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11.
Influences of Nutrient Outwelling from the Mangrove Swamp on the Distribution of Phytoplankton in the Matang Mangrove Estuary, Malaysia 总被引:1,自引:0,他引:1
Distributions of dissolved nutrients and Chl. a were investigated in the Sangga Besar River Estuary in the well-managed Matang Mangrove Forest in West Malaysia. In the estuary, spring tide concentrations of ammonium, silicate and phosphate were higher than those in the neap tide, which suggests that these nutrients are flushed from the mangrove area by the inundation and tidal mixing of the spring tide. Ammonium comprised over 50% of the dissolved inorganic nitrogen in the spring tide, while nitrite tended to dominate in the neap tide, indicating the predominance of nitrification inside the estuary in neap tides. Nutrient concentrations in the creek water were higher than those of estuarine water, indicating the nutrient outwelling from the mangrove swamp and ammonium regeneration from mangrove litter in the creek sediments. The maximum concentration of Chl. a in spring tides reached 80 g/l while it was below 20 g/l in the neap tides. These variations in the phytoplankton biomass and nutrients probably reflect the greater nutrient availability in the spring tide due to outwelling from the mangrove swamp and creek. 相似文献
12.
13.
Jean-Marie Auzende Eiichi Honza Xavier Boespflug Satendra Deo Jean-Philippe Eissen Jun Hashimoto Philippe Huchon Junichiro Ishibashi Yo Iwabuchi Philip Jarvis Masato Joshima Kiyoyuki Kisimoto Yasuto Kuwahara Yves Lafoy Tsuyoshi Matsumoto Jean-Pierre Maze Kiyohiko Mitsuzawa Hiroyasu Monma Takeshi Naganuma Yukihiro Nojiri Suguru Ohta Kiyoshi Otsuka Yoshihisa Okuda Hélène Ondreas Akira Otsuki Etienne Ruellan Myriam Sibuet Manabu Tanahashi Takeo Tanaka Tetsuro Urabe 《Marine Geophysical Researches》1990,12(4):269-283
The aim of the Japanese-French Kaiyo 87 cruise was the study of the spreading axis in the North Fiji Basin (SW Pacific). A
Seabeam and geophysical survey allowed us to define the detailed structure of the active NS spreading axis between 16° and
22° S and its relationships with the left lateral motion of the North Fiji Fracture Zone. Between 21° S and 18°10′ S, the
spreading axis trends NS. From 18°10 S to 16°40 S the orientation of the spreading axis changes from NS to 015°. North of
16°40′ S the spreading axis trends 160°. These two 015° and 160° branches converge with the left lateral North Fiji fracture
zone around 16°40′ S to define an RRFZ triple junction. Water sampling, dredging and photo TV deep towing give new information
concerning the hydrothermal activity along the spreading axis. The discovery of hydrothermal deposits associated with living
communities confirms this activity. 相似文献
14.
Detecting fluctuations of the Kuroshio axis south of Japan using TOPEX/POSEIDON altimeter data 总被引:1,自引:0,他引:1
Shiro Imawaki Mayumi Gotoh Hiroyuki Yoritaka Noriya Yoshioka Atsunobu Misumi 《Journal of Oceanography》1996,52(1):69-92
Sea surface dynamic topography (SSDT) can be divided into temporal mean SSDT and fluctuation SSDT. The former is approximated with a climatological mean SSDT and the latter is derived from satellite altimetry data, to give an approximated total SSDT (called a composite SSDT). The method is applied to detecting fluctuations of the Kuroshio axis south of Japan using TOPEX/POSEIDON altimeter data from the first year mission in 1992–1993. The fluctuation SSDT averaged over a wide area south of Japan clearly shows an annual cycle with an amplitude of about 15 cm. Temporal changes of SSDT along a subsatellite track crossing the Kuroshio compare moderately well with those estimated from repeated hydrographic observations, although there is a discrepancy of unknown origin. The composite SSDT also compares well with SSDT estimated from the same hydrographic data. Horizontal distribution of the surface geostrophic velocity component normal to subsatellite tracks is derived every ten days from the composite SSDT. Most locations of estimated strong eastward geostrophic velocities coincide well with locations of the Kuroshio axis determined every 15 days fromin situ surface velocity measurements on various vessels; for example, a fairly large meander of the Kuroshio south of Honshu is clearly detected. It is concluded that the composite SSDT can be used reliably to detect fluctuations of the Kuroshio axis south of Japan. 相似文献
15.
