The distribution of chlorophylla,protein, RNA and DNA in the North Pacific Ocean     

Masayuki Takahashi  Hiroko Nagai  Yukuya Yamaguchi  Shun-ei Ichimura 《Journal of Oceanography》1974,30(3):137-150

Chla, protein, RNA and DNA were measured in 400 samples taken from the surface down to 5,000 m at 27 oceanographical stations in the North Pacific Ocean. Two section diagrams of these cellular constituents were given along 155°E and 155°W meridians, and several vertical profiles of the four constituents were also given at some stations near Japan. The average concentration ranges of Chla, protein, RNA and DNA obtained in this study area were 0.025–0.862, 11.4–88.1, 1.36–35.3 and 0.13–5.24g/l, respectively. Chla was distributed mostly in the photic zone as we would expect. However protein, RNA were in high concentrations within the photic zone and sometimes extremely high concentrations in the deep aphotic zone.  相似文献   

A comparison of four methods for integrating14C-primary productivity measurements per unit area     

Shun-ei Ichimura  Timothy R. Parsons  Masayuki Takahashi  Humitake Seki 《Journal of Oceanography》1980,36(5):259-262

Four methods were compared for the integration of¹⁴C-primary productivity per m²; (1) thein situ method at 0, 2.5, 5, 7.5, 10 and 12.5 m (standard depths 1); (2) thein situ method at 0, 5, 10 and 12.5 m (standard depths 2); (3) thein situ method at 2.5, 7.5 and 11.5 m for each sample pumped over depth intervals 0 to 5 m, 5 to 10 m, and 10 to 12.5 m, respectively (integrated depths); and (4) the simulatedin situ method for samples collected from light standard depths. The method which appeared to give the most reliable results was that (3) in which samples were averaged by pumping water over the euphotic depth followed by incubation of integrated samples at the middle of each depth interval.  相似文献   

Distribution of the subsurface chlorophyll maximum and its nutrient-light environment in and around the Euroshio off Japan     

Masayuki Takahashi  Toshisuke Nakai  Takashi Ishimaru  Hiroshi Hasumoto  Yoshihiko Fujita 《Journal of Oceanography》1985,41(2):73-80

Continuous distribution of the subsurface chlorophyll maximum (SCM) was confirmed in the Kuroshio and neighbouring areas in observations at 15 to 40 km intervals. Chlorophyll amounts occurring in and immediately around the SCM constituted 60 to 80% of the total chlorophyll in the water column above the 1% light level. The SCM zone received 1 to 10% of the surface irradiance at its center and contained sufficient macronutrients to support approximately one doubling of the existing phytoplankton biomass at most stations. There were several stations where there were higher nutrient concentrations that would support more than one doubling of the existing biomass around the SCM zone, and this was interpreted as resulting from uplift of the SCM zone due to upwelling.  相似文献   

Forced convection accompanying wind waves     

Yoshiaki Toba  Masayuki Tokuda  Kuniaki Okuda  Sanshiro Kawai 《Journal of Oceanography》1975,31(5):192-198

Wind-wave tunnel experiments reveal, by use of techniques of the flow visualization, that wind waves are accompanied by the wind drift surface current with large velocity shear and with horizontal variation of velocity relative to the wave profile. The surface current converges from the crest to a little leeward face of the crest, making a downward flow there, even though the wave is not breaking. Namely, wind waves are accompanied by forced convections relative to the crests of the waves. Since the location of the convergence and the downward flow travels on the water surface as the crest of the wave propagates, the motion as a whole is characterized by turbulent structure as well as by the nature of water-surface waves. In this meaning, the term of real wind waves is proposed in contrast with ordinary water waves. The study of real wind waves will be essential in future development of the study of wind waves.  相似文献   

Photosynthetic pigment system of picophytoplankton of cyanophytes isolated from subsurface water in the Kuroshio area     

Tohru Ikeya  Kaori Ohki  Masayuki Takahashi  Yoshihiko Fujita 《Journal of Oceanography》1991,47(1):1-6

Photosynthetic pigment system of picophytoplankton of cyanophytes was examined with five strains isolated from the Kuroshio water at the depth of 70 m. Examination was made for the absorption spectra of intact cells of each strain. Analysis of pigment composition was also made withSynechococcus NIBB 1059 and 1071, which were isolated from surface waters of the Gulf Stream and Kuroshio area, respectively. Results indicated that (1) all strains contain phycoerythrin with a very high concentration, and (2) the phycoerythrin in these strains contains two chromophores, phycoerythrobilin and phycourobilin, and (3) a large abundance of phycoerythrin and phycourobilin in the phycoerythrin enablesSynechococcus picophytoplankton to absorb effectively the light in the blue-green region at the subsurface depth. These characteristics suggest that cyanophytes in the subsurface water can collectt the blue-green light and perform actively photosynthesis even at the bottom of euphotic layer.  相似文献   

A pump-sampler as a method of collecting plankton and its preliminary operation     

Akihiko Kuwahara  Tsuneyuki Abe  Masayuki Shimono  Makoto Kashiwai  Masatosi Sinoda 《Journal of Oceanography》1973,29(3):106-112

A pump-sampler was designed to study the distribution of marine plankton and its possible relationship with the temperature and salinity of the water. Sea water was pumped up through a 2 inch diameter hose and plankton contained in it was collected on a filter cup (2 inches in diameter, 139 meshes/inch) without being damaged. The filter cup, when clogged by plankton organisms, was washed by spraying with about 100 cu. cm of water. The differences between two continuous with an interval of more than 3–4 seconds could be detected.A preliminary operation along a 2.82 km course in Maizuru Bay was carried out simultaneously with temperature-salinity measurements at sampling intervals of 30 m. Temperature was measured by a thermistor resistance thermometer, and salinity was measured by a salinometer with a subsample of water which was collected from an additional opening of the pump-sampler. The temperature-salinity record showed that four zones of water were characterized.It was found that wide variation of plankton counts indicated dense concentrations of particular species or group of species, and on the mesoscale it was possible to examine the size of the aggregation.  相似文献   

