Early stage incorporation of biolipids into kerogen in a lacustrine sediment: Evidence from alkaline potassium permanganate oxidation of sedimentary lipids and humic matter     

Ryoshi Ishiwatari  Tsutomu Machihara 《Organic Geochemistry》1983,4(3-4)

Lipids, fulvic acid, humic acid and kerogen were isolated from a lacustrine sediment in which the organic matter is probably derived predominantly from phytoplankton (Lake Haruna, Japan). An alkaline KMnO₄ oxidation study of the organic matter showed that distributions of polymethylene chain lengths in the lipids, humic acid and kerogen fractions are almost the same. The polymethylene chains in the sediment are dominant in the kerogen, lipids and humic acid, their relative abundance estimated by the oxidation being: kerogen (42% of the total amounts of polymethylene chains estimated) > lipids (38%) > humic acid (19%) > fulvic acid (1%). It was concluded that algal lipids may have been incorporated into the kerogen and humic acid fractions after the death of the algae and during, after, their deposition.  相似文献   

Bathymetry, biota and sediments on the Hirota Reef, Tane-ga-shima – the northernmost coral reef in the Ryukyu Islands     

Emiko  Ikeda  Yasufumi  Iryu  Kaoru  Sugihara  Hideo  Ohba  Tsutomu  Yamada 《Island Arc》2006,15(4):407-419

Abstract Investigations were conducted on bathymetry, reef biota and sediments on the Hirota Reef, Tane‐ga‐shima, North Ryukyus, near the northern limit for coral‐reef formation. A bathymetric profile from shore to the reef edge was depicted along an approximately 420‐m transect on the Hirota Coast of this island. A total of 20 quadrats (1 m × 1 m) were analyzed along the profile at 10‐ or 20‐m intervals to clarify distribution of macrobenthos inhabiting the reef. The Hirota Reef is divided into four geomorphologic zones according to their depth, gradient, surface roughness, substrate and characteristic macrobenthos. They are, from shore to offshore, shallow lagoon, seaward reef flat, reef edge and reef slope. The shallow lagoon comprises a shoreward depression (∼160 m wide on the transect) with a sand/gravel bottom that inclines gently toward offshore, and a seaward patch zone (∼70 m wide). The patches (<2 m high) are covered with fleshy algae, coralline algae and hermatypic corals. The seaward reef flat (∼190 m wide) is a flat plane that is constructed by biogenic carbonates and is covered with turf algae, with hermatypic corals scattered. Although the seaward reef flat of the Hirota Reef cannot be differentiated into different geomorphologic zones, similar seaward reef flat areas in the Central and South Ryukyus can be clearly subdivided into inner reef flat, reef crest and outer reef flat. This difference may be attributed to a lower reef growth rate and/or the later reef formation of the Hirota Reef in Holocene time than the southern examples. The coral fauna on the Hirota Reef is delineated by low diversity and characterized by taxa typical of high‐latitude, non‐reefal communities. The algal flora consists of tropical to subtropical species associated with warm‐temperate species. These faunal and floral characteristics may be related largely to lower water temperature in Tane‐ga‐shima than those in typical coral‐reef regions.  相似文献   

²³⁰Th/²³⁴U and ¹⁴C dating of a lowstand coral reef beneath the insular shelf off Irabu Island, Ryukyus, southwestern Japan     

Keiichi  Sasaki  Akio  Omura  Tetsuo  Miwa  Yoshihiro  Tsuji  Hiroki  Matsuda  Toru  Nakamori  Yasufumi  Iryu  Tsutomu  Yamada  Yuri  Sato  Hiroshi  Nakagawa 《Island Arc》2006,15(4):455-467

Abstract   High-resolution seismic reflection profiles delineated the distribution of mound-shaped reflections, which were interpreted as reefs, beneath the insular shelf western off Irabu Island, Ryukyus, southwestern Japan. A sediment core through one of the mounded structures was recovered from the sea floor at a depth of −118.2 m by offshore drilling and was dated by radiometric methods. The lithology and coral fauna of the core indicate that the mounded structure was composed of coral–algal boundstone suggesting a small-scaled coral reef. High-precision α-spectrometric ²³⁰Th/²³⁴U dating coupled with calibrated accelerator mass spectrometric ¹⁴C ages of corals obtained reliable ages of this reef ranging from 22.18 ± 0.63 to 30.47 ± 0.98 ka. This proves that such a submerged reef was formed during the lowstand stage of marine oxygen isotope stages 3–2. The existence of low-Mg calcite in the aragonitic coral skeleton of 22.18 ± 0.63 ka provides evidence that the reef had once been exposed by lowering of the relative sealevel to at least −126 m during the last glacial maximum in the study area. There is no room for doubt that a coral reef grew during the last glacial period on the shelf off Irabu Island of Ryukyus in the subtropical region of western Pacific.  相似文献   

Abundances of ethylene oxide and acetaldehyde in hot molecular cloud cores.     

