Loss Processes of Sinking Fecal Pellets of Zooplankton in the Mesopelagic Layers of the Antarctic Marginal Ice Zone     

Hidekatsu Suzuki  Hiroshi Sasaki  Mitsuo Fukuchi 《Journal of Oceanography》2003,59(6):809-818

A time-series sediment trap deployment was carried out in the marginal ice zone (MIZ) of the Antarctic Ocean (64°42′ S, 139°58′E; sea depth of 2930 m), during the austral summer. Cylindrical fecal pellets were the predominant sinking particles at 537 m in the middle of January and most of them disappeared below that depth, the loss of which were 25.3 mg C m⁻² day⁻¹ in the depth range of 537–796 m. Small-sized sinking particles other than fecal pellets increased in that depth range. Analyses of fecal pellets for remnant DNA corresponding to 16S mitochondrial RNA and 28S ribosomal RNA suggested that the large cylindrical fecal pellets at 537 m were produced by Antarctic krill (Euphausia superba) and copepods. According to the presence of the DNA associated with sinking particles, E. superba fecal pellets rapidly disappeared below 537 m, while copepod fecal pellets still remained in the mesopelagic and bathypelagic layers. Small-sized amorphous sinking particles at 537 m also contained E. superba- and copepod-derived DNA. The abundance of trap-collected copepods (Oithona spp. and Oncaea spp.) which are known to be coprophagous increased at 796 m where many fecal pellets disappeared. We suggest that those rapidly sinking pellets were fragmented by copepods with intensified coprorhexy activity (fragmentation of fecal pellets) in the mesopelagic layers, reducing their sinking rates. These smaller and slower sinking particles can be important food sources for detritivorus or coprophagous animals in mesopelagic and bathypelagic layers in the MIZ. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Dating of Japanese Quaternary tephras by ESR and luminescence methods   总被引：1，自引：0，他引：1  

S. Toyoda  S. Tsukamoto  S. Hameau  H. Usui  T. Suzuki 《Quaternary Geochronology》2006,1(4):320-326

Electron spin resonance (ESR) and red thermoluminescence (RTL) methods were applied to quartz of eight Japanese Quaternary tephras ranging from 30 to 900 kyr, which have independent ages from other dating methods. The ESR ages were consistent for younger samples, while those from the Ti–Li center are older than those for the Al center for older samples. RTL ages are consistent with the age references and are roughly consistent with Al center ages. The dose response of the Ti–Li center after heating at 260 °C for 15 min implies that thermally unstable component is created in Ti–Li center by irradiation, leading to possible overestimations in the dose values.  相似文献   

Geological causes and geomorphological precursors of the Tsaoling landslide triggered by the 1999 Chi-Chi earthquake, Taiwan   总被引：5，自引：0，他引：5  

Masahiro Chigira  Wen-Neng Wang  Takahiko Furuya  Toshitaka Kamai   《Engineering Geology》2003,68(3-4):259-273

The Tsaoling landslide, one of the largest landslide areas in Taiwan, has been affected by catastrophic events triggered by rain or earthquakes six times since 1862. These landslides, including that caused by the 1999 earthquake, have essentially not been reactivated old slides, but were sequential new ones that developed upslope, retrogressively. The landslide area is underlain by Pliocene sandstone and shale to form a dip slope with a bedding plane, dipping uniformly at 14°. The slip surface of the 1999 landslide was smooth and planar, parallel to the bedding plane with a slightly stepped profile; it formed within thinly alternated beds of fine sandstone and shale with ripple lamination or in a shale bed. The shale is weathered by slaking and probably by sulfuric acid, which is inferred to be one of the major causes of the intermittent retrogressive development of the landslides. The weathering was likely accelerated by the removal of overlying beds during earlier landslides in 1941 and 1942. The top margin of the 1999 landslide, in plan view, coincided with a V-shaped scarplet, which can be clearly recognized on aerial photographs taken before the landslide. This geomorphological feature indicates that this landslide had already moved slightly before its 1999 occurrence, providing precursory evidences.  相似文献   

Filamentation Instability of Nonlinear Alfvén Waves and Plasma Heating associated with Recombination Effect     

