Numerical study of the oxidation process of dimethylsulfide in the marine atmosphere   总被引：1，自引：0，他引：1  

Seizi Koga  Hiroshi Tanaka 《Journal of Atmospheric Chemistry》1993,17(3):201-228

A box model, involving simple heterogeneous reaction processes associated with the production of non-sea-salt sulfate (nss-SO ₄ ^2– ) particles, is used to investigate the oxidation processes of dimethylsulfide (DMS or CH₃SCH₃) in the marine atmosphere. The model is applied to chemical reactions in the atmospheric surface mixing layer, at intervals of 15 degrees latitude between 60° N and 60° S. Given that the addition reaction of the hydroxyl radical (OH) to the sulfur atom in the DMS molecule is faster at lower temperature than at higher temperature and that it is the predominant pathway for the production of methanesulfonic acid (MSA or CH₃SO₃H), the results can well explain both the increasing tendency of the molar ratio of MSA to nss-SO ₄ ^2– toward higher latitudes and the uniform distribution with latitude of sulfur dioxide (SO₂). The predicted production rate of MSA increases with increasing latitude due to the elevated rate constant of the addition reaction at lower temperature. Since latitudinal distributions of OH concentration and DMS reaction rate with OH are opposite, a uniform production rate of SO₂ is realized over the globe. The primary sink of DMS in unpolluted air is caused by the reaction with OH. Reaction of DMS with the nitrate radical (NO₃) also reduces DMS concentration but it is less important compared with that of OH. Concentrations of SO₂, MSA, and nss-SO ₄ ^2– are almost independent of NO _x concentration and radiation field. If dimethylsulfoxide (DMSO or CH₃S(O)CH₃) is produced by the addition reaction and further converted to sulfuric acid (H₂SO₄) in an aqueous solution of cloud droplets, the oxidation process of DMSO might be important for the production of aerosol particles containing nss-SO ₄ ^2– at high latitudes.  相似文献   

Erratum     

Vanavan Ekambaram  Iwao Kawabe  Tsuyoshi Tanaka  Andrew M. Davis  Lawrence grossman 《Geochimica et cosmochimica acta》1985,49(5):1293

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Refractory inclusions in the Murchison meteorite     

Glenn J. MacPherson  Miryam Bar-Matthews  Tsuyoshi Tanaka  Edward Olsen 《Geochimica et cosmochimica acta》1983,47(4):823-839

Mineralogical and petrographic studies of a wide variety of refractory objects from the Murchison C2 chondrite have revealed for the first time melilite-rich and feldspathoid-bearing inclusions in this meteorite, but none of these is identical to any inclusion yet found in Allende. Blue spinel-hibonite spherules have textures indicating that they were once molten, and thus their SiO₂-poor bulk composition requires that they were exposed to higher temperatures (>1550°C) than those deduced so far from any Allende inclusion. Melilite-rich inclusions are similar to Allende compact Type A's, but are more Al-, Ti-rich. One inclusion (MUCH-1) consists of a delicate radial aggregate of hibonite crystals surrounded by alteration products, and probably originated by direct condensation of hibonite from the solar nebular vapor. The sinuous, nodular and layered structures of another group of inclusions, spinel-pyroxene aggregates, suggest that these also originated by direct condensation from the solar nebular gas. Each type of inclusion is characterized by a different suite of alteration products and/or rim layers from all the other types, indicating modification of the inclusions in a wide range of different physico-chemical environments after their primary crystallization. All of these inclusions contain some iron-free rim phases. These could not have formed by reaction of the inclusions with fluids in the Murchison parent body because the latter would presumably have been very rich in oxidized iron. Other rim phases and alteration products could have formed at relatively low temperatures in the parent body, but some inclusions were not in the locations in which they were discovered when this took place. Some of these inclusions are too fragile to have been transported from one region to another in the parent body, indicating that low temperature alteration of these may have occurred in the solar nebula.  相似文献   

ASCA observations of the Galactic superluminal sources GRO J1655–40 and GRS 1915+105     

Kazutaka Yamaoka  Yoshihiro Ueda  Hajime Inoue  Fumiaki Nagase  Ken Ebisawa  Taro Kotani  Yasuo Tanaka 《Astrophysics and Space Science》2001,276(1):19-22

We summarize the ASCA observations of the two Galactic superluminal sources GRO J1655–40 and GRS 1915+105, focusing on theabsorption line features.The high spectroscopic capability of ASCA enabled us to detectiron-K absorption line features from both objects. This is direct evidence for the presence of highly ionized plasma in a non-spherical configuration around a black hole, and is considered to be a unique signature of superluminal jet systems. The candidate of the line-absorber would be a part of an accretion disk at a distance of 10^9-11 cm from the central X-ray source.  相似文献   

Geological age of the Yokawa Formation of the Kobe Group (Japan) on the basis of terrestrial mammalian fossils     

Takehisa  Tsubamoto  Takashi  Matsubara  Satoshi  Tanaka  Haruo  Saegusa 《Island Arc》2007,16(3):479-492

