The phytoplankton of some saline lakes in Central Asia     

Yoshiko Kawabata  Hiroyuki Nakahara  Yukio Katayama  Norio Ishida 《International Journal of Salt Lake Research》1997,6(1):5-16

The Aral Sea, Lake Balkhash, and Lake Kamyslybas are closed lakes in Central Asia. They range from oligosaline to metasaline. The salinity of the Aral Sea has increased by more than 30 g L⁻¹ since widespread irrigation began in its catchment area. Few studies of the phytoplankton have been conducted on these lakes since extensive irrigation started. The investigation reported here compares the flora of phytoplankton in these saline lakes. In the Small Aral Sea, phytoplankton density gradually decreased with increasing electrical conductivity (EC) (∼ salinity), but there was no such relation in Lake Balkhash and Lake Kamyslybas. In the Aral Sea, Dinophyceae and Bacillariophyceae were frequently observed in most areas of high EC value, and Cyanophyceae were most conspicuous in the area of medium and lower EC values. In Lake Balkhash, Cyanophyceae were most conspicuous, but Chlorophyceae were also noticeable. Most Cyanophyceae in Aral Sea formed filaments with heterocysts. The distinct characteristic of the phytoplankton of the Lake Balkhash was that all dominant species form colonies covered with a gelatinous film. Siliceousplankton diversity gradually decreased with increasing EC values in the Aral Sea and Lake Balkhash.  相似文献   

Damage Evaluation of Agro-meteorological Hazards in the Maize-Growing Region of Songliao Plain,China: Case Study of Lishu County of Jilin Province     

Zhang  Jiquan  Okada  Norio  Tatano  Hirokazu  Hayakawa  Seiji 《Natural Hazards》2004,31(1):209-232

Agro-meteorological hazards such as drought, waterlogging and cool summer occur with very high frequency and affect maize production and social-economic development in the maize-growing region of Songliao Plain, China. Moreover, both the frequency of these hazards and loss from them are considered to be increasing with global warming. The purpose of this paper is to quantitatively analyze the relationships between the fluctuation of maize yield and drought, waterlogging and cool summer, and to evaluate the consequences of these hazards in the maize-growing area of Songliao Plain, taking Lishu county as a case study area based on GIS (Geographic Information System). Crop yield-climate analysis and regression analysis were employed to analyze and quantify relationships between the fluctuation of maize yield and drought, waterlogging and cool summer, and to evaluate the consequences of these hazards. The parameters and model of damage evaluation were presented using weighted comprehensive analysis, and the degree of damage of drought, waterlogging and cool summer to maize production was comprehensively evaluated and regionalized. It is shown that from 1949 to 1990, the negative value years of the fluctuation of maize yield due to meteorological hazards accounted for 55% of seasons, of which 14% was caused by drought, 30% by waterlogging, 4% by cool summer and drought, 9% by cool summer and waterlogging, 13% by drought and waterlogging, 30% by drought, waterlogging and cool summer. Studies on the instability and spatial variation of the fluctuations in maize yield in Lishu county showed that the middle plains are stable areas to climatic influence, while southeastern hills and low mountains, the low lands of the plains along the East Liao River and the western plain are unstable areas in terms of areas in maize yield. The synthetic index of the degree of damage to maize of drought, waterlogging and cool summer showed a strong positive correlation with the ratio of the amount damaged to the normal yield of maize. This suggests that this index can be used to evaluate such damage. The degree of damage of drought, waterlogging and cool summer to maize in Lishu county shows the regional characteristics, which increase gradually from the center to the west and east, this being almost identical with the spatial distribution of the fluctuation of maize yield due to these hazards. This study can be expected to provide the basis for developing strategies to mitigate agro-meteorological hazards and reducing the losses from them, and adjust the medium and long-term distribution of agricultural activities so as to adapt to environmental changes.  相似文献   

Phase relation of CaSO<Subscript>4</Subscript> at high pressure and temperature up to 90 GPa and 2300 K     

Taku Fujii  Hiroaki Ohfuji  Toru Inoue 《Physics and Chemistry of Minerals》2016,43(5):353-361

