Deep-Sea Chemoautosynthesis-Based Communities in the Northwestern Pacific   总被引：3，自引：0，他引：3  

Shigeaki Kojima 《Journal of Oceanography》2002,58(2):343-363

I review chemoautosynthesis-based faunal communities which have been discovered in the deep-sea areas in the Northwestern Pacific. Fauna of each community and further biological studies are summarized. Zoogeographical and evolutionary status of communities in the Northwestern Pacific is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Biomass and production of bacterioplankton at the hydrothermal vent areas in the rift system of the North Fiji Basin     

Utsumi  Motoo  Kojima  Shigeaki  Nojiri  Yukihiro  Ohta  Suguru  Seki  Humitake 《Journal of Oceanography》1994,50(6):635-642

Mesoscale distribution of the density and productivity of bacterioplankton at representative geological locations in the rift ecosystem of the North Fiji Basin were clarified by sampling using a mannedShinkai 6500 submersible. The bacterioplankton density inside the hot and warm fluids of hydrothermal vents was one order magnitude greater than that in the deep water outside the vent plume. The bacterial production was highest inside the hot and warm vent fluids, and was higher just outside the hot and warm vent fluids than further outside in the deep water surrounding the vent plume, respectively. Productivity from outside to inside the vent fluid varied from 0.01 to 0.71 gC m^–3 day^–1.  相似文献   

LONG-RANGE CHANGES OF CORRELATION BETWEEN THE TYPHOON FREQUENCIES IN SEVEN REGIONS IN EAST ASIA AND SEA SURFACE TEMPERATURE IN THE NORTH PACIFIC     

解思梅  MASATOSHI M. YOSHINO  TAKASHI AOKI 《海洋学报(英文版)》1985,4(3):382-394

The correlation coefficients between the typhoon frequencies for the seven regions in East Asia (i. e. Xisha, Guangzhou, Xiamen, Shanghai, Naha, Kagoshima and Nagoya) and the monthly-mean sea surface temperature (SST) from 2 years before to 1 year after are calculated, indicating that the most significant correlation appears in the period from the summer of 2 years before to the summer of 1 year before. During this period negative correlations are located in the northwestern part of the North Pacific while the positive ones located in the southeastern part. It is found that the positive correlations change into the negative ones in Equatorial East Pacific in the same year (simultaneous correlation). The high-level correlation region in 1 year after is found in the area of Alaska Current. It is also suggested that there are interannual variations of about 1,1.5 and 2 years for the changes of the correlation intensity.  相似文献   

Effect of incorporation of iron and aluminum on the thermoelastic properties of magnesium silicate perovskite     

Norimasa Nishiyama  Takehiko Yagi  Shigeaki Ono  Hirotada Gotou  Tatsuhiko Harada  Takumi Kikegawa 《Physics and Chemistry of Minerals》2007,34(3):131-143

In situ X-ray diffraction measurements of Fe- and Al-bearing MgSiO₃-rich perovskite (FeAl-Pv), which was synthesized from a natural orthopyroxene, were performed at pressures of 19–32 GPa and temperatures of 300–1,500 K using a combination of a Kawai-type apparatus with eight sintered-diamond anvils and synchrotron radiation. Two runs were performed using a high-pressure cell with two sample chambers, and both MgSiO₃ perovskite (Mg-Pv) and FeAl-Pv were synthesized simultaneously in the same cell. Thus we were able to measure specific volumes (V/V ₀) of Mg-Pv and FeAl-Pv at the same P−T conditions. At all the measurement conditions, values of the specific volume of FeAl-Pv are consistent with those of Mg-Pv within 2 Standard Deviation, strongly suggesting that effect of incorporation of iron and aluminum on the thermoelastic properties of magnesium silicate perovskite is undetectable in this composition, pressure, and temperature range. Two additional runs were performed using a high-pressure cell that has one sample chamber and unit-cell volumes of FeAl-Pv were measured at pressures and temperatures up to 32 GPa and 1,500 K, respectively. All the unit-cell volume data of FeAl-Pv perovskite were fitted to the high temperature Birch–Murnaghan equation of state and a complete set of thermoelastic parameters of this perovskite was determined with an assumption of K′ _300,0 = 4. The determined parameters are K _300,0 = 243(3) GPa, (∂K _T,0/∂T) _P = −0.030(8) GPa/K, a ₀ = 2.78(18) × 10⁻⁵ K⁻¹, and b ₀ = 0.88(28) × 10⁻⁸ K⁻², where a ₀ and b ₀ are the coefficients of the following expression describing the zero-pressure thermal expansion: α _T,0 = a ₀ + b ₀ T. The equation-of-state parameters of FeAl-Pv are in good agreement with those of MgSiO₃ perovskite at the conditions corresponding to the uppermost part of the lower mantle.  相似文献   

