Degradation rates of organic matter in the sediment of Mikawa Bay     

Katsuji Matsunaga  Nobuhiko Handa 《Journal of Oceanography》1983,39(3):101-109

Sedimentary core samples were collected from Mikawa Bay and analyzed for organic C, N and P, carbohydrate and protein including amino acids. Sedimentation rates for each of the core samples were found to lie in the range of 0.21–0.24 g cm^–2yr^–1 by the²¹⁰Pb method. Degradation rate constants of organic C, N and P, carbohydrate and protein including amino acids had ranges of 3.8–5.5, 4.7–5.9, 6.3–7.4, 5.7–6.8 and 3.9–6.8×10^–2yr^–1, respectively. The rate of degradation of organic matter in the sediment was also calculated and is discussed in relation to the flux of particulate organic matter to the surface of the sediment.  相似文献   

Monitoring the Kuroshio Extension with Dynamically Constrained Synthesis of the Acoustic Tomography, Satellite Altimeter and in situ Data     

Konstantin V. Lebedev  Max Yaremchuk  Humio Mitsudera  Iwao Nakano  Gang Yuan 《Journal of Oceanography》2003,59(6):751-763

A finite-difference quasigeostrophic (QG) model of an open ocean region has been employed to produce a dynamically constrained synthesis of acoustic tomography and satellite altimetry data with in situ observations. The assimilation algorithm is based upon the 4D variational data interpolation scheme controlled by the model's initial and boundary conditions. The data sets analyzed include direct and differential travel times measured at the array of five acoustic transceivers deployed by JAMSTEC in the region of the Kuroshio Extension in 1997, Topex/Poseidon altimetry, CTD soundings, and ADCP velocity profiles. The region monitored is located within the area 27.5°–36.5°N, 143°–155°. The results of assimilation show that mesoscale variability can be effectively reconstructed by five transceivers measuring direct and reciprocal travel times supported by relatively sparse in situ measurements. The misfits between model and data lie within the observational error bars for all the data types used in assimilation. We have compared the results of assimilation with the statistical inversion of travel time data and analyzed energy balances of the optimized model solution. Energy exchange between the depth-averaged and shear components of the observed currents reveals a weak decay of the barotropic mode at the rate of 0.2 ± 0.7⋅10⁻⁵ cm²/s³ due to topographic interaction. Mean currents in the region are unstable with an estimate of the available potential energy flux from the mean current to the eddies of 4.7 ± 2.3⋅10⁻⁵ cm²/s³. Kinetic energy transition has the same sign and is estimated as 2.8 ± 2.5⋅10⁻⁵ cm²/s³. Potential enstrophy is transferred to the mesoscale at a rate of 5.5 ± 2.7⋅10⁻¹⁸ s⁻³. These figures provide observational evidence of the properties of free geostrophic turbulence which were predicted by theory and observed in numerical experiments. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Reconstruction of sea surface dimethylsulfide in the North Pacific during 1970s to 2000s     

Y.W. Watanabe  H. Yoshinari  A. Sakamoto  Y. Nakano  N. Kasamatsu  T. Midorikawa  T. Ono 《Marine Chemistry》2007,103(3-4):347-358

We proposed an empirical equation of sea surface dimethylsulfide (DMS, nM) using sea surface temperature (SST, K), sea surface nitrate (SSN, μM) and latitude (L, °N) to reconstruct the sea surface flux of DMS over the North Pacific between 25°N and 55°N: ln DMS = 0.06346 · SST − 0.1210 · SSN − 14.11 · cos(L) − 6.278 (R² = 0.63, p < 0.0001). Applying our algorithm to climatological hydrographic data in the North Pacific, we reconstructed the climatological distributions of DMS and its flux between 25 °N and 55 °N. DMS generally increased eastward and northward, and DMS in the northeastern region became to 2–5 times as large as that in the southwestern region. DMS in the later half of the year was 2–4 times as large as that in the first half of the year. Moreover, applying our algorithm to hydrographic time series datasets in the western North Pacific from 1971 to 2000, we found that DMS in the last three decades has shown linear increasing trends of 0.03 ± 0.01 nM year^− 1 in the subpolar region, and 0.01 ± 0.001 nM year^− 1 in the subtropical region, indicating that the annual flux of DMS from sea to air has increased by 1.9–4.8 μmol m^− 2 year^− 1. The linear increase was consistent with the annual rate of increase of 1% of the climatological averaged flux in the western North Pacific in the last three decades.  相似文献   

Flux determination over a smooth surface under strongly unstable conditions     

Michiaki Sugita  Tetsuya Hiyama  Nobuhiko Endo  Shao-Fen Tian 《Boundary-Layer Meteorology》1995,73(1-2):145-158

