Unique hydrothermal fluid from the DESMOS caldera, Manus Basin: reply to comments by J. A. Resing and F. J. Sansone     

Toshitaka Gamo  Junichiro Ishibashi  Kiminori Shitashima 《Deep Sea Research Part I: Oceanographic Research Papers》1996,43(11-12)

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Relationship between atmospheric fluxes and concentrations of terrigenous materials in the surface air over the Japan Sea     

Suzuki  Toshitaka 《Journal of Oceanography》1994,50(2):173-178

Relationship between atmospheric deposition fluxes and concentrations of Si and²¹⁰Po in the surface air were examined through daily basis simultaneous observation at the coast of the Japan Sea. Both the Si and²¹⁰Po, the atmospheric fluxes were highly variable from day to day. According to correlation analysis, there was no significant correlation between flux and atmospheric concentration of these terrigenous materials in the surface air. On the other hand, flux of Si and²¹⁰Po significantly correlated to precipitation rate. These results indicate that the atmospheric flux of terrigenous material is not constantly proportional to atmospheric concentration in the surface air. This may be due to the deposition flux represents an integrated value throughout the air column of in-and below-cloud, while the air concentration represents only the environment of earth's surface.  相似文献   

Density,biomass and community structure of demersal fishes off the Pacific coast of northeastern Japan   总被引：8，自引：0，他引：8  

Toshihiko Fujita  Tadashi Inada  Yoshio Ishito 《Journal of Oceanography》1993,49(2):211-229

Demersal fish communities were studied on the lower continental shelf and the upper continental slope along the Pacific coast of northeastern Japan. Species composition, number and weight of each species were examined based on otter trawl samples at 45 stations. Mean density and biomass of demersal fishes were 131 ha^–1 and 21 kg ha^–1, respectively. The ten most abundant species comprised of about 95% of total number and weight of overall catch indicating simple species composition. Gadiform fishesTheragra chalcogramma, Gadus macrocephalus andPhysiculus maximowiczi were the most important species by number, weight and frequency of occurrences, and three main community types represented by the three key species were recognized.Theragra-dominant community showed higher density and biomass, and lower diversity thanPhysiculus-dominant community did. Species diversity of demersal fish community was negatively correlated to density and biomass. Density and biomass of demersal fish community were high on the uppermost slope, and the high abundance resulted from low-diversity communities dominated byT. chalcogramma andG. macrocephalus.  相似文献   

In-situ survey of nanomolar manganese in seawater using an autonomous underwater vehicle around a volcanic crater at Teishi Knoll,Sagami Bay,Japan     

Takashi Doi  Michiaki Takano  Kei Okamura  Tamaki Ura  Toshitaka Gamo 《Journal of Oceanography》2008,64(3):471-477

We present the results of a chemical survey at a submarine volcano, Teishi Knoll, obtained using a submersible in-situ Mn analyzer (GAMOS) mounted on an autonomous underwater vehicle (AUV) platform. During this survey, high-resolution data of dissolved Mn were obtained in three dimensions in nearly real time. The AUV enabled continuous detailed observations along a preprogrammed pathway, which could not have been performed with conventional CTD hydrocasts. During this observation, anomalously high dissolved Mn concentrations were obtained within the crater, corresponding to high water temperatures. The anomalies might be a hydrothermal signature due to volcanic activity from the crater.  相似文献   

Silver in Tokyo Bay estuarine waters and Japanese rivers     

Yan Zhang  Hajime Obata  Toshitaka Gamo 《Journal of Oceanography》2008,64(2):259-265

Dissolved and particulate concentrations of silver in Tokyo Bay estuarine waters and Japanese rivers were determined in this study. The dissolved silver concentrations in the surface water of Tokyo Bay range from 5.9 to 15.1 pmol kg⁻¹, which is comparable to those in the surface water of the Japan Sea, but two or three times higher than those in the surface water of the open ocean. However, elevated concentrations of dissolved silver are not found in Tokyo Bay compared with those in other highly urbanized estuaries, such as San Francisco Bay (20∼243 pmol kg⁻¹). In the Tokyo Bay estuary, silver typically exhibits non-conservative mixing behavior, which is a common feature in the other estuaries reported previously. Dissolved silver concentrations decrease with salinity from the rivers to the mouth of Tokyo Bay. Silver is efficiently scavenged by suspended particulates, as evidenced by the high conditional distribution coefficients for silver throughout the estuary (log K_d > 5.0 ± 0.6). The silver fluxes into Tokyo Bay via inflowing rivers and atmospheric deposition were estimated as 83 kg y⁻¹ and 15 kg y⁻¹, respectively. A simple budget calculation shows that the silver supplied from rivers and atmosphere must be rapidly scavenged within the Tokyo Bay estuary.  相似文献   

Long-term bottom water warming in the north Ross Sea     

Hirokazu Ozaki  Hajime Obata  Mikio Naganobu  Toshitaka Gamo 《Journal of Oceanography》2009,65(2):235-244

We measured potential temperature, salinity, and dissolved oxygen profiles from the surface to the bottom at two locations in the north Ross Sea (65.2°S, 174.2°E and 67.2°S, 172.7°W) in December 2004. Comparison of our data with previous results from the same region reveals an increase in potential temperature and decreases in salinity and dissolved oxygen concentration in the bottom layer (deeper than 3000 m) over the past four decades. The changes were significantly different from the analytical precisions. Detailed investigation of the temperature, salinity, dissolved oxygen and σ ₃ value distributions and the bottom water flow in the north Ross Sea suggests a long-term change in water mass mixing balance. That is to say, it is speculated that the influence of cool, saline, high-oxygen bottom water (high-salinity Ross Sea Bottom Water) formed in the southwestern Ross Sea has possibly been decreased, while the influences of relatively warmer and fresher bottom water (low-salinity Ross Sea Bottom Water) and the Adélie Land Bottom Water coming from the Australia-Antarctic Basin have increased. The possible impact of global warming on ocean circulation needs much more investigation.  相似文献   

