Basin-Scale Geographic Patterns of Bacterioplankton Biomass and Production in the Subarctic Pacific, July–September 1997     

Toshi Nagata  Rumi Fukuda  Hideki Fukuda  Isao Koike 《Journal of Oceanography》2001,57(3):301-313

Bacterial biomass and production rate were measured in the surface (0–100 m) and mesopelagic layers (100–1,000 m) in the subarctic Pacific and the Bering Sea between July–September, 1997. Depth profiles were determined at stations occupied in oceanic domains including the subarctic gyres (western, Bering Sea, and Gulf of Alaska) and a boundary region south of the gyres. In the surface layer (0–100 m), both bacterial biomass and production were generally high in the western and Bering Sea gyres, with the tendency of decrease toward east. This geographic pattern was consistent with the dominant regime of phytoplankton biomass at the time of our survey. A significant portion of variation in bacterial production was explained by the concentration of chlorophyll a (r ² = 0.340, n = 60, P < 0.001) and, to the greater extent, by the concentration of semilabile total organic carbon (SL-TOC = TOC at a given depth—TOC at 1,000 m, r ² = 0.488, n = 59, P < 0.0001). Temperature significantly improved the regression model: temperature and chlorophyll jointly explained 60% of variation in bacterial production. These results support the hypothesis that bacteiral growth is largely regulated by the combination of temperature and the supply of dissolved organic carbon in subarctic surface waters. In the mesopelagic layer (100–1,000 m), the geographic pattern of bacterial production was strikingly different from the surface phytoplankton distribution: the production was high in the boundary region where the phytoplankton biomass was lowest. Bacterial growth appeared to be largely controlled by the supply of organic carbon, as indicated by the strong dependency of bacterial production on SL-TOC (r ² = 0.753, n = 75, P < 0.0001). The spatial uncoupling between surface phytoplankton and mesopelagic bacterial production suggests that the supply rate of labile dissolved organic carbon in the mesopelagic zone does not simply reflect the magnitude of the particulate organic carbon flux in the subarctic Pacific.  相似文献   

Vertical Distributions of Phyllosoma Larvae of Palinurid and Scyllarid Lobsters in the Western North Pacific     

Hideki Minami  Nariaki Inoue  Hideo Sekiguchi 《Journal of Oceanography》2001,57(6):743-748

Vertical distributions of phyllosoma larvae were examined in waters east of the Philippines or west of the Mariana Islands (18°56′ N to 19°04′ N; 129°10′ E to 129°35′ E) based on zooplankton samples collected with an Isaacs-Kidd Midwater Trawl on September 22–24, 1986. Phyllosoma larvae belonged to the two families Scyllaridae and Palinuridae comprising 4 genera and 9 species. Of the collected phyllosoma larvae, those of Scyllarus cultrifer and Panulirus longipes were most abundant and showed similar vertical distributions: (1) both species were collected from the mixed layer at night but not in the day, (2) their vertical distributions did not change with their stages, and (3) the upper limit of their vertical distributions during the day accorded with the base of mixed layer. Furthermore, their vertical distributions were similar to those of lepthocephalus larvae which were collected using the same sampling stations and gear in the present study. Vertical distributions of phyllosoma larvae were discussed in relation to their horizontal distributions. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Magma intrusion and discharge process at the initial stage of the 2000 activity of Miyakejima, Central Japan, inferred from tilt and GPS data   总被引：2，自引：0，他引：2  

Hideki Ueda  Eisuke Fujita  Motoo Ukawa  Eiji Yamamoto  Meilano Irwan  Fumiaki Kimata 《Geophysical Journal International》2005,161(3):891-906

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Structure of the Jan Mayen microcontinent and implications for its evolution     

Shuichi Kodaira  Rolf Mjelde  Karl Gunnarsson  Hajime Shiobara  & Hideki Shimamura 《Geophysical Journal International》1998,132(2):383-400

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T waves from deep earthquakes generated exactly at the bottom of deep-sea trenches     

Hideki Shimamura  Toshi Asada 《Earth and Planetary Science Letters》1975,27(2):137-142

T waves (seismic water waves), which were generated by deep-focused earthquakes, have been found by an array of sensitive ocean-bottom seismographic observations depolyed on the western Pacific basin. The points of generation of T waves have been exactly located by use of the accurate velocity of water waves which were known from explosions. The positions obtained are at the bottom of deep-sea trenches; however, the positions are slightly (10–35 km) ocean-side of the trench. T waves have been known to be generated by seismic waves which were transmitted from the focus to the trench bottom along the descending lithosphere. The intensity of the observed T waves implies that the Q value along the descending lithosphere is more than 4000. The positions of T-wave generation are consistent with the 8.2- to 8.6-km/s stratified structure of the oceanic lithosphere. T waves from shallow earthquakes beneath the lower continental slope are also clearly observed by bottom seismography.  相似文献   

Crustal structure between the Knipovich Ridge and the Van Mijenfjorden (Svalbard)     

Ritzmann  Oliver  Jokat  Wilfried  Mjelde  Rolf  Shimamura  Hideki 《Marine Geophysical Researches》2002,23(5-6):379-401

Marine Geophysical Research - The Alfred Wegener Institute of Polar and Marine Research, the University of Bergen and Hokkaido University acquired new seismic refraction data along a transect from...  相似文献   

