Sensitive determination of enzymatically labile dissolved organic phosphorus and its vertical profiles in the oligotrophic western North Pacific and East China Sea     

Fuminori Hashihama  Shinko Kinouchi  Shuhei Suwa  Masahiro Suzumura  Jota Kanda 《Journal of Oceanography》2013,69(3):357-367

Trace concentrations of labile dissolved organic phosphorus (LDOP) in oligotrophic seawater were measured by use of an enzymatic procedure and a nanomolar phosphate analytical system consisting of a gas-segmented continuous flow analyzer with a liquid waveguide capillary cell. LDOP, defined as DOP hydrolyzed by alkaline phosphatase (AP) from Escherichia coli, was quantified as the difference between the phosphate concentrations of the seawater sample with and without AP treatment. For sensitive measurement of LDOP, we found that phosphate contamination derived from commercially available AP must be corrected, and azide treatment before AP treatment proved effective in removing biological effect that occurs during DOP hydrolysis. Field observations at six stations of the western North Pacific and the East China Sea during the boreal summer revealed that, in the upper 200 m of the water column, LDOP concentrations ranged from the detection limit (3 nM) to 243 nM, and phosphate concentrations ranged from 5 to 374 nM. The spatial distribution patterns of LDOP were similar to those of phosphate. Most of the depth profiles for LDOP and phosphate showed concentrations were extremely low, <25 nM, between the surface and the deep chlorophyll maximum layer (DCML) and increased below the DCML. Strongly depleted LDOP and phosphate above the DCML suggest that LDOP is actively hydrolyzed under phosphate-depleted conditions and utilized by microbes.  相似文献   

Potential and gravity changes raised by point dislocations   总被引：9，自引：0，他引：9  

Shuhei Okubo 《Geophysical Journal International》1991,105(3):573-586

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Numerical studies on the two-dimensional flow in horizontally homogeneous canopy layers     

Junsei Kondo  Shuhei Akashi 《Boundary-Layer Meteorology》1976,10(3):255-272

The two-dimensional equation of motion containing the pressure gradient and Coriolis force is numerically solved for the wind field in and above the layers of a horizontally homogeneous canopy with a vertical distribution of leaf-area densities. The solution shows that, in the case of descending through the canopy, the wind vector turns with an angle which depends on the profile of leaf-area densities. In particular, for the canopy of a forest consisting of upper layers with higher densities and lower layers with smaller densities, the turning is striking; a secondary maximum in wind profile appears in the lower layers.Variations of the aerodynamic parameters for the flow above the canopy are indicated with respect to the leaf-area density. The roughness length varies in such a manner that a maximum appears in intermediate density values, depending on the shape of the profile of leaf-area density. In the case of very dense canopies, the shearing stress acting on the flow above the canopy is determined by the contribution from only the upper canopy elements, but not by that from the lower parts of the canopy.  相似文献   

Equation of state of hexagonal aluminous phase in basaltic composition to 63 GPa at 300 K     

S. Ono  K. Hirose  M. Isshiki  K. Mibe  Y. Saito 《Physics and Chemistry of Minerals》2002,29(8):527-531

A laser-heated diamond-anvil cell that is capable of operating up to a pressure of 63 GPa, with X-ray diffraction facilities using a synchrotron radiation source at the SPring-8, has been developed to observe the compressibility of a hexagonal aluminous phase, [K_0.15Na_1.66Ca_0.11Mg_1.29Fe²⁺ _0.86Al_3.13Ti_0.09Si_1.98] _Σ9.27O₁₂. The hexagonal aluminous phase is a potassium host mineral from the subducted oceanic crust in the Earth's lower mantle. A sample was heated using a YAG laser at each pressure increment to relax the deviatoric stress in the sample. X-ray diffraction measurements were carried out at 300 K using an angle-dispersive technique. Pressure was measured using an internal platinum pressure calibrant. The observed unit-cell volumes were used to obtain a third-order Birch–Murnaghan equation of state: unit-cell volume V _o=185.94(±16) ų, density ρ _o=4.145 g/cm³, and bulk modulus K _o=198(±3) GPa when the first pressure is derivative of the bulk modulus K ^′ _o is fixed to 4. The density of hexagonal aluminous phase is lower than that of coexisting Mg-perovskite in the subducted oceanic crust.  相似文献   

Compressibility of the calcium aluminosilicate, CAS, phase to 44 GPa     

Shigeaki Ono  Tsuyoshi Iizuka  Takumi Kikegawa 《Physics of the Earth and Planetary Interiors》2005,150(4):331-338

