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31.
We have developed a rapid and accurate method to determine Zr, Nb, Hf and Ta (denoted as HFSE) in geological samples by inductively coupled plasma-mass spectrometry fitted with a flow injection system (FI-ICP-MS). The method involves sample decomposition by HF followed by HF dissolution of HFSE coprecipitated with insoluble M and Ca fluoride residues formed during the initial HF attack. This HF solution was directly nebulized into an ICP mass spectrometer. An external calibration curve method and an isotope dilution method (ID) were applied for the determination of Nb and Ta, and of Zr and Hf, respectively. Recovery yields of HFSE were > 96% for peridotite, basalt and andesite compositions, apart from Zr and Hf for peridotite (> 85%). No matrix effects for either signal intensities of HFSE or isotope ratios of Zr and Hf were observed in basalt, andesite and peridotite solutions down to a dilution factor of 100. Detection limits in silicate rocks were 40, 2, 1 and 0.1 ng g-1 for Zr, Nb, Hf and Ta, respectively. This technique required only 0.1 ml of sample solution, and thus is suitable for analysing small and/or precious samples such as meteorites, mantle peridotites and their mineral separates. We also present newly determined data for the Zr, Nb, Hf and Ta concentrations in USGS silicate reference materials DTS-1, PCC-1, BCR-1, BHVO-1 and AGV-1, GSJ reference materials JB-1, -2, -3, JA-1, -2 and -3, and the Smithsonian reference Allende powder. 相似文献
32.
Upper Mantle Velocity Structure Estimated From Ps-Converted Wave Beneath the North-Eastern Japan Arc 总被引:2,自引:0,他引:2
Toru Matsuzawa Norihito Umino Akira Hasegawa Akio Takagi 《Geophysical Journal International》1986,86(3):767-787
Summary. The upper boundary of the descending oceanic plate is located by using PS -waves (converted from P to S at the boundary) in the Tohoku District, the north-eastern part of Honshu, Japan. the observed PS-P time data are well explained by a two-layered oceanic plate model composed of a thin low-velocity upper layer whose thickness is less than 10 km and a thick high-velocity lower layer; the upper and lower layers respectively have 6 per cent lower and 6 per cent higher velocity than the overriding mantle. the estimated location of the upper boundary is just above the upper seismic plane of the double-planed deep seismic zone. This result indicates that events in the upper seismic plane, at least in the depth range from 60 to 150 km, occur within the thin low-velocity layer on the surface of the oceanic plate. 相似文献
33.
34.
We found that the suppression of signals for 88 Sr, 140 Ce and 238 U in rock solution caused by rock matrix in ICP-MS (matrix effects) was reduced at high power operation (1.7 kW) of the ICP. To make the signal suppression by the matrix negligible, minimum dilution factors (DF) of the rock solution for Sr, Ce and U were 600, 400 and 113 at 1.1, 1.4 and 1.7 kW, respectively. Based on these findings, a rapid and precise determination method for Rb, Sr, Y, Cs, Ba, REE, Pb, Th and U using FI (flow injection)-ICP-MS was developed. The amount of the sample solution required for FI-ICP-MS was 0.2 ml, so that 1.8 mg sample was sufficient for analysis with a detection limit of several ng g-1 . Using this method, we determined the trace element concentrations in the USGS rock reference materials, DTS-1, PCC-1, BCR-1 and AGV-1, and the GSJ rock reference materials, JP-1, JB-1, -2, -3, JA-1, -2 and -3. The reproducibilities (RSD %) in replicate analyses (n=5) of BCR-1, AGV-1, JB-1, -2, -3, JA-1, -2, and -3 were < 6 %, and typically 2.5%. The difference between the average concentrations of this study for BCR-1 and those of the reference values were < 2%. Therefore, it was concluded that the method can give reliable data for trace elements in silicate rocks. 相似文献
35.
36.
The present study deals with the elucidation of sterol composition of the marine sediments in Kagoshima Bay. The identification of each sterol was performed by gas-liquid chromatography, Ag+ impregnated column chromatography, mass spectrometry, and nuclear magnetic resonance spectrometry. The sediment obtained near the estuary of River Koutsuki contained large portions of 5-stanols such as coprostanol and 24-ethylcoprostanol basides 5-stanols such as cholestanol, 24-methylcholestanol, and 24-ethylcholestanol in the sterol fraction. These 5-stanols in the marine sediment may be derived from the fecal contamination by domestic sewages. 相似文献
37.
Akio Ishida Kisaburo Nakata Shigeaki Aoki Hiroshi Kutsukake Michio J. Kishi Masahisa Kubota 《Journal of Oceanography》2001,57(4):433-450
Distributions and characteristics of water mass and chlorofluorocarbons (CFCs) in the North Pacific are investigated by using
a General Circulation Model (GCM). The anthropogenic CO2 uptake by the ocean is estimated with velocity fields derived from the GCM experiments. The sensitivity of the uptake to
different diffusion parameterizations and different surface forcing used in the GCM is investigated by conducting the three
GCM experiments; the diffusive processes are parameterized by horizontal and vertical eddy diffusion which is used in many
previous models (RUN1), parameterized by isopycnal diffusion (RUN2), and isopycnal diffusion and perpetual winter forcing
for surface temperature and salinity (RUN3). Realistic features for water masses and CFCs can be simulated by the isopycnal
diffusion models. The horizontal and vertical diffusion model fails to simulate the salinity minimum and realistic penetration
of CFCs into the ocean. The depth of the salinity minimum layer is better simulated under the winter forcing. The results
suggest that both isopycnal parameterization and winter forcing are crucial for the model water masses and CFCs simulations.
