Todorokite formation in seawater by microbial mediation     

Noburu Takematsu  Hiroo Kusakabe  Yoshio Sato  Shiro Okabe 《Journal of Oceanography》1988,44(5):235-243

Microbial manganese oxidation in seawater was carried out in enrichment cultures which were obtained from the seawater supply system at the Marine Science Museum, Tokai University (Shimizu-shi, Japan). The manganese oxide formed was well-crystallized todorokite. The major element composition was within the range of marine manganese concretions and the O/Mn molar ratio was 1.8. The conditions for formation of manganese oxide minerals in marine environments are discussed on the basis of these results.  相似文献   

Excess CO2 and pHexcess in the Intermediate Water Layer of the Northwestern Pacific     

Andrey Andreev  Makio Honda  Yuichiro Kumamoto  Masashi Kusakabe  Akihiko Murata 《Journal of Oceanography》2001,57(2):177-188

Excess CO₂ and pH_excess showing an increase in dissolved inorganic carbon and a decrease in pH from the beginning of the industrial epoch (middle of the 19th century) until the present time have been calculated in the intermediate water layer of the northwestern Pacific and the Okhotsk Sea. It is concluded that: (1) The Kuril Basin (Okhotsk Sea) and the Bussol' Strait areas are characterized by the greatest concentrations of excess CO₂ at isopycnal surfaces due to the processes of formation and transformation of intermediate water mass. (2) The largest difference in excess CO₂ concentration between the Okhotsk Sea and the western subarctic Pacific (about 8 µmol/kg) is found at the = 27.0. (3) The difference in excess CO₂ between the western subarctic Pacific and subtropical regions is significant only in the upper part of the intermediate water layer ( = 26.7–27.0). (4) About 10% of the excess CO₂ accumulation in the subtropical north Pacific is determined by water exchange with the subarctic Pacific and the Okhotsk Sea.  相似文献   

Air-Sea Gas Transfer Velocity in Stormy Winter Estimated from Radon Deficiency     

Hitoshi Kawabata  Hisashi Narita  Koh Harada  Shizuo Tsunogai  Masashi Kusakabe 《Journal of Oceanography》2003,59(5):651-661

Thirteen vertical profiles of ²²⁶Ra and ²²²Rn in the near-surface water were obtained in the western North Pacific in winter, and the gas transfer velocities across the air-sea interface were estimated. The transfer velocities found by applying a steady state model varied widely from 2.1 to 30.2 m day⁻¹ with a mean of 9.4 m day⁻¹. The mean value is almost 5 times higher than that in summer in other oceans, and the maximum value is a record high for world oceans. This is partly due to the inadequacy of the steady state model, which overestimates when stronger winds blow in more recent days than the ²²²Rn half-life of about 4 days. In fact, a strong low pressure zone passed through the station about 2 days earlier, which was one of the low pressure zones that with a period of develop once a week or so in the northwestern North Pacific in winter. Instead of steady-state removal, if half of the radon removal occurred sporadically every 7 days, and the last removal took place two days before the observation, the transfer velocity would be 26 m day⁻¹. Our mean transfer velocity, which is less than 20% different from the steady state value including both overestimated and underestimated values, 9.4 ± 4.8 m day⁻¹, seems to represent the mean state of this region in winter. This suggests that the gas exchange fluxes under extremely rough conditions in the open ocean are larger than those estimated by using a transfer velocity equation with a linear or quadratic relationship with wind speed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Temperatures and Oxygen Isotopic Compositions of Hydrothermal Fluids for the Takatori Tungsten-copper Deposit, Japan     

Yasuhiro Shibue    Hitoshi Chiba    Minoru Kusakabe  Yuichi Morishita 《Resource Geology》2005,55(2):101-110

