Microbial community structure analysis of euxinic sediments using phospholipid fatty acid biomarkers     

Narasimmalu Rajendran  Osamu Matsuda  Norifumi Imamura  Yoshikuni Urushigawa 《Journal of Oceanography》1995,51(1):21-38

Microbial community structure in sediments, as determined by the phospholipid ester-linked fatty acid (PLFA) analysis, collected from Kojima Lake during summer and winter was described with reference to the environmental quality of the lake. A characteristic feature of the study area was the persistence of anoxia in summer and winter in the deeper area, and the sediments were under the reduced condition with high levels of sulfide, chemical oxygen demand, and low values of oxidation-reduction potential. PLFA profiles of the sediment were dominated by the saturated, branched and monounsaturated fatty acids. Small amounts (less than 5% of the total PLFA) of polyunsaturated fatty acids (biomarker fatty acids of microeukaryotes) and long chain fatty acids were detected in sediments. Total PLFA concentrations in sediments were higher in summer than in winter. Microbial community structure in the lake sediments was predominated by the prokaryotes, as evidenced from the larger amounts of bacterial biomarker fatty acids in the range of C₁₀ to C₂₀. The presence of signature fatty acids of sulfate reducing bacteria in sediments was consistent with the high levels of sulfide in the sediment and anoxic condition in the study area. PLFA showed significant differences in PLFA profiles between shallow and deeper areas, indicating the differences in the lipid contributing communities. However, no such a significant difference was observed between summer and winter.  相似文献   

Phosphorus content of zooplankton from the Inland Sea of Japan     

Shin-ichi Uye  Osamu Matsuda 《Journal of Oceanography》1988,44(6):280-286

Measurements of phosphorus content were made for eleven species of copepods, two species of mysids, shrimps (including mysis stage) and chaetognaths, and one species ofNoctiluca, cirriped (naupliar stage) and crab (zoeal stage) from the Inland Sea of Japan. The body phosphorus content (P, inµg) is highly correlated to prosome length (L, inµm) for copepods, which is expressed as logP=2.90 ×logL–9.34. Mean phosphorus content expressed as percent of dry weight is 1.30% for copepods, 1.39% for mysids, 0.63% for a decapod shrimpAcetes japonicus, and 0.80% for chaetognaths.Noctiluca contains phosphorus of only 0.36%. The comparatively higher phosphorus content of suspension-feeding copepods may be related to the constant supply of phosphorus-rich phytoplankton in this region.  相似文献   

Behavior of manganese in aqua-benthic environment in the Hiro Bay     

Shizuko Hirata  Osamu Takimura  Takayuki Shiozawa 《Journal of Oceanography》1978,34(6):237-241

The horizontal and vertical distributions of manganese in sea water, interstitial water and sediments in the Hiro Bay, Seto Inland Sea, Japan, have been investigated. The outflow from a pulp mill is the primary source of manganese in this bay. The industrial waste water contained 0.19 mg l^–1 of manganese, mostly in a dissolved form. This manganese diffused out both horizontally and vertically into the surrounding sea water. The content of manganese in the liquid and solid phases in the sediments, however, are inverse with that in the sea water; namely the lowest concentration of manganese in the sediments was observed at the station near the outfall and manganese concentration increased with the distance from the outfall.  相似文献   

Vertical distribution of heavy metals and its seasonal variations in Beppu Bay     

Takayuki Shiozawa  Kichiichiro Kawana  Akira Hoshika  Terumi Tanimoto  Osamu Takimura 《Journal of Oceanography》1977,33(6):350-356

From July to November, the thermocline which has strong temperature gradient (0.7C m^–1) is formed in the bottom water of Beppu Bay, and it prevents the downward mixing of surface water. This has caused the bottom water of the basin to become depleted in oxygen, and in November the bottom water below about 60 m depth becomes anoxic. Accordingly manganese and iron are reduced and more soluble under the anoxic condition, those concentrations are high relative to surface water, and the maximums are 1,240g l^–1 and 80g l^–1. Under the anoxic condition, the flux of dissolved manganese from the sediment is about 10g cm^–2 day^–1.  相似文献   

