Lethality of increasing CO2 levels on deep-sea copepods in the western North Pacific

The first CO₂ exposure experiments on several species of pelagic copepods inhabiting surface and deep layers in the western North Pacific were conducted. Living organisms were collected from two layers between the surface and 1,500 m between latitudes of 11 and 44°N, and they were exposed aboard ship to various pCO₂ up to about 98,000 μatm. Mortality of copepods from both shallow and deep layers in subarctic to subtropical regions increased with increasing pCO₂ and exposure time. Deep-living copepods showed higher tolerance to pCO₂ than shallow-living copepods. Furthermore, deep-living copepods from subarctic and transitional regions had higher tolerances than the subtropical copepods. The higher tolerances of the deep-living copepods from subarctic and transitional regions may be due to the adaptation to the natural pCO₂ conditions in the subarctic ocean.     

Geostrophic response near the coast

Geostrophic response of a two-layer fluid near a straight coast is investigated for a successive disturbance by the use of the inviscid, reduced gravity model. Poincare waves, coastal motion (which is trapped by the coast) and a geostrophic eddy are created. The energy of these motions is obtained. The manner in which the ocean responds is found to depend considerably on the way the disturbance is applied. When the water is supplied continuously to a calm upper layer adjacent to the coast, a quasi-steady geostrophic eddy is formed and its energy increases in proportion toT ² (T is the duration for which water is supplied). The energy of the coastal motion increases in proportion toT. When the water is supplied continuously into the upper layer from a certain portion of the coast, a geostrophic eddy is not formed. The coastal motion has the same structure as in the former case and its energy increases in proportion toT.     

CFD, system-based and EFD study of ship dynamic instability events: Surf-riding, periodic motion, and broaching

CFD and system-based simulation are used to predict broaching, surf-riding, and periodic motion for the ONR Tumblehome model, including captive and free model test validation studies. CFD shows close agreement with EFD for calm water resistance, static heel (except for sway force and yaw moment), and static drift (except for roll moment). CFD predictions of static heel in following waves also compare well with EFD except for surge force, sway force, and pitch angle. Froude-Krylov calculations of wave-induced surge force in following waves provides good agreement for high Froude number, but significantly overestimates for Froude number less than 0.2. On the other hand, CFD successfully reproduces the reduction of the wave-induced surge force near Froude number 0.2, probably because CFD can capture the 3D wave pattern. CFD free model simulations are performed for several speeds and headings and validated for the first time for surf-riding, broaching, and periodic motions. System-based simulations are carried out based on inputs from EFD, CFD, and Froude-Krylov for a dense grid of speeds and headings to predict the instability map, which were found to produce fairly similar results.     

Volcanic gases and sublimates from Showashinzan

Volcanic gases from Showashinzan are qualitatively the same as those liberated from igneous rocks when they are heated in vacuum. Their main components are H₂O, CO₂, and H₂. Then follow HCl, HF, N₂, SO₂, H₂S, S, CH₄, CO, Ar, Si, B, Mg, Na, K, Ca, Al, Fe, P, Br, NH₃, As, Zn, Sr, Ba, Cu, Pb, Sn, Sb, Bi, Ge, Ag, Cr, Ni, Mo, Rn, Ra, etc. They come through fumaroles of high temperature (～750°C.). Metallic compounds deposit as sublimates around the outlet of fumaroles. They are fractionated there according to their thermodynamic properties. When the temperature of gases falls, heavy metal elements deposit before reaching the surface of the earth. Ra is among them. Owing to the contribution of Ra thus depositted, Rn content of vapor is larger in low temperature fumaroles than in high temperature ones. Chemical compounds of H, C, N, O, and S vary their composition according to the condition of temperature and pressure. Sulfur exists as SO₂ more than H₂S. As the temperature of gases falls, SO₂ and H₂ decrease and H₂S increases. Mutual relation among them is ruled by the chemical equilibrium: SO₂+3H₂=H₂S+2H₂O. The structure of Showashinzan is not simple. Some deviations from the general rule are explained in connection with ground water.     

