Annual Anthropogenic Carbon Transport into the North Pacific Intermediate Water through the Kuroshio/Oyashio Interfrontal Zone: An Estimation from CFCs Distribution     

Tsuneo Ono  Yutaka W. Watanabe  Katsuyuki Sasaki 《Journal of Oceanography》2000,56(6):675-689

Vertical distribution of anthropogenic carbon content of the water (exDIC) in the Oyashio area just outside of the Kuroshio/Oyashio Interfrontal Zone (K/O Zone) was estimated by the simple 1-D advection-diffusion model calibrated by the distribution of chlorofluorocarbons (CFCs). The average concentration of exDIC for = 26.60–27.00 is multiplied by the volume transport of Oyashio water into the North Pacific Intermediate Water (NPIW) to estimate the annual transport of exDIC into NPIW through K/O Zone. The estimated transport of exDIC was 0.018–0.020 GtC/y, which corresponds to 15% of the whole total exDIC accumulation in the temperate North Pacific. A simple assessment using the NPIW 1-box model indicates that the current study explains at least 70% of the total annual transport of exDIC into NPIW, and that small exDIC sources for NPIW still exists in addition to K/O Zone.  相似文献   

GEK measurements in a shallow water region     

Yutaka Nagata  Kimie Yonemura  Hideo Nishida 《Journal of Oceanography》1981,37(1):21-29

Evidence for the applicability of GEK (Geomagnetic Electrokinetography) measurements to shallow water regions is provided from observations in the shelf region of the East China Sea. The reason for the effectiveness of GEK measurements in this case is investigated theoretically, and it is shown to be attributable to the existence of a thick conductive sedimentary layer. In addition, it is shown that low conductive basement rock can be regarded as a good conductor for GEK measurements if the current width is broad enough and if the ratio of current width to water depth is larger than the resistivity ratio of basement rock to sea water. This implies that barotropic tidal currents can be measured with GEK in any ocean on the earth if they have significant magnitudes.  相似文献   

A field study of physico-chemical states of artificial radionuclides in seawater     

Yutaka Nagaya  Kiyoshi Nakamura 《Journal of Oceanography》1974,30(4):179-184

The physico-chemical states of artificial radionuclides,⁹⁰Sr,¹³⁷Cs and¹⁴⁴Ce in seawater were investigated by radiochemical analysis of filtered and unfiltered seawater. The difference of radionuclide concentrations between unfiltered and filtered seawaters was defined as the particulate form radioisotope and its particle ratio was discussed.Practically no particulate⁹⁰Sr, greater than 0.22 in size, was observed in both coastal and open seawaters, but some of¹³⁷Cs seemed to be insoluble in some circumstances, especially in coastal waters. A considerable amount of¹⁴⁴Ce was found to be particulate.An estimation of the radionuclides in particulate form was made for Kashima-nada seawaters collected in 1970 to 1972, and it was shown that the possible occurrence of particulate radionuclides, greater than 0.22 in size, were 1% or less for⁹⁰Sr and 6% for¹³⁷Cs. In the coastal water, 80 % of¹⁴⁴Ce were seemed to be in particulate form, but in the open seawater only a few%. The influences of suspended materials to¹³⁷Cs and¹⁴⁴Ce concentration levels in seawater were not negligible and further investigations are desirable.  相似文献   

Bacteria on petroleum globules in the Philippine sea in January, 1973     

Humitake Seki  Hideshi Abe  Yukuya Yamaguchi  Shun-ei Ichimura 《Journal of Oceanography》1974,30(3):151-156

About 10⁶ of total bacteria (direct microscopic count) or heterotrophic bacteria (colony count with Medium 2216E) and about 10⁴ of petroleumlytic bacteria (oil-oxidizing bacteria) were enumerated per square centimeter of the surface of petroleum globules suspended in the topmost 10 meters of water from a station (22°00.2N, 125°51.9E) in the western North Pacific central water, where about 10⁷ of total bacteria, about 10³ of heterotrophic bacteria and about 10 of petroleumlytic bacteria were enumerated per liter of seawater.  相似文献   

