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1.
Under strong surface wind forcing during winter, direct current observations in the northern Sea of Japan show the existence of strong near-inertial currents in the deep water that is characterized by the extremely homogeneous vertical structures of temperature and salinity. However, the mechanism generating internal waves in the deep water of the northern Sea of Japan has not been well understood. In this study, to clarify the dynamical link between the surface wind forcing and near-inertial currents in the deep water of the northern Sea of Japan, we drive a general circulation model taking into account realistic wind stress, ocean bottom and land topography. In the northern Sea of Japan, the numerical results show that vertically coherent horizontal currents with a speed of ~ 0.05 m s?1 are excited throughout the homogeneous deep water. A two-layer model successfully reproduces the pattern of the horizontal current velocities shown by the general circulation model, indicating that internal waves emanate westward from the northwestern coast of Japan through coastal adjustment to the strong wind forcing event and, while propagating into the ocean interior, they excite evanescent near-inertial response throughout the lower layer below the interface. 相似文献
2.
1 IntroductionAnicecoreobtainedfrom polarglaciersoricesheetsisoneofthemostimportantarchivestoreconstructpaleoclimaticandpaleoatmosphericcondition .Informationonpale o environmentcanbeextractedfromicecoresaschemicaland/orphysicalsignals.Amongthechemicalsignals,heavymetalsarenotedassignalsofterrestrialenvironmentalchangeandanthropogenicpollution (e.g .Murozumietal.1 969;NgandPatterson 1 981 ;Hongetal.1 994) .SinceconcentrationsofmostofthemetalsinpolarsnowincentralGreen landareatorbelowthepptl… 相似文献
3.
4.
Kyu Han Kim Keisuke Nagao Hirochika Sumino Tsuyoshi Tanaka Takamasa Hayashi Toshio Nakamura Jong Ik Lee 《Chemical Geology》2008,253(3-4):180-195
We report analyses of noble gases and Nd–Sr isotopes in mineral separates and whole rocks of late Pleistocene (< 0.2 Ma) monzonites from Ulleungdo, South Korea, a volcanic island within the back arc basin of the Japan island arc. A Rb–Sr mineral isochron age for the monzonites is 0.12 ± 0.01 Ma. K–Ar biotite ages from the same samples gave relatively concordant ages of 0.19 ± 0.01and 0.22 ± 0.01 Ma. 40Ar/39Ar yields a similar age of 0.29 ± 0.09 Ma. Geochemical characteristics of the felsic plutonic rocks, which are silica oversaturated alkali felsic rocks (av., 12.5 wt% in K2O + Na2O), are similar to those of 30 alkali volcanics from Ulleungdo in terms of concentrations of major, trace and REE elements. The initial Nd–Sr isotopic ratios of the monzonites (87Sr/86Sr = 0.70454–0.71264, 143Nd/144Nd = 0.512528–0.512577) are comparable with those of the alkali volcanics (87Sr/86Sr = 0.70466–0.70892, 143Nd/144Nd = 0.512521–0.512615) erupted in Stage 3 of Ulleungdo volcanism (0.24–0.47 Ma). The high initial 87Sr/86Sr values of the monzonites imply that seawater and crustally contaminated pre-existing trachytes may have been melted or assimilated during differentiation of the alkali basaltic magma.A mantle helium component (3He/4He ratio of up to 6.5 RA) associated with excess argon was found in the monzonites. Feldspar and biotite have preferentially lost helium during slow cooling at depth and/or during their transportation to the surface in a hot host magma. The source magma noble gas isotopic features are well preserved in fluid inclusions in hornblende, and indicate that the magma may be directly derived from subcontinental lithospheric mantle metasomatized by an ancient subduction process, or may have formed as a mixture of MORB-like mantle and crustal components. The radiometric ages, geochemical and Nd–Sr isotopic signatures of the Ulleungdo monzonites as well as the presence of mantle-derived helium and argon, suggests that these felsic plutonic rocks evolved from alkali basaltic magma that formed by partial melting of subcontinental lithospheric mantle beneath the back arc basin located along the active continental margin of the southeastern part of the Eurasian plate. 相似文献
5.
Yuhei Yamamoto Yoshio Takahashi Yutaka Kanai Yoshio Watanabe Tomoya Uruga Hajime Tanida Yasuko Terada Hiroshi Shimizu 《Applied Geochemistry》2008,23(8):2452-2461
The uranium LIII-edge XANES spectra for natural rocks at the concentration range of 0.96–124 mg kg−1 were measured using a log spiral bent crystal Laue analyzer (BCLA) combined with a multi-element Ge detector. It was found that the quality of the XANES spectra using the BCLA was greatly improved due to a reduction of interfering fluorescence from major components such as Rb and Sr. The ratio of signal to background intensities in the U LIII-edge XANES spectra increased by a factor of 2.9–17 with the use of the BCLA, which greatly enhanced the detection limit for the speciation of the oxidation states of U or the U(IV)/U(VI) ratio of natural samples. In addition, it was demonstrated that the fluorescence XANES method coupled with the BCLA enable determination of the speciation of U for various natural samples such as acidic igneous rocks, ferromanganese nodules, sediments, and some sedimentary rocks such as shale and limestone. 相似文献
6.
