Vergleichende Betrachtungen zur Talausbildung Schwedischer und hessischer Flüsse

Ohne ZusammenfassungTitularbeitrag.     

Turbulence in a Katabatic Flow

Turbulence measurements performed in a stable boundary layer over the sloping ice surface of the Vatnajökull in Iceland are described. The boundary layer, in which katabatic forces are stronger than the large-scale forces, has a structure that closely resembles that of a stable boundary layer overlying a flat land surface, although there are some important differences. In order to compare the two situations the set-up of the instruments on an ice cap in Iceland was reproduced on a flat grass surface at Cabauw, the Netherlands. Wind speed and temperature gradients were calculated and combined with flux measurements made with a sonic anemometer in order to obtain the local stability functions _m and _h as a function of the local stability parameter z/L. Unlike the situation at Cabauw, where _m was linear as a function of z/L, in the katabatically forced boundary layer, the dependence of _m on stability was found to be non-linear and related to the height of the wind maximum. Thermal stratification and the depth of the stable boundary layer however seem to be rather similar under these two different forcing conditions.Furthermore, measurements on the ice were used to construct the energy balance. These showed good agreement between observed melt and components contributing to the energy balance: net radiation (supplying 55% of the energy), sensible heat flux (30%) and latent heat flux (15%).Local sources and sinks in the turbulent kinetic energy budget are summed and indicate a reasonable balance in near-neutral conditions but not in more stable situations. The standard deviation of the velocity fluctuations _u, _v, and _w, can be scaled satisfactorily with the local friction velocity u_* and the standard deviation of the temperature fluctuation with the local temperature scale _*.     

Comparison of metal homogeneity in grab,quartered, and crushed — sieved portions of stream sediments and metal content change resulting from crushing — sieving activity

Restricted grain size sediment samples were collected along two streams. Metal content in some samples may have been influenced by landfill emissions. Each sample was divided into a grab portion, a quartered portion, and a portion crushed and sieved to a smaller size and then quartered. A duplicate sample from each of these portions was extracted. The Cu, Pb, Zn, Co, Ba, Fe, Mn, and Ca quantities were determined for each duplicate sample. Relative standard deviation was used to reflect homogeneity of metal content. Metal occurrence represented speciated metals or major components of chemical phases. Results indicated that variation of metal content among portions was uniform and did not vary as a function of absolute metal quantity. Homogeneity was similar in the same size grab and quartered samples. A more homogeneous metal state was displayed by the crushed and sieved sediments. However, this activity enriched softer chemical phases and associated speciated metals. It was concluded that sediments need not be quartered to obtain a better homogeneity of metal distribution and that field samples should not be crushed and sieved prior to chemical analyses. Assessment of sediments affected by metal emission sources must include a knowledge of metal homogeneity in individual samples.     

Petrogenesis of some Ligurian peridotites—I. Mineral and bulk-rock chemistry

Bulk-rock and mineral compositions of eleven lherzolitic specimens have been determined. Eight samples are from the Erro-Tobbio thrust sheet of the Gruppo di Voltri, western Liguria; three samples are from allochthonous eastern Ligurian masses within the External Ligurides. All specimens consist of spinel (±plagioclase) in addition to ol + opx + cpx, and have been derived from mantle portions of the South Alpine-Apennine lithospheric plate.Electron microprobe analyses of 11 olivines, 17 orthopyroxenes, 13 clinopyroxenes, eight spinels and one plagioclase have been performed. Except for Ca-rich and Ca-poor lamellae in some pyroxenes, and iron-enriched rims in a few spinels, the analyzed phases are remarkably homogeneous. Mineral compositions vary insignificantly from rock to rock. Consideration of major element partitioning in coexisting opx + cpx pairs, combined with the petrogenetic grid for aluminous lherzolite bulk compositions, yield the following provisional P-Tequilibration conditions: Erro-Tobbio complex, 1150 ± 50°C, 16 ± 6 kbar; External Ligurides, 1000 ± 50°C, 14 ± 6 kbar. Evidently the western Ligurian peridotites equilibrated at higher temperatures and possibly at slightly greater depths with the upper mantle than those from eastern Liguria.The lherzolite samples have nearly identical bulk-rock major element compositions. Comparisons with estimated compositions for the upper mantle, and for model pyrolite indicate that these Ligurian peridotites are primitive or only very slightly depleted in basaltic constituents. Thus, based on major element chemistry, the Ligurian peridotites cannot be regarded as residua left after extensive partial fusion, hence evidently cannot have produced large proportions of oceanic tholeiite liquid; on the other hand, they seem to represent a fertile mantle source for such melts.Relics of garnet have not been found, and apparent temperatures for both Erro-Tobbio and eastern Ligurian ultramafic suites exceed the classical intraplate oceanic geotherm; accordingly, these bodies may represent rising mantle material that recrystallized during ascent in the general vicinity of a spreading center, without having undergone extensive partial melting.     

Neue Bücher und Zeitschriften

Ohne ZusammenfassungDie Transkription der Autorennamen und der geographischen Namen erfolgte nach den Richtlinien der Zentralstelle für wissenschaftliche Literatur, Berlin NW 7, vom 7. Dezember 1955.     

Die Bedeutung der Kondensationskerne in der hygienischen Forschung

Zusammenfassung Eine erschöpfende Beurteilung des Verunreinigungsgrades der Luft ist nur auf Grund von Registrierungen der wichtigsten gasförmigen und korpuskulärne Beimengungen möglich. Eine grobe Aussage wird in vielen Fällen bereits auf Grund gleichzeitiger Messungen des Kern- und Staubgehalts der Luft gemacht werden können.Eine Aussage über die schädigende bzw. belästigende Wirkung einer Luftheimengung nur auf Grund einer Kernzahlbestimmung, wird nur in wenigen besonderen Fällen möglich sein. Als Beispiel sei angeführt, daß bei der Verunreinigung der Luft mit Tabakrauch die Kernzahl ein grobes Maß für den Nikotingehalt und die Kernzahl in Verbindung mit der Staubzahl ein Maß für den Gehalt der Luft an Tabakteeren darstellt.Auf Grund eigener Untersuchungen und den bisher in der Literatur veröffentlichten Meßergebnissen werden maximale Mittelwerte für den Kern- und Staubgehalt der Luft für verschiedene Orte angegeben. Somit wird es den Gesundheitsämtern möglich sein, durch einfache Kern- und Staubmessungen den geforderten Reinheitsgrad der Luft zu kontrollieren. Eine Vorraussetzung hierfür ist die Schaffung einheitlicher, leicht transportabler und einfach zu bedienender Meßgeräte.

---

Summary An exhaustive assessment of the degree of contamination of the air is possible only from records of its most important gaseous and corpuscular admixtures. A rough assessment will be possible in many cases by using simultaneous measurements of the nuclei and dust content of the air.A statement on the injurious or annoying effect of an air admixture based only on the determination of the number of nuclei will be possible only in few special cases. As an example may be mentioned that with the contamination of the air due to tobacco smoke the number of nuclei represents a rough measure of the nicotine content and the number of nuclei together with the number of dust particles is a measure of the content of the tobaceo tars in the air.Based on personal investigations and on the results of measurements so far published highest averages of the nucleus and dust content of the air for various places are given. Thus, it will be possible for the health authorities by means of simple measurements of nuclei and dust concentration to check the prescribed purity of the air. A condition for this is the design of uniform measuring instruments which are very portable and simple to operate.