A Nummelin  J E Dickens  P Bergman  A Hjalmarson  W M Irvine  M Ikeda  M Ohishi 《Astronomy and Astrophysics》1998,337(1):275-286

We have searched for millimetre-wave line emission from ethylene oxide (c-C2H4O) and its structural isomer acetaldehyde (CH3CHO) in 11 molecular clouds using SEST. Ethylene oxide and acetaldehyde were detected through multiple lines in the hot cores NGC 6334F, G327.3-0.6, G31.41+0.31, and G34.3+0.2. Acetaldehyde was also detected towards G10.47+0.03, G322.2+0.6, and Orion 3'N, and one ethylene oxide line was tentatively detected in G10.47+0.03. Column densities and rotational excitation temperatures were derived using a procedure which fits the observed line intensifies by finding the minimum chi 2-value. The resulting rotational excitation temperatures of ethylene oxide and acetaldehyde are in the range 16-38 K, indicating that these species are excited in the outer, cooler parts of the hot cores or that the excitation is significantly subthermal. For an assumed source size of 20", the deduced column densities are (0.6-1)x10(14) cm-2 for ethylene oxide and (2-5)x10(14) cm-2 for acetaldehyde. The fractional abundances with respect to H2 are X[c-C2H4O]=(2-6)xl0(-10), and X[CH3CHO]=(0.8-3)x10(-9). The ratio X[CH3CHO]/X[c-C2H4O] varies between 2.6 (NGC 6334F) and 8.5 (G327.3-0.6). We also detected and analysed multiple transitions of CH3OH, CH3OCH3, C2H5OH, and HCOOH. The chemical, and possibly evolutionary, states of NGC 6334F, G327.3-0.6, G31.41+0.31, and G34.3+0.2 seem to be very similar.  相似文献   

The effect of surface characteristics on diffuse reflection radiation at λ=0.40 μm     

Tsutomu Takashima 《Astrophysics and Space Science》1976,43(1):213-232

The diffuse radiation in the upward direction at the top and at an internal level of an inhomogeneous atmosphere is computed at =0.40 m. The surface is assumed to reflect light in accordance with a hybrid mode of a diffuse and specular reflector. The objective is to estimate the effect of underlying surface characteristics in terms of the diffuse radiation field. By making use of these results, accuracy in monitoring the atmospheric aerosols would be increased for the use of remote sensing satellite techniques. Junge power lawv ^*=3 is adopted for the size distribution of aerosols (1963), while the data given by McClatchyet al. (1971) is used for the number density of aerosols with height distribution. It is noted from the computations that the diffuse reflection radiation is affected by the surface characteristics, even if the albedo of the surface is a fixed constant and very small.On leave from the Meterological Research Institute, Tokyo, Japan.bl]References  相似文献   

Dynamics of Wood Transport in Streams: A Flume Experiment     

Christian A. Braudrick  Gordon E. Grant  Yoshiharu Ishikawa  Hiroshi Ikeda 《地球表面变化过程与地形》1997,22(7):669-683

The influence of woody debris on channel morphology and aquatic habitat has been recognized for many years. Unlike sediment, however, little is known about how wood moves through river systems. We examined some dynamics of wood transport in streams through a series of flume experiments and observed three distinct wood transport regimes: uncongested, congested and semi-congested. During uncongested transport, logs move without piece-to-piece interactions and generally occupy less than 10 per cent of the channel area. In congested transport, the logs move together as a single mass and occupy more than 33 per cent of the channel area. Semi-congested transport is intermediate between these two transport regimes. The type of transport regime was most sensitive to changes in a dimensionless input rate, defined as the ratio of log volume delivered to the channel per second (Q_log) to discharge (Q_W); this ratio varied between 0·015 for uncongested transport and 0·20 for congested transport. Depositional fabrics within stable log jams varied by transport type, with deposits derived from uncongested and semi-congested transport regimes having a higher proportion of pieces orientated normal to flow than those from congested transport. Because wood input rates are higher and channel dimensions decrease relative to piece size in low-order channels, we expect congested transport will be more common in low-order streams while uncongested transport will dominate higher-order streams. Single flotation models can be used to model the stability of individual pieces, especially in higher-order channels, but are insufficient for modelling the more complex intractions that occur in lower-order streams. © 1997 John Wiley & Sons, Ltd.  相似文献   

