Photo-inhibition of phytoplankton photosynthesis as a function of exposure time     

Masayuki Takahashi  Sooji Shimura  Yukuya Yamaguchi  Yoshihiko Fujita 《Journal of Oceanography》1971,27(2):43-50

The photo-inhibition of phytoplankton photosynthesis at higher intensities was examined with a cultured marine diatom,Phaeodactylum tricornutum, and natural samples. The question was to determine whether photo-inhibition results from excretion of photosynthetic products from cell or from an actual decrease in photosynthetic rate. P. tricornutum cultured at 15 klux showed very little photo-inhibition up to 70 klux, and, in the sample cultured at 1 klux, most marked photo-inhibition was observed in 3 hours experiment. Extracellular release was less than 30% of particulate fixation, and did not show any extreme increase to supplement photosynthesis depression at higher light intensities. When the photosynthesis was measured during 10 minutes, both samples showed no photo-inhibition. The photosynthesis by low light sample lost the linearity of time-course with prolonged exposure at high light intensity. Observed photo-inhibition, therefore, we explained with the actual decrease in photosynthetic rate. Similar photo-inhibition could be seen in marine phytoplankton samples concentrated by filtration.  相似文献   

Upwelling plumes in sagami bay and adjacent water around the Izu Islands,Japan     

Masayuki Takahashi  Isao Koike  Takashi Ishimaru  Toshiro Saino  Ken Furuya  Yoshihiko Fujita  Akihiko Hattori  Shun-ei Ichimura 《Journal of Oceanography》1980,36(4):209-216

Water plumes, 20 km long or less, identified by low temperature, high salinity and high nutrient concentrations, were observed on the eastern side of Izu Islands where the Kuroshio Current or its branch flowed eastward. The T-S diagrams and the vertical profiles of oceanographic variables indicated that the water plumes resulted from the upwelling of subsurface water. A newly formed plume, characterized by a sharp temperature front and high nutrient concentrations, contained less chlorophyll than did old plumes. It is suggested that the upwelling plumes are maintained for a period long enough to allow luxuriant growth of phytoplankton.  相似文献   

Water-rock interaction in a zone of lateral flow: A natural example from the active geothermal field and gold-mineralized zone of Beppu (Kyushu Island,Japan)     

G. Gianelli  Y. Yusa  S. Battaglia  K. Takemura 《Mineralogy and Petrology》1992,45(3-4):247-259

Summary Beppu is a water-dominated active geothermal system in Kyushu (Japan). Gold mineralization exists in places within altered Pleistocene volcanites in the southernmost part of this field. A shallow 300 m well was drilled in an alluvial fan deposit made up of unsorted volcanic clasts of andesite and dacite. Water and core samples were collected and a temperature log was carried out. In the depth range of 150-230 m and at temperatures of 126-148° C the main authigenic minerals are quartz, calcite, K-feldspar, mixed layers illite/smectite, stilbite and pyrite. The chemical data of the waters indicate that mixing occurs between shallow bicarbonate waters and deep Na-Cl geothermal waters in the outflow zone. The authigenic mineral assemblages found in the well are analogous to those found in the epithermal gold deposits of southern Kyushu. Au concentration data for the hydrothermal springs of Beppu (0.53 g/kg) indicate that the fluids found in the borehole at 148° C could theoretically deposit gold. It is reasonable to hypothesise that a process of mixing between deep Na-Cl fluids and shallow Ca-HCO₃-SO₄ fluids were responsible for massive silicate deposition, accompanied in places by Au mineralizations.

