PSP-toxicification of the carnivorous gastropod Rapana venosa inhabiting the estuary of Nikoh River, Hiroshima Bay, Hiroshima Prefecture, Japan     

Ito K  Asakawa M  Beppu R  Takayama H  Miyazawa K 《Marine pollution bulletin》2004,48(11-12):1116-1121

During surveillance on the toxicity of invertebrates such as bivalves inhabiting the coasts of Hiroshima Bay in 2001 and 2002, the carnivorous gastropod rapa whelk Rapana venosa collected in the estuary of Nikoh River, was found to contain toxins which showed paralytic actions in mice; the maximum toxicities (as paralytic shellfish poison, PSP) were 4.2 MU/g (May 2001) and 11.4 MU/g (April 2002). Their total toxicities were 224 and 206 MU/viscera of one specimen throughout the monitoring period. Attempts were made to identify the toxic principle in the gastropod. The viscera were extracted with 80% ethanol acidified with acetic acid, followed by defatting with dichloromethane. The aqueous layer obtained was treated with activated charcoal and then applied to a Sep-Pak C18 cartridge. The unbound toxic fraction was analyzed by high-performance liquid chromatography techniques. The gastropod toxin was rather unexpectedly identified as PSP. It was comprised of high toxic component (gonyautoxin-3; GTX3, GTX2, saxitoxin; STX) as the major components, which accounted for approximately 91 mol% of all components along with C1 and C2, which are N-sulfocarbamoyl derivatives. Judging from their toxin patterns, it is suggested that the PSP toxification mechanism of the gastropod that PSP toxins produced by phytoplankton such as Alexandrium tamarense, are transferred to and accumulated in plankton feeders such as the short-necked clam, and then transferred to this carnivorous rapa whelk R. venosa through predation.  相似文献   

Strong ligands for thorium complexation in marine bacteria     

Hirose K  Tanoue E 《Marine environmental research》2001,51(2):95-112

The interaction between thorium and marine organisms (cultured heterotrophic bacteria) was experimentally examined by using chemical equilibrium techniques. Thorium (Th) quantitatively reacts with a binding site on bacteria (Alteromonas, Vibrio, Pseudomonas and Flavobacterium) in 0.1 M HCl solution. According to mass balance analysis of adsorption experiment data, Th forms a 1:1 complex with a binding site similar in reactivity among bacteria used in this study, whose conditional stability constants are in the range from 10(6.63) to 10(7.07) M-1 under the experimental conditions of a 0.1 M HCl solution. The mole ratio of the strong ligand to organic carbon in bacteria ranged from 2.3 to 4.3 mmol/mol C. The strong ligand/carbon ratios in bacteria were more than one order of magnitude greater than in phytoplankton, zooplankton or other organic ligands in surface waters. The results suggest that the strong organic ligand reacting with Th is one of the functional groups commonly existing in oceanic microorganisms. The conditional stability constants of the Th complexes with the binding site in marine microorganisms are in the same order of magnitude as that with the strong ligand found in particulate and dissolved organic matter. These findings strongly suggest that the strong ligand in particulate and dissolved organic matter, reacting with trace metals under the conditions of seawater, originates from marine organisms.  相似文献   

Wells turbine with end plates for wave energy conversion   总被引：1，自引：0，他引：1  

Manabu Takao  Toshiaki Setoguchi  Yoichi Kinoue  Kenji Kaneko 《Ocean Engineering》2007,34(11-12):1790-1795

In order to improve the performance of the Wells turbine for wave energy conversion, the effect of end plate on the turbine characteristics has been investigated experimentally by model testing. As a result, it is found that the characteristics of the Wells turbine with end plates are superior to those of the original Wells turbine, i.e., the turbine without end plate and the characteristics are dependent on the size and position of end plate. Furthermore, by using a computational fluid dynamics (CFD), reason of the performance improvement of the turbine has been clarified and the effectiveness of the end plate has been demonstrated.  相似文献   

Sequential forecasting of the surface and subsurface conditions in the Japan Sea   总被引：1，自引：0，他引：1  

Naoki Hirose  Hideyuki Kawamura  Ho Jin Lee  Jong-Hwan Yoon 《Journal of Oceanography》2007,63(3):467-481