Depositional ages and characteristics of Middle–Upper Jurassic and Lower Cretaceous lacustrine deposits in southeastern Mongolia

Lower Cretaceous lacustrine oil shales are widely distributed in southeastern Mongolia. Due to the high organic carbon content of oil shale, many geochemical studies and petroleum exploration have been conducted. Although most of the oil shales are considered to be Early Cretaceous in age, a recent study reveals that some were deposited in the Middle Jurassic. The present study aims at establishing depositional ages and characteristics of the Jurassic and Cretaceous lacustrine deposits in Mongolia. The Lower Cretaceous Shinekhudag Formation is about 250 m thick and composed of alternating beds of shale and dolomite. The Middle Jurassic Eedemt Formation is about 150 m thick and composed of alternating beds of shale, dolomitic marl, and siltstone. The alternations of shale and dolomite in both formations were formed by lake level changes, reflecting precipitation changes. Shales were deposited in the center of a deep lake during highstand, while dolomites were formed by primary precipitation during lowstand. Based on the radiometric age dating, the Shinekhudag Formation was deposited between 123.8 ±2.0 Ma and 118.5 ±0.9 Ma of the early Aptian. The Eedemt Formation was deposited at around 165–158 Ma of Callovian–Oxfordian. The calculated sedimentation rate of the Shinekhudag Formation is between 4.7 ±2.6 cm/ky and 10.0 ±7.6 cm/ky. Shales in the Shinekhudag Formation show micrometer‐scale lamination, consisting of algal organic matter and detrital clay mineral couplets. Given the average thickness of micro‐laminae and calculated sedimentation rate, the micro‐lamination is most likely of varve origin. Both Middle–Upper Jurassic and Lower Cretaceous lacustrine oil shales were deposited in intracontinental basins in the paleo‐Asian continent. Tectonic processes and basin evolution basically controlled the deposition of these oil shales. In addition, enhanced precipitation under humid climate during the early Aptian and the Callovian–Oxfordian was another key factor inducing the widespread oil shale deposition in Mongolia.     

Two layer model of the steady ocean response to large-scale heating and cooling

Steady response of a linear, two-layer baroclinic ocean to a steady thermal forcing was investigated on a mid-latitude -plane. Surface heat flux and its relaxation processes were parametrized as a form of heating function and Newtonian cooling term of cross interfacial velocityw in the continuity equation. Ageostrophic linear drag terms were employed to represent the western boundary layer for accomplishment of the steady circulation in the closed domain. In the interior, the dynamics belongs to thef-plane regime. The flow in the upper layer is zonal and eastward, which is the same as that expected in the channel without meridional boundary. The eastern boundary region is the so called Sverdrup region, in which the vortex stretching balances the term, thoughw contains a damping term. It directs the zonal flow southward (northward) in the south (north) followed by upwelling (downwelling) and forms the two gyres. Western boundary region is of the Stommel type except the upwelling (downwelling) in the south (north). The meridional circulation is similar to the Hadley Cell except southern and northern boundary layers. However, its strength is much greater than the latters.     

Evaluation of Containment Performance from Viewpoints of Diffusion and Dispersion for Impervious Structures at Coastal Landfill Sites

The containment performance of impervious structures is considered the most important performance, which the toxic substances are enclosed in coastal landfill sites. The containment performance is evaluated generally by the hydraulic conductivity and the thickness of impervious structures to focus on an advection. However, the leakage of toxic substances is affected by a diffusion and a dispersion. The diffusion and the dispersion are considered to be easily distinguished on the impervious structure which has the low-hydraulic conductivity. Such phenomena should be considered due to evaluate the containment performance. This is because to improve the containment performance and comprehend leakage of the toxic substances. The containment performance is evaluated from the viewpoint of the diffusion and the dispersion in this research. Concretely, the influence which the toxic substances leaks from impervious structures on the diffusion and the dispersion is evaluated by the infiltration and advection–dispersion analysis on steel-made side impervious walls. In other word, The relation between the leaking amount of toxic substances and coefficient of molecular diffusion, the relation between the travel time or the flow velocity and the leaking amount and the change in the water-level difference are considered respectively. So, the leaking amount which is influenced by a diffusion and a dispersion is considered. Consideration about to secure the containment performance of impervious structure which is restrained leakage by a diffusion and a dispersion.     

