plus, en suspendant le flotteur par un cheveu fin et en supprimant la tension superficielle de liquide par l'addition de plusieurs gouttes d'une solution de détersion on réussit à faire glisser sans friction le flotteur. Ces deux opérations permettent de mesurer le poids à l'extrême précision de 0,05 mg près, ce qui est identique à la sensibilité de 0,01 S. — Pour des mesures on se sert d'une balance compacte à torsion munie d'une échelle circulaire à lecture. Cette échelle se trouve installée à une hauteur convenable aux yeux. L'étendue totale de la balance va jusqu'à 200 mg, ce qui permet d'étudier l'entière étendue de mesure océanique de 0 à 40 S sans changer de flotteur. — Confrontant la méthode de titrage du chlore avec la nouvelle méthode, on remarquera que la lecture de l'aiguille et du thermomètre est beaucoup moins fatigante que la pénible addition par gouttes du nitrate d'argent et l'observation simultanée du moment de l'équilibre, surtout dans le cas où les circonstances demandent l'observation d'une sensibilité un peu élevée ou une plus grande rapidité de travail lors des recherches en série. — Le calcul définitif de la salinité se fait à l'aide de deux valeurs observées, à savoir le poids (sur la balance à torsion) et la température (sur le thermomètre), et au moyen d'un nomogramme bien lisible. — La méthode de mesure elle-même ne demande ni emploi de substances chimiques, ni distribution d'eau, ni installation d'énergie.

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Un aréomètre de simple construction pour la précise détermination de la salinité et de la densité de l'eau de mer

     

The misrepresentation of the planktonic diatom assemblage in traps and sediments: southern Lake Malaŵi,Africa

Sediment trap collections near Cape Maclear, Lake Malai, were compared to phytoplankton and surface sediment diatoms to assess taphonomic variations. The sedimenting diatom community became progressively different from the diatom plankton with increasing depth: long Nitzschia species were strongly under-represented in the traps (annually, 53% among planktonic diatoms vs. 14% in the offshore 29 m trap; p0.005 by Kruskal-Wallis test), while Melosira was greatly over-represented in traps (32% vs. 57%; p<0.005). The abundances of the minor taxa (Rhopalodia, Fragilaria, Cymbella, and Surirella) were greatly enhanced in traps relative to the plankton, but they were still relatively uncommon (<3% of all diatoms each). Differences in grazing, dissolution, and sinking rates alone are insufficient to account for these distortions; a combination of these, plus perhaps unknown factors, strongly influence the deposited assemblage.These misrepresentations were also present at the sediment surface. The greatest discrepancy was noted for Melosira (32% of plankton vs. 53% of sediment surface diatoms; p<0.005) and for elongate Nitzschia species (53% of plankton vs. 0.8% in sediments; p<0.005). In Lake Malai, at least, paleolimnologists must not assume a straightforward correlation of modern and fossil assemblages.     

Reconstructed summer temperature in the northern Rocky Mountains wilderness, USA

Ring widths from whitebark pine (Pinus albicaulis Englem.) and subalpine larch (Larix lyallii Parl.) collected at three high-elevation sites were used to develop tree-growth chronologies to reconstruct summer temperature anomalies. A step-wise multiple regression procedure was used to screen potential predictor variables to generate a transfer function capable of skillfully reconstructing summer temperature. The resulting regression model explained approximately 38% of the adjusted variance in the instrumental temperature record. The fidelity of the reconstruction was verified using product mean and sign tests, both of which suggested significant predictive power in the reconstructions (p < 0.05). Reduction of error (RE) and coefficient of efficiency (CE) measures were both positive, indicating the reconstruction contained useful climate information. Cool periods often coincided with reduced solar activity and/or periods of increased volcanic activity. Differences between this reconstruction and others encompassing a broader geographic scale highlight the importance of developing local reconstructions of climate variability, particularly when used in conjunction with ecological data sets that describe the occurrence of fires or insect epidemics. Mixed and divergent climate-response relationships were evident in the whitebark pine chronologies and suggest subalpine larch may be a more useful species than whitebark pine to target for the development of temperature reconstructions in this region.     