In situ X-ray diffraction measurements on a calcium aluminosilicate (CAS) phase have been carried out using a laser-heated diamond anvil cell up to a pressure of 44 GPa, employing a synchrotron radiation source. CAS is the major mineral formed from sediments subducted into the Earth's mantle. The sample was heated using a YAG laser after each pressure increment to relax the deviatoric stress in the sample. X-ray diffraction measurements were carried out at T = 300 K using an angle-dispersive technique. The pressure was calculated using an internal platinum metal pressure calibrant. The Birch–Murnaghan equation of state for the CAS phase obtained from the experimental unit cell parameters showed a density of ρ₀ = 3.888 g/cm³ and a bulk modulus of K₀ = 229 ± 9 GPa for K^′₀ = 4.7 ± 0.7. When the first pressure derivative of the bulk modulus was fixed at K^′₀ = 4, then the value of K₀ = 239 ± 2 GPa. From the experimental compressibility, the density of the CAS phase was observed to be lower than the density of co-existing Al-bearing stishovite, calcium perovskite, calcium ferrite-type phases, and (Fe,Al)-bearing Mg-perovskite in subducted sediments in the lower mantle. Therefore, the density of subducted sediments in the lower mantle decreases with increasing mineral proportion of the CAS phase.  相似文献   

Notes　on　Extended-Range　Atmospheric　Prediction　in　the　Northern　Hemisphere　Winter     

Shingo Yamada Forecast Division  Japan Meteorological Agency  Tokyo    Japan Shuhei Maeda Administration Division  Climate  Marine Department  Japan Meteorological Agency  Tokyo    Japan K. Gambo c/o Department of Earth  Planetary Physi 《大气科学进展》1997,(1)

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Magnetic grain‐size distribution of the enhanced component in the loess–palaeosol sequences in the western Loess Plateau of China     

Toshiaki Mishima  Masayuki Torii  Hitoshi Fukusawa  Yugo Ono  Xiao-Min Fang  Bao-Tian Pan  Ji-Jun Li 《Geophysical Journal International》2001,145(2):499-504

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Accuracy of gravimetric deflections of the vertical and optimization of gravity networks     

S. Ono 《Journal of Geodesy》1985,59(3):275-288

In order to solve the problems of determining the shape of a part of the earth of national or continental extent, that is, of rigorous constituting and computing of the astrogeodetic network, it is required to determine gravimetric deflections of the vertical with an accuracy of, say, 0″.3. For this it is adequate to carry out additional gravity surveys in the neighborhoods of computation points, in addition to a given uniform gravity survey (normal density gravity survey). The study offers a method to determine the optimal distribution of gravity stations in such a gravity survey, which guarantees a given accuracy of computed gravimetric deflections of the vertical for a given statistical condition which characterizes the variation of the gravity field. The approach used here is based on the concept of the error of representation and the error propagation of Vening Meinesz integrals.  相似文献   

Green's functions of coseismic strain changes and investigation of effects of Earth's spherical curvature and radial heterogeneity   总被引：2，自引：0，他引：2  

Wenke Sun  Shuhei Okubo  Guangyu Fu 《Geophysical Journal International》2006,167(3):1273-1291

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Characterization of serpentinization in olivine-orthopyroxene-H2O system revealed by thermogravimetric and multivariate statistical analyses     

Atsushi Okamoto  Shuhei Tanaka  Masaoki Uno  Otgonbayar Dandar  Kazuki Yoshida 《Island Arc》2024,33(1):e12519

Thermogravimetric (TG) analyses were used to characterize the products and quantify the extent of serpentinization as a stepwise weight loss during heating (TG loss) or its derivative (DTG). Multivariate analyses are powerful tools for extracting information from complicated spectrum data; however, no studies have applied them to characterize serpentinites. In this study, hydrothermal experiments of olivine-H₂O, olivine–orthopyroxene-H₂O and orthopyroxene-H₂O were conducted at 250–400°C and under vapor-saturated pressure. The product minerals observed were serpentine+brucite+magnetite in the olivine-H₂O experiments and serpentine±talc in the orthoyroxene-H₂O and olivine-orthopyroxene-H₂O experiments. These results are consistent with those of previous studies; however, the positions and width of DTG peaks for individual minerals were varied depending on the experimental conditions. To extract systematics from the TG spectra, non-negative matrix factorization (NMF), an unsupervised machine learning technique, was applied to the DTG spectra of the experimental products. NMF revealed that the DTG profiles were explained by a linear combination of six basis spectra, which corresponded to the characteristic products, including three types of serpentine minerals (low-, medium-, and high-T), two types of brucite (low-and high-T), two type of talc (talc+serpentine mixture, well-crystallized talc) with different crystallinity, and noise during the TG measurement. Systematic changes in the factor loading revealed that, in the olivine-H₂O systems, the products changed from medium-T serpentine+low-T brucite to high-T serpentine+high-T brucite as serpentinization progressed. In the olivine-orthopyroxene system, low-T serpentine or poorly crystallized talc+serpentine mixture was initially formed, followed by the formation of well-crystallized talc, resulting in dehydration. Applying NMF to DTG showed the mineralogical differences between olivine and orthopyroxene systems and increases of the crystallinity during the progress of serpentinization, suggesting its potential for characterizing various serpentinites within oceanic lithospheres that suffer from several stages of alteration and weathering at different temperatures.  相似文献