Chlorophyll a Biomass of Netplankton in Surface Waters of the Northern North Pacific Ocean and the Adjacent Seas from Summer to Autumn     

Dong-Hoon Han  Masayuki Mac Takahashi 《Journal of Oceanography》2000,56(2):213-222

Chlorophyll a concentrations of net (retained on 30 m mesh net) and total plankton in surface waters were determined along cruise tracks in an area of the northern North Pacific Ocean and the adjacent Bering Sea and the Gulf of Alaska from summer to autumn. Total chlorophyll a concentrations were high with a great areal and temporal variations in the western northern North Pacific compared to the eastern part. Chlorophyll a concentrations of netplankton varied from 0.001 to 0.230 g chl a l^–1 (average, 0.029 ± 0.040 g chl a l^–1), and showed a positive relation but a weak regression coefficient (r ² = 0.551) against the "average total chlorophyll a" (average of total chlorophyll a at the beginning and at the end during sampling of netplankton). However there were several data points showing high "average total chlorophyll a" but low netplankton and vice versa. Average percentage share of netplankton in the total chlorophyll a was estimated to be as large as 4.26%.  相似文献   

Taylor-Görtler vortices expected in the air flow on sea surface waves—II     

Masayuki Tokuda 《Journal of Oceanography》1976,32(3):128-138

The instability of Taylor-Görtler vortices which are expected in the air flow on water waves was studied in part I, under the assumption that the curvature around the crest or the trough of water waves, where the instability was expected to take place first, was constant, namely that the characteristics of the vortices were affected little by the local change of the curvature along the direction of the progress of water waves (the direction ofx-axis) However, the curvature actually varies from positive to negative, or vice versa. In order to study this effect, the instability of Taylor-Görtler vortices is examined with respect to the range of the part of a constant curvature, in the model in which the curvature is positive constant near the trough and negative constant near the crest, and zero in the intermediate regions, respectively. It is shown that as the region of the constant curvature becomes narrower, the instability tends to weaken. For the same example with part I, namely, when the wind of 12.2 m s^–1 is blowing over swells of 15 m in wavelength, if the range of constant curvature near the trough is taken as a quarter of one wave length, the critical wave height becomes 0.96 m instead of 0.50 m, and conversely, the wave length and the height of center of the vortex become 11.9 m and 2.1 m instead of 24 m and 3.7 m, respectively.Further, using the energy equations, quantitative estimates are performed of the intensity of the vortices which develop when the wave height of the swell is 1.05 m in the above described example, and also of the influence of the vortices upon the wind profile when the equilibrium state is reached. When the vortices are generated and grow to attain to an equilibrium state interacting with the mean flow, the maximumx-component of velocity in the vortices is about 1.04 m s^–1. Consequently, the wind profile undergoes a considerable distortion from the logarithmic one near the level of 2 m height. This distorted wind profile has a form similar to those sometimes observed above the sea surface.  相似文献   

Dynamical instability of the envelope of red supergiants and the lower mass limit for carbon detonation supernovae     

Masayuki Y. Fujimoto  Ken'ichi Nomoto  Daiichiro Sugimoto 《Astrophysics and Space Science》1976,45(1):71-77

We investigated the lower mass limitM _l for the carbon detonation supernovae by testing the dynamical instability of the envelopes of red supergiants. It was found that the dependence ofM _l on the mixing lengthl of convection is appreciable. As a smaller value ofl is assumed,M _l becomes larger. It may be as large as 8M ifl is a third of the pressure scale-height. This is one of the ways to remove the difficulty of overproduction of iron-peak elements involved in the model of the carbon detonation supernovae.  相似文献   

Two geomagnetic excursions during the Brunhes chron recorded in Chinese loess-palaeosol sediments     

Tianshui Yang  Masayuki Hyodo  Zhenyu Yang  Jianli Fu 《Geophysical Journal International》2007,171(1):104-114

Detailed palaeomagnetic integrated with rock magnetic studies have been carried out on a loess-palaeosol sequence in Baoji, Shaanxi province, southern Chinese Loess Plateau. For most samples stepwise thermal demagnetization revealed two well-defined magnetization components. A low-temperature component (LTC), which was isolated between 100 and 200 °C, is consistent with the present geomagnetic field direction. A high-temperature component (HTC), which was isolated between 250 and 620–680 °C, shows normal, reversed or transitional polarities. Our new magnetostatigraphy revealed two distinct geomagnetic excursions recorded in loess unit of L5 and palaeosol unit of S7, respectively, and the Matuyama-Brunhes (M-B) polarity boundary in loess unit of L8. Rock magnetic experiments demonstrated that the specimens from the excursion zones have the same magnetic properties as those from the Brunhes normal or Matuyama reversed polarity zones. Measurements of anisotropy of magnetic susceptibility (AMS) showed that the sediments have primary sedimentary fabrics. Based on the palaeoclimatological and magnetostratigraphic age models, the middle Brunhes excursion in loess L5 is dated at 413–433 ka, and the early Brunhes excursion is estimated to occur 23–33 ka after the M-B reversal. Comparing with previously reported geomagnetic excursions in the Brunhes chron, the middle Brunhes excursion (L5) is likely global. For the early Brunhes excursion (S7), we need further studies to examine its global occurrence.  相似文献