Synthesis and thermal stability of 2 \frac{1}{2}-octahedral sodium mica,NaMg2.5 (OH)2∫i4O10]

A new 2 \(\frac{1}{2}\) -octahedral sheet silicate, NaMg_2.5 Si₄O₁₀ (OH)₂, has been synthesized from oxide mixtures in the temperature range 500–600°C at pressures between 1 and 5 kb. The lattice parameters are a ₀ = 5.298 Å, b ₀ = 9.047 Å, c ₀ = 9.479 Å and ß=99.55°. X-ray data are given in the text. At temperatures above 605° C/1 kb and 630° C/5 kb, it decomposes to magnesiorichterite plus quartz.     

Genesis and distribution of mineral waters as a consequence of recent lithospheric dynamics: the Rhenish Massif,Central Europe

Three major, interdependent processes control the genesis and distribution of mineral and thermal waters in the Rhenish Massif, Central Europe: (a) Magmatic processes in the upper mantle provide most of the CO₂ to produce bicarbonate waters in shallow aquifers. (b) Extension of the brittle upper crust enables the ascent of sodium chloride waters. (c) Uplift and erosion shape the massif's relief, which determines the extent of flow systems and the distribution of thermal springs. The chemistry of mineral waters further depends on the aquifers' mineral composition. A comprehensive set of hydrological, chemical, tectonic and geophysical data on the Rhenish Massif has been compiled. It was used to classify the mineral waters and to map the spatial distribution of water properties. The composition of cuttings from several representative wells producing different water types shows that the hydrothermal alteration of the aquifer rocks consists mainly of kaolinization of chlorite and dissolution of feldspar. Numerical transport simulations favour two modes of groundwater flow: topography-driven flow and the pressure-driven ascent of basement brines along active faults. Thermal convection is less important.     

The color of pumice: case study on a trachytic fall deposit, Meidob volcanic field, Sudan

 This paper examines the cause of color variations of trachytic pumices which are essentially uniform in chemical composition and proposes a geological model for their formation. A pyroclastic sequence of distinct subunits with brown, buff, and black pumices was deposited during the 5000-B.P. eruption of a tuff ring in the central Meidob volcanic field (Sudan). Subunits of buff pumices locally contain minor amounts of streaky pumice with pale-gray and dark-gray domains. The combined evidence of petrographic studies, chemical analyses of whole pumices and groundmass separates, electron microprobe analyses, optical spectroscopy, transmission electron microscopy, and magnetic susceptibility measurements show that color variations of the pumice clasts are related to the size and distribution of Fe³⁺-rich oxide microcrysts. Buff pumice and light-gray domains of streaky pumice have a colorless, transparent groundmass with very few microcrysts. Dark-gray domains of streaky pumice contain abundant hematite and/or magnetite microcrysts visible in thin section within a transparent, colorless glass groundmass. The groundmass of the black pumice clasts is brown in thin section which is most likely caused by submicroscopic magnetite microcrysts. Brown pumice clasts have a mixed groundmass consisting of brown domains and domains with opaque microcrysts in transparent glass. Variations in the eruption dynamics have been inferred from lithological observations. Subunits of black pumices are related to eruption pulses with low magma discharge and high water/magma mass ratio, whereas subunits of buff pumice were deposited during eruption pulses with high magma discharge and low water/magma mass ratio. Brown pumices represent the top part of the magma body, and the initial stage of the eruption probably had a low magma discharge. Streaky pumices are interpreted as the product of syn-eruptive mixing of Fe³⁺-rich oxide microcryst-bearing magma and microcryst-free magma. Received: 3 February 1997 / Accepted: 28 July 1997     

An ecohydrological approach to predicting regional woody species distribution patterns in dryland ecosystems

This paper presents a quantitative ecohydrological framework for predicting regional distribution patterns of woody species in dryland ecosystems. The framework is based on an existing stochastic model for the daily mass balance of water that represents the interactions between soils, climate, and vegetation. Individual species selection is based on an optimality trade-off hypothesis, which states that dryland vegetation patterns are constrained by maximization of water use and simultaneous minimization of water stress. The relative importance of water use and stress avoidance to the overall fitness of three Acacia species is determined from the heterogeneous basin, the Upper Ewaso Ng’iro river basin, of the central Kenya highlands. The model results indicate that overall fitness is more strongly influenced by water use than stress avoidance but that consideration of both stress avoidance and water use is critical to predicting basin-scale patterns of species distribution. We identify a linear trend in the frequency and intensity of storms with the same annual total using a basin-wide gauge precipitation dataset. After calibration, we apply the basin average linear trends in time for average rain per storm and storm arrival rates. The model results indicate the upslope migration of two species, Acacia tortilis and Acacia xanthophloea to areas with higher total rainfall. Lastly, we explore the modeled changes of species cover in the basin influenced by changes in rainfall total holding growing season rainfall variability constant and changes in growing season rainfall variability holding total rainfall constant. We find that changes in dryland species distribution patterns and relative abundance may be as sensitive to growing season rainfall variability as they are to changes in total rainfall amounts.     

