Wind-Tunnel Experiment on Logarithmic-Layer Turbulence under the Influence of Overlying Detached Eddies

A wind-tunnel experiment was carried out to test a hypothesis that the turbulence characteristics in the near-neutral surface layer are largely determined by detached eddies from above. The surrogate detached eddies were generated by using an active turbulence grid installed at the front of the test section and the parameters of the grid were chosen such that the fully developed logarithmic layer downstream consists of a turbulent flow that has similar normalized intensity to that typically observed in the near-neutral atmospheric surface layer. The effects of the detached eddies on turbulence characteristics were investigated by comparison with a second experiment without detached eddies. The influence of the detached eddies on the logarithmic layer was mostly on the coherent structures; the logarithmic layer with the detached eddies revealed a multi-layer structure similar to that found in the atmosphere where the lower part of the surface layer is dominated by sweep-like events and the upper part by ejection-like events. Our experiments show that the mean velocity gradient and the Reynolds shear stress were, however, not affected significantly by the detached eddies and hence the eddy viscosity.     

Intelligent seismic isolation system using air bearings and earthquake early warning

Recently strong seismic waves or long period seismic waves have been observed in various earthquakes that occurred in Japan. As a result improvements of existing seismic isolation systems are deemed necessary. The present study proposed an intelligent seismic isolation system encompassing air bearings and earthquake early warning (EEW) system. Such system exhibits adequate isolation performance. The air bearings are isolation device that may render infinite the superstructure natural period by floating them, and the EEW is applied for a trigger of isolation. This paper illustrates the proposed system and discusses the experimental results of a test carried out with the system. Laboratory tests carried out in the present research demonstrate the effectiveness of the proposed base isolated systems and prove its efficacy in mitigating the effects of three-dimensional seismic waves. For example, the system suppressed the horizontal response acceleration of an isolation target to 38% of input acceleration.     

Compensatory response of the unicellular-calcifying alga <Emphasis Type="Italic">Emiliania huxleyi</Emphasis> (Coccolithophoridales,Haptophyta) to ocean acidification

Ocean acidification damages calcareous organisms, such as calcifying algae, foraminifera, corals, and shells. In this study, we made a device equipped with a Clark-type oxygen electrode and a pH-stat to examine how the most abundant calcifying phytoplankton, the coccolithophorid Emiliania huxleyi, responded to acidification and alkalization of the seawater medium. When E. huxleyi was incubated at pH 8.2, close to oceanic pH, the medium was alkalized during photosynthesis, and the alkalization rate [determined as μmol HCl added (mg Chl)⁻¹ h⁻¹] was identical to the activity of photosynthesis [determined as μmol O₂ evolved (mg Chl)⁻¹ h⁻¹]. When pH was maintained at 7.2 by the pH-stat, alkalization activity was stimulated and exceeded photosynthetic activity, resulting in an increase in the ratio of alkalization to photosynthesis (Alk/PS). On the other hand, no alkalization and photosynthesis were observed at pH 9.2. In contrast, acidification of seawater was observed in the dark because of the release of respiratory CO₂ from cells at pH 8.2–9.2, but not at pH 7.2. When orthophosphate was rapidly depleted within a day in the batch culture, intracellular calcification gradually increased, and both photosynthesis and alkalization decreased gradually. During the period the Alk/PS ratio also decreased gradually. These results indicate that E. huxleyi possesses an ability to compensate for the acidification of seawater when photosynthesis is more actively driven than respiration. These results suggest that the E. huxleyi cells may not be severely damaged by oceanic acidification during photosynthesis because of their homeostatic function to avoid negative effects on cellular activity. Finally, we concluded that E. huxleyi cells possess a buffering ability to reduce acidification effects when photosynthesis is actively driven.     

Monitoring system for environmental risk management of a landfill disposal site

A landfill disposal site can be described as “an artificial vessel” and must satisfy the following three demands (1) storage and disposal of waste; (2) protection of the environment; and (3) benefit for nearby residents by taking advantage of consequential effects. The concept of risk was effectively considered to emphasize the importance of monitoring systems in landfill disposal sites, especially to protect the environment. Because a part of the R&D was involved in creating a monitoring system for a landfill disposal site, the present development and future potential of a system which can detect the leakage of watershield sheets, was discussed.     

