Archaeal Communities of Frozen Quaternary Sediments of Marine Origin on the Coast of Western Spitsbergen

Izvestiya, Atmospheric and Oceanic Physics - The archaeal composition of permafrost samples taken during the drilling of frozen marine sediments in the area of the Barentsburg coal mine on the east...     

Horizontal and vertical zones of influence for root systems of four Mojave Desert shrubs

Horizontal and vertical zones of influence for root systems of four Mojave Desert shrubs were characterized using ³²P as a nutrient tracer. Larrea tridentata's horizontal zone of influence was sparse near the plant's stem base, with a maximum probability of accessing ³²P (P_max) of 41%. However, its horizontal zone of influence extended beyond 5 m, and the distance from the stem base at which the probability of accessing ³²P was half P_max (L₅₀3 m) was significantly greater than the other three shrubs. Ambrosia dumosa's zone of influence was dense near the plant's stem base (P_max78%), but was rare at distances >2 m (L₅₀1 m). Zones of influence for Lycium andersonii and Lycium pallidum were intermediate between those of L. tridentata and A. dumosa. For vertical zones of influence, L. tridentata was more likely to obtain ³²P from 5 m soil depths than A. dumosa, but L. pallidum was not significantly different from either A. dumosa or L. tridentata. Horizontal zones of influence did not change with treatments that altered soil water and nitrogen availability, but vertical zones of influence increased with a flood irrigation treatment that increased water availability to 5 m soil depth. These differences among species likely reflect compromises between their shoot growth strategies and their need to acquire spatially and temporally limited soil resources, especially through competitive interactions.     

Influence of wind upon water quality in Liverpool Bay

Comprehensive distribution patterns of physical and chemical characteristics have been obtained from a series of cruises in Liverpool Bay. The marked feature of these distributions was their temporal variability, suggesting that the surface residual circulation is also temporally variable. The influence of wind stress upon the circulation pattern and hence water quality of this sea area is illustrated.     

A regional model for studies of atmosphere-ice-ocean interaction in the western Arctic

Summary Asa step in the development of a fully coupled regional model of the atmosphere-ice-ocean system, atmospheric and sea ice models have been adapted to a western Arctic domain centered on the Bering Strait. Lateral boundary conditions derived from operational analyses drive the models through simulations on grids having horizontal resolutions of 21 km and 7 km. Sensitivities to the presence of sea ice are large after only 48 hours, by which time the surface temperatures in the Bering and Chukchi Seas are 10–15°C higher without sea ice than with sea ice. The temperatures, in turn, modify the fields of sea level pressure, surface wind and precipitation. By influencing the surface wind stress through the static static stability, the surface state feeds back to the surface momentum exchange, ice/ocean transport, and the rate of formation of new ice. The results also show a resolution-dependence of the surface winds, precipitation rates and new ice formation rates, particularly in areas in which the coastal configuration and topography are spatially complex. The experiments will be augmented by the implementation of an ocean model on the same grids.With 12 Figures     

Developing a modern pollen–climate calibration data set for Norway

Bjune, A. E., Birks, H. J. B., Peglar, S. M. & Odland, A. 2010: Developing a modern pollen–climate calibration data set for Norway. Boreas, Vol. 39, pp. 674–688. 10.1111/j.1502‐3885.2010.00158.x. ISSN 0300‐9483. Modern pollen–climate data sets consisting of modern pollen assemblages and modern climate data (mean July temperature and mean annual precipitation) have been developed for Norway based on 191 lakes and 321 lakes. The original 191‐lake data set was designed to optimize the distribution of the lakes sampled along the mean July temperature gradient, thereby fulfilling one of the most critical assumptions of weighted‐averaging regression and calibration and its relative, weighted‐averaging partial least‐squares regression. A further 130 surface samples of comparable taphonomy, taxonomic detail and analyst became available as a result of other projects. These 130 samples, all from new lakes, were added to the 191‐lake data set to create the 321‐lake data set. The collection and construction of these data sets are outlined. Numerical analyses involving generalized linear modelling, constrained ordination techniques, weighted‐averaging partial least‐squares regression, and two different cross‐validation procedures are used to asses the effects of increasing the size of the calibration data set from 191 to 321 lakes. The two data sets are used to reconstruct mean July temperature and mean annual precipitation for a Holocene site in northwest Norway and a Lateglacial site in west‐central Norway. Overall, little is to be gained by increasing the modern data set beyond about 200 lakes in terms of modern model performance statistics, but the down‐core reconstructions show less between‐sample variability and are thus potentially more plausible and realistic when based on the 321‐lake data set.     