This study estimates a realistic change of the Japan Sea by assimilating satellite measurements into an eddy-resolving circulation model. Suboptimal but feasible assimilation schemes of approximate filtering and nudging play essential roles in the system. The sequential update of error covariance significantly outperforms the asymptotic covariance in the sequential assimilation due to the irregular sampling patterns from multiple altimeter satellites. The best estimates show an average rms difference of only 1.2°C from the radiometer data, and also explain about half of the sea level variance measured by the altimeter observation. The subsurface conditions associated with the mesoscale variabilities are also improved, especially in the Tsushima Warm Current region. It is demonstrated that the forecast limit strongly depends on variable, depth, and location.  相似文献   

Active oceanic spreading in the northern North Fiji Basin: Results of the NOFI cruise of R/V L'Atalante (newstarmer project)   总被引：1，自引：0，他引：1  

Yves Lagabrielle  Etienne Ruellan  Manabu Tanahashi  Jacques Bourgois  Georges Buffet  Giovanni de Alteriis  Jérôme Dyment  Jean Goslin  Eulàlia Gràcia-Mont  Yo Iwabushi  Philip Jarvis  Masato Joshima  Anne-Marie Karpoff  Takeshi Matsumoto  Hélène Ondréas  Bernard Pelletier  Olivier Sardou 《Marine Geophysical Researches》1996,18(2-4):225-247

The South Pandora and the Tripartite Ridges are active spreading centers located in the northern part of the North Fiji Basin. These spreading centers were surveyed over a distance of 750 km during the NOFI cruise of R/V L'Atalante (August–September 1994) which was conducted in the frame of the french-japanese Newstarmer cooperation project. SIMRAD EM12-dual full coverage swath bathymetric and imagery data as well as airgun 6-channel seismic, magnetics and gravity profiles were recorded along and offaxis from 170°40 E to 178° E. Dredging and piston coring were also performed along and off-axis. The axial domain of the South Pandora Ridge is divided into 5 first-order segments characterized by contrasted morphologies. The average width of the active domain is 20 km and corresponds either to bathymetric highs or to deep elongated grabens. The bathymetric highs are volcanic constructions, locally faulted and rifted, which can obstruct totally the axial valley. The grabens show the typical morphology of slow spreading axes, with two steep walls flanking a deep axial valley. Elongated lateral ridges may be present on both sides of the grabens. Numerous volcanoes, up to several kilometers in diameter, occur on both flanks of the South Pandora Ridge. The Tripartite Ridge consists of three main segments showing a sigmoid shape. Major changes in the direction of the active zones are observed at the segment discontinuities. These discontinuities show various geometrical patterns which suggest complex transform relay zones. Preliminary analysis of seismic reflection profiles suggest that the Tripartite Ridge is a very young feature which propagates into an older oceanic domain characterized by a significant sedimentary cover. By contrast, a very thin to absent sedimentary cover is observed about 100 km on both flanks of the South Pandora Ridge active axis. The magnetic anomaly profiles give evidence of long and continuous lineations, parallel to the South Pandora Ridge spreading axis. According to our preliminary interpretation, the spreading rate would have been very low (8 km/m.y. half rate) during the last 7 Ma. The South Pandora and Tripartite Ridges exhibit characteristics typical of active oceanic ridges: (1) a segmented pattern, with segments ranging from 80 to 100 km in length; (2) an axial tectonic and volcanic zone, 10 to 20 km wide; (3) well-organized magnetic lineations, parallel to the active axis; (4) clear signature on the free-air gravity anomaly map. However, no typical transform fault is observed; instead, complex relay zones are separating first-order segments.  相似文献   

A Numerical Study of Turbulence Statistics and the Structure of a Spatially-Developing Boundary Layer Over a Realistic Urban Geometry     

Atsushi Inagaki  Manabu Kanda  Nurul Huda Ahmad  Ayako Yagi  Naoyuki Onodera  Takayuki Aoki 《Boundary-Layer Meteorology》2017,163(2):161-177