M. Suzuki  J. I. Sakai 《Solar physics》1998,178(1):43-53

We investigate plasma heating associated with the effect of recombination and the filamentation instability of Alfvén waves propagating along homogeneous magnetic field in low-beta plasmas, by using an MHD simulation code. The linear instability of Alfvén waves leading to the filamentation is investigated by imposing small density perturbations across a magnetic field. We show results of the nonlinear stage of the above filamentation instability and the plasma heating through a two-dimensional simulation. It is shown that the plasma heating is caused by localized heating and whole heating, which are associated with the filamentation instability and the effect of recombination, respectively. We discuss the implication of these results for plasma heating processes observed in the chromosphere of the Sun.  相似文献   

The Rotation of Sunspots During Activity Cycle 22     

Suzuki  Miyosi 《Solar physics》1998,178(2):259-265

The solar rotation rate derived from the measurements of daily sunspot positions during activity cycle 22 (1988–1996) are presented. The averaged differential rotation is nearly symmetric with respect to the equator. The comparisons of our measurement with those for previous cycles show that the equatorial rotation rate gradually increases from cycle 18 to 22.  相似文献   

Lateral structural variation across a collision zone in central Hokkaido, Japan, as revealed by wide-angle seismic experiments     

Takaya Iwasaki  Oguz Ozel  Takeo Moriya  Shin'ichi Sakai  Sadaomi Suzuki  Gen Aoki  Takuya Maeda†  & Takashi Iidaka 《Geophysical Journal International》1998,132(2):435-457

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Late Olenekian Radiolarians from Bedded Chert of Ashio Terrane, Northeast Japan,and Faunal Turnovers in Western Panthalassa during Early Triassic     

NoritoshiSuzuki  NatsumiAkiba 《中国地质大学学报(英文版)》2002,13(2):124-140,T001

Late Olenekian assemblages in the western Panthalassa have been recovered from bedded radiolarian chert sequences of an accretionary complex, the Ashio belt. These faunas are documented and considered in terms of radiolarian diversity and faunal turnover during the latest Permian to Middle Triassic time. The fauna includes 30 radiolarians belonging to Spumellaria or Entactinaria, with two relicts from the Late Permian. This late Olenekian fauna is markedly different from Permian and Asisian faunas, respectively, and is herein named the Minowa fauna. Study of the literaure indicates that radiolarian provinces were significantly disconnected between the western Panthalassa and eastern Tethys during late Olenekian time. Furthermore, 121 of 143 species disappeared during late Olenekian time, and in turn 118 new species appeared in the western Panthalassa around the Olenekian-Anisian boundary. It is concluded that faunal turnover occurred at least three times between the latest Permian and Middle Triassic.The first turnover is the Poalaozoie-type radiolarian extinction at the Permain-Triassic boundary,the second is the diversification of spheroidal Spumellaria and Entactinaria between early and late Olenekian time, and the third is a faunal turnover from the Minowa fauna to the true Mesozoic-type radiolarian famas that are characterized by mulit0segmented Nassellaria.  相似文献   

Seismic activity in the northeastern Japan arc     

Akio Takagi  Akira Hasegawa  Norihito Umino  Ziro Suzuki 《Physics of the Earth and Planetary Interiors》1979,18(4):351-354

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Thermal expansion of single-crystal tephroite     

Shinichi Okajima  Isao Suzuki  Kiyoshi Seya  Yoshio Sumino 《Physics and Chemistry of Minerals》1978,3(2):111-115

The thermal expansion of tephroite (Mn₂SiO₄) at temperatures between 25 and 850°C has been determined by a dilatometric technique. The analysis of data in terms of Grüneisen's theory yields the Grüneisen's parameter γ=1.04, and the pressure derivative of rigidity (?G/?P)=0.7.  相似文献   

Examination of a Correction Procedure for the Flow Attenuation in Orthogonal Sonic Anemometers     

Takanori Shimizu  Masakazu Suzuki  Akira Shimizu 《Boundary-Layer Meteorology》1999,93(2):227-236

In this study we examine the calibration of wind speed measured by a sonic anemometer, with an orthogonal probe configuration, with regard to the approximation of the flow angle, and the wind-speed dependence of the flow attenuation attributed to the transducer shadow. The flow angle should be calculated by the iterative method when the attenuation is relatively high. For a probe manufactured by Kaijo Co. TR-61C, the wind-speed dependence of the transducer shadow effect is formulated from the results of the wind-tunnel experiment. Assuming the equation is applicable to field observations, significant errors possibly remain especially when the wind speed is low, and /or the angle between the flow vector and the sonic path is small, if the wind-speed dependence in measurement errors is neglected.  相似文献