Zoned Calc-Alkaline Plutons in Northeastern Kamchatka,Russia: Implications for the crustal growth in magmatic arcs

Summary The Upper Cretaceous oceanic and island-arc terranes of Northeastern Kamchatka (Russia) are intruded by numerous ultramafic and mafic to intermediate plutons. Ultramafic plutons north of Epilchik Lake show a concentric structure: dunites in the core pass progressively outwards into wehrlites and pyroxenites and into gabbros along the rim which are occasionally phlogopite- and amphibole-bearing. Compositional layering and mineral orientations marked by spinel clusters in the dunites and by acicular amphiboles in the marginal gabbros are parallel to the contacts. The mafic to intermediate plutons studied in the Machevna area show similar concentric structure with a dioritic core and a gabbroic rim. Magmatic flow lines are near-vertical in the central part of the plutons. These internal structures and general geometry of the plutons suggest vertical magma intrusion into mega-tension gashes developed initially at a high angle to the subduction zone.Olivine, pyroxenes, and plagioclase have primitive compositions. Al-rich, highpressure amphiboles are followed by Al-poor, low-pressure hornblendes. A two stage model of pluton crystallization and emplacement is proposed: initial crystallization and seggregation at the Moho level below the intraoceanic island are (approximately 22–25 km depth) and final emplacement followed by partial recycling of primary ultramafic cumulates and solidification at upper crustal levels (approximately 8–10 km depth). Emplacement of the arc plutons was accompanied by epidote amphibolite-facies contact metamorphism of host volcanic and pyroclastic rocks.Major- and trace-element analyses of plutonic rocks indicate calc-alkaline affinities and emplacement in a primitive arc setting. The tectonic setting, age, and emplacement structures suggest that these plutons mark the change of geodynamic conditions from arc-related compression to local extension probably related to the initial stages of opening of the proto-Komandorsky basin. A two stage model for the crustal growth in magmatic arcs is proposed based on northeastern Kamchatka plutons. During stage I, primitive basaltic melts were emplaced along the crust-mantle boundary below the arc. Continuous fractionation and accumulation of olivine-rich cumulate rocks at the base of the growing island-arc crust resulted in production of evolved melt which was further emplaced in the upper arc crust. Crystal fractionation of a shallow, stage II magmatic reservoir below the active arc volcanoes resulted in formation of a significant amount of plutonic rocks and eruption of mafic to intermediate calc-alkaline lavas at the surface.

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Zonierte kalk-alkalische Plutone im nardöstlichen Kamchatka, Russland: Hinweise auf Krusten Wachstum inmagmatischen Bögen

Zusammenfassung Zahlreiche ultramafische, Bowie mafische bis intermediäre Plutone intrudieren die oberkretazischen ozeanischen und Inselbogen-Terrains in Nordost-Kamchatka (Russland). Ultramafische Plutone nördlich des Epilchik Lake zeigen eine konzentrische Struktur: Dunite im Kern gehen graduell in Wehrlite und Pyroxenite, und schließlich am Rand in Gabbros über, die gelegentlich Phlogopit und Amphibol führen. Lagenbau und Orientierung von Mineralkörnern sind durch Spinell-Kluster in den Duniten und durch nadelige Amphibole in den randlichen Gabbros gekennzeichnet und liegen parallel zu den Kontakten. Die mafischen bis intermediären Plutone in dem Machevna-Gebiet zeigen ähnliche konzentrische Strukturen mit einem dioritischen Kern und einem gabbroischen Rand. Magmatische Flußlinien Bind fast vertikal in den zentralen Teilen der Plutone. Diese internen Strukturen und die allgemeine Geometrie der Plutone legen es nahe, daß es sich hier um vertikale Magmen-Intrusion in Mega-Strukturen handelt, die sich ursprünglich in einem hohen Winkel zur Subduktionszone gebildet haben.Olivine, Pyroxene und Plagioklase haben primitive Zusammensetzungen. Auf Alreiche Hochdruck-Amphibole folgen Al-arme Tiefdruck-Hornblenden. Ein Modell, das zwei Stadien der Pluton-Kristallisation und Platznahme vorsieht, wird vorgeschlagen: Ursprüngliche Kristallisation und Segregation im Moho-Niveau zwischen dem intraozeanischen Inselbogen (ungefähr 22–25 km Tiefe) und schließliche Platznahme gefolgt von teilweise Recycling primärer ultramafischer Kumulate und Verfestigung in oberen Krustenniveaus (ungefähr 8–10 km Tiefe). Die Platznahme der Bogen-Plutone war von Epidot-Amphibolit-Fazies Kontaktmetamorphose der intrudierten Vulkanite und Pyroklastite begleitet.Haupt- und Spurenelement-Analysen der plutonischen Gesteine weisen auf kalkalkalischen Charakter und eine Platznahme in einem primitiven Insenbogensetting hin. Die tektonische Situation, das Alter und die Strukturen der Platznahme lassen erkennen, daß these Plutone den Wechsel in geodynamischen Bedingungen von Inselbogenbezogener Kompression zu lokaler Extension repräsentieren, Vorgänge die mit den initialen Stadien der Öffnung des proto-Komandorsky Beckens zusammenhängen. Auf der Basis der Plutone des nordöstlichen Kamchatka wird ein Modell des Krustenwachstums in magmatischen Bögen vorgeschlagen, das auf zwei Stadien beruht. Während des ersten Stadiums werden primitive basaltische Schmelzen längs der Kruste-MantelGrenze unter dem Bogen intrudiert. Andauernde Fraktionicrung und Akkumulation Olivin-reicher Kumulatgesteine an der Basis der wachsenden Inselbogenkruste resultiert dann in der Produktion einer entwickelten Schmelze die spdter in der Kruste des oberen Bogens Platz genommen hat. Kristallfraktionierung eines seichten magmatischen Reservoirs des zweiten Stadiums unter den aktiven Vulkanen des Bogens führte dann zur Bildung signifikanter Mengen plutonischer Gesteine und zur Eruption von mafischen bis intermediären kalk-alkalischen Laven an der Oberfläche.

