Observations of the countercurrent on the inshore side of the Kuroshio northeast of Taiwan

Intensive current measurements in the area northeast of Taiwan indicate subsurface, southwestward flow existed between the inshore edge of the Kuroshio and the East China Sea continental slope. At 70 km away from Taiwan, this countercurrent has a mean speed about 30 cm s^–1 at mid-depth. Closer to Taiwan, the flow turns along with the topography, and subjects to sidewall and bottom friction. Both the magnitude and the vertical shear of this countercurrent are comparable with that inferred from hydrographic survey. The wind field features short-period (a few days) fluctuations associated with the cold front passages, however, this is not reflected on the current records. It appears that the countercurrent is fairly steady. Together with similar reversing flow found at places much further to the north, the overall pattern seems to be a general quasi-steady feature along most part of the shelf edge of the East China Sea.     

Effects of presence of a circumpolar region on buoyancy-driven circulation

Effects of the presence of a circumpolar region on buoyancy-driven circulation are investigated by using an idealized numerical ocean model. Comparison of circulation and meridional density (heat) transport is made between a closed ocean and an ocean with a cyclic gap near its southern boundary. The presence of the circumpolar region leads to disconnection of the meridional overturning across the circumpolar region. And the circumpolar eastward flow reaches the bottom of the ocean. It is essential for this that the pycnocline is deeper than the bottom of the gap. Since the amount of the mass transported northward must return southward at the levels deeper than the bottom of the cyclic gap, the weak stratification, hence weak vertical geostrophic shear, at the deeper levels leads to inactive communication across the circumpolar region. Meridional heat transport across the circumpolar region is made mainly by horizontal diffusion for the ocean with the cyclic gap, while the contribution of the advection is dominant for the closed ocean. Sensitivity of meridional heat transport to change in horizontal diffusivity is studied. The meridional heat transport for the ocean with the cyclic gap is more sensitive than for the closed ocean. The change in heat transport occurs not only in the circumpolar region but also in the rest of the ocean. It is suggested that subgrid scale phenomena, especially mesoscale eddies, in the circumpolar region controls the whole ocean to a great extent.     

Experimental Studies of Aerosols in the Atmosphere of Semiarid Landscapes of Kalmykia: 1. Microphysical Parameters and Mass Concentration of Aerosol Particles

Izvestiya, Atmospheric and Oceanic Physics - This paper summarizes the results of long-term (2004–2016) comprehensive experimental studies of microphysical parameters and the mass...     

Natural attenuation, biostimulation and bioaugmentation on biodegradation of polycyclic aromatic hydrocarbons (PAHs) in mangrove sediments

The biodegradability of a mixture of PAHs, namely fluorene (Fl), phenanthrene (Phe) and pyrene (Pyr), in mangrove sediment slurry was investigated. At the end of week 4, natural attenuation based on the presence of autochthonous microorganisms degraded more than 99% Fl and Phe but only around 30% of Pyr were degraded. Biostimulation with addition of mineral salt medium degraded over 97% of all three PAHs, showing that nutrient amendment could enhance Pyr degradation. Bioaugmentation with inoculation of a PAH-degrading bacterial consortium enriched from mangrove sediments did not show any promotion effect and the degradation percentages of three PAHs were similar to that by natural attenuation. Some inhibitory effect was observed in bioaugmentation treatment in week 1 with only 50% Fl and 70% Phe degraded. These results indicate that autochthonous microbes may interact and even compete with the enriched consortium during PAH biodegradation. Natural attenuation appeared to be the most appropriate way to remedy Fl- and Phe-contaminated mangrove sediments while biostimulation was more capable to degrade Pyr-contaminated sediments. The study also shows that although a large portion of the added PAHs (more than 95%) was adsorbed onto the sediments at the beginning of the experiment, most PAHs were degraded in 4 weeks, suggesting that the degraders could utilize the adsorbed PAHs efficiently.     

Paléo-bactéries et minéralisations plombo-zincifères du Bled Zelfane (tunisie centrale)

Résumé Le Bled Zelfane est un synclinal mio-pliocène sur la bordure septentriono-orientale de l'ile de Kasserine. L'ile de Kasserine est une plate-forme devenue insulaire à partir du Crétacé supérieur et restée émergée jusqu'au Miocène moyen. Ce môle a été soumis apparemment pendant sa période continentale à un climat oxydant de type méditerranéen relativement sec. On note une certaine diversification dans la nature des dépôts en zones basses (secteur de Kasserine) et en zones hautes (secteur du Bled Zelfane). En zones basses, la sécheresse climatique a favorisé la formation de dépôts de gypse, d'argiles rouges et de calcrêtes. En zones hautes, une érosion par lessivage acide a créé des dépressions karstiques dans les calcaires du Crétacé supérieur (Aïn Khamouda) et dans les calcaires du Maëstrichtien (Sidi Mabrouk et Guémata). Le remplissage des cavités karstiques (poches, crevasses) s'est fait avec de l'argile blanche (halloysite), contenant des micro-cristaux de galène, avec de la calamine et des oxydes de fer. Les conditions climatiques étaient trop oxydantes pour que le zinc se dépose autrement que sous forme de calamine. Elles expliquent aussi la présence de paléo-algobactéries (aérobies) sur la calamine. La présence de micro-cristaux de galène dans l'halloysite serait liée à un sulfuretum et non à des conditions réductrices réelles. Il semble en effet que dans ces karsts du Bled Zelfane une flore bactérienne très riche a joué un rôle essentiel dans le piégeage d'éléments lourds et notamment dans la genèse de galènes supergènes et dans la cristallisation de la calamine. Une minéralisation, elle aussi plombo-zincifère, de type stratiforme, s'observe à la base de Miocène inférieur et montre de même des bactéries fossiles à foison.

