In situ strength measurements on natural upper-mantle minerals   总被引：1，自引：0，他引：1  

Junji Yamamoto  Jun-ichi Ando  Hiroyuki Kagi  Toru Inoue  Akihiro Yamada  Daisuke Yamazaki  Tetsuo Irifune 《Physics and Chemistry of Minerals》2008,35(5):249-257

Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700°C, we examined rheological properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential stress of 4–6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600°C. Neither orthopyroxene nor spinel shows complete stress relaxation, but both retain some stress even at 700°C. The strength of the minerals decreases in the order of chromian-spinel ≈ orthopyroxene > olivine for these conditions. This order of strength is consistent with the residual pressure of fluid inclusions in mantle xenoliths.  相似文献   

Vertical residual flow in Kasado Bay     

Tetsuo Yanagi 《Journal of Oceanography》1979,35(3-4):168-172

Some observations were carried out to understand the structure of the vertical residual flow in Kasado Bay. The results of current measurements at three points in the lower layer indicated that a horizontal counterclockwise tidal residual circulation converges in the lower layer. The velocity of upward residual flow was estimated to be about 4.5×10^–3 cm s^–1. The distributions of water temperature, salinity and grain size in the sediment support the existence of this upward motion.  相似文献   

CO<Subscript>2</Subscript> Flux Measurements over the Sea Surface by Eddy Correlation and Aerodynamic Techniques     

Toru?Iwata  Keiko?Yoshikawa  Katsutoshi?Nishimura  Yoshihisa?Higuchi  Takao?Yamashita  Shigeru?Kato  Eiji?OhtakiEmail author 《Journal of Oceanography》2004,60(6):995-1000

The measurements of the vertical transport of CO₂ were carried out over the Sea of Japan using the specially designed pier of Kyoto University on September 20 to 22, 2000. CO₂ fluxes were measured by the eddy correlation and aerodynamic techniques. Both techniques showed comparable CO₂ fluxes during sea breeze conditions: −0.001 to −0.08 mg m⁻²s⁻¹ with the mean of −0.05 mg m⁻²s⁻¹. This means that the measuring site satisfies the fetch requirement for meteorological observations under sea breeze conditions. Moreover, the eddy diffusivity coefficient used in the aerodynamic technique is found to be consistent with the coefficient used in the eddy correlation technique. The present result leads us to conclude that the aerodynamic technique may be applicable to underway CO₂ flux measurements over the ocean and may be used in place of the bulk technique. The important point is the need to maintain a measuring accuracy of CO₂ concentration difference of the order of 0.1 ppmv on the research vessels or the buoys.  相似文献   

Mercury distribution in seawater in Minamata Bay and the origin of particulate mercury     

Mikio Kumagai  Hajime Nishimura 《Journal of Oceanography》1978,34(2):50-56

Horizontal and vertical distributions of mercury were determined in seawater in Minamata Bay and Yatsushiro Sea. The concentrations of total and particulate mercury respectively ranged from 56–285 ng l^–1 and 2.1–506 ng l^–1. They were both highest in the inner most part of Minamata Bay where the sediment was most heavily polluted, and decreased with increasing distance from there. Vertically, an evident increase in concentration was observed near the bottom. A good agreement was found between the mercury content in suspended matter and that in fine sediment particles.These facts show that the particulate mercury is supplied mostly from the bottom sediment, and that it is spreading offshore with dispersing in seawater. This process would eventually result in the pollution of sediment in Yatsushiro Sea.  相似文献   

Episodic outflow of suspended sediments from the Kii Channel to the Pacific Ocean in winter     

Tetsuo Yanagi  Takahide Hagita  Toshiro Saino 《Journal of Oceanography》1994,50(1):99-108

Episodic outflow of suspended sediments from the Kii Channel to the Pacific Ocean in winter was observed by the sediment traps experiment above the shelf slope. When the current speed was weak and its direction was south or southwestward above the shelf slope the sinking sediment flux was nearly zero but the sinking sediment flux increased to 22g m^–2 day^–1 after the current speed was strong, its direction changed to south-west or westward and water temperature fell. Such intermitten sinking sediment flux above the shelf slope is considered to be related to the intermittent intrusion of the turbid and cold shelf water into the sub-surface layer of the transparent and warm slope water. Such episodic events may play a very important role in the material transport from the coastal sea to the open ocean.  相似文献   