Taitiro Fujinaga Tooru Kuwamoto Eiichiro Nakayama Shinji Tanaka 《Journal of Oceanography》1980,36(4):196-200
A precise and accurate technique for the determination of Li and Rb in sea water has been developed by using a double channel flame emission spectrophotometer. The advantage of this technique is that it is possible to correct the background emission by making use of the double channel system of the apparatus and to obtain constant intensity of emission even if there are large scale changes in the salinity of the sample. Sea water samples collected in the open sea and coastal areas of Japan were analyzed by this method. In one of the coastal areas, an extraordinarily high concentration of Li was found. 相似文献
16.
The sea surface dynamic topography (the sea surface height relative to the geoid; hereafter abbreviated SSDT) can be divided into the temporal mean SSDT and the fluctuation SSDT around the mean. We use the optimal interpolation method to reduce the satellite radial orbit error and estimate the fluctuation SSDT southeast of Japan from Seasat altimetry data during the 17-day near-repeat mission. The fluctuation SSDT is further combined with the mean geopotential anomalies estimated from hydrographic data during the Seasat mission in order to give the approximated total SSDT, called here the composite SSDT (the approximated mean plus fluctuation SSDT's). The fluctuation SSDT is in accord with the low-frequency sea-level fluctuation recorded at tide gauge stations in the Japanese islands. The composite SSDT describes thoroughly variations of the location of the Kuroshio axis south of Japan determined on the basis of the GEK (Geomagnetic Electro-Kinematograph) surface velocities and the horizontal temperature distribution. The composite SSDT also agrees with oceanic variations east of Japan found in the temperature distribution at the depth of 200 m. These results confirm that the SSDT derived from altimetry data can provide fairly precise synoptic views of low-frequency oceanic phenomena. 相似文献
17.
Electrokinetic phenomena in a water-porous medium with a fractal structure above percolation threshold are theoretically investigated. Fracture zone with space-variable porosity is considered as a model of an earthquake hypocenter zone in which the electrokinetic current results from fluid filtration in a fractal pore network. A critical exponent of the streaming potential coefficient is found to depend on both the transport critical exponent and correlation length critical exponent. In this model, logarithmic dependence of electric field amplitude E on the earthquake magnitude M is derived which is compatible with the one observed by the VAN group. Without fractal properties, this form of dependence contradicts the empirical data. The electromagnetic field far from the hypocenter is calculated, which leads to the prediction of weak magnetic field variations. To explain the observed amplitude of VAN's Seismic Electric Signals (SES), the electric source must be at a distance of about 10 km from the registration point if the medium is homogeneous. Therefore, some conductive channel(s) are needed to explain the long distance selective SES transmission. 相似文献
18.
H. Ogasawara K. Fujimori N. Koizumi N. Hirano S. Fujiwara S. Otsuka S. Nakao K. Nishigami K. Taniguchi Y. Iio R. Nishida K. Oike Y. Tanaka 《Pure and Applied Geophysics》2002,159(1-3):91-109
—?Microseismicity (M?0) induced by heavy rainfall was investigated around the flooded, vertically dipping Tertiary ore veins with dimensions of about 1?km?×?1?km in the Ikuno mine, Japan. The ore veins had rock bursts (M?3) before the mine was closed in 1973, as well as seismic events (M?3) during flooding after it was closed down. The stress state is therefore critical to failure, at least within one stress drop of a seismic event. Since 1987, when the veins had become mostly flooded, 56 mine tremors (M?0) were observed over a 5-year period. Several times during this five-year period the mine sustained heavy rainfall of several tens of millimeters per day, and the water table flooding over the ore veins was elevated by several meters. Significant changes in strain larger than 10?6 were also monitored at a crustal movement monitoring station located several hundred meters from the veins. It was found that the opening of the vertical ore veins primary led to significant strain and tilt, but not to seismicity, because the delay and the longer duration of the seismicity were significant. Most seismic events involve thrusting mechanisms that are consistent with the present stress state of E-W-oriented tectonic compression, but are not consistent with the opening of the deepest ore vein. Interstingly, all the events within a few months of the heavy rainfall occurred near the faults that offset the deepest ore veins, wheareas all those events located away from the deepest ore veins occurred many months after the heavy rainfall. Consequently, the delayed diffusion of water appears to have played a dominant role in reducing rock strength, which led to seismicity in the Ikuno mine. 相似文献
19.
20.
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