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Bled Zelfane is a Mio-Pliocene syncline on the NE edge of the palaeo-island of Kasserine, a platform which became insular at the beginning of the Upper Cretaceous and remained emergent until the Middle Miocene. During its long emergence this platform was affected by an oxidising, relatively dry, Mediterranaean-type climate. There exists a certain diversity in the sedimentary accumulations in both the lower (Kasserine area) and upper (Bled Zelfane area) sectors of this palaeo-relief. In the lower sectors the dry climate has favourised gypsum, red clays and calcrete formation. In the higher sectors erosion and leaching by acid waters has created karstic depressions in the Upper Cretaceous (Aïn Khamouda) and in the limestones of Maestrichtian (Sidi Mabrouk and Guémata). The karst cavities (pockets and fissures) are filled with white, halloysite clays containing micro-crystals of galena associated with calamine (Zn) and iron oxides. The climatic conditions were too oxidising to permit the formation of Zn other than in the form of calamine. The dry climate is also an explanation for the presence of aerobic palaeo-algobacteria on this calamine. The presence of micro-crystals of galena within the halloysite is probably related to a sulfuretum and not to effective reducing conditions. It would seem that the presence of a rich bacterial flora within the karst at Bled Zelfane has played a significant role in the stabilisation of heavy elements, and especially the supergene genesis of the galena. A Lead/Zinc mineralisation also exists at the base of the Miocene. This latter is diffused through the cement in conglomerates and sandstones.

     

Fatigue-Damage Evolution Characteristics of Interbeded Marble Subjected to Dynamic Uniaxial Cyclic Loads

In this work, uniaxial fatigue tests combined with post-test X-ray computed tomography (CT) scanning were conducted on marble samples with different interbed orientations, in order to reveal the anisotropic damage evolution characteristics during rock failure. The dynamic elastic modulus, damping ratio, fatigue deformation, damage evolution, accumulative damage modeling and crack pattern were systematically analyzed. The testing results indicate that the interbed structure in marble affects the damage evolution and the associated dynamic mechanical behaviors. The damage curve in “S” style indicates three-stage trend, namely, initial damage stage, steady damage stage and the accelerated damage stage. The damage index during cyclic deformation for marble presents obvious discrepancy. In addition, a fatigue damage prediction models was employed numerically as double-term power equations based on the experimental data. It is found that the selected damage model is suitable in modeling the rapid damage growth in the early and final stage of rock fatigue lifetime. Moreover, post-test CT scanning further reveals the anisotropic damage characteristics of marble, the crack pattern in the fractured sample is controlled by the interbed structure. What is more, the most striking founding is that the fracture degree is in consistent with the damage accumulation within the steady damage stage. Through a series of damage mechanical behavior analysis, the internal mechanism of the effect of interbed orientation on damage evolution of marble is firstly documented.

     

Elemental abundance analyses with DAO spectrograms. XXVIII. Comparisons with two series of automated elemental abundance analyses

We compare the results of our series of fine analyses based on Dominion Astrophysical Observatory long camera coudé spectra with those of the same stars from the series of automated elemental abundance analyses by Hill (1995) and by Erspamer and North (2003). We usually find good agreement with the results of the first paper for those elements with well-determined abundances and somewhat poorer agreement with results of the second paper.     

THE WASHOUGAL METEORITE

The Washougal, Washington, U.S.A., howardite fell in 1939. We studied its mineralogy optically and determined the ranges of composition of plagioclase and pyroxenes from measurements of densities and indices of refraction. Notable among many unique xenoliths are a round object whose morphology is that of an armored chondrule; a stratified fragment; and a centimeter-sized dunite xenolith (olivine Fa_12.8). The abundances of 27 elements, including all major elements and 15 trace elements (Sc, V, Co, Ni, Cu, Ga, Sr, Y, Ba, La, Sm, Eu, Yb, Lu and Hf) are reported. To a first approximation, the composition of Washougal corresponds to a mixture of 51 weight percent of eucritic material and 49 percent of a diogenitic component, but excesses of some elements suggest a minor component of chondritic composition     

Infrared–red cores in nearby elliptical galaxies

We present the Spitzer Space Telescope Infrared Array Camera observations for a sample of local elliptical galaxies to study later stages of active galactic nucleus (AGN) activity. A sample of 36 elliptical galaxies is selected from the Palomar spectroscopic survey. We detect nuclear non-stellar infrared emission in nine of them. There is unambiguous evidence of circumnuclear dust in these nine galaxies in their optical images. We also find a remarkable correlation between the infrared excess emission and the nuclear radio/X-ray emission, suggesting that infrared excess emission is tightly related to nuclear activity. The possible origin of infrared excess emission from hot dust heated by the central AGN is supported by the spectral indices of the infrared excess emission.