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1.
Irvine WM Friberg P Hjalmarson A Ishikawa S Kaifu N Kawaguchi K Madden SC Matthews HE Ohishi M Saito S Suzuki H Thaddeus P Turner BE Yamamoto S Ziurys LM 《The Astrophysical journal》1988,334(2):L107-L111
We report the astronomical identification of the cyanomethyl radical, CH2CN, the heaviest nonlinear molecular radical to be identified in interstellar clouds. The complex fine and hyperfine structures of the lowest rotational transitions at about 20.12 and 40.24 GHz are resolved in TMC-1, where the abundance appears to be about 5 x 10(-9) relative to that of H2. This is significantly greater than the observed abundance of CH3CN (methyl cyanide) in TMC-1. In Sgr B2 the hyperfine structure is blended in the higher frequency transitions at 40, 80, and 100 GHz, although the spin-rotation doubling is clearly evident. Preliminary searches in other sources indicate that the distribution of CH2CN is similar to that for such carbon chain species as HC3N or C4H. 相似文献
2.
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
3.
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
4.
In situ strength measurements on natural upper-mantle minerals 总被引:1,自引:0,他引:1
Junji Yamamoto Jun-ichi Ando Hiroyuki Kagi Toru Inoue Akihiro Yamada Daisuke Yamazaki Tetsuo Irifune 《Physics and Chemistry of Minerals》2008,35(5):249-257
Using in situ strength measurements at pressures up to 10 GPa and at room temperature, 400, 600, and 700°C, we examined rheological
properties of olivine, orthopyroxene, and chromian-spinel contained in a mantle-derived xenolith. Mineral strengths were estimated
using widths of X-ray diffraction peaks as a function of pressure, temperature, and time. Differential stresses of all minerals
increase with increasing pressure, but they decrease with increasing temperature because of elastic strain on compression
and stress relaxation during heating. During compression at room temperature, all minerals deform plastically at differential
stress of 4–6 GPa. During subsequent heating, thermally induced yielding is observed in olivine at 600°C. Neither orthopyroxene
nor spinel shows complete stress relaxation, but both retain some stress even at 700°C. The strength of the minerals decreases
in the order of chromian-spinel ≈ orthopyroxene > olivine for these conditions. This order of strength is consistent with
the residual pressure of fluid inclusions in mantle xenoliths. 相似文献
5.
Sedimentation process of fine-grained terrigenous red soils was observed on the seafloor by coral reefs near an estuary using a paired mooring of turbidity meter and sediment trap or a mooring of sediment trap and current meter. Silty clays contained in the bottom calcareous sands were mainly resuspended and trapped in both surface and bottom layer traps, at noncatastrophic normal sedimentation periods. In addition, silty clays were supplied to this mooring site by inflowing river. Turbidity and the flux rate determined by sediment traps show certain relationship accompanied with the coefficient, which is changed by precipitation, current, and other conditions. Resuspension process caused by a typhoon was recorded as both core sequence of sediment trap and time-series data of bottom current. Maximum velocity of 49.5 cm/s was recorded from bottom currents resulting from the passing of attyphoon at the mooring site. A graded sand layer is interbedded in dark-gray, silty clay and considered to be a resuspended sediment resulting from the passing of the typhoon. Flux of the resuspended sediments by the typhoon was estimated from this core sequence and compared to the flux observed at the normal sedimentation. 相似文献
6.
Satoshi Yamamoto 《Journal of Oceanography》1984,40(1):80-89
The pattern of distribution of detrital mineral grains in the water column was investigated at three stations in the western Pacific during July through August of 1979. The sedimentation of detrital mineral grains was also studied using piston cores from two sites adjacent to the three stations. The concentration of suspended detrital mineral grains in the subsurface waters becomes lower with increasing distance from the land, and shows a prominent peak in the intermediate zone of the water column. The sharp increase in water density and viscosity in the pycnocline in the intermediate zone decreases the settling velocity of grains, and may result in the accumulation of falling grains in the intermediate layer. Proportion of detrital mineral grains to organic remains in the sediment was more than two orders of magnitude larger than in the overlying water column, and reasons for this are briefly discussed. 相似文献
7.