Abstract. Fluid inclusion and oxygen isotope studies are performed to obtain temperatures and oxygen isotopic compositions of hydrothermal fluids for the vein-type tungsten-copper deposit at Takatori in Ibaraki Prefecture, Japan. Temperatures of the hydrothermal fluids are calculated from fluid inclusion data. The calculation incorporates the effects of the salinity, gas concentration, and fluid pressure. The fluid temperatures range from 370 to 460C. For these calculations, this study obtains a density equation for H₂O-NaCl-CO₂ solution at the vapor-liquid two-phase boundary. Then the present study combines the obtained equation with the equation of state by Bowers and Helgeson (1983).
The fluid temperatures determined in this study are applied to the calculation of oxygen isotopic compositions of the hydrothermal fluids. The calculation of the oxygen isotopic compositions is based on the oxygen isotope analyses of vein quartz. The oxygen isotopic compositions of vein quartz range from +13.5 to +14.4 % relative to SMOW. Then, the oxygen isotopic compositions of the hydrothermal fluids in equilibrium with the vein quartz are calculated to be from +9.7 to +10.5 %. These δ¹⁸O_fluid values agree with those of magmatic fluids derived from the ilmenite-series granitic rock, which is related to the mineralization. Keywords: Takatori tungsten-copper deposit, fluid inclusion, oxygen isotope, vein quartz, H₂O-NaCl-CO₂ solution, density  相似文献   

Olivine phenocrysts in some Cameroonian Basalts—implications for primary magma composition     

Hiroaki Sato  Felix Tchoua  Minoru Kusakabe 《Mineralogy and Petrology》1991,44(3-4):253-269

Summary The chemical composition of olivine phenocrysts was determined for 13 basaltic samples taken from the central part of the Cameroon Volcanic line to estimate the compositions of the primary olivine phenocrysts and the primary magmas. The Mg/(Mg + Fe) ratios of the olivines attain 0.91, though many of the magnesian olivines are identified on a textural basis as xenocrysts from peridotite inclusions. Most magnesian olivine phenocrysts have Mg/(Mg + Fe) ratios of 0.87–0.88 and NiO contents of 0.32–0.35 wt %. The NiO versus Mg/(Mg + Fe) ratios of the olivines can be used to estimate the compositions of the primary phenocrysts in a range of Mg/(Mg + Fe) = 0.88–0.90. Assuming the Fe(3)/(total Fe) ratios of the magmas are 0.17–0.25, which is estimated from the Fe-Mg partitioning between plagioclase and groundmass, the compositions of the primary magmas were obtained from the Fe²⁺-Mg partition equilibrium with the primary olivine phenocrysts. The primary magmas of the Cameroonian basalts have 13.5 ± 4.0 wt MgO, which is similar to the compositions of basalts with highest MgO contents reported so far from the Cameroon volcanic line.

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Olivin Kristalle in einigen Basalten aus Kamerun: Hinweise auf die Zusammensetzung des primitiven Magmas

Zusammenfassung Die chemische Zusammensetzung von Olivin Phenokristallen wurde in 13 Basalt-Proben, die vom Zentralteil .des Kamerun-Vulkangürtels stammen, bestimmt, um Hinweise auf die Zusammensetzung der primären Olivineinsprenglinge and des primären Magmas zu erlangen. Die Mg/(Mg + Fe) Verhältnisse der Olivine reichen bis 0.91, obwohl viefle dieser Mg-Olivine auf Grund textureller Kriterien als aus Peridotit-Einschlüssen stammende Xenokristalle zu identifizieren sind. Die Mg/(Mg + Fe) Verhältnsse der Hauptmasse der Olivin-Phenokristalle liegen im Bereich von 0.87 bis 0.88, die Ni0 Gehalte zwischen 0.32 und 0.35 Gew %. Die Ni0 gegen Mg/(Mg + Fe) Verhältnisse eignen sich zur Abschätzung der Zusammensetzung der primären Phenokristalle, solange die Mg/(Mg + Fe) Verhältnisse im Bereich von 0.88 bis 0.90 liegen. Die Zusammensetzung des Primärmagmas wurde mittels der Fe²⁺-Mg-Verteilung zwischen dem Magma und den sich mit dem Magma im Gleichgewicht befindlichen primären Olivinkristallen unter der Annahme eines Fe³⁺/Fe total Verhältnisses von 0.17–0.25, welches sich aus der Mg-Fe Verteilung zwischen Plagioklas und Grundmasse ergibt, bestimmt. Demnach ergibt sich für das primäre Magma der Kamerun Basalte ein MgO Gehalt von 13.5 + 4.0 Gew%. Dieser Wert ist mit der Zusammensetzung von Basalten mit höchsten MgO-Gehalten, wie sie bisher vom Kamerun-Vulkangürtel berichtet worden sind, vergleichbar.