Use of Magnet Technology for Phosphate Elimination from Municipal Sewage

The present report describes the set-up and first operation results of a novel carousel magnetic separator. This carousel magnetic separator is suitable for continuous separation of magnetized particles from water. Continuous operation is achieved by a segmented rotating separation matrix. This matrix also allows the use of low-cost permanent magnets, by means of which magnetic fields of up to 0.5 T can be generated without energy consumption. The suitability of a first prototype of this carousel magnetic separator was tested for elimination of magnetite-containing iron phosphate and iron hydroxide flocs. These flocs result from conventional precipitation/flocculation of municipal sewage with FeCl₃ and the addition of magnetite particles generated by wet-chemical processes. First results demonstrate that the carousel magnetic separator can reduce phosphate concentrations of up to 14 mg/L PO₄^3–-P in the inlet to below 1 mg/L PO₄^3–-P in the outlet at filtration rates of about 40 m/h. Magnetite dosage in the range of 50 mg/L affects phosphate precipitation positively via a slight reduction of the precipitant volume. However, the total amount of chemicals required for phosphate elimination is increased by the substances needed for magnetite production. Therefore, a further reduction of magnetite dosage must be achieved.     

Über die Bestimmung von Differenzen der Lotrichtung mit Hilfe des GradientenU zzs

Zusammenfassung R. v. Eötvös hat für die Bestimmung von Lotrichtungsdifferenzen mit seiner Drehwaage zwei Verfahren angegeben, die aber nur unter Hinzuziehung astronomisch-geodätischer Messungen zum Ziel führen. Beide Verfahren sind sehr umständlich, und in der einschlägigen Literatur finden sich keine Hinweise, daß eines der genannten Verfahren seitEötvös nochmals angewandt wurde. — In Freiburg i. Br. wird zur Zeit eine Drehwaage erprobt, mit der voraussichtlich die direkte Messung des GradientenU _zzs möglich sein wird. Es soll nun gezeigt werden, daß die Bestimmung der Lotrichtungsdifferenz zweier Feldpunkte mit Hilfe dieser Größe, ohne Zuhilfenahme von astronomisch-geodätischen Messungen, möglich ist.

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Summary R. v. Eötvös has showed two methods for the measurement of differences between vertical lines with his torsion-balance. Both methods are only applicable, if they are connected with astronomic and geodetic measurements, and they are very troublesome. In the special publications are no remarks, that one of these methods everytime has been applied since the measurement ofEötvös. —At Freiburg i. Br. (Western Germany) now a new torsion-balance is built, with which foreseeable the direct measurement of the gradientU _zzs will be possible. In the following publication will be demonstrated, that the fixation of differences between the vertical lines of two points of the gravity field of the earth is possible with this gradientU _zzs without astronomic and geodetic measurements.

     

Registrierungen der langwelligen Gegenstrahlung in Frankfurt

Zusammenfassung Es wird über Registrierungen der langwelligen Gegenstrahlung berichtet, die von März bis Oktober 1953 tags und nachts in Frankfurt durchgeführt wurden. Bei der Bearbeitung des Materials wurden erstmalig die gemessenen stündlichen Summenwerte und keine Einzelwerte zugrundegelegt, wodurch die hier gefundenen Beziehungen für Berechnungen der Gegenstrahlung grössere Allgemeingültigkeit haben. Die langwellige Strahlung ist fast doppelt so gross wie die kurzwellige Sonnen- und Himmelsstrahlung auf die Horizontalfläche. Die gemessenen Werte der Gegenstrahlung stimmen im grossen Mittel mit den nach derFeussner-schen Formel berechneten gut überein, doch sind die einzelnen Abweichungen davon sehr gross. Wie schon von anderen Autoren wurde auch hier festgestellt, dass die Gegenstrahlung mit zunehmender Bewölkung quadratisch zunimmt, allein bei tiefer Bewölkung ist tagsüber ein annähernd linearer Zusammenhang vorhanden. Negative Effektivstrahlung ist weit häufiger, als bisher angenommen, jedoch kommt sie fast nur in den Vormittagsstunden vor. Bei dichter niedriger Bewölkung ist der Wärmestrom nach Sonnenaufgang daher von oben nach unten gerichtet. Die Gegenstrahlung lässt sich hinreichend gut berechnen, wenn man dieFeussnersche Formel, Mittelwerte der Temperatur, des Dampfdruckes, der Bewölkungsstärke und die hier gefundene Bewölkungs-Beziehung zugrundelegt.