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Wasser-Gesteins-Wechselwirkung in einer Zone lateraler Fließbewegung: ein natürliches Beispiel aus der aktiven Geothermal-Golderz-Zone von Beppu (Kyushu, Japan)

Zusammenfassung Beppu ist ein geothermales System auf der Insel Kyushu, Japan, in der Wasser die dominante Rolle spielt. Goldvererzungen treten stellenweise in umgewandelten pleistozänen Vulkaniten im südlichsten Teil des Gebietes auf. Ein 300 m tiefes Bohrloch wurde in einem alluvialen Sedimentations-Fächer, der aus unsortierten vulkanischen Klasten, aus Andesit und Dazit besteht, niedergebracht. Wasserproben und Kernproben wurden genommen und die Temperaturen im Bohrloch systematisch gemessen. In Tiefen von 150–230 m und bei Temperaturen von 126–148°C sind die wichtigsten autigen gebildeten Minerale Quarz, Calcit, K-Feldspat, Illit/Smectit, Stilbit und Pyrit. Der Chemismus der Wässer zeigt, daß eine Mischung zwischen seichten Bikarbonat-Wässern und aus der Tiefe stammenden Na-Cl geothermalen Wässern erfolgt. Die autigenen Mineralassoziationen in diesem. Bohrloch sind vergleichbar mit denen in epithermalen Goldlagerstätten des südlichen Kyushu. Auf der Basis von existierenden Goldkonzentrationsdaten für die hydrothermalen Quellen auf Beppu (0.53 g/kg) läßt sich zeigen, daß die Fluide, die in dem Bohrloch bei 148 angetroffen wurden, theoretisch Gold absetzen könnten. Daher läßt sich die Theorie vertreten, daß Mischungsvorgänge zwischen einem aus der Tiefe stammenden Na-Cl Fluid und einem oberflächennahen Ca-HCO₃-SO₄ Wasser für die massive Silikatausscheidung verantwortlich waren, die stellenweise von Goldmineralisation begleitet wurden.

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Contribution No 4. Foreign Visiting Scientist Section, Beppu Geophysical Research Laboratory, Kyoto University.

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This paper was presented at the IGCP 291 Project Symposium Metamorphic Fluids and Mineral Deposits, ETH Zurich, March 21–23, 1991.  相似文献   

Recent developments in seismically isolated buildings in Japan     

Shin Okamoto  Nagahide Kani  Masahiko Higashino  Norihide Koshika  Masayuki Kimizuka  Mitsumasa Midorikawa  Masanori Iiba 《地震工程与工程振动(英文版)》2002,1(2):213-225

The Building Standard Law of Japan and related Enforcement Order and Notifications have been substantially revised since the year 2000 to introduce a performance-based regulatory and deregulation system for building control systems. Up to then, time-history analyses were mandatory for isolated buildings and had to be specially approved by the Minster of the Ministry of Construction (MOC). Simplified design procedures based on the equivalent linear method for seismically isolated buildings have been issued as “Notification 2009 — Structural calculation procedure for buildings with seismic isolation” from MOC, and are now integrated into the Ministry of Land, Infrastructure, and Transportation (MLIT). Along with Notification 2009, “Notification 1446 of year 2000 — Standard for specifications and test methods for seismic isolation devices” was also issued. Buildings with heights equal to or less than 60m and that are designed according to these Notifications, including base isolated buildings, only need approval from local building officials, and no longer require the special approval of the Minister of MLIT. This paper summarizes: 1) some statistics related to buildings with seismic isolation completed up to the end of 2001; 2) simplified design procedures required by Notification 2009 of year 2000; and 3) performance of seismic isolation devices required by Notification 1446 of year 2000.  相似文献   

Process of Housing Damage Assessment: The 1995 Hanshin-Awaji Earthquake Disaster Case     

Horie  Kei  Maki  Norio  Kohiyama  Masayuki  Lu  Hengjian  Tanaka  Satoshi  Hashitera  Shin  Shigekawa  Kishie  Hayashi  Haruo 《Natural Hazards》2003,29(3):341-370