Seasonal variation in the transport of suspended matter in the East China Sea   总被引：8，自引：0，他引：8  

Tetsuo Yanagi  Satoru Takahashi  Akira Hoshika  Terumi Tanimoto 《Journal of Oceanography》1996,52(5):539-552

Seasonal variation in the transport of suspended matter across the East China Sea is investigated with the use of results of field observations and diagnostic numerical experiments. Suspended matter is transported from the shelf edge to the inner shelf in summer and from the inner shelf to the shelf edge in autumn and winter due to the vertical circulation mainly induced by the monsoon wind. The maximum transport of suspended matter from the inner shelf to the shelf edge occurs in autumn.  相似文献   

Coastal upwelling and downwelling events in the Seto Inland Sea     

Tetsuo Yanagi 《Journal of Oceanography》1985,41(6):435-440

Prominent coastal upwelling and downwelling events due to Ekman transport were observed during the period from 14 to 18 August 1983 along the Misaki Peninsula in the Seto Inland Sea, Japan. The coastline of the Misaki Peninsula is aligned approximately in an ENE-WSW direction. When an ENE wind continued blowing for about two days, the warm water in the upper layer was pushed offshore and cold water in the lower layer upwelled along the peninsula. The estimated upwelling speed 3 m below the sea surface was 0.032 cm sec^–1. On the other hand, when a WSW wind continued blowing for about two days the warm water in the upper layer sank into the lower layer along the peninsula. The estimated downwelling speed 3 m below the sea surface was 0.080 cm sec^–1. The time lag between the variations of the alongshore wind and offshore current was about 0.5 days.  相似文献   

Degradation of lubricating oils by marine bacteria observed by quantitative mass spectrometry     

Yasushi Kawakami  Hajime Nishimura 《Journal of Oceanography》1981,37(1):1-7

Bacterial degradation of the hydrocarbons of lubricating oils was investigated by mass spectrometric analysis which gives both total amount and the composition of hydrocarbon types of residual oil. An unused lubricating oil, which mainly consisted of hydrocarbon types with only a small percentage ofn-alkanes, was degraded by marineBacillus sp. andPseudomonas sp. with 55 % and 25 % decreases in 10 days, respectively. Susceptibility of respective hydrocarbon types to biodegradation was in the following order: alkanes > non-condensed cycloalkanes, mono-aromatics > condensed cycloalkanes. A used lubricating oil of different brand showed a larger decrease than the unused oil. Both species of bacteria degraded large portions of alkane fraction of Arabian light crude oil.  相似文献   

Convergence,divergence and vertical velocity at a tidal front in Hiuchi-Nada,Japan   总被引：2，自引：0，他引：2  

Tetsuo Yanagi  Koji Ishikawa  Koh-ichi Inoue  Satoshi Susami 《Journal of Oceanography》1995,51(2):225-238

The detailed flow structure around a tical front in Hiuchi-Nada, Japan was observed with the use of ADCP (Acoustic Doppler Current Profiler). The surface convergence region is observed at the transition zone between vertically well mixed area and the stratified area. The surface divergence regions exist next to the surface convergence region. The strong downward current is estimated in the middle layer just below the surface convergence region. The maximum surface convergence and the maximum downward velocity in the middle layer are 1.0×10^–4 s^–1 and 0.12 cm s^–1, respectively.  相似文献   

Seasonal variation of water temperature in the Seto Inland Sea     

Tetsuo Yanagi 《Journal of Oceanography》1984,40(6):445-450

The seasonal variation of water temperature in the Seto Inland Sea, Japan is examined using data analysis and numerical experiments and is shown to be controlled by heat exchange through the sea surface and horizontal heat dispersion from the Pacific Ocean. The average water temperature goes down from the Pacific Ocean to the center of the Seto Inland Sea indicating that 4.0 to 6.0×10¹⁵ cal day^?1 (1.6 to 2.5×10¹⁶ joule day^?1) of heat is transported from the Pacific Ocean to the Seto Inland Sea and is lost through the sea surface. The amplitude of seasonal variation of water temperature is large at the center of the Seto Inland Sea and the maximum water temperature is reached first at Bisan Straits and last at Iyo-Nada.  相似文献