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With 6 Figures  相似文献   

Geomorphological study on a clastic accretionary prism: The Nankai Trough     

Kyoko  Okino Yukihiro  Kato 《Island Arc》1995,4(3):182-198

Abstract The Nankai Trough, off southwest Japan, is one of the best sites for the study of geomorphic characteristics of a clastic accretionary prism. A recent multibeam survey over the central and eastern parts of the Nankai accretionary prism has revealed a large variation of the topography along the trough axis. Analysis of the bathymetric data suggests the existence of prism deformational features of different scales, such as depressions, embayment structures and cusps. These structures are the results of slope instability caused by basement relief of subducted oceanic plate. Unstable slopes recover by new accretion and development of a low angle thrust. Small-scale deformation due to the subduction of a small isolated seamount is then adjusted to the regional trend. By contrast, a 30 km indentation of the wedge observed in the eastern part of the Nankai Trough, the Tenryu Cusp, has seemed to retain its geometry. The subducted Philippine Sea plate has deformed greatly near the eastern end of the Nankai Trough, because of the collision between the Izu-Ogasawara (Bonin) arc and central Japan. Therefore, the indentation may be the result of the continuous subduction of a basement high, such as the Zenisu Ridge, which has been formed under north-south compression due to the arc-arc collision.  相似文献   

Sulfate reduction using methane in sediments beneath a bathyal “cold seep” giant clam community off Hatsushima Island, Sagami Bay, Japan     

Toshiyuki Masuzawa  Nobuhiko Handa  Hiroyuki Kitagawa  Minoru Kusakabe 《Earth and Planetary Science Letters》1992,110(1-4):39-50

Two sandy sediment cores (Cores D227-120 and D380) were collected from inside a deep-sea giant clam (Calyptogena soyoae) community off Hatsushima Island, western Sagami Bay, central Japan (35°59.9′N, 139°13.6′E; 1160 m deep) and a muddy sediment core (Core D227-202) was obtained from outside the community by the submersibleShinkai 2000. The chloride concentration of the pore waters is constant vertically and sulfate reduction using sedimentary organic matter occurs in Core D227-202 (21 cm long). The chloride concentrations are lower by 7% at the 7.5–9 cm depth in Core D227-120 (9 cm long) and by 3% at the 11–12 cm depth in Core D380 (16 cm long) than those of the overlying bottom waters in the cores from inside of the community. Sulfate concentration decreases remarkably and dissolved inorganic carbon, alkalinity, ammonium-N, and hydrogen sulfide concentrations increase significantly with increasing depth in Core D380.δ³⁴S values of sulfate ions increase from +20.5 to +35.3‰ andδ¹³C values of dissolved inorganic carbon decrease drastically from −7.0 to −45‰ with increasing depth from the top to the bottom of the core, although theδ¹³C values of the organic carbon of the sediments are−23.7 ± 0.9‰ in Core D380. These results indicate that sulfate reduction using methane is active within the sediments just beneath the living clams and that the hydrogen sulfide produced can be used by endosymbiotic sulfur oxidizing bacteria living in the gills ofC. soyoae in the community.  相似文献   

Cases-97: Late-Morning Warming And Moistening Of The Convective Boundary Layer Over The Walnut River Watershed     

Margaret A. LeMone  Robert L. Grossman  Robert T. Mcmillen  Kuo-Nan Liou  S.C. Ou  Stuart Mckeen  Wayne Angevine  Kyoko Ikeda  Fei Chen 《Boundary-Layer Meteorology》2002,104(1):1-52