Rebuilding of victims' livelihoods was a crucial issue in the restoration process in the1995 Hanshin-Awaji Earthquake Disaster. Housing damage assessment influencedmost of the rebuilding of the livelihood in the long term, because the Victim Certificatesissued by the local governments based on the results of the Housing damage assessmentwas required to receive most of the individual assistance measures. In the process ofHousing damage assessment, many complex problems arose, leading to extensivework on the part of the disaster responders. Consequently, a considerable number ofvictims were dissatisfied with the assessment and applied for a resurvey. Due to a floodof requests for resurvey, disaster responders had to work on damage assessment, leavingrelief activities aside.In order to facilitate Housing damage assessment, this paper discusses thefollowing five points: (1) the processes and the problems of assessments performedin the Hanshin-Awaji Earthquake Disaster, (2) the changes in the nature of informationneeded by the victims, (3) the improvements over the present damage assessment, (4)the housing situation in Japan, and (5) the international situation on damage assessment.It is obvious from the results that a poor damage assessment system and the size ofthe disaster produced a very large work load. Differences in appreciation among theinvestigators also contributed to unfair assessments and led to the victims beingincreasingly dissatisfied by the survey results. Finally, a design concept for acomprehensive damage assessment system, which has been derived from theabove five points, is proposed for post-disaster management.  相似文献   

Impact of the winter North Atlantic Oscillation (NAO) on the Western Pacific (WP) pattern in the following winter through Arctic sea ice and ENSO. Part II: multi-model evaluation of the NAO–ENSO linkage     

Tetsu Nakamura  Masayuki Hara  Miki Oshika  Yoshihiro Tachibana 《Climate Dynamics》2015,45(11-12):3547-3562

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Tectonic evolution of lower crustal rocks in an exposed magmatic arc section in the Hidaka metamorphic belt, Hokkaido, northern Japan   总被引：3，自引：0，他引：3  

Tsuyoshi  Toyoshima  Masayuki  Komatsu Toshiaki  Shimura 《Island Arc》1994,3(3):182-198

Abstract : The Hidaka metamorphic belt consists of an island-arc assembly of lower to upper crustal rocks formed during early to middle Paleogene time and exhumed during middle Paleogene to Miocene time. The tectonic evolution of the belt is divided into four stages, D₀rs, D₁, D₂rs, and D₃, based on their characteristic deformation, metamorphism, and igneous activity. The premetamorphic and igneous stage (D₀) involves tectonic thickening of an uppermost Cretaceous and earliest Tertiary accretionary complex, including oceanic materials in the lower part of the complex. D₁ is the stage of prograde metamorphism with increasing temperatures at a constant pressure during an early phase, and with a slight decrease of pressure at the peak metamorphic phase, accompanying flattening of metamorphic rocks and intrusions of mafic to intermediate igneous rocks. At the peak, incipient partial melting of pelitic and psammitic gneisses took place in the amphibolite–granulite facies transition zone, the melt and residuals cutting the foliations formed by flattening. In the deep crust, large amounts of S-type tonalite magma formed by crustal anatexis, intruded into the granulite facies gneiss zone and also into the upper levels of the metamorphic sequence during the subsequent stage. During D₁ stage, mafic and intermediate magmas supplied and transported heat to form the arc-type crust and at the same time, the magmatic underplating caused extensional doming of the crust, giving rise to flattening and vertical uplifting of the crustal rocks. D₂ stage is characterized by subhorizontal top-to-the-south displacement and thrusting of lower to upper crustal rocks, forming a basal detachment surface (décollement) and duplex structures associated with intrusions of S-type tonalite. Deformation structures and textures of high-temperature mylonites formed along the décollement, as well as the duplex structures, show that the D₂ stage movement occurred under a N-S trending compressional tectonic regime. The depth of intra-crustal décollement in the Hidaka belt was defined by the effect of multiplication of two factors, the fraction of partial melt which increases downward, and the fluid flux which decreases downward. The crustal décollement, however, might have extended to the crust-mantle boundary and/or to the lithosphere and asthenosphere boundary. The subhorizontal movement was transitional to a dextral-reverse-slip (dextral transpression) movement accompanied by low-temperature mylonitization with retrograde metamorphism, the stage defined as D₃. The crustal rocks from the basal décollement to the upper were tilted eastward on the N–S axis and exhumed during the D₃ stage. During D₂ and D₃ stages, the intrusion of crustal acidic magmas enhanced the crustal deformation and exhumation in the compressional and subsequent transpressional tectonic regime.  相似文献   

