Comment on “Evaluation of palaeo-oxygenation of the ocean bottom cross the Permian–Triassic boundary” by Kakuwa (2008): Was the Late Permian deep-superocean really oxic?     

Yasuhiro Kato  Yukio Isozaki 《Global and Planetary Change》2009,69(1-2):79-81

Nearly 15 years after the proposal of the superanoxia concept (Isozaki, Y., 1994. Superanoxia across the Permo–Triassic boundary: record in accreted deep-sea pelagic chert in Japan. In: Embry, A.F., Beauchamp, B., Glass, D.J. (Eds.), Pangea: Global Environments and Resources. Memoir, Canadian Society of Petroleum Geologists, 17, pp. 805–812.), it is an appropriate timing to re-evaluate its geological context with the updated dataset. Kakuwa (Kakuwa, Y., 2008. Evaluation of palaeo-oxygenation of the ocean bottom across the Permian–Triassic boundary. Global and Planetary Change 63, 40–56.) lately discussed that the deep-sea anoxia across the Permian–Triassic boundary (P–TB) may have been much shorter than previously proposed, on the basis of ichnofabrics and geochemical data; however, his interpretations of the data do not appear straightforward nor persuading, and thus his claim is likely misled. Here we raise comments to his explanation on the following four issues: 1) invalid application of ichnofabric indices for shallow sea sediments to deep-sea cherts, 2) misinterpretation of Ce anomaly as a redox indicator, 3) improper application of various redox sensitive trace elements, and 4) questionable interpretations of δ³⁴S data of pyrites.  相似文献   

Multiple temporal scale variability during the twentieth century in global carbon dynamics simulated by a coupled climate–terrestrial carbon cycle model     

Tomomichi Kato  Akihiko Ito  Michio Kawamiya 《Climate Dynamics》2009,32(7-8):901-923

A coupled climate–carbon cycle model composed of a process-based terrestrial carbon cycle model, Sim-CYCLE, and the CCSR/NIES/FRCGC atmospheric general circulation model was developed. We examined the multiple temporal scale functions of terrestrial ecosystem carbon dynamics induced by human activities and natural processes and evaluated their contribution to fluctuations in the global carbon budget during the twentieth century. Global annual net primary production (NPP) and heterotrophic respiration (HR) increased gradually by 6.7 and 4.7%, respectively, from the 1900s to the 1990s. The difference between NPP and HR was the net carbon uptake by natural ecosystems, which was 0.6 Pg C year^?1 in the 1980s, whereas the carbon emission induced by human land-use changes was 0.5 Pg C year^?1, largely offsetting the natural terrestrial carbon sequestration. Our results indicate that monthly to interannual variation in atmospheric CO₂ growth rate anomalies show 2- and 6-month time lags behind anomalies in temperature and the NiNO₃ index, respectively. The simulated anomaly amplitude in monthly net carbon flux from terrestrial ecosystems to the atmosphere was much larger than in the prescribed air-to-sea carbon flux. Fluctuations in the global atmospheric CO₂ time series were dominated by the activity of terrestrial vegetation. These results suggest that terrestrial ecosystems have acted as a net neutral reservoir for atmospheric CO₂ concentrations during the twentieth century on an interdecadal timescale, but as the dominant driver for atmospheric CO₂ fluctuations on a monthly to interannual timescale.  相似文献   

Thermal generation of magnetic fields with radiation pressure in rotating stars     

Shoji Kato  Y. Nakagawa 《Astrophysics and Space Science》1969,5(2):171-179

It has been suggested by Biermann that in rotating stars the electron partial pressure could generate a toroidal magnetic field of a considerable strength. However, Mestel and Roxburgh have shown recently that the generation of such a toroidal magnetic field could almost completely be suppressed when a weak primodial poloidal magnetic field exists in the star. In this paper it is shown that a toroidal magnetic field of a moderate strength could be generated even in the presence of a primodial poloidal magnetic field, if the effect of radiation pressure is taken into consideration. This considered mechanism is effective for moderately massive stars, and numerical estimate indicates that in A type stars a toroidal magnetic field of the order of a thousand gauss can be generated near the surface within the time scale of the evolution of the star.Visiting Scientist to the High Altitude Observatory on leave of absence from the Department of Astronomy, University of Tokyo, Japan.  相似文献   