Evolution of West Rota Volcano, an extinct submarine volcano in the southern Mariana Arc: Evidence from sea floor morphology, remotely operated vehicle observations and ⁴⁰Ar–³⁹Ar geochronological studies     

Robert J.  Stern  Yoshihiko  Tamura  Robert W.  Embley  Osamu  Ishizuka  Susan G.  Merle  Neil K.  Basu  Hiroshi  Kawabata  Sherman H.  Bloomer 《Island Arc》2008,17(1):70-89

Abstract West Rota Volcano (WRV) is a recently discovered extinct submarine volcano in the southern Mariana Arc. It is large (25 km diameter base), shallow (up to 300 m below sealevel), and contains a large caldera (6 × 10 km, with up to 1 km relief). The WRV lies near the northern termination of a major NNE‐trending normal fault. This and a second, parallel fault just west of the volcano separate uplifted, thick frontal arc crust to the east from subsiding, thin back‐arc basin crust to the west. The WRV is distinct from other Mariana Arc volcanoes: (i) it consists of a lower, predominantly andesite section overlain by a bimodal rhyolite‐basalt layered sequence; (ii) andesitic rocks are locally intensely altered and mineralized; (iii) it has a large caldera; and (iv) WRV is built on a major fault. Submarine felsic calderas are common in the Izu and Kermadec Arcs but are otherwise unknown from the Marianas and other primitive, intraoceanic arcs. ⁴⁰Ar–³⁹Ar dating indicates that andesitic volcanism comprising the lower volcanic section occurred 0.33–0.55 my ago, whereas eruption of the upper rhyolites and basalts occurred 37–51 thousand years ago. Four sequences of rhyolite pyroclastics each are 20–75 m thick, unwelded and show reverse grading, indicating submarine eruption. The youngest unit consists of 1–2 m diameter spheroids of rhyolite pumice, interpreted as magmatic balloons, formed by relatively quiet effusion and inflation of rhyolite into the overlying seawater. Geochemical studies indicate that felsic magmas were generated by anatexis of amphibolite‐facies meta‐andesites, perhaps in the middle arc crust. The presence of a large felsic volcano and caldera in the southern Marianas might indicate interaction of large normal faults with a mid‐crustal magma body at depth, providing a way for viscous felsic melts to reach the surface.  相似文献   

Continental basalts in the accretionary complexes of the South-west Japan Arc: Constraints from geochemical and Sr and Nd isotopic data of metadiabase     

Hiroo Kagami  Masaki Yuhara  Shigeru Iizumi  Yoshiaki Tainosho  Masaaki Owada  Yasuo Ikeda  
  Osamu Okano  Shuji Ochi  Yoshikazu Hayama and  Terukazu Nureki 《Island Arc》2000,9(1):3-20

Abstract The Ryoke Belt is one of the important terranes in the South‐west Japan Arc (SJA). It consists mainly of late Cretaceous granitoid rocks, meta‐sedimentary rocks (Jurassic accretionary complexes) and mafic rocks (gabbros, metadiabases; late Permian–early Jurassic). Initial ?_Sr (+ 25– + 59) and ?_Nd (? 2.1–?5.9) values of the metadiabases cannot be explained by crustal contamination but reflect the values of the source material. These values coincide with those of island arc basalt (IAB), active continental margin basalt (ACMB) and continental flood basalt (CFB). Spiderdiagrams and trace element chemistries of the metadiabases have CFB‐signature, rather than those of either IAB or ACMB. The Sr–Nd isotope data, trace element and rare earth element chemistries of the metadiabases indicate that they result from partial melting of continental‐type lithospheric mantle. Mafic granulite xenoliths in middle Miocene volcanic rocks distributed throughout the Ryoke Belt were probably derived from relatively deep crust. Their geochemical and Sr–Nd isotopic characteristics are similar to the metadiabases. This suggests that rocks, equivalent geochemically to the metadiabases, must be widely distributed at relatively deep crustal levels beneath a part of the Ryoke Belt. The geochemical and isotopic features of the metadiabases and mafic granulites from the Ryoke Belt are quite different from those of mafic rocks from other terranes in the SJA. These results imply that the Ryoke mafic rocks (metadiabase, mafic granulite) were not transported from other terranes by crustal movement but formed in situ. Sr–Nd isotopic features of late Cretaceous granitoid rocks occurring in the western part of the Japanese Islands are coincident with those of the Ryoke mafic rocks. Such an isotopic relation between these two rocks suggests that a continental‐type lithosphere is widely represented beneath the western part of the Japanese Islands.  相似文献   