Recent Dasycladales (Chlorophyta) in Okinawa Jima in the Central Ryukyus,southwestern Japan: Paleontological implications

Recent dasycladalean algae (Dasycladales, Chlorophyta) are classified into two families, 11 genera, and 44 species, and inhabit the tropical to warm‐temperate waters of the world. Twelve species of dasycladalean algae occur in Okinawa Jima, Ryukyu Islands. In this paper, the present‐day dasycladalean species and their distributions in Okinawa Jima are reported and their paleontological implications are discussed. Dasycladalean algae grow mainly on coral rubble and rocks, often forming large meadows in calm shallow lagoons. However, Dasycladus vermicularis occurs in deeper waters, at depths of 15–89 m, around Okinawa Jima. Neomeris annulata is found at water depths of 0–30 m. These data throw doubt on the interpretation that the occurrence of dasycladalean algae is linked to warm shallow habitats.     

End bearing capacity comparison of screw pile with straight pipe pile under similar ground conditions

In the present study, the end bearing capacity of screw and straight pipe pile under similar pile tip area and ground conditions were investigated. The effect of increasing overburden pressure was also considered in this research. Pile load tests on close-ended screw and straight pipe piles were conducted in the small scale. Dry Toyoura sand was used to develop the model ground. The sand was compacted at relative density of 70, 80 and 92 %. It was observed that in case of straight pipe pile, load settlement curve plunges downward without increase in load around settlement equals to 10 % of pile tip diameter, whereas in case of screw pile, the load settlement curve plunges around settlement equals to 15 % of pile tip diameter. Moreover, the screw piles having helix-to-shaft diameter ratio 2–4.1 showed 2–12 times higher end bearing capacity than straight pipe piles with similar pile shaft diameter. It was also observed from the test results that the end bearing capacity of single-helix screw pile was in average 16.25 % less than straight pipe pile with similar pile tip area and ground conditions irrespective of the effect of increasing overburden pressure.     

Paleomagnetic evidence for post-Cretaceous internal deformation of the Chuan Dian Fragment in the Yangtze block: a consequence of indentation of India into Asia

Paleomagnetic samples of Paleocene–Eocene red sandstones were collected at 36 sites from the Jiangdihe-4 and Zhaojiadian formations around the Yongren (26.1°N, 101.7°E) and Dayao areas (25.7°N, 101.3°E). These areas are located in the Chuxiong basin of the Chuan Dian Fragment, southwestern part of the Yangtze block. After stepwise thermal demagnetization, a high-temperature component with unblocking temperature of about 680 °C is isolated from 26 sites. The primary nature of this magnetization is ascertained through positive fold and reversal tests at 95% confidence level. The tilt-corrected mean paleomagnetic directions for the Yongren and Dayao areas are D=17.2°, I=26.6° with α₉₅=5.8° and D=16.5°, I=31.1° with α₉₅=4.8, respectively. Easterly deflected declinations from this study are consistent with those reported from other areas of the Chuxiong basin, indicating its wide presence in the Cretaceous–Eocene formations of the said basin. Comparison with declination values expected from the Cretaceous–Eocene APWP of Eurasia indicates that the magnitude of clockwise rotation systematically increases toward the southeast within the Chuxiong basin as well as in the Chuan Dian Fragment. This trend of the differential tectonic rotation in the Chuan Dian Fragment is consistent with curvature of the Xianshuihe–Xiojiang fault system. Deformation of the Chuxiong basin can fairly be associated with the formation of eastward bulge in the southern part of the Chuan Dian fragment. During southward displacement, the Chuan Dian Fragment was probably subjected to tectonic stresses as a result interaction with the Yangtze and Indochina blocks, which resulted into east–west extension and north–south shortening.