Beitrag zur quantitativen Analyse von Mineralphasen mittels Röntgendiffraktion

Zusammenfassung Bei der Durchführung quantitativer Gemenge-Analysen mit Hilfe der Röntgendiffraktionsmethode kann man den Massenschwächungskoeffizienten (^*) verwenden, den man bei der Röntgenfluoreszenzanalyse Röhrenhauptlinienverfahren vonSchroll-Stepon erhalten hat. Er wird von der Wellenlänge der Röntgenfluoreszenzstreustrahlung auf die Wellenlänge der Diffraktionsröhre transformiert. Ein Intensitäts-Konzentrationsdiagramm, in dem die Intensität der gewählten Diffraktionslinie durch das Produkt von Intensität und dem jeweiligen Wert von ^* ersetzt wird, ergibt eine allgemeingültige Eichgerade. Als Beispiel werden Messungen an Zweistoffsystemen wie Magnesit-Quarz, Albit-Quarz, Calcit-Quarz, Stilpnomelan-Quarz und Siderit-Quarz angeführt.Die vorgeschlagene Methode ist für kombinierte Diffraktions- und Röntgenfluoreszenzanalysen sehr zweckmäßig.

---

Summary Applicating the quantitative X-ray-diffraction-analysis für mixtures of minerals the use of the mass absorption coefficient (^*) is possible, which is received by the X-ray-fluorescence-analysis of the same sample following the method proposed by the authors. The mass absorption coefficients must be transformed to the new wave length of the X-ray-diffraction tube. In the intensity-concentration-diagram the intensity is substituted by the product of intensity and mass absorption coefficient. An uniform standard line is received, as the measurement of quartz shows in the systems of two-substances, such as magnesite-quartz, albite-quartz, calcite-quartz, stilpnomelan-quartz and siderite-quartz.The proposed method is very useful for the combined X-ray-diffraction and X-ray fluorescence analysis.

---

---

Mit 6 Textabbildungen     

Linear and planar structure in ordered multivariate data as applied to progressive demagnetization of palaeomagnetic remanence

Summary. Consider a sequence of, say, 10 to 20 vector observations in three-dimensional space. It is suspected that a few subsets of consecutive observations are made up of collinear points. The purpose of this paper is to construct a statistically based algorithm to find such linear segments and to assess their accuracy. A similar assessment is made for coplanar sets of points.
This algorithm is applied here to palaeomagnetic data and is claimed to be superior to previous methods of palaeomagnetic analysis in terms of completeness and balance of analysis, treatment of measurement errors and other sources of scatter, criteria for identification of linear and planar sets of points, and statistical rigour. Stability spectra, with statistically based confidence limits, are obtained as a by-product.     

Schorlomite: a discussion of the crystal chemistry, formula, and inter-species boundaries

Examination of schorlomite from ijolite at Magnet Cove (USA) and silicocarbonatite at Afrikanda (Russia), using electron-microprobe and hydrogen analyses, X-ray diffraction and Mössbauer spectroscopy, shows the complexity of substitution mechanisms operating in Ti-rich garnets. These substitutions involve incorporation of Na in the eightfold-coordinated X site, Fe²⁺ and Mg in the octahedrally coordinated Y site, and Fe³⁺, Al and Fe²⁺ in the tetrahedrally coordinated Z site. Substitutions Ti⁴⁺Fe³⁺Fe³⁺_–1Si_–1 and Ti⁴⁺Al³⁺Fe³⁺_–1Si_–1 are of major significance to the crystal chemistry of schorlomite, whereas Fe²⁺ enters the Z site in relatively minor quantities (<3% Fe). There is no evidence (either structural or indirect, such as discrepancies between the measured and calculated Fe²⁺ contents) for the presence of ^[6]Ti³⁺ or ^[4]Ti⁴⁺ in schorlomite. The simplified general formula of schorlomite can be written as Ca₃Ti⁴⁺₂[Si_3-x(Fe³⁺,Al,Fe²⁺)_xO₁₂], keeping in mind that the notion of end-member composition is inapplicable to this mineral. In the published analyses of schorlomite with low to moderate Zr contents, x ranges from 0.6 to 1.0, i.e. Ti⁴⁺ in the Y site is <2 and accompanied by appreciable amounts of lower-charged cations (in particular, Fe³⁺, Fe²⁺ and Mg). For classification purposes, the mole percentage of schorlomite can be determined as the amount of ^[6]Ti⁴⁺, balanced by substitutions in the Z site, relative to the total occupancy in the Y site: (^[6]Ti⁴⁺–^[6]Fe²⁺–^[6]Mg²⁺– ^[8]Na⁺)/2. In addition to the predominant schorlomite component, the crystals examined in this work contain significant (>15 mol.%) proportions of andradite (Ca₃Fe³⁺₂Si₃O₁₂), morimotoite (Ca₃Fe²⁺TiSi₃O₁₂), and Ca₃MgTiSi₃O₁₂. The importance of accurate quantitative determination and assignment of Fe, Ti and other cations to the crystallographic sites for petrogenetic studies is discussed.