Takeshi Umezu Hiroshi Ebihara Yōko Minamisako Hiroshi Watanabe 《Journal of Oceanography》1984,40(5):382-390
Sperm whales are notable squid-eaters. They feed mainly on medium to large-sized cephalopods at midwater levels and defecate near the surface. This suggests the existence of an upward transport of60Co by sperm whales from the mesopelagic zone (150–1,200 m). To elucidate this squid-whale route for this artificial radionuclide,60Co content was determined in squid and in predator whales captured by commercial whaling. In the Cephalopoda livers60Co levels of 30–500 mBq kg–1 wet were found and in the viscera of Odontoceti (toothed whales) 15–40 mBq kg–1 wet. About 0.3% of80Co ingested was estimated to be retained in a 23-year-old male sperm whale. In the livers of Bryde's whales,60Co levels of 40–80 mBq kg–1 wet were detected, but not in euphausiids and sardines, their possible prey. The level of Co in sperm whales was nearly the same as in Bryde's whales. Specific radioactivity60Co/59Co in mBq µg–1 was several times higher in sperm whale (1.1–1.6) than in cephalopods (0.19–0.77). Eating prey with a high content of60Co in the 1960's may have contributed to the present body burden in sperm whales with a long-life span. However, the origin of60Co in Bryde's whales is unknown. 相似文献
7.
以双功能褐藻胶裂解酶 (Pseudoalteromonas sp.strain No. 2 72 )分别降解均聚古罗糖醛酸(PG)和均聚甘露糖醛酸 (PM) ,经 Bio- Gel- P6和 POROS- HQ2 0分离得到 2种三糖纯品 ,经 ESI- MS,1 H- NMR,1 3 C- NMR,1 H- 1 H COSY,1 H- 1 3 C HMQC确定其结构为 Δ4,5-古罗糖醛酸 - α(1→ 4 ) - L-古罗糖醛酸 -α(1→ 4 ) - L -古罗糖醛酸 (简写为Δ GG)和Δ4,5-甘露糖醛酸 -β (1→ 4 ) - D-甘露糖醛酸 -β (1→ 4 ) - D-甘露糖醛酸 (ΔMM) ,为进一步从事构效关系研究提供结构信息。 相似文献
8.
The spring bloom of phytoplankton was studied in March in Funka Bay, Japan, to test the Tsunogai (1979)'s hypothesis regarding the role of silicate in the bloom. The hypothesis comprises two parts. 1) Diatoms are predominant when all the physical and chemical conditions are adequate for plankton growth. 2) Since the Si:P ratio of the diatom body is usually much larger than that of sea water, flagellates (non-siliceous phytoplankton) replace diatoms after dissolved silicate in the sea water has been almost completely consumed by diatoms. At the end of the bloom in late March phosphate still remained in the water but silicate was exhausted and the main species of phytoplankton changed from diatoms to flagellates. Grazing pressure by zooplankton at this time was not so great. A model using the data on assimilation rates of silicate showed a dramatic change of silicate uptake in late March. Poison in scallops caused byProtogonyaulux sp. (dinoflagellates) rapidly increased from mid-April at all stations along the coast of Funka Bay. All of these findings support Tsunogai's hypothesis. 相似文献
9.
Methane in the East China Sea water 总被引:1,自引:0,他引:1
Methane in the East China Sea water was determined four times at a fixed vertical section along PN line consisting of 11–14 stations, in February 1993, October 1993, June 1994 and August 1994. The mean concentration of methane in the surface water was not significantly higher than that in the open ocean. The methane concentration below the pycnocline increased during the stratified period in summer to autumn and reached to 15 nmoles/l at most in October. The concentration of methane was fairly well correlated with AOU in the layer below the pycnocline in the stratified season. This means that methane in the bottom water has only a single source, which is expected to be anoxic sediments near the coast, and that the oxidation rate of methane in the water is extremely slow in the oxic water. The high methane observed in October completely disappeared in February, indicating that the methane was escaped to the atmosphere or transported to the pelagic ocean by the Kuroshio current. The East China Sea, therefore, is not a large direct and stationary source for the atmospheric methane, but may have some role as a source by supplying it sporadically to the atmosphere in early winter or indirectly from the surface of the pelagic ocean. 相似文献
10.
Shuichi Watanabe Naoto Higashitani Nobuo Tsurushima Shizuo Tsunogai 《Journal of Oceanography》1994,50(4):415-421
The concentration of methane in seawater was determined approximately once a month for one year from August 1990 to July 1991 at a station close to the center of Funka bay (92 m depth) and some supplementary observations were also carried out. The concentration of methane was usually increased with increasing depth, suggesting that methane was emitted from the bottom of the bay. While highly variable both spatially and temporally, the emission was intense in March and April, a period immediately after the spring bloom of phytoplankton. The maximum of methane found in the intermediate water suggests its source from the slope of the bay. The concentration of methane in the surface water changed seasonally and also interannually. The annually averaged flux of methane transferred to the atmosphere in the bay was estimated to be 6×10–3 gCH4m2/day. The coastal zone in the world may be a significant source of the atmospheric methane, although its source strength has yet to be accurately estimated from more data in different coastal seas. 相似文献