     

Relationship between regional changes of soil physical properties and volcanic stratigraphy on the southern slope of Batur volcano in the island of Bali,Indonesia

The present paper shows the relationship between the regional changes of soil physical properties and the volcanic stratigraphy on the southern slope of Batur volcano in the island of Bali, Indonesia, from the hydrogeological point of view based on the data obtained from field observations and laboratory experiments. The Bali soils data showed marked differences in regional distribution and their characteristics are closely correlated to the distribution of the volcanic stratigraphy derived from the Batur volcanic activities with the eruption about 23,700 years ago. On the basis of these data, the hydrogeological situation of the slope are presented schematically and groundwater flow regimes on the slope, such as recharge and discharge areas, are also classified according to the hydrogeological information. These classifications of groundwater flow regimes are useful to consider the occurrence of hydrological phenomena such as springs and paddy field distributions observed on the slope.     

Development of a numerical model for nitrates in groundwater in the reservoir area of the Komesu subsurface dam, Okinawa, Japan

A numerical model consisting of simplified equations was developed to simulate nitrate concentrations in groundwater in a reservoir area of a subsurface dam in a Quaternary limestone region. The model was composed of a water balance sub-model and a nitrogen balance sub-model; the water balance sub-model was built from tank models which can express the quick dilution near caves and the effect of dam construction; and the nitrogen balance sub-model was made to represent changes in nitrogen forms and movement of nitrogen in the soil and aquifer zones. The model was calibrated and verified by observed data before and after the dam construction and then applied to a predictive simulation under a simple assumption that rainfall descends gradually. The model seemed applicable to long-term prediction of changes in NO₃-N in the reservoir area.     

River Water Pollution in Developed and Developing Countries: Judge and Assessment of Physicochemical Characteristics and Selected Dissolved Metal Concentration

To compare water quality in rivers of developed and developing countries, a study based on physicochemical parameters and dissolved metals levels was conducted. Water samples were collected from selected sites in Dhaka, Bangladesh; Hokkaido and Osaka, Japan; Erdenet, Mongolia and West Java, Indonesia. Analysis of least significant differences revealed that most water quality parameters were within comparable low levels in both developed and developing countries. The dissolved metals concentrations were found to be similar and below those of water standards except for manganese and cadmium at every sampling point, and lead in Erdenet, Mongolia. Some metals showed high enrichment factors in the rivers of Osaka, Japan and Erdenet, Mongolia, indicating accumulation possibility of metals in the river‐bed sediments. High concentrations of dissolved organic carbon, Escherichia coli and dissolved metals suggested greater water pollution in some rivers of developing countries than in the rivers of Japan. Principal component analysis showed strong correlations between “dissolved organic carbon and chemical oxygen demand” and “conductivity and total dissolved solids” at each sampling point, and E. coli, nitrate (NO), nitrite (NO), and pH levels were found to be higher in the rivers of Dhaka and Erdenet. In addition, there were high levels of Al and Zn in West Java, Pb in Erdenet, and Mn, Fe, and Cr in the rivers of Dhaka and Japan. Based on pressures and impacts, it is evident that dissolved metal, organic, and fecal pollution in the rivers of developing countries are in somewhat dreadful condition in comparison with the rivers of developed country.