Structure of Subsurface Intrusion of the Oyashio Water into the Kuroshio Extension and Formation Process of the North Pacific Intermediate Water     

Kuniaki Okuda  Ichiro Yasuda  Yutaka Hiroe  Yugo Shimizu 《Journal of Oceanography》2001,57(2):121-140

In order to understand the actual formation process of the North Pacific Intermediate Water (NPIW), structure of subsurface intrusions of the Oyashio water and the mixing of the Oyashio and the Kuroshio waters in and around the Kuroshio Extension (KE) were examined on the basis of a synoptic CTD observation carried out in May-June 1992. The fresh Oyashio water in the south of Hokkaido was transported into KE region through the Mixed Water Region (MWR) in the form of subsurface intrusions along two main paths. The one was along the east coast of northern Japan through the First Branch of the Oyashio (FBO) and the other along the eastern face of a warm streamer which connected KE with a warm core ring through the Second Branch of the Oyashio (SBO). The fresh Oyashio water extended southward through FBO strongly mixed with the saline NPIW transported by the Kuroshio in the south of Japan (old NPIW) in and around the warm streamer. On the other hand, the one through SBO well preserved its original properties and extended eastward beyond 150°E along KE with a form of rather narrow band. The intrusion ejected Oyashio water lens with a diameter of 50–60 km southward across KE axis and split northward into the MWR involved in the interaction of KE and a warm core ring, which were supposed to be primary processes of new NPIW formation.  相似文献   

The structure of the kuroshio front in the vicinity of separation point where the Kuroshio leaves the Japanese coast     

Hong-Ryeol Shin  Yutaka Michida  Yutaka Nagata 《Journal of Oceanography》1991,47(4):111-125

By using existing data obtained in the offshore area from the Boso Peninsula to the Joban Coast, it was shown that the double structure of the Kuroshio Front — which is usually found along the northern edge of the Kuroshio Extension to the east 143°E (Nagataet al., 1986 ; Shinet al., 1988) — is hardly found at the edge of the Kuroshio when it is flowing along the Japanese coast or in the area to the west of 142°E. It was suggested that the cold and fresh water core beneath the density front of the double structure originates from the fresh and cold Oyashio Water which is captured beneath the Kuroshio Front just off the Kashima Coast. The double structure of the Kuroshio Front would be generated and developed very rapidly in the region between 142°E and 143°E just after the Kuroshio leaves the Japanese coast.  相似文献   

Quaternary bedrock erosion and landscape evolution in the Sør Rondane Mountains, East Antarctica: Reevaluating rates and processes     

Norikazu Matsuoka  Cline E. Thomachot  Chiaki T. Oguchi  Tamao Hatta  Masahiro Abe  Hiroyuki Matsuzaki 《Geomorphology》2006,81(3-4):408-420

Rates and processes of rock weathering, soil formation, and mountain erosion during the Quaternary were evaluated in an inland Antarctic cold desert. The fieldwork involved investigations of weathering features and soil profiles for different stages after deglaciation. Laboratory analyses addressed chemistry of rock coatings and soils, as well as ¹⁰Be and ²⁶Al exposure ages of the bedrock. Less resistant gneiss bedrock exposed over 1 Ma shows stone pavements underlain by in situ produced silty soils thinner than 40 cm and rich in sulfates, which reflect the active layer thickness, the absence of cryoturbation, and the predominance of salt weathering. During the same exposure period, more resistant granite bedrock has undergone long-lasting cavernous weathering that produces rootless mushroom-like boulders with a strongly Fe-oxidized coating. The red coating protects the upper surface from weathering while very slow microcracking progresses by the growth of sulfates. Geomorphological evidence and cosmogenic exposure ages combine to provide contrasting average erosion rates. No erosion during the Quaternary is suggested by a striated roche moutonnée exposed more than 2 Ma ago. Differential erosion between granite and gneiss suggests a significant lowering rate of desert pavements in excess of 10 m Ma^− 1. The landscape has been (on the whole) stable, but the erosion rate varies spatially according to microclimate, geology, and surface composition.  相似文献   