Early Cretaceous (Valanginian – Hauterivian) belemnites from western Morocco: stratigraphy and palaeoecology

Recent field work in Lower Cretaceous successions of the Agadir-Essaouira region, western High Atlas, Morocco, have resulted in 489 belemnite guards collected bed-by-bed from the lower Valanginian – upper Hauterivian interval. These findings are described and discussed in their biostratigraphic, taxonomic, palaeoecologic and palaeobiogeographic context. The most common belemnite genera, Hibolithes, Vaunagites?, and Duvalia, are of Meditteranean affinities and closely related to Spanish, French, and Bulgarian faunas. Less common taxa include Pseudoduvalia and Berriasibelus. The genus Pseudobelus, however, common in southeastern France and southern Spain, is rare in the Moroccan sections. The palaeoecological interpretation of these observations result in the recognition of three belemnite assemblages, characterizing different marine settings: 1) A Hibolithes - Duvalia assemblage which is typical for inner to middle shelf settings. These are relatively shallow marine environments with a high input of siliciclastics. 2) A Duvalia - Hibolithes assemblage of the outer shelf setting. Duvalia spp. is the most common genus, Hibolithes spp. is less common, while Berriasibelus spp. and Pseudobelus spp. are rare. 3) A Duvalia - Pseudobelus assemblage of hemi-pelagic preference. Duvalia is most common, next is Pseudobelus.     

Biodegradation effects over different types of coastal rocks

Modern coastal areas have natural and transported rocks (armourstone) on which various types of organisms live. Burrowing, boring and feeding by these organisms can destroy or modify the coastal rocks and hence change the coastal morphology. Two rock types and three dominant types of organisms have been studied in Mersin Bay, Eastern Mediterranean of southern Turkey. In this study area, Plio-Quaternary conglomerates and variously aged limestone armourplates have been affected by Phoronida worms, bivalve Brachidontes pharaonis (Fischer P. 1870) and the limpet Patella sp. Phoronida colonies were found covering the hard substratum as a mat and form tubular endolithes of 35.0 mm depth and 1.5 mm diameter, whilst Brachidontes pharaonis (Fischer P. 1870) form 44 mm deep vase-shaped gastrochaenolites. The bioerosive activity of Limpet Patella sp., found intertidal and within the spray zone, cannot be significantly observed on the rocks over short time periods. The soft sandy matrix of the conglomerates present were found to disintegrate by bioerosional processes, with the released gravels being transported and deposited onto the beach. Within the armourstone limestone blocks, a maximum of 44.0 mm deep holes developed after 50–60 years. However, these biological activities do not threaten the stability of the blocks due to their hard and homogeneous internal structure. Furthermore, the organism colonies that cover these rocks as a strong mat (maximum 29.0 mm) act to protect their surfaces from further biological attack and wave action.     

Mouvements actuels des blocs tectoniques dans l’arc Bético-Rifain à partir des mesures GPS entre 1999 et 2005

GPS velocities and seismicity across the Betic–Rif Arc structural domains (Morocco and Iberia) provide a basis to evaluate present-day seismotectonic processes between different deformation belts. The results show asymmetric movements in the complex Alboran system accommodating the convergence between the African (Nubian) and Eurasian plates. While the Betic Mountains are attached to Iberia, moving toward the southeast with respect to Africa, the Rif is divided into three blocks with distinct displacements relative to Nubia: (1) the Tangier block moving southeastward, (2) the Central Rif block moving SSW, and (3) the Oriental Rif block undergoing clockwise rotation. GPS-derived motions decrease in rate from the Rif nappes complex to the foreland.     

Tektonische Probleme in Sachsen

Ohne Zusammenfassung     

Fidelity and repeatability of wave fields reconstructed from multicomponent streamer data

Wave field reconstruction – the estimation of a three‐dimensional (3D) wave field representing upgoing, downgoing or the combined total pressure at an arbitrary point within a marine streamer array – is enabled by simultaneous measurements of the crossline and vertical components of particle acceleration in addition to pressure in a multicomponent marine streamer. We examine a repeated sail line of North Sea data acquired by a prototype multicomponent towed‐streamer array for both wave field reconstruction fidelity (or accuracy) and reconstruction repeatability. Data from six cables, finely sampled in‐line but spaced at 75 m crossline, are reconstructed and placed on a rectangular data grid uniformly spaced at 6.25 m in‐line and crossline. Benchmarks are generated using recorded pressure data and compared with wave fields reconstructed from pressure alone, and from combinations of pressure, crossline acceleration and vertical acceleration. We find that reconstruction using pressure and both crossline and vertical acceleration has excellent fidelity, recapturing highly aliased diffractions that are lost by interpolation of pressure‐only data. We model wave field reconstruction error as a linear function of distance from the nearest physical sensor and find, for this data set with some mismatched shot positions, that the reconstructed wave field error sensitivity to sensor mispositioning is one‐third that of the recorded wave field sensitivity. Multicomponent reconstruction is also more repeatable, outperforming single‐component reconstruction in which wave field mismatch correlates with geometry mismatch. We find that adequate repeatability may mask poor reconstruction fidelity and that aliased reconstructions will repeat if the survey geometry repeats. Although the multicomponent 3D data have only 500 m in‐line aperture, limiting the attenuation of non‐repeating multiples, the level of repeatability achieved is extremely encouraging compared to full‐aperture, pressure‐only, time‐lapse data sets at an equivalent stage of processing.