Decomposition of Polycyclic Aromatic Hydrocarbon （PAHs） on Mineral Surface under Controlled Relative Humidity     

Shuji TAMAMURA Tsutomu SATO Yukie OTA Ning TANG Kazuichi HAYAKAWA 《《地质学报》英文版》2006,80(2):185-191

The fate of Polycyclic Aromatic Hydrocarbons （PAHs） residing in the atmosphere has received enormous attention in recent years due to their mutagenic and carcinogenic risks on human health. In this context, the stability of pyrene （as a representative PAHs） on quartz, alumina, montmorillonite, kaolinite, humic acid and quartz coated with sorbed humic acid was investigated at controlled relative humidity （RH： i.e. 5% and 30%） without light irradiation in order to detect the presence of catalytic effect of mineral surface on PAHs decomposition. The stability of pyrene was found to depend strongly on the physicochemical properties of the substrates. Quartz showed a strong catalytic effect for the decomposition of pyrene even though it was coated with sorbed humic acid. Pyrene sorbed on montmorillonite and humic acid remained stable during the experimental period （i.e. 3 days）. Moisture in the experimental cell also affected the stability of pyrene in particular minerals. Especially, pyrene sorbed on alumina was rapidly decomposed at higher RH. However, there were almost no effect in the case of quartz, kaolinite and humic acid. Depending on the physicochemical properties of aerosols and RH, PAHs associated with minerals in the atmosphere would be decomposed and/or stably reside in the atmosphere.  相似文献   

Study on Paleoearthquakes of the Eastern Liupanshan Piedmont Fault Zone   总被引：2，自引：0，他引：2  

Xiang Hongfa  Yasutaka Ikeda  Zhang Wanxia  Zhang Bingliang  Guo Shunmin  and He HonglinInstitute of Geology  CSB  Beijing  China Tokyo University  Tokyo  Japan 《中国地震研究》1999,(4)

Based on trench excavation and detailed field investigation, the authors have ascertained that 6 paleoearthquake events have occurred in the Haizixia area of the Eastern Liupanshan Piedmont fault zone since 46Ka B.P. The recurrence time of 6 events were about 15000a, 20250a, 14750a, 12150a, 8550a and 4000a B.P., respectively, the recurrence intervals were about 15000a, 5500a, 2600a, 3600a and 4550a, respectively. According to M-D empirical relations, the vertical dislocation of events 1 and 2 corresponded to the dislocation of the earthquake with M8.0; the vertical dislocation of events 3-6, was corresponded to the dislocation of earthquakes with M6.5~7.5.  相似文献   

Damage sequence and safety margin assessment of expansion joints by shake table testing     

Yu Otsuki  Masahiro Kurata  Konstantinos A. Skalomenos  Yoshiki Ikeda 《地震工程与结构动力学》2019,48(1):3-26

The performance of nonstructural components has attracted attention, and previous large earthquakes have resulted in widespread damage to expansion joints. In contrast to the main structural components, for which ductility beyond the design tolerance is ensured, the safety margin of nonstructural components classified as the product of mechanical engineering, such as expansion joints, is uncertain. This paper investigates the damage sequence and safety margin of expansion joints through shake table testing. The expansion joints were installed to connect 2 rigid steel frames with short and long natural periods. Four commonly used types, high-performance and standard-performance floor and wall expansion joints, were tested. Seven damage patterns of the 4 expansion joints were observed, and most of the damage patterns were considered displacement dependent. The damage mechanisms and relative displacements at the moment of damage were identified by using strain gauges attached near collision and damage locations. The high-performance expansion joints showed only minor damage beyond the design motion range, whereas the standard-performance expansion joints exhibited minor damage below the design motion range and failure at the design motion range or slightly beyond. For each damage state, repair information was obtained through a questionnaire to an expansion joint manufacturer, and the sum of the initial cost and repair cost for high-performance and standard-performance expansion joints was compared. The results will be useful for the selection of expansion joints in the design process.  相似文献   

New scenario of turbulence theory and wall-bounded turbulence: theoretical significance     

Tsutomu Kambe 《地球物理与天体物理流体动力学》2017,111(6):448-507

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