Temporal variability in physicochemical properties,phytoplankton standing crop and primary production for 7 years (2002–2008) in the neritic area of Sagami Bay,Japan     

Koichi Ara  Koh Yamaki  Keisuke Wada  Satoshi Fukuyama  Takeshi Okutsu  Sadao Nagasaka  Akihiro Shiomoto  Juro Hiromi 《Journal of Oceanography》2011,67(1):87-111

Seasonal and interannual variations in physicochemical properties (i.e., temperature, salinity, dissolved oxygen and dissolved inorganic nutrients), chlorophyll a (Chl-a), particulate carbon and nitrogen (PC and PN, respectively), and primary production were investigated in the neritic area of Sagami Bay, Kanagawa, Japan, from January 2002 to December 2008. These abiotic/biotic variables, except for NH₄ ⁺–N, repeated similar seasonal variations for all 7 years. On the basis of the analysis of data obtained on 167 sampling dates, depth-integrated primary production in this water can be easily estimated from Chl-a at the surface using the regression equations obtained in the present study. Intermittently high values of dissolved inorganic nutrients, Chl-a, PC, PN and primary productivity at the surface during the summer stratified period were induced by high freshwater discharge from the rivers after rainfalls and by the expansion of nutrient-rich Tokyo Bay Water. Temperature, salinity and dissolved inorganic nutrients showed drastic variations within a scale of a few days and/or weeks, and these variations were related to sea levels that represent the intrusion of the Kuroshio Water, Intermediate Oyashio Water or deep water from the continental slope. However, there was no consistent trend in the variations in Chl-a, PC, PN and primary production due to the complex effects of these waters.  相似文献   

Tree ring information and rainfall characteristic for landslide in the Kobe District,Japan     

Kenji Kashiwaya  Takashi Okimura And  Takeshi Kawatani 《地球表面变化过程与地形》1989,14(1):63-71

Heavy rainfall on the south side of the Rokko Mountains has often caused severe landslides and debris flows. Analysis of the annual summation of rainfall in excess of 100 mm/day shows that the rainfall in this area has dominant periodicities of about 25–30, 10–13, and 5–7 years. The period of about 25–30 years corresponds to that of occurrence of the natural disasters produced by heavy rainfall; years when the maximum rainfall correspond to years when there have been severe landslides and debris flows in the area. Temporal change in this rainfall may provide a first approximation for erosional force. Analyses of tree ring width from these mountains indicate that the sequences have a dominant periodicity of about 25–30 years. Cross-spectral analyses for rainfall and ring width in this area show high coherency for the periods of about 25–30 years; evidence that variations in the ring width may be used as proxy data for erosional force.  相似文献   

Two-stage model of incorporation of seamount and oceanic blocks into sedimentary melange: Geochemical and biostratigraphic constraints in Jurassic Chichibu accretionary complex, Shikoku, Japan   总被引：1，自引：0，他引：1  

Seiji  Matsuda Yujiro  Ogawa† 《Island Arc》1993,2(1):7-14

Abstract The significance of timing and formation of mélange in accretionary prisms, particularly concerning basaltic and related rocks and pelagic sediments, is exemplified in the Sawadani area of the Jurassic Chichibu accretionary complex in Shikoku, southwest Japan. Major and trace element geochemistry of the basaltic and related rocks indicates that all are of a hot-spot origin which produced a seamount. Most of the rocks have a trend of differentiation from an alkalic parental magma. The time relationship between the blocks and matrices of the mélange deduced from radiolarian fossil evidence and macro- to microscopic characteristics of contacts between different lithologies indicates two stages of mixing of materials in the seafloor. The first mixing occurred on the flank of the seamount in the pelagic environments in the Late Permian, and the second occurred on the trench floor or in the accretionary prism after the Early Jurassic. These two stages show respectively the geological phenomena of a seamount within the Izanagi-Kula plate and its incorporation into the Asian continental margin.  相似文献   

Interplate coupling and relative plate motion in the Tokai district, central Japan, deduced from geodetic data inversion using ABIC   总被引：1，自引：0，他引：1  

Shoichi Yoshioka  Tetsuichiro Yabuki  Takeshi Sagiya  Takashi Tada  Mitsuhiro Matsu'ura 《Geophysical Journal International》1993,113(3):607-621

  相似文献   

River Water Pollution in Developed and Developing Countries: Judge and Assessment of Physicochemical Characteristics and Selected Dissolved Metal Concentration   总被引：1，自引：0，他引：1  

M. Tajuddin Sikder  Yusuke Kihara  Masaomi Yasuda  Yustiawati  Yoshihiro Mihara  Shunitz Tanaka  Dalkhjav Odgerel  Badamtsetseg Mijiddorj  Suhaemi M. Syawal  Toshiyuki Hosokawa  Takeshi Saito  Masaaki Kurasaki 《洁净——土壤、空气、水》2013,41(1):60-68