Classification of Geomagnetic Micropulsations     

J. A. Jacobs  Y. Kato  S. Matsushita  V. A. Troitskaya 《Geophysical Journal International》1964,8(3):341-342

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Potosiite and incaite from the Hoei mine,Japan     

M. Shimizu  G. H. Moh  A. Kato 《Mineralogy and Petrology》1992,46(2):155-161

Summary Potosiite and incaite have been found at the Hoei mine, Oita Prefecture, Japan. Potosiite occurs as tabular crystals (3 cm x 2 cm in size), and is associated with arsenopyrite, pyrrhotite, stannite,jamesonite and pyrite, whereas incaite occurs as polycrystalline aggregates rimming galena or as hair-like masses in a matrix of kutnahorite. X-ray powder data reveal that these minerals are potosiite and incaite, respectively. Electron-microprobe analyses of potosiite and incaite gave the general formula (Pb, Sn)²⁺ _6+xFeSb₂Sn⁴⁺ ₂S_14+x, with x < 2. Potosiite is homogeneous, whereas incaite, in contact with galena, is quite heterogeneous. Reflectance data for potosiite show that its bireflectance is one of the lowest among opaque minerals with a sheet-like structure.

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Potosiit und incait von der Hoei-mine, Japan

Zusammenfassung Potosiit and Incait wurden in Erzen der Hoei-Mine, Oita Präfektur, Japan, nachgewiesen. Potosiit kommt in plattigen Kristallen (3 cm x 2 cm) vor and ist mit Arsenkies, Magnetkies, Zinnkies, Jamesonit and Pyrit assoziiert. Incait kommt in polykristallinen Aggregaten, die Ränder um Bleiglanz bilden, oder als Haar-artige Massen in einer Matrix von Kutnahorite vor. Röntgendiffraktionsdaten zeigen, daß es sich hier um Potosiit and Incait handelt; Mikrosondenanalysen der beiden Minerale geben die allgemeine Formel (Pb, Sn)²⁺ _6+x(FeSb₂ ⁴⁺)₂S_4+x, with x < 2. Potosiit ist homogen, während Incait in Kontakt mit Bleiglanz inhomogen ist. Quantitative Reflexionsdaten für Potosiit zeigen, daß seine Bireflexion zu den niedrigsten bei opaken Mineralen mit Schichtgitter gehört.

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APPLICATION OF MEM SPECTRAL ESTIMATION TO MU RADAR OBSERVATION   总被引：1，自引：0，他引：1       下载免费PDF全文

Li Wei  L&#;Daren  Shoichiro Fukao  Mamoru Yamamoto  Toshitaka Tsu  Susumu Kato 《Acta Meteorologica Sinica》1991,5(3):293-298

Preliminary results of the wind velocity estimation using the Maximum Entropy Method (MEM) to MUradar observation data sets are presented. The comparison of the results from the periodogram method and theMEM shows that the MEM estimation is reliable, and has higher accuracy, resolution and detectability than theestimation from periodogram method. The high accuracy power spectrum obtained by the MEM is veryuseful to studying the atmospheric turbulence structure. However. the MEM needs the longer computingtime for obtaining the high accuracy spectrum. Particularly, the estimation of MEM will bring serious devia-tion at lower signal-to-noise ratio.  相似文献   

青海海北高寒草甸五种植被生物量及环境条件比较   总被引：11，自引：4，他引：11  

李英年  赵新全  王勤学  古松  杜明远  加藤知道  王启兰  赵亮 《山地学报》2003,21(3):257-264

分析了高寒草甸不同植被类型植物种类组成、生物量变化规律及其差异。研究表明不同植被类型的分布与土壤湿度和温度有很大的关系。藏篙草草甸、金露梅灌丛草甸、矮篙草草甸、正恢复的矮篙草草甸、小嵩草草甸这5种不同植被类型所对应的土壤湿度依次降低，而所对应的土壤温度依次升高；植物种类数量表现为矮嵩草草甸＞金露梅灌丛草甸＞小篙草草甸＞正恢复的矮篙草草甸＞藏篙草草甸。地上生物量高低依次为小嵩草革甸＞矮嵩草草甸＞金露梅灌丛草甸＞正恢复的矮篙草草甸＞藏篙草草甸；地下生物量则表现出金露梅灌丛革甸＞矮嵩草甸＞小篙草草甸＞正恢复的矮篙草草甸的特征，而其在年内的周转值表现出金露梅灌丛草甸＞正承复的矮嵩草草甸＞小篙草草甸＞矮篙草草甸;土壤有机质的季节变化表现为0—40cn整层土壤有机质含量小嵩草草甸＞金露梅灌丛草甸＞矮嵩草草甸＞正恢复的矮篙草草甸，0—10cm的表层土壤有机质金露梅灌丛草甸＞矮嵩草草甸＞小嵩草草甸＞正恢复的矮篙草草甸。  相似文献   