Numerical investigation on the failure criterion of normally consolidated clays     

Shinya Tachibana  Atsushi Iizuka  Katsuyuki Kawai  Ichizou Kobayashi  Thirapong Pipatpongsa  Hideki Ohta 《国际地质力学数值与分析法杂志》2007,31(6):809-833

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Geospatial analysis of surface hydrological parameters for Kyushu Island,Japan     

Shehata  Mohammad  Mizunaga  Hideki 《Natural Hazards》2019,96(1):33-52

Defining the surface hydrological parameters represents a crucial factor for the sustainable development purposes. In areas with heavy precipitation and rugged topography, these parameters control the occurrence of some natural hazards, from which the flash flood gets the most attention. Traditional methods for the assessment of the surface hydrological parameters are costly, time-consuming and provide information for limited geographic extent. On the other hand, remotely sensed data provide a cost-effective, rapid and wide aerial coverage with adequate accuracy. Geospatial analysis of these remotely sensed data provides a suitable and effective method for the reconnaissance determination of the surface hydrological parameters. In this work, digital elevation models, Landsat 8 satellite images as well as digital maps of soil and land use for Kyushu Island were acquired and analyzed using geographic information system. Surface hydrological parameters were determined in terms of watershed boundaries, soil moisture, initial abstraction as well as flash flood potentiality. Results of this research show a great correlation with historical flash flood events that occurred in the island. The northern parts of the island are subjected to the threat of flash floods. A follow-up is recommended in some areas on the island. As a conclusion, the geospatial analysis performs an accurate reconnaissance method for hydrological analysis at regional scale, which in turn guides the detailed field observation saving time and cost.

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Metamorphic petrology of the Barchi–Kol metabasites, western Kokchetav ultrahigh-pressure–high-pressure massif, northern Kazakhstan     

Hideki Masago 《Island Arc》2000,9(3):358-378

Abstract In the Barchi–Kol area, located at the westernmost part of the Kokchetav ultrahigh pressure (UHP) to high-pressure (HP) massif, northern Kazakhstan, metabasites from the epidote amphibolite (EA) facies to the coesite eclogite (CEC) facies are exposed. Based on the equilibrium mineral assemblages, the Barchi–Kol area is divided into four zones: A, B, C and D. Zone A is characterized by the assemblage: epidote + hornblende + plagioclase + quartz, with minor garnet. Zone B is characterized by the assemblage: garnet + hornblende + plagioclase + quartz + zoisite. Zone C is defined by the appearance of sodic–augite, with typical assemblage: garnet + sodic–augite + tschermakite–pargasite + quartz ± plagioclase ± epidote/clinozoisite. Zone D is characterized by the typical eclogite assemblage: garnet + omphacite + quartz + rutile, with minor phengite and zoisite. Inclusions of quartz pseudomorph after coesite were identified in several samples of zone D. Chemical compositions of rock-forming minerals of each zone were analyzed and reactions between each zone were estimated. Metamorphic P-T conditions of each zone were estimated using several geothermobarometers as 8.6 ± 0.5 kbar, 500 ± 30 °C for zone A; 11.7 ± 0.5 kbar, 700 ± 30 °C for zone B; 12–14 kbar, 700–815 °C for zone C; and 27–40 kbar, 700–825 °C for zone D.  相似文献   

A cross-system analysis of sedimentary organic carbon in the mangrove ecosystems of Xuan Thuy National Park, Vietnam   总被引：1，自引：0，他引：1  

Nguyen Tai Tue  Nguyen Thi NgocTran Dang Quy  Hideki HamaokaMai Trong Nhuan  Koji Omori 《Journal of Sea Research》2012,67(1):69-76

A cross-system analysis of bulk sediment composition, total organic carbon (TOC), atomic C/N ratio, and carbon isotope composition (δ¹³C) in 82 surface sediment samples from natural and planted mangrove forests, bank and bottom of tidal creeks, tidal flat, and the subtidal habitat was conducted to examine the roles of mangroves in sedimentation and organic carbon (OC) accumulation processes, and to characterize sources of sedimentary OC of the mangrove ecosystem of Xuan Thuy National Park, Vietnam. Sediment grain sizes varied widely from 5.4 to 170.2 μm (mean 71.5 μm), with the fine sediment grain size fraction (< 63 μm) ranging from 11 to 99.3% (mean 72.5%). Bulk sediment composition suggested that mangroves play an important role in trapping fine sediments from river outflows and tidal water by the mechanisms of tidal current attenuation by vegetation and the ability of fine roots to bind sediments. The TOC content ranged from 0.08 to 2.18% (mean 0.78%), and was higher within mangrove forests compared to those of banks and bottoms of tidal creeks, tidal flat, and subtidal sediments. The sedimentary δ¹³C ranged from − 27.7 to − 20.4‰ (mean − 24.1‰), and mirrored the trend observed in TOC variation. The TOC and δ¹³C relationship showed that the factors of microbial remineralization and OC sources controlled the TOC pool of mangrove sediments. The comparison of δ¹³C and C/N ratio of sedimentary OC with those of mangrove and marine phytoplankton sources indicated that the sedimentary OC within mangrove forests and the subtidal habitat was mainly composed of mangrove and marine phytoplankton sources, respectively. The application of a simple mixing model showed that the mangrove contribution to sedimentary OC decreased as follows: natural mangrove forest > planted mangrove forest > tidal flat > creek bank > creek bottom > subtidal habitat.  相似文献