The 3D spiral structure pattern in the atmosphere   总被引：3，自引：0，他引：3  

Liu Shi  Xin Guojun  Liu Shikuo  Liang Fuming 《大气科学进展》2000,17(4):519-524

1. IntroductionSpiral structures of vortices in different scales have been widely studied. From thesynoptic map we can see that the trough line orientation of Rossby wave changes with latitude. A barotropic model in the polar coordinate system was established for the explanationof this observational fact (Chao and Ye, 1977). In the framework of the wave propagationtheory, the spiral structure would be organized by the phase isoline of Rossby wave and be responsible for the trough line tiltin…  相似文献   

一种简单与稳健的自适应阵处理     

吴士达  张铭 《成都信息工程学院学报》1991,(2)

本文提出了一种简单的自适应干扰对消的阵处理方法。它避免了经典方法所需的相关矩阵逆的大量运算(尤其是阵元数较多时),还减少了对到达方向(DOA)估计误差的敏感性。  相似文献   

Flare activity in AM Canum Venaticorum     

Kenji Tanabe  Osamu Ohshima  Kohzoh Kosaka 《Astrophysics and Space Science》1990,172(1):155-158

Flare activity on AM CVn was observed photometrically at 16^h20^m UT of 20 February, 1990. The amplitude of the flare is about 0.2 mag. The shape of the flare and the subsequent amplitude enhancement of the 1051 s period are quite similar to those previously observed by Mararet al. (1988).  相似文献   

Interrelationships Between Topography,Quaternary Vertical Displacement,Active Faults and Short-term Horizontal Crustal Strain in Honshu,Japan     

Thomas H.?WilsonEmail author  Kazuhiko?Kano  Osamu?Nishizawa 《Pure and Applied Geophysics》2004,161(1):93-122

Regional and local characteristics of active fault patterns and elevation variation throughout Honshu, Japan are characterized in terms of their fractal dimensions; this allows variation in these complex variables to be compared directly to the scalar properties of net Quaternary vertical displacement, elevation and 10- and 110-year horizontal strains. The comparisons reveal that, throughout Honshu as a whole, there is significant correlation (r=0.75) between Quaternary vertical displacement, elevation, and its fractal properties. There is poor correlation, however, of elevation and its fractal properties to horizontal crustal strain, and also between Quaternary vertical displacement and horizontal crustal strain. A slight negative correlation is observed between the fractal properties of the active fault system and horizontal crustal strain measured over 10- and 110-year time periods (–0.43 and –0.26, respectively). The correlation between the 10-year (1985–1994) and 110-year (1883–1994) area strains, 0.48, reveals the occurrence of considerable change in the distribution of regional strain over these short time frames. Local computations of the correlation between data sets made for overlapping 160 km length windows of data spaced every 20 km along analysis lines reveal internal fluctuations in the correlation between variables. The local correlation between Quaternary vertical displacement and elevation is highest through central Japan and the Kinki Triangle. There is weak negative correlation between area strain and fractal dimensions of the active fault network. The local correlation between the fractal dimensions of active faults and horizontal area strain over the recent 10-year time period averages about –0.6 through central Japan in an area that extends across the Kinki Triangle through the northern part of central Honshu and northeast across the Itoigawa Shizuoka Tectonic Line. In general, regions of greatest complexity in the active fault network are associated with persistent negative area or compressional strain. Sparsely faulted areas in general coincide with areas of positive or roughly zero area strain. The presence of negative correlation through central Japan and the Kinki Triangle area in the recent 10-year period results from a decrease of area strain within an increasingly complex active fault system that reaches maximum negative values concentrated in the Kinki Triangle during the 1985–1994 time period.  相似文献