Ableitung der Magnitudengleichung für die Erdbebenstationen Wien und Graz und allgemeine Bemerkungen zur Magnitudenberechnung

Zusammenfassung Nach einer knappen Einführung in die Magnitudenberechnung wird über die Ableitung der Stationsgleichungen für Wien (12) und Graz (13) berichtet. Den Berechnungen lagen 158, bzw. 121 Erdbeben normaler Herdtiefe und von der GrößeM7,0 zugrunde. Für beide Stationskonstanten wurde der gleiche WertC=+0,15 gefunden. Die Tabelle 2 enthält 94 von beiden Stationen registrierte Erdbeben mit Angabe der UnterschiededM (=D) von Wien und Graz gegenüber denM-Werten von Pasadena.Verschiedene Schwierigkeiten, die bei der Aufstellung der maximalen Horizontalamplitude auftauchen können, werden besprochen und an Hand eines Beispieles (Tabelle 3) dargelegt. Ferner wird angedeutet, daß das letzte GliedD der Magnitudengleichung definitionsmäßig überlastet ist und daß eine Aufteilung nach den wirklich individuellen Eigenschaften und den Gruppeneigenschaften des Einzelbebens notwendig wäre. Alle Erdbeben aus einer bestimmten Region tragen gemeinsame Merkmale, jedes einzelne hat dazu einen eigenen Habitus.

---

Summary After a short introduction into the computation of magnitude we show the derivation of the respective equations for Vienna (12) and Graz (13). The basis of the computations were 158, 121 respectively, teleseisms of normal depth of focus and of the magnitudeM7.0. The same value was found for both station constants, namelyC=+0.15. Table 2 contains 94 earthquakes recorded at both stations, showing the differencesdM (=D) of Vienna and Graz, in comparison with theM-values of Pasadena.Various difficulties that can arise by establishing the total horizontal amplitude, are considered and discussed by means of an example (Table 3). Further we find that the last termD of the equation of magnitude is overcharged according to the definition, and that a separation according to the really individual qualities and to the group qualities of each earthquake would be necessary. All earthquakes from a certain area have specified qualities, and in addition each one shows a special behaviour of its own.

---

Résumé Après une introduction concise du calcul de magnitude on est informé sur les équations qui en dérivent et qui sont valables pour les stations de Vienne (12) et de Graz (13). Resp. 158 et 121 séismes d'une profondeur de foyer normale et de magnitudeM7.0 forment la base de ces calculs. Une valeur identiqueC=+0,15 a été trouvée comme constante des deux stations. Le tableau 2 contient 94 séismes, enregistrés par les deux stations, avec indication des différencesdM (=D) de Vienne et de Graz vis-à-vis des valeursM de Pasadena.Diverses difficultés qui peuvent surgir en établissant l'amplitude horizontale maximum, sont discutées et démontrées par un exemple (tableau 3). En outre on trouve que le dernier coefficientD de l'équation est «surchargé» selon la définition. Une distribution d'après les véritables qualités individuelles et d'après les qualités de groupe du séisme particulier serait nécessaire. Tous les séismes provenant d'une certaine région ont des propriétés communes, de plus chacun a son caractère particulier.

     

Principles of tabling

The mechanism of concentration on the shaking table is discussed and a fresh attempt is made to obtain the theoretical model describing the velocity of a fluid in depth and time when in contact with a symmetrically reciprocating surface.The significance of the many design and operational variables and their interrelationships are examined. The various areas where the shaking table plays its role are then considered.The relevant features of micropanner, superpanner and the subsequent macropanner and pulsepanner are also treated since they all, like the shaking table, have the differential motion in common.