Diagenetic control on arsenic partitioning in sediments of the Meghna River delta,Bangladesh     

H. Anawar  K. Komaki  J. Akai  J. Takada  T. Ishizuka  T. Takahashi  T. Yoshioka  K. Kato 《Environmental Geology》2002,41(7):816-825

A stratigraphic profile of solid phase As was measured to investigate the diagenetic cycling of arsenic and related elements in fluvial sediments of the Meghna River delta plain. The distributions of Fe, Mn, and Al are typically characterized by surficial solid phase enrichment, and As is distributed down to 36.6 m showing similar alternate layers of maxima and minima with Fe, Mn and TOC, which reflects the diagenetic remobilization and periodical differences in source materials of As. Lithological characteristics and geochemical data suggest that elevated levels of As are found in organic-matter-rich clay and silty sand rather than sand samples, with occasionally enriched As content in iron-oxyhydroxide-coated sand grains. Arsenic demonstrates a positive and significant co-variation with total organic carbon in sediments, which suggests the important role of particulate and colloidal organic matter and biological activity in controlling the distribution of arsenic in the Bengal delta. However, the concentrations of Fe and Mn weakly correlate with As contents, whereas Al contents show no relationship with As. The results of this study suggest that reactive oxides or hydroxides of Fe and Mn, rather than Fe and Mn with other minerals, might control arsenic distribution.  相似文献   

Geochemical Features and Tectonic Setting of Greenstones from Kunimiyama, Northern Chichibu Belt, Central Shikoku, Japan     

Tatsuo Nozaki    Kentaro Nakamura  Hiroshi Osawa    Koichiro Fujinaga  Yasuhiro Kato 《Resource Geology》2005,55(4):301-310

Abstract. We report whole‐rock chemical data for the greenstones from the Kunimiyama area in the Northern Chichibu Belt and their implications on the tectonic setting of these rocks. The Kunimiyama greenstones are associated with stratiform fer‐romanganese deposits or bedded cherts in the northern part of the study area, but are closely associated with a thick limestone block or bedded cherts in the southern part. The constituent minerals of greenstones are albitized plagioclase, clinopy‐roxene, chlorite, calcite, epidote, pumpellyite, prehnite, quartz, celadonite, sericite and opaque minerals such as iron oxyhy‐droxide and hematite. These mineral assemblages, epidote + pumpellyite + chlorite and chlorite + pumpellyite + prehnite, suggest that the metamorphic grade of greenstones from the Kunimiyama area is prehnite‐pumpellyite facies. The whole‐rock chemical compositions of greenstones associated with ferromanganese deposits are generally similar to those of normal mid‐ocean ridge basalt (N‐MORB). In contrast, the chemical compositions of the greenstones associated with the limestone block are comparable to those of ocean island alkaline basalt. Greenstones associated with bedded cherts are of enriched MORB and ocean island basalt, as well as N‐MORB origins, suggesting they probably formed as a result of plume‐related MOR volcanism in the Panthalassa Ocean in Early Permian and by tectonic mixing of ocean island basalts with oceanic ridge crustal fragments during accretion/subduction processes. These geological and geochemical lines of evidence suggest that the Kunimiyama greenstones are allochthonous blocks of accreted oceanic crust and seamounts. The ferromanganese deposits are frequently accompanied by reddish greenstones. Compared to common greenish greenstones, the reddish greenstones are characterized by high MnO and rare earth element contents and distinct negative Ce anomalies, implying a slight contribution of hydro thermal component forming the ferromanganese deposits.  相似文献   

Application of the inversion method to a GPS network for estimating the stress increment in Japan     

Muneo Hori  Toshio Kameda  Teruyuki Kato 《Geophysical Journal International》2001,144(3):597-608

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