Determination of the second critical end point in silicate-H₂O systems using high-pressure and high-temperature X-ray radiography     

Kenji Mibe  Masami Kanzaki  Kyoko N. Matsukage  Shigeaki Ono 《Geochimica et cosmochimica acta》2004,68(24):5189-5195

To determine the second critical end point in silicate-H₂O systems, a new method for the direct observations of immiscible fluids has been developed using a synchrotron X-ray radiography technique. High-pressure and high-temperature experiments were carried out with a Kawai-type, double-stage, multi-anvil high-pressure apparatus (SPEED-1500) installed at BL04B1, SPring-8, Japan. The Sr-plagioclase (SrAl₂Si₂O₈)-H₂O system was used as an illustrative example. A new sample container composed of a metal (Pt) tube with a pair of lids, made of single crystal diamonds, was used under pressures between 3.0 and 4.3 GPa, and temperatures up to ∼1600°C. The sample in the container could be directly observed through the diamond lids with X-ray radiography. At around 980 to 1060°C and pressures between 3.0 and 4.0 GPa, light gray spherical bubbles moving upward through the dark gray matrix were observed. The light gray spheres that absorb less X-rays represent an aqueous fluid, whereas the dark gray matrix represents a silicate melt. These two immiscible phases (aqueous fluid and silicate melt) were observed up to 4.0 GPa. At 4.3 GPa, no bubbles were observed. These observations suggest that the second critical end point in the Sr-plagioclase-H₂O system occurs at around 4.2 ± 0.2 GPa and 1020 ± 50°C. Our new technique can be applied to the direct observations of various systems with two coexisting fluids under deep mantle conditions.  相似文献   

Mineralogical evidence for the origin of diamond in ureilites     

Y. NAKAMUTA  Y. AOKI 《Meteoritics & planetary science》2000,35(3):487-493

Abstract— The x‐ray powder diffraction patterns of 50–100 μm C‐rich grains from five ureilitic meteorites—Kenna, Allan Hills (ALH) 78019, Yamato (Y)‐82100, Y‐791538, and ALH 77257—were obtained by using a Gandolfi camera. The results reveal that the basal spacing of part of the graphite coexisting with diamond is slightly smaller compared to the normal spacing. Compressed graphite is experimentally known to occur at the initial stage of the direct transformation from graphite to diamond structures at high pressures and temperatures. The presence of the compressed graphite in ureilites, therefore, gives clear evidence that the diamond formed by high‐pressure conversion of graphite. The modes of occurrence of C minerals observed with reflected light through an optical microscope reveal that graphite coexisted with olivine and pyroxene during igneous or metamorphic processes and, furthermore, that part of the graphite was converted to diamond by impact. The relative x‐ray intensity of diamond to graphite increases in the following order: ALH 78019 and Y‐82100 < Y‐791538 < Kenna < ALH 77257. This correlates with the shock level that is estimated mainly on the basis of the shock features of silicates. Therefore, the relative amounts of diamond to graphite suggested by x‐ray intensities may be useful as a measure of the degree of shock.  相似文献   