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Summary From March to Oct. 1953, the atmospheric long wave radiation has been recorded in Frankfurt during day and night time. For evaluating the records, no instantaneous values were taken, but the hourly sums, so that the relations found can more generally be used for computations. The atmospheric long wave radiation is almoust twice as strong as the short wave radiation from sun and sky on a horizontal plane. The mean measured values of the atmospheric long wave radiation coincide well with theFeussners formula. However, the deviations of the single values are very large. Confirming the results of other authors, it has been found that the atmospheric long wave radiation increases with the second power of the cloudiness, only with low clouds in daytime the increase is approximatly linear. Negative values of the effektive radiation occurs more frequently than expected uptil to day, but only in the time before noon. So with a dense low cloud cover the flow of heat after sunrise is directed downward. The atmospheric long wave radiation may satisfactorily be computed, ifFeussners formula, mean values of temperature, vapour pressure, cloudiness, and the mentioned cloudiness relation are taken.

     

Cyclic organochlorines in North Sea sediments,relation with size and organic matter

Summary The geographical distribution of organic matter and particles <20 m in North Sea sediments as well as the correlation between organic content, <20 m fraction and PCB (as the sum of content of 24 individual components), p, p-DDE, HCB, -HCH and Lindane (-HCH) is reported. High amounts of organic matter and fine particles have been found in Fladen Ground, Kattegat/Skagerrak/Norwegian Channel, and the inner German Bight. Organic matter settling in the Kattegat/Skagerrak/Norwegian Channel is probably degraded by benthic organisms, including mineralization by bacteria. The smelter in south Norway and the rivers Ems and Elbe are point sources for HCB, the mud-area south-east of Helgoland is a point source for HCB and PCBs. No point source, however, was found for p,p-DDE. Sediment content of PCB, p,p-DDE and HCB show a good correlation to the amount of organic matter and to the <20 m fraction. -HCH and Lindane are only poorly adsorbed onto sediments.

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Zyklische organische Chlorverbindungen in Nordseesedimenten: Verteilung von organischer Substanz und feinpartikulärem Material

Zusammenfassung Es wird über die Verteilung von organischer Substanz und feinpartikulärem Material <20 m in Nordseesedimenten sowie über die Korrelation der Sedimentparameter mit den Konzentrationen von polychlorierten Biphenylen (24 Einzelisomere), p,p-DDE, HCB, -HCH und Lindan (-HCH) berichtet. Hohe Gehalte an organischer Substanz und der <20 m Fraktion wurden im Fladengrund, Kattegat/ Skagerrak/Norwegische Rinne sowie in der inneren Deutschen Bucht gefunden. Die Ergebnisse legen den Schluß nahe, daß ein Großteil des sedimentierten organischen Materials vor der norwegischen Küste von Benthosorganismen und Bakterien verstoffwechselt wird. Durch die mit Søderbergelektroden arbeitenden Metallschmelzen Südnorwegens sowie durch die Flüsse Elbe und Ems werden die Sedimente punktuell mit HCB belastet. Das Schlammgebiet südöstlich von Helgoland tritt als Emittent für PCBs in Erscheinung. Für p,p-DDE konnte keine Punktquelle nachgewiesen werden. Im Gegensatz zu -HCH und Lindan korrelieren die Sedimentkonzentrationen an PCBs, HCB und p,p-DDE gut mit den Gehalten an organischer Substanz bzw. feinpartikulärem Material.

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Les Organochlorines cycliques dans les Sédiments de la Mer du Nord, relation avec la taille et les matières organiques

Résumé La distribution géographique de matière organique et des particules de taille inférieure à 20 m dans les sédiments de la Mer du Nord ainsi que la corrélation entre le contenu organique, (la fraction <20 m) et PCB (somme des contenus de 24 composants individuels), p, p-DDE, HCB, -HCH et Lindane (-HCH) est décrite. D'importantes quantités de matières organiques et de particules fines ont été trouvées à Fladen Ground, Kattegat/Skagerrak/Norwegian Channel et dans le baie intérieur allemende. Les composants organiques qui se trouvent dans le Kattegat/ Skagerrak/Norwegian Channel sont probablement soumis à la dégradation par des organismes (benthic), et aussi à une minéralisation par bactéries. Les usines de métallurgie du Sud de la Norvège et la rivière l'Ems et l'Elbe sont des points sources pour HCB, les zones de boue au Sud Est de Helgoland sont des points sources pour HCB et PCB. Aucun point source ne fût trouvé cependant pour p, p-DDE. Le contenu en sédiment de PCB, p, p-DDE et HCB montre une bonne corrélation avec la quantité de matière organique et la fraction <20 m. -HCH et Lindane ne sont que peu absorbés dans les sédiments.