To compare water quality in rivers of developed and developing countries, a study based on physicochemical parameters and dissolved metals levels was conducted. Water samples were collected from selected sites in Dhaka, Bangladesh; Hokkaido and Osaka, Japan; Erdenet, Mongolia and West Java, Indonesia. Analysis of least significant differences revealed that most water quality parameters were within comparable low levels in both developed and developing countries. The dissolved metals concentrations were found to be similar and below those of water standards except for manganese and cadmium at every sampling point, and lead in Erdenet, Mongolia. Some metals showed high enrichment factors in the rivers of Osaka, Japan and Erdenet, Mongolia, indicating accumulation possibility of metals in the river‐bed sediments. High concentrations of dissolved organic carbon, Escherichia coli and dissolved metals suggested greater water pollution in some rivers of developing countries than in the rivers of Japan. Principal component analysis showed strong correlations between “dissolved organic carbon and chemical oxygen demand” and “conductivity and total dissolved solids” at each sampling point, and E. coli, nitrate (NO), nitrite (NO), and pH levels were found to be higher in the rivers of Dhaka and Erdenet. In addition, there were high levels of Al and Zn in West Java, Pb in Erdenet, and Mn, Fe, and Cr in the rivers of Dhaka and Japan. Based on pressures and impacts, it is evident that dissolved metal, organic, and fecal pollution in the rivers of developing countries are in somewhat dreadful condition in comparison with the rivers of developed country.  相似文献   

A heuristic for the maximum value region problem in raster space     

Takeshi Shirabe 《International journal of geographical information science》2013,27(7):1097-1116

From a single-attribute raster layer in which each cell is assigned a numerical value, a connected set of a specified number of cells that has the maximum (or minimum) total value is selected. This is a highly common decision problem in the context of raster-based geographic information systems (GIS) and seems general enough to deserve inclusion in the standard functionality of such systems. Yet it is a computationally difficult optimization problem, for which no efficient exact solution method has been found. This article presents a new dynamic programming-based heuristic method for the problem. Its performance is tested with randomly generated raster layers with various degrees of spatial autocorrelation. Results suggest that the proposed heuristic is a promising alternative to the existing integer programming-based exact method, as it can handle significantly larger raster data with fair accuracy.  相似文献   

A submillimetre survey of Lyman α haloes in the SA 22 protocluster at z= 3.1     

J. E. Geach  Y. Matsuda  Ian Smail  S. C. Chapman  T. Yamada  R. J. Ivison  T. Hayashino  K. Ohta  Y. Shioya  Y. Taniguchi 《Monthly notices of the Royal Astronomical Society》2005,363(4):1398-1408

  相似文献   

A cyclic viscoelastic–viscoplastic constitutive model for clay and liquefaction analysis of multi-layered ground     

Fusao Oka  Takeshi Kodaka  Yong-Seong Kim 《国际地质力学数值与分析法杂志》2004,28(2):131-179

  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114000280     

Yoshiaki Ishihara  Masaki Kanao  Masa-yuki Yamamoto  Shigeru Toda  Takeshi Matsushima  Takahiko Murayama 《地学前缘(英文版)》2015,6(2)

Characteristic infrasound waves observed at Antarctic stations demonstrate physical interaction involving environmental changes in the Antarctic continent and the surrounding oceans.A Chaparraltype infrasound sensor was installed at Syowa Station(SYO;39°E,69°S),East Antarctica,as one of the projects of the International Polar Year(IPY2007—2008).Data continuously recorded during the three seasons in 2008—2010 clearly indicate a contamination of the background oceanic signals(microbaroms)with peaks between 4 and 10 s observed during a whole season.The peak amplitudes of the microbaroms have relatively lower values during austral winters,caused by a larger amount of sea-ice extending around the L(u|")tzow-Holm Bay near SYO,with decreasing ocean wave loading effects.Microbaroms measurements are useful tool for characterizing ocean wave climate,complementing other oceanographic and geophysical data.A continuous monitoring by infrasound sensors in the Antarctic firmly contributes to the Comprehensive Nuclear-Test-Ban Treaty(CTBT) in the southern high latitude,together with the Pan-Antarctic Observations System(PAntOS) under the Scientific Committee on Antarctic Research(SCAR).Detailed measurements of the infrasound waves in Antarctica,consequently,could be a new proxy for monitoring regional environmental change as well as the temporal climate variations in the polar regions.  相似文献   

Apatite and zircon fission-track dating from the Hirabayashi-NIED borehole, Nojima Fault, Japan: Evidence for anomalous heating in fracture zones   总被引：1，自引：0，他引：1  

Ryuji Yamada  Tatsuo Matsuda  Kentaro Omura 《Tectonophysics》2007,443(3-4):153

Fission-track (FT) analysis using apatite and zircon was performed on samples from two fracture zones (FZ) at the depths of 1140 and 1310 m within the 1838 m borehole core penetrating the Ryoke Granitic Rocks in the Nojima Fault at Nojima-Hirabayashi, Awaji Island, Japan, drilled just after the 1995 Hyogo-ken Nanbu earthquake. Clear discordance in apatite and zircon FT age was found for two samples located at  2 m below the central part of each FZs where the presence of pseudotachylyte and/or fault gouge would predict the largest amount of slip. Asymmetric distribution was identified by discordant ages with respect to the central part of FZs. These very local discordant ages in the fault reflect thermal anomalies caused by secondary heating with an inferred maximum temperature in the region between apatite and zircon closure temperatures at a time post-48 Ma. As a source of the secondary heating, heat transfer or dispersion via geothermal fluids caused presumably the observed similarity in asymmetric distribution of discordant FT ages at two different FZs. Other samples yield concordant FT zircon and apatite ages and these indicate rapid cooling within the bounds of two closure temperatures of these minerals at  60 Ma of the Ryoke Granitic Rocks.  相似文献