Sonic anemometer measurements are analyzed from two primary field programs and 12 supplementary sites to examine the behaviour of the turbulent heat flux near the surface with high wind speeds in the nocturnal boundary layer. On average, large downward heat flux is found for high wind speeds for most of the sites where some stratification is maintained in spite of relatively intense vertical mixing. The stratification for high wind speeds is found to be dependent on wind direction, suggesting the importance of warm-air advection, even for locally homogenous sites. Warm-air advection is also inferred from a large imbalance of the heat budget of the air for strong winds. Shortcomings of our study are noted.  相似文献   

A Late Winter Hydrography in Hidaka Bay, South of Hokkaido, Japan     

Manabu Shimizu  Yutaka Isoda  Kazumi Baba 《Journal of Oceanography》2001,57(4):385-395

Hydrographic observations in Hidaka Bay, south of Hokkaido, Japan were carried out in late winter 1996 and 1997 to examine the spatial distributions and circulation features of two different water masses, i.e., Coastal Oyashio Water (COW) and Tsugaru Warm Water (TWW), and their modifications. It is known that COW is mostly composed of cold and low-salinity water of the melted drift ice coming from the Okhotsk Sea and flows into Hidaka Bay from winter to spring and TWW with high-salinity continuously supplies from the Tsugaru Strait to the North Pacific. Cold surface mixed layers (<26.2σ_θ, 0–100 m depth) were found mainly over the shelf slope, confirming that anti-clockwise flow of COW was formed. TWW was relatively high in salinity and low in potential vorticity, and had some patch-like water masses with a temperature and salinity maximum in the limited area in the further offshore at the deeper density levels of 26.6–26.8σ_θ. The fine structure of vertical temperature and salinity profiles appeared between TWW and COW is an indication of enhanced vertical mixing (double-diffusive mixing), as inferred from the estimated Turner angles. At a mouth of the Tsugaru Strait in late winter 1997, a significant thermohaline front between TWW and the modified COW was formed and a main path of TWW spreaded south along the Sanriku coast, probably as the bottom controlled flow. Hence, the patch-like TWW observed in late winter is isolated from the Tsugaru Warm Current and then rapidly modified due to a diapycnal mixing. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Dissociation of CAS phase in the uppermost lower mantle     

Kazufusa Ishibashi  Kei Hirose  Nagayoshi Sata  Yasuo Ohishi 《Physics and Chemistry of Minerals》2008,35(4):197-200

The high-pressure stability limit of calcium aluminosilicate (CAS) phase has been examined in its end-member CaAl₄Si₂O₁₁ composition at 18–39 GPa and 1,670–2,300 K in a laser-heated diamond-anvil cell (LHDAC). The in-situ synchrotron X-ray diffraction measurements revealed that the CAS phase decomposes into three-phase assemblage of cubic Al-bearing CaSiO₃ perovskite, Al₂O₃ corundum, and SiO₂ stishovite above 30 GPa and 2,000 K with a positive pressure–temperature slope. Present results have important implications for the subsolidus mineral assemblage of subducted sediment and the melting phase relation of basalt in the lower mantle.  相似文献   

Pi-SAR极化数据与K分布指数估算森林生物量与实验验证   总被引：1，自引：0，他引：1  

王海鹏  金亚秋  大内和夫  渡边学  岛田政信 《遥感学报》2008,12(3):477-482

用2002年和2003年日本Pi-SAR全极化数据,研究日本北海道苫小牧森林地区的森林生物量.雷达后向散射系数随森林生物量的增大而增大并迅速达到饱和,L波段雷达数据饱和点约为40t/hm2,X波段仅约为20t/hm2.在SAR数据统计分布中,K分布的指数参数在饱和点以上仍随生物量的增大而增大,并且HV极化方式时相关性最高.根据交叉极化数据K分布的指数参数与森林生物量的关系,本文估算了23个观测点的森林生物量,结果表明平均准确率为85%.因此该算法可以作为一种新的估算森林生物量的手段.  相似文献   

Diatom-inferred limnological changes in Lake Inawashiro-ko,Japan, over the past 1700 years     

Hirose  Kotaro  Gotoh  Toshikazu  Nagahashi  Yoshitaka 《Journal of Paleolimnology》2021,66(3):355-369

Journal of Paleolimnology - We inferred paleoenvironmental conditions in Lake Inawashiro-ko, Japan, over the past 1700&nbsp;years, using diatom assemblages in the uppermost 2&nbsp;m of...  相似文献