Abstract   The age of the Yokawa Formation of the Cenozoic Kobe Group distributed in Hyogo Prefecture of western Japan based on mammalian fossils is discussed. Two fossil dental specimens of terrestrial mammals discovered from the lowest part of the Yokawa Formation in the Sanda area are described. These two fossils described here are: (i) a right mandibular fragment with p2–m3 of Bothriodon sandaensis sp. nov. (selenodont anthracotheriid artiodactyl), which appears to be the most primitive among the species of the genus; and (ii) right m1–m3 of cf. Hyrachyus sp. (primitive rhinocerotoid perissodactyl). In the lower part of the Yokawa Formation, Zaisanamynodon (amynodontid perissodactyl) was previously reported. The morphology ('evolutionary stage') of B. sandaensis is indicative of the latest Middle to Late Eocene, that of cf. Hyrachyus sp. is indicative of the Early to Middle Eocene, and Zaisanamynodon is indicative of the Late Middle to Late Eocene. Therefore, the fossil mammals of the Yokawa Formation indicate an latest Middle Eocene ( ca . 38 Ma) correlation for the lower part of the formation, as a working hypothesis. Although the resolution of the geological age based on these mammalian fossils is relatively low compared to that based on marine index fossils, this result is concordant with the recent radiometric correlation of the lower part of the Yokawa Formation in the Sanda area.  相似文献   

Preface     

T. Shimamoto  K. Takemura  K. Fujimoto  H. Tanaka  C. A. J. Wibberley 《Island Arc》2001,10(3-4):357-359

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Simulations of seasonal variations of sulfur compounds in the remote marine atmosphere   总被引：1，自引：0，他引：1  

Seizi Koga  Hiroshi Tanaka 《Journal of Atmospheric Chemistry》1996,23(2):163-192

A photochemical box model is used to simulate seasonal variations in concentrations of sulfur compounds at latitude 40° S. It is assumed that the hydroxyl radical (OH) addition reaction to sulfur in the dimethyl sulfide (DMS) molecule is the predominant pathway for methanesulfonic acid (MSA) production, and that the rate constant increases as the air temperature decreases. Concentration of the nitrate radical (NO₃) is a function of the DMS flux, because the reaction of DMS with NO₃ is the most important loss mechanism of NO₃. While the diurnally averaged concentration of OH in winter is a factor of about 8 smaller than in summer, due to the weak photolysis process, the diurnally averaged concentration of NO₃ in winter is a factor of about 4–5 larger than in summer, due to the decrease of DMS flux. Therefore, at middle and high latitudes in winter, atmospheric DMS is mainly oxidized by the reaction with NO₃. The calculated ratio of the MSA to SO₂ production rates is smaller in winter than in summer, and the MSA to non-sea-salt sulfate (nssSO₄ ^2-) molar ratio varies seasonally. This result agrees with data on the seasonal variation of the MSA/nssSO₄ ^2- molar ratio obtained at middle and high latitudes. The calculations indicate that during winter the reaction of DMS with NO₃ is likely to be a more important sink of NO_x (NO+NO₂) than the reaction of NO₂ with OH, and to serve as a significant pathway of the HNO₃ production. If dimethyl sulfoxide (DMSO) is produced through the OH addition reaction and is heterogeneously oxidized in aqueous solutions, half of the nssSO₄ ^2- produced in summer may be through the oxidation process of DMSO. It is necessary to further investigate the oxidation products by the reaction of DMS with OH, and the possibility of the reaction of DMS with NO₃ during winter.  相似文献   

Possible europium-normal rare-earth abundances estimated from the lunar samples,and the terrestrial analogue     

Akimasa Masuda  Tsuyoshi Tanaka 《Contributions to Mineralogy and Petrology》1972,34(4):336-342

From the mathematical analysis of the rare-earth data on some of the Apollo 12 samples studied by Hubbard et al. (1971), the possible europium-normal primitive rare-earth pattern, in which europium is normal with respect to the adjacent rare-earth elements, has been estimated. A fact that the igneous rocks (Japanese geosynclinal basalts) appearing to reflect the analogous effect occur locally on the earth enhances our interests in the pattern resulting from the above estimation.  相似文献   

Rare earth elements in metagabbros from the Mid-Atlantic Ridge and their possible implications for the genesis of alkali olivine basalts as well as the lizard peridotite     

Akimasa Masuda  Noboru Nakamura  Tsuyoshi Tanaka 《Contributions to Mineralogy and Petrology》1971,32(4):295-306

Two foliated metagabbros from the Mid-Atlantic Ridge near 30° N were analyzed for rare earth elements. The chondrite-normalized rare earth pattern for one of them is quite similar to those for abyssal tholeiites. The pattern for another sample, however, is somewhat different from the above one. A new set of bulk partition coefficients for rare earth elements has been estimated correspondingly. This set throws a new light on the interpretation that many alkali olivine basalts were produced by a zone melting or partial melting of primary-liquid-type material. Also the same partition coefficients lead us to an inference that the high-temperature peridotite intrusion in the Lizard area, Cornwall, England, is a secondary-solid-type material which was once in equilibrium with a primary-solid-type material, whereas the pyroxenite, Canyon Mountain, Oregon, is a primary-solid-type material.Both of the metagabbros studied show positive europium anomaly.  相似文献   

Structure and time variations of the Jovian ionosphere     

T. Tanaka  K. Hirao 《Planetary and Space Science》1973,21(5):751-762

The problem of the ionospheric formation in the Jovian upper atmosphere is examined. By adopting two plausible atmospheric models, we solve coupled time-dependent continuity equations for ions H₂⁺, H₅⁺, H⁺, H₃⁺ and H_eH⁺ simultaneously. It is shown that both radiative and three body association of H⁺ to H₂ are important for the determination of the structure of the Jovian ionosphere. The maximum electron density in the daytime is found to be about 10⁵ cm^?3. It is also shown that diurnal variation with large-amplitude can exist in the Jovian ionosphere.  相似文献