Petrological feature of spinel lherzolite xenolith from Oki-Dogo Island: An implication for variety of the upper mantle peridotite beneath southwestern Japan     

Natsue Abe  Masao Takami  Shoji Arai 《Island Arc》2003,12(2):219-232

Abstract   Spinel lherzolite is a minor component of the deep-seated xenolith suite in the Oki-Dogo alkaline basalts, whereas other types of ultramafic (e.g. pyroxenite and dunite) and mafic (e.g. granulite and gabbro) xenoliths are abundant. All spinel lherzolite xenoliths have spinel with a low Cr number (Cr#; < 0.26). They are anhydrous and are free of modal metasomatism. Their mineral assemblages and microtextures, combined with the high NiO content in olivine, suggest that they are of residual origin. But the Mg numbers of silicate minerals are lower (e.g. down to Fo₈₆) in some spinel lherzolites than in typical upper mantle residual peridotites. The clinopyroxene in the spinel lherzolite shows U-shaped chondrite-normalized rare-earth element (REE) patterns. The abundance of Fe-rich ultramafic and mafic cumulate xenoliths in Oki-Dogo alkali basalts suggests that the later formation of those Fe-rich cumulates from alkaline magma was the cause of Fe- and light REE (LREE)-enrichment in residual peridotite. The similar REE patterns are observed in spinel peridotite xenoliths from Kurose and also in those from the South-west Japan arc, which are non-metasomatized in terms of major-element chemistry (e.g. Fo > 89), and are rarely associated with Fe-rich cumulus mafic and ultramafic xenoliths. This indicates that the LREE-enrichment in mantle rocks has been more prominent and prevalent than Fe and other major-element enrichment during the metasomatism.  相似文献   

GPS-measured land subsidence in Ojiya City, Niigata Prefecture, Japan   总被引：1，自引：0，他引：1  

Hiroshi P. Sato  Kaoru Abe  Osamu Ootaki 《Engineering Geology》2003,67(3-4):379-390

Land subsidence caused by compression of clay layers in Ojiya City, Japan was measured by global positioning system (GPS) between 1 April 1996 and 31 December 1998.

Three baselines were selected in and around the city, and height difference on a WGS-84 ellipsoid was measured by GPS on each baseline. The ground at the GPS station in the city subsides and rebounds 7 cm every winter and spring, respectively. Measurement accuracy was 9.5 mm standard deviation. Ground water level was observed at a well near the GPS station. Regression analysis between total strain, calculated as ratio of the height difference displacement to the total thickness of the clay layers, and the layers' effective stress change with ground water level change gave good correlation. The slope of regression line 7.0×10⁻¹¹ m²/N was obtained as an average apparent coefficient of volume compressibility of the layers.  相似文献   

Thermal and chemical evolution of the terrestrial magma ocean   总被引：8，自引：0，他引：8  

Yutaka Abe 《Physics of the Earth and Planetary Interiors》1997,100(1-4):27-39

The Earth is likely to have experienced a magma ocean stage during accretion. Thermal and chemical evolution of magma ocean is investigated based on a one-dimensional two-phase-flow heat and mass transfer model. Differentiation at lower mantle pressure depends on the type of magma ocean and surrounding atmosphere. If the magma ocean is formed by the blanketing effect of a solar-type proto-atmosphere, extensive differentiation proceeds at lower mantle pressure. If the magma ocean is formed by the blanketing effect of an impact-induced steam atmosphere, no differentiation at lower mantle pressure is likely. If a very deep magma ocean is formed by a giant impact, whether differentiation proceeds at lower mantle pressure or not depends on grain size, viscosity of melt and/or properties of a transient atmosphere. On the contrary, chemical differentiation likely proceeds at upper mantle pressure irrespective of magma ocean type. A shallow magma ocean can remain for 100 200 My without any heating processes.  相似文献