Careful micrometeorological measurements on an empty parking lot allowed determination of the surface fluxes of sensible heatH and of momentum by applying profile equations derived from Monin-Obukhov similarity theory with two sets of the stability correction function for momentum _m and sensible heat _h . These fluxes were compared with reference values ofH independently determined by means of an eddy correlation technique. In general, better agreement was found betweenH values derived from profiles with the stability functions of Brutsaert (1992) and referenceH values, than when the Businger-Dyer functions were used to deriveH. The disagreement in the latter comparison was especially serious under strongly unstable conditions, with the value ofy=–z/L (wherez is the height andL is the Obukhov length) larger than 10. A closer look at the procedure for calculatingH from the profiles revealed that the large differences between theH values derived with these two different versions of the stability correction functions were caused by the small differences of the _h values, and not by the larger differences of the _m values. This result stems from the strong sensitivity of the resultingH values on the choice of _h .  相似文献   

2500年来艾比湖的环境演变信息   总被引：22，自引：9，他引：22  

阎顺  穆桂金  远藤邦彦  Nobuhiko Handa  Masao Uchida  Naomi Harada 《干旱区地理》2003,26(3):227-232

通过对艾比湖缘1，8m浅孔的沉积相和孢粉组合，结合14C测年资料分析。指出近2500年来艾比湖的沉积环境总体是比较稳定的，但由于气候波动引起艾比湖水位曾发生较明显的变化。约在公元前300～400年，是艾比湖面积缩小时期；约公元前300—公元300年，即东周末至西晋，是艾比湖水位较高时期；约公元300—1400年，即东晋至15世纪初，是艾比湖的高水位时期；约15世纪初至17世纪中是艾比湖的水位下降期，但水位比现代仍然高；约17世纪中至19世纪初的小冰期是艾比湖的水位上升期。研究还提供了历史时期湖泊的盐度变化和湖周发生大火的信息。  相似文献   

Report of the International Symposium of IGCP-440 and LEGENDS Proposal in Sri Lanka, March-April 2003     

Masaru Yoshida  Yasuhito Osanai  Masaaki Owada  Nobuhiko Nakano  Wilbert K.W. Kehelpannala 《Gondwana Research》2003,6(4):939-941

  相似文献   

Transport of water in frozen soil: V, Method for measuring the vapor diffusivity when ice is absent     

Yoshisuke Nakano  Allen R. Tice  Thomas F. Jenkins 《Advances in water resources》1984,7(4):172-179

A new experimental method is introduced for determining the relative magnitudes of liquid and vapor diffusion by using a small amount of soluble chemical as a tracer. The theoretical justification of the method is presented for the case where ice is absent. The feasibility of the method is demonstrated by an experiment using marine-deposited clay.  相似文献   

On the stable growth of segregated ice in freezing soil under negligible overburden pressure     

Yoshisuke Nakano 《Advances in water resources》1986,9(4)

The stable growth condition of a segregated ice layer is studied by the use of the principle of mass and heat conservation. This condition evidently depends upon the properties of a thin transitional zone, which is believed to exist between the boundary of an ice layer and a 0[°C] isotherm. All probable models of the transitional zone are classified and the conditions for each model is derived. The effect of the small amount of soil minerals contained in an ice layer is also studied.  相似文献   

Transport of water in frozen soil: I: Experimental determination of soil-water diffusivity under isothermal conditions     

Yoshisuke Nakano  Allen Tice  Joseph Oliphant  Thomas Jenkins 《Advances in water resources》1982,5(4):221-226

A new experimental method for measuring the soil-water diffusivity of frozen soil under isothermal conditions is introduced. The theoretical justification of the method is presented and the feasibility of the method is demonstrated by experiments conducted using marine deposited clay. The measured values of the soil-water diffusivity are found comparable to reported experimental data.  相似文献   

Seepage and consolidation of bentonite saturated with pure- or salt-water by the method of unified molecular dynamics and homogenization analysis     

Y. Ichikawa  K. Kawamura  M. Nakano  K. Kitayama  T. Seiki  N. Theramast 《Engineering Geology》2001,60(1-4):127-138

Bentonite clay is a micro-inhomogeneous material, which consists of clay minerals (mainly montmorillonite), macro-grains (mainly quartz), water, air and others. Properties of the saturated bentonite clay are essentially characterized by the montmorillonite and water (i.e. montmorillonite hydrate). We analyze the molecular behavior of sodium montmorillonite hydrate Na_1/3Al₂[Si_11/3Al_1/3]O₁₀(OH)₂·nH₂O by applying a molecular dynamics (MD) simulation method. And by using the MD results we calculate the swelling property of the montmorillonite hydrate, and compare with an experimental result. Next, by using the same MD procedure we treat a montmorillonite mineral with a large number of external water molecules to check the properties of the water. Here we treat pure- and salt-water. Then we calculate the diffusivity and viscosity of water molecules and Na⁺ and Cl⁻ ions.

For extending the microscopic characteristics of constituent materials to a macroscopic seepage behavior of the micro-inhomogeneous material we apply a homogenization analysis (HA). That is, starting with the Navier–Stokes equation with distributed viscosity that is calculated by the former MD procedure we determine macroscopic permeability characteristics of bentonite for both cases of pure- and salt-water. Then, by using the permeability property we calculate long-term consolidation behavior of buffering clay, which is planed to be used for high-level radioactive waste (HLRW) management. Here the deformation is treated under the well-defined Cam clay model.  相似文献