Parallel Implementation of Dispersive Tsunami Wave Modeling with a Nesting Algorithm for the 2011 Tohoku Tsunami     

Toshitaka Baba  Narumi Takahashi  Yoshiyuki Kaneda  Kazuto Ando  Daisuke Matsuoka  Toshihiro Kato 《Pure and Applied Geophysics》2015,172(12):3455-3472

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Research on the stabilization treatment of clay slope topsoil by organic polymer soil stabilizer     

Jin Liu  Bin Shi  Hongtao Jiang  He Huang  Gonghui Wang  Toshitaka Kamai 《Engineering Geology》2011,117(1-2):114-120

The topsoil of clayey slope is easy to erosion because it is weak in its strength, water stability and erosion resistance. A new organic polymer soil stabilizer, which was developed for the stabilization treatment of clay slope topsoil and was named as STW, was introduced in this study. In order to understand the effect of STW on the stabilization of clayey soil, laboratory tests on the unconfined compressive strength, shear strength, water stability and erosion resistance of untreated and treated soil specimens are performed, The results indicated that STW soil stabilizer can significantly increased the unconfined compression strength, shear strength, water stability and erosion resistance of clayey soil. The unconfined compression strength increased with the increasing of curing time and the variation mainly occurs in the first 24-hour. With the addition amounts of STW increasing, the strength, water stability and erosion resistance increased at the curing time being 48 h, but in the case of friction angle, no major change was observed. Based on the scanning electron microscopy (SEM) analysis of the stabilized soil, the stabilization mechanisms of STW soil stabilizer in the clayey soil were discussed. Finally, a field test of the stabilization treatment of clay slope topsoil with STW was carried out, and the results indicated that the STW soil stabilizer on the stabilization treatment of clay slope topsoil is effective for improving the erosion resistance of slope topsoil, reducing the soil loss and protecting the vegetation growth. Therefore, this technique is worth popularizing for the topsoil protection of clay slope.  相似文献   

The Kellwasser events in the Upper Devonian Frasnian to Famennian transition in the Toc Tat Formation,northern Vietnam     

Toshifumi Komatsu  Ryota Urakawa  Toshitaka Inada  Kazuki Yamauchi  Takumi Maekawa  Reishi Takashima  Mark Williams  Phong D. Nguyen  Hung D. Doan  Minh T. Nguyen  Shuji Niko  Gengo Tanaka  Tatsuhiko Yamaguchi 《Island Arc》2019,28(1)

Upper Devonian carbonates of the Toc Tat Formation in the Si Phai Pass area of Dong Van District, northern Vietnam were deposited in carbonate platform, slope, and basin environments. These carbonates yield abundant conodonts indicative of the Palmatolepis nasuta, Pa. linguiformis and Pa. triangularis zones, the Frasnian–Famennian stage boundary being identified by the first occurrence of Pa. triangularis. Two positive carbon isotope excursions are recognized, the lower excursion peaking in the interval of the lower to middle Pa. nasuta Zone, whilst the upper excursion peaks just above the local Frasnian–Famennian boundary. Based on the biostratigraphy, these excursions equate to the Lower and Upper Kellwasser events. Locally, tentaculitoid taxa (Nowakia, Styliolina, Homoctenus, and Metastyliolina?) are abundant in the interval of the Pa. nasuta Zone, but show a drastic decline in abundance before the Lower Kellwasser Event, and only two taxa survived into the Famennian.  相似文献   

High-resolution atmospheric observations by the Mars Odyssey Thermal Emission Imaging System     

Ai Inada  Mark I. Richardson  Timothy H. McConnochie  Melissa J. Strausberg  Huiqun Wang  James F. Bell III 《Icarus》2007,192(2):378-395

High-resolution observations of atmospheric phenomena by the Mars Odyssey Thermal Emission Imaging System (THEMIS) during its first mapping year are presented. An atmospheric campaign was implemented on the basis of previous spacecraft imaging. This campaign, however, proved of limited success. This appears to be due to the late local time of the Odyssey orbit (the locations of activity at 4–6 p.m. appear to be different from those at 2 p.m.). Ironically, images targeting the surface were more useful for study of the atmosphere than those images specifically targeting atmospheric features. While many previously recognized features were found, novel THEMIS observations included persistent clouds in the southern polar layered deposits, dust or condensate plumes on the northern polar layered deposits, dust plumes as constituent parts of local dust storms, and mesospheric clouds. The former two features tend to be aligned parallel and normal to polar troughs, respectively, suggesting a wind system directed normal to troughs and radially outward from the center of the polar deposits. This is consistent with katabatic drainage of air off the polar deposits, analogous to flow off Antarctica. The observation of dust lifting plumes at unprecedented resolution associated with local dust storms not only demonstrates the importance of mean wind stresses (as opposed to dust devils) in initiation of dust storms, but is also seen to be morphologically identical to dust lifting in terrestrial dust storms. As Odyssey moves to earlier local times, we suggest that the atmospheric campaign from the first mapping year be repeated.  相似文献