Long-term climato-limnological cycles found in a 3.5-million-year continental record     

Kenji Kashiwaya  Hideo Sakai  Masayuki Ryugo  Masae Horii  Takayoshi Kawai 《Journal of Paleolimnology》2001,25(3):271-278

Analysis of physical properties in long sediment cores (BDP96) from Academician Ridge in Lake Baikal indicates that major climato-limnological changes during the past 3.5 Myr occurred at about 2.5–2.8, 1.7–1.9, and 0.9–1.2 Ma, which were close to times of major geomagnetic polarity reversals (Matuyama/Gauss, Olduvai, Jaramillo + Matuyama/Brunhes). The principal climato-limnological oscillation has a long-term period of nearly 1,000 kyr, which corresponds to the periodicity of fluctuation in solar insolation. It also seems to be related to geomagnetic field intensity. Other long-term period of 400 kyr corresponds to Milankovitch parameters of eccentricity. These results suggest that changes in solar insolation were closely related to long-term environmental variations in the deep continental interior.  相似文献   

Quaternary vertical offset and average slip rate of the Nojima Fault on Awaji Island, Japan   总被引：5，自引：0，他引：5  

Akihiro Murata  Keiji Takemura  Takao Miyata  Aiming Lin 《Island Arc》2001,10(3-4):360-367

Abstract Drilling was carried out to penetrate the Nojima Fault where the surface rupture occurred associated with the 1995 Hyogo-ken Nanbu earthquake. Two 500 m boreholes were successfully drilled through the fault zone at a depth of 389.4 m. The drilling data show that the relative uplift of the south-east side of the Nojima Fault (south-west segment) was approximately 230 m. The Nojima branch fault, which branches from the Nojima Fault, is inferred to extend to the Asano Fault. From the structural contour map of basal unconformity of the Kobe Group, the vertical component of displacement of the Nojima branch–Asano Fault is estimated to be 260–310 m. Because the vertical component of displacement on the Nojima Fault of the north-east segment is a total of those of the Nojima Fault of the south-west segment and of the Nojima branch–Asano Fault, it is estimated to total to 490–540 m. From this, the average vertical component of the slip rate on the Nojima Fault is estimated to be 0.4–0.45 m/10³ years for the past 1.2 million years.  相似文献   

Crack-filling clays and weathered cracks in the DPRI 1800 m core near the Nojima Fault, Japan: Evidence for deep surface-water circulation near an active fault     

Shin-Ichi Uda  Aiming Lin  Keiji Takemura 《Island Arc》2001,10(3-4):439-446

Abstract Crack-filling clays and weathered cracks were observed in the Disaster Prevention Research Institute, Kyoto University (DPRI) 1800 m cores drilled from the Nojima Fault Zone, which was activated during the 1995 Hyogo-ken Nanbu earthquake (Kobe earthquake). The crack-filling clays consist mainly of unconsolidated fine-grained materials that fill opening cracks with no shear textures. Most of the cracks observed in the DPRI 1800 m cores are yellow-brown to brown in color due to weathering. Powder X-ray diffraction analyses show that the crack-filling clays are composed mainly of clay minerals and carbonates such as siderite and calcite. Given that the top of the borehole is approximately 45 m above sea level, most of the core is far below the stable groundwater table. Hence, it is suggested that the crack-filling clays and weathered cracks in the cores taken at depths of 1800 m were formed by the flow of surface water down to the deep fractured zone of the Nojima Fault Zone during seismic faulting.  相似文献