Roles of Continental Shelves and Marginal Seas in the Biogeochemical Cycles of the North Pacific Ocean 总被引:4,自引:0,他引:4
Chen-Tung Arthur Chen Andrey Andreev Kyung-Ryul Kim Michiyo Yamamoto 《Journal of Oceanography》2004,60(1):17-44
Most marginal seas in the North Pacific are fed by nutrients supported mainly by upwelling and many are undersaturated with
respect to atmospheric CO2 in the surface water mainly as a result of the biological pump and winter cooling. These seas absorb CO2 at an average rate of 1.1 ± 0.3 mol C m−2yr−1 but release N2/N2O at an average rate of 0.07 ± 0.03 mol N m−2yr−1. Most of primary production, however, is regenerated on the shelves, and only less than 15% is transported to the open oceans
as dissolved and particulate organic carbon (POC) with a small amount of POC deposited in the sediments. It is estimated that
seawater in the marginal seas in the North Pacific alone may have taken up 1.6 ± 0.3 Gt (1015 g) of excess carbon, including 0.21 ± 0.05 Gt for the Bering Sea, 0.18 ± 0.08 Gt for the Okhotsk Sea; 0.31 ± 0.05 Gt for
the Japan/East Sea; 0.07 ± 0.02 Gt for the East China and Yellow Seas; 0.80 ± 0.15 Gt for the South China Sea; and 0.015 ±
0.005 Gt for the Gulf of California. More importantly, high latitude marginal seas such as the Bering and Okhotsk Seas may
act as conveyer belts in exporting 0.1 ± 0.08 Gt C anthropogenic, excess CO2 into the North Pacific Intermediate Water per year. The upward migration of calcite and aragonite saturation horizons due
to the penetration of excess CO2 may also make the shelf deposits on the Bering and Okhotsk Seas more susceptible to dissolution, which would then neutralize
excess CO2 in the near future. Further, because most nutrients come from upwelling, increased water consumption on land and damming
of major rivers may reduce freshwater output and the buoyancy effect on the shelves. As a result, upwelling, nutrient input
and biological productivity may all be reduced in the future. As a final note, the Japan/East Sea has started to show responses
to global warming. Warmer surface layer has reduced upwelling of nutrient-rich subsurface water, resulting in a decline of
spring phytoplankton biomass. Less bottom water formation because of less winter cooling may lead to the disappearance of
the bottom water as early as 2040. Or else, an anoxic condition may form as early as 2200 AD.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
The contents of major and some of the minor elements, nickel, cobalt, copper, zinc and lead were studied on sediments collected from three inlets of Nanao Bay located at eastern side of Noto Peninsula. Little variation was found on the average contents of silicon, iron, titanium, aluminum, manganese, magnesium and potassium among the sediments of West, South and North Bays in Nanao Bay. Whereas significant difference was found on the contents of calcium, chlorine, sulfur and nitrogen among sediments of three bays.As to the minor elements, the average contents of nickel (20±5 ppm), cobalt (5±1 ppm), copper (18±5 ppm) and lead (17±8 ppm) are relatively low but zinc content is high in these sediments comparing with those of coastal deposit around Japan Island. From the results obtained here, it became clear that no environmental contamination of nickel, cobalt, copper and lead, and a little organic pollution were found in Nanao Bay sediments. 相似文献
9.
A repeat hydrographic section has been maintained over two decades along the 180° meridian across the subarctic-subtropical
transition region. The section is naturally divided into at least three distinct zones. In the Subarctic Zone north of 46°N,
the permanent halocline dominates the density stratification, supporting a subsurface temperature minimum (STM). The Subarctic
Frontal Zone (SFZ) between 42°–46°N is the region where the subarctic halocline outcrops. To the south is the Subtropical
Zone, where the permanent thermocline dominates the density stratification, containing a pycnostad of North Pacific Central
Mode Water (CMW). The STM water colder than 4°C in the Subarctic Zone is originated in the winter mixed layer of the Bering
Sea. The temporal variation of its core temperature lags 12–16 months behind the variations of both the winter sea surface
temperature (SST) and the summer STM temperature in the Bering Sea, suggesting that the thermal anomalies imposed on the STM
water by wintertime air-sea interaction in the Bering Sea spread over the western subarctic gyre, reaching the 180° meridian
within a year or so. The CMW in this section originates in the winter mixed layer near the northern edge of the Subtropical
Zone between 160°E and 180°. The CMW properties changed abruptly from 1988 to 1989; its temperature and salinity increased
and its potential density decreased. It is argued that these changes were caused by the climate regime shift in 1988/1989
characterized by weakening of the Aleutian Low and the westerlies and increase in the SST in the subarctic-subtropical transition
region.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Toshio Yamagata 《Journal of Oceanography》1976,32(3):116-127
A stability of planetary waves on an infinite beta-plane is investigated in an idealized two-layer fluid system for the large local Rossby numberM. When a primary wave is barotropic, two kinds of barotropic instability modes are found. One of them was previously discussed byGill (1974). When a primary wave is baroclinic, two different kinds of modes that enable barotropic and baroclinic energy transfers are found. The one that has the larger growth rate gains its energy mainly from the mean shear of the primary wave when the internal rotational Froude numberF is smaller than 1/2. WhenF is larger than 1/2, however, the available energy conversion of the primary wave is dominant. This mode has a fairly large part of its energy in the barotropic motion although the primary wave is purely baroclinic.The effect ofO(M
–2) corrections is found to have a stabilizing influence on all symmetrical modes. The geophysical applications of the present analysis are suggested in the context. 相似文献