Aircraft, radiosonde, surface-flux, and boundary-layer windprofiler data from the Cooperative Atmosphere Surface Exchange Study's 1997 field project, CASES-97, are combined with synoptic data to study the evolution of the vertically-averaged mixed-layerpotential temperature []and mixing-ratio [Q] onthree nearly-cloudless days from 1000 CST to 1200CST (local noon is approximately 1230 CST). This was achieved through examination of the terms in the time-tendency (`budget')equations for []and [Q]. We estimate three of the terms –local time rate of change, vertical flux divergence, andhorizontal advection. For the [Q]-budget, vertical flux divergence usually dominates, buthorizontal advection is significant on one of the three days. The [Q]-budget balances for two of the three days to within the large experimental error. For the -budget,vertical flux divergence accounts for most of the morningwarming, with horizontal advection of secondary importance.The residual in the -budget has the same sign for all three days, indicating that not all the heating is accounted for. We can balance the []-budgets to within experimental error on two of the three days by correcting the vertical-flux divergence for apparent low biases in the flux measurements of one of the aircraft and in the surface fluxes, and accounting for direct heating of the mixed layer by radiative flux divergence allowing for the effects of carbonaceous aerosols. The [];-budget with these corrections also balances on the third day if horizontal gradients from synoptic maps are used to estimate the horizontal advection. However, the corrected budget for this day does not balance if the horizontal gradient in the advection term is estimated using CASES-97aircraft and radiosondes; we suggest that persistent mesoscale circulations led to an overestimate of the horizontal gradient andhence horizontal advection.  相似文献   

Oxygen isotope fractionation factors between anhydrite and water from 100 to 550°C     

Hitoshi Chiba  Minoru Kusakabe  Shin-Ichi Hirano  Sadao Matsuo  Shigeyuki Somiya 《Earth and Planetary Science Letters》1981,53(1):55-62

Oxygen isotope exchange between anhydrite and water was studied from 100 to 550°C, using the partial equilibrium method. The exchange rate was extremely low in NaCl solution. In the lower-temperature range, acid solutions were used to produce sufficient reaction to determine the oxygen isotope fractionation factors. The fractionation factors obtained in the present study are definitely different from those given by Lloyd [8]. They are similar to those for the HSO₄^?-water system studied by Mizutani and Rafter [19], and are consistently 2‰ higher than those of the barite-water system by Kusakabe and Robinson [5]. The temperature dependence of the oxygen isotope fractionation factors was calculated by the least squares method in which the weight was taken to be inversely proportional to the experimental error. The fractionation is given by:10³lnαanhydrite-water=3.21×(10³/T)²?4.72Available δ¹⁸O values of natural anhydrite were used to test the validity of this expression. It is shown that this newly revised geothermometer can be successfully applied to natural hydrothermal anhydrite.  相似文献   

Under‐ice salinity and stable isotope distribution of Saroma‐ko Lagoon,Hokkaido, northern Japan     

Maki Morimoto  Kyoko Kawanobe  Osamu Abe  Takayoshi Kawai  Toshiyuki Kawamura  Kunio Shirasawa 《水文研究》2010,24(7):904-916

In winter, lakes and lagoons at high altitudes or high latitudes have interesting hydrological cycles that differ from those in other seasons or in other regions, because water surfaces are covered with ice. Hydrological balances of lakes and lagoons are complex dynamic systems, and to elucidate them, isotopic tracers of water have been used as effective tools along with observations of precipitation, evaporation, inflows, and outflows. Here, to understand hydrological processes during freezing periods in the brackish Saroma‐ko Lagoon, Hokkaido, northern Japan, we examined horizontal and vertical distributions of salinity and isotope compositions of lagoon water and ice in 2005 and 2006. Horizontal and vertical gradients of salinity and isotope compositions were observed from the river mouth to the sea channel, and factors determining these distributions were considered. The mixing of freshwater and seawater and a freezing effect were presumed to be factors in relationships between salinity and isotopes and in relationships between surface waters and ice just above the water. A simple box model for water balance was constructed based on these putative factors to reproduce the distributions of salinity and isotope compositions of surface waters and ice. An evaluation of the model revealed that this hydrological system is controlled primarily by horizontal advection of the epilimnion, freshwater influx, and the ice growth rate. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献