High temperature stability limit of phase egg, AlSiO3(OH)   总被引：1，自引：1，他引：0  

Shigeaki Ono 《Contributions to Mineralogy and Petrology》1999,137(1-2):83-89

The stability relations of phase egg, AlSiO₃(OH), have been investigated at pressures from 7 to 20 GPa, and temperatures from 900 to 1700 °C in a multi-anvil apparatus. At the lower pressures phase egg breaks down according to the univariant reaction, phase egg = stishovite + topaz-OH, which extends from 1100 °C at 11 GPa to 1400 °C at 13 GPa where it terminates at an invariant point involving corundum. At pressures above the invariant point, the stability of phase egg is limited by the breakdown reaction, phase egg = stishovite + corundum + fluid, which extends from the invariant point to 1700 °C at 20 GPa. Stishovite crystallized in the Al₂O₃-SiO₂-H₂O system contains Al₂O₃, and the amount of Al₂O₃ increases with increasing temperature. It is inferred that the Al₂O₃ content is controlled by the charge-balanced substitution of Si⁴⁺ by Al³⁺ and H⁺. Aluminum-bearing stishovite coexisting with an H₂O-rich fluid may contain a certain amount of water. Therefore, phase egg and stishovite in a subducting slab could transport some H₂O into the deep Earth. Received: 14 October 1998 / Accepted: 19 May 1999  相似文献   

Age compositions of flatfish stocks as determined by a new otolithometric method, its application in the estimation of growth, spawning potential and fisheries management     

Satoshi Katayama  Masayuki Yamamoto  Shigeaki Gorie 《Journal of Sea Research》2010,64(4):451-456

We developed an ageing methodology and examined age composition of three flatfish stocks inhabiting the Seto Inland Sea, Japan. Ages were difficult to determine for three-lined tongue sole (Cynoglossus abbreviates) and ridged-eye flounder (Pleuronichthys cornutus) because the first year annulus ring was often indistinct; therefore, we used directional change in otolith growth to distinguish it. Sectioning and etching methods were powerful tools for identifying annual checks for red tongue sole (Cynoglossus joyneri). Using these ageing methods, we determined age–length relationships and growth curves. The age composition of the populations studied and of the landings showed that a large proportion of the latter consisted of individuals under the mean age of sexual maturity, thereby reducing the percent spawning potential ratio (%SPR) to ≈ 20% for all species. These findings suggest that fishing pressure on immature fish is leading to overfishing of these flatfish stocks.  相似文献   

Hydrographic conditions in the Tsushima Strait revisited   总被引：1，自引：1，他引：0  

Tomoharu Senjyu  Shigeaki Matsui  In-Seong Han 《Journal of Oceanography》2008,64(2):171-183

Long-term averaged temperature and salinity distributions in the Tsushima Strait are investigated on the basis of a concurrent dataset of the eastern and western channels during 1971–2000. Both temperature and salinity show a clear seasonal variation with weak and strong stratifications in December–April and June–October, respectively. The largest standard deviations occur in summer around the thermocline for temperature and in the surface layer for salinity. This indicates large interannual variability in the development of a thermocline and low salinity water advection from the East China Sea. The water masses in both channels are distinctly different from each other; the water in the western channel is generally colder and fresher than that in the eastern channel throughout the year. Baroclinic transport based on the density distributions shows a seasonal variation with a single peak in August for the eastern channel and double peaks in April and August for the western channel. However, this cannot explain the seasonal variation in the total volume transport estimated from the sea level differences across the channels. The spatial distribution of baroclinic transport shows a year-round negative transport towards the East China Sea behind the Iki Island in the eastern part of the eastern channel. This negative transport reflects the baroclinic structure between the offshore Tsushima Current Water and cold coastal water. The corresponding southwestward currents are found in both Acoustic Doppler Current Profiler (ADCP) and high frequency (HF) radars observations.  相似文献   

Genetic diversity and population structure of three dominant myctophid fishes (<Emphasis Type="Italic">Diaphus theta,Stenobrachius leucopsarus</Emphasis>, and <Emphasis Type="Italic">S. nannochir</Emphasis>) in the North Pacific Ocean     

Shigeaki Kojima  Masatoshi Moku  Kouichi Kawaguchi 《Journal of Oceanography》2009,65(2):187-193

We compared the genetic diversity of three dominant myctophid fishes in the North Pacific Ocean that have different diel vertical migration patterns on the basis of the nucleotide sequences of the mitochondrial gene for cytochrome b. No genetic structure was detected for each of these three species. The genetic diversity progressively increased for Diaphus theta, a diel migrant species showing clear diel vertical migration; Stenobrachius leucopsarus, a semi-diel migrant, in which only part of the population migrates vertically; S. nannochir, a non-diel migrant. All three species were suggested to have experienced a recent, sudden population expansion. Interspecific differences in genetic diversity might be attributable to differences in the degree of population size reduction during the glacial periods; this degree in turn corresponds to the energy demand of the fishes.  相似文献