The oceanic uptake of anthropogenic CO2 in RUN3 is about 19.8 GtC in 1990, which is larger by about 10% than that in RUN1 with horizontal and vertical diffusive
parameterization. RUN3 well simulates the realistic water mass structure of the intermediate layer considered as a candidate
of oceanic sink for anthropogenic CO2. The results suggest that the previous models with horizontal and vertical diffusive parameterization may give the oceanic
uptake of anthropogenic CO2 underestimated.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
38.
Volume transport of the Soya Warm Current revealed by bottom-mounted ADCP and ocean-radar measurement 总被引:2,自引:2,他引:0
Yasushi Fukamachi Iori Tanaka Kay I. Ohshima Naoto Ebuchi Genta Mizuta Hideo Yoshida Shiro Takayanagi Masaaki Wakatsuchi 《Journal of Oceanography》2008,64(3):385-392
The vertical structure of the Soya Warm Current (SWC) was observed by a bottom-mounted acoustic Doppler current profiler (ADCP)
in the region of the SWC axis near the Soya Strait during a 1-year period from May 2004. The ADCP data revealed a marked seasonal
variability in the vertical structure, with positive (negative) vertical shear in summer and fall (winter and spring). The
volume transport of the SWC is estimated on the basis of both the vertical structure observed by the ADCP and horizontal structure
observed by the ocean radars near the strait. The transport estimates have a minimum in winter and a maximum in fall, with
the yearly-averaged values in the range of 0.94–1.04 Sv (1 Sv = 106 m3 s−1). These lie within a reasonable range in comparison to those through other straits in the Japan Sea. 相似文献
39.
Youichi Oyama Bunkei Matsushita Takehiko Fukushima Kazuo Matsushige Akio Imai 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(1):73-85
The remote sensing of Case 2 water has been far less successful than that of Case 1 water, due mainly to the complex interactions among optically active substances (e.g., phytoplankton, suspended sediments, colored dissolved organic matter, and water) in the former. To address this problem, we developed a spectral decomposition algorithm (SDA), based on a spectral linear mixture modeling approach. Through a tank experiment, we found that the SDA-based models were superior to conventional empirical models (e.g. using single band, band ratio, or arithmetic calculation of band) for accurate estimates of water quality parameters. In this paper, we develop a method for applying the SDA to Landsat-5 TM data on Lake Kasumigaura, a eutrophic lake in Japan characterized by high concentrations of suspended sediment, for mapping chlorophyll-a (Chl-a) and non-phytoplankton suspended sediment (NPSS) distributions. The results show that the SDA-based estimation model can be obtained by a tank experiment. Moreover, by combining this estimation model with satellite-SRSs (standard reflectance spectra: i.e., spectral end-members) derived from bio-optical modeling, we can directly apply the model to a satellite image. The same SDA-based estimation model for Chl-a concentration was applied to two Landsat-5 TM images, one acquired in April 1994 and the other in February 2006. The average Chl-a estimation error between the two was 9.9%, a result that indicates the potential robustness of the SDA-based estimation model. The average estimation error of NPSS concentration from the 2006 Landsat-5 TM image was 15.9%. The key point for successfully applying the SDA-based estimation model to satellite data is the method used to obtain a suitable satellite-SRS for each end-member. 相似文献
40.
Akio K. Inoue Akinori Oka Taishi Nakamoto 《Monthly notices of the Royal Astronomical Society》2009,393(4):1377-1390
The temperature in the optically thick interior of protoplanetary discs is essential for the interpretation of millimetre observations of the discs, for the vertical structure of the discs, for models of the disc evolution and the planet formation, and for the chemistry in the discs. Since large icy grains have a large albedo even in the infrared, the effect of scattering of the diffuse radiation in the discs on the interior temperature should be examined. We have performed a series of numerical radiation transfer simulations, including isotropic scattering by grains with various typical sizes for the diffuse radiation as well as for the incident stellar radiation. We also have developed an analytic model including isotropic scattering to understand the physics concealed in the numerical results. With the analytic model, we have shown that the standard two-layer approach is valid only for grey opacity (i.e. grain size ≳10 μm) even without scattering. A three-layer interpretation is required for grain size ≲10 μm. When the grain size is 0.1–10 μm, the numerical simulations show that the isotropic scattering reduces the temperature of the disc interior. This reduction is nicely explained by the analytic three-layer model as a result of the energy loss by scatterings of the incident stellar radiation and of the warm diffuse radiation in the disc atmosphere. For grain size ≳10 μm (i.e. grey scattering), the numerical simulations show that the isotropic scattering does not affect the interior temperature. This is nicely explained by the analytic two-layer model; the energy loss by scattering in the disc atmosphere is exactly offset by the 'green-house effect' due to the scattering of the cold diffuse radiation in the interior. 相似文献