Calcium sulfate (CaSO₄), one of the major sulfate minerals in the Earth’s crust, is expected to play a major role in sulfur recycling into the deep mantle. Here, we investigated the crystal structure and phase relation of CaSO₄ up to ~90 GPa and 2300 K through a series of high-pressure experiments combined with in situ X-ray diffraction. CaSO₄ forms three thermodynamically stable polymorphs: anhydrite (stable below 3 GPa), monazite-type phase (stable between 3 and ~13 GPa) and barite-type phase (stable up to at least 93 GPa). Anhydrite to monazite-type phase transition is induced by pressure even at room temperature, while monazite- to barite-type transition requires heating at least to 1500 K at ~20 GPa. The barite-type phase cannot always be quenched from high temperature and is distorted to metastable AgMnO₄-type structure or another modified barite structure depending on pressure. We obtained the pressure–volume data and density of anhydrite, monazite- and barite-type phases and found that their densities are lower than those calculated from the PREM model in the studied P–T conditions. This suggests that CaSO₄ is gravitationally unstable in the mantle and fluid/melt phase into which sulfur dissolves and/or sulfate–sulfide speciation may play a major role in the sulfur recycling into the deep Earth.  相似文献   

Simplified formulae for designing coastal forest against tsunami run-up: one-dimensional approach   总被引：2，自引：0，他引：2  

Nguyen Ba Thuy  N. A. K. Nandasena  Vu Hai Dang  Norio Tanaka 《Natural Hazards》2018,92(1):327-346

In the present study, laboratory experiments were conducted to validate the applicability of a numerical model based on one-dimensional nonlinear long-wave equations. The model includes drag and inertia resistance of trees to tsunami flow and porosity between trees and a simplified forest in a wave channel. It was confirmed that the water surface elevation and flow velocity by the numerical simulations agree well with the experimental results for various forest conditions of width and tree density. Further, the numerical model was applied to prototype conditions of a coastal forest of Pandanus odoratissimus to investigate the effects of forest conditions (width and tree density) and incident tsunami conditions (period and height) on run-up height and potential tsunami force. The modeling results were represented in curve-fit equations with the aim of providing simplified formulae for designing coastal forest against tsunamis. The run-up height and potential tsunami forces calculated by the curve-fit formulae and the numerical model agreed within ± 10% error.  相似文献   

Persistent organochlorine residues in sediments from the Chukchi Sea, Bering Sea and Gulf of Alaska   总被引：14，自引：0，他引：14  

Hisato Iwata  Shinsuke Tanabe  Mari Aramoto  Norio Sakai  Ryo Tatsukawa 《Marine pollution bulletin》1994,28(12):746-753

Three surface sediments and two sediment cores were collected from the Gulf of Alaska, Bering Sea and Chukchi Sea, and analysed for persistent organochlorines (OCs). The geographical distributions of OCs showed different patterns according to their physicochemical properties. The concentrations of HCHs and HCB revealed rather uniform distribution, suggesting their more transportable nature in long-range atmospheric transport. On the other hand, DDTs and PCBs were predicted to be less transportable via the atmosphere due to the decreasing trends of residue levels in sediments from south to north. The OC profiles in the sediment core from the Gulf of Alaska which seemed to be preserved without turbation revealed the elevated residue levels from bottom to surface layers. This implies that the aerial inputs of OCs in the cold ocean are still continuing significantly. The accumulation rates of OCs into sediments were rather smaller than the atmospheric inputs, indicating that the residue levels in water bodies are unlikely to decrease rapidly in the near future.  相似文献   

Introduction to the Special Issue of the Symposium on deep-seated landslides and large-scale rock avalanches     

Norio Oyagi  Marino Sorriso-Valvo  Barry Voight 《Engineering Geology》1994,38(3-4):187-188

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Carbon isotopic fractionation during the CO₂ exchange process between air and sea water under equilibrium and kinetic conditions     

Hisayuki Inoue  Yukio Sugimura 《Geochimica et cosmochimica acta》1985,49(11):2453-2460

Carbon isotopic fractionation during the air/sea exchange process is not fully understood at present. Information on the equilibrium and kinetic fractionation factors is an essential requirement, together with the value of the CO₂ partial pressure, for understanding the carbon cycle in the atmosphere and marine environments. Using a specially designed countercurrent equilibrator system, the fractionation factors between gaseous CO₂ and dissolved inorganic carbon in sea water were determined under both kinetic and equilibrium conditions. The following results were obtained: kinetic fractionation factor for air to sea (α_as) is 0.998 at 288.2 K; kinetic fractionation factor for sea to air (α_sa) is 0.990; equilibrium fractionation factor (α_eq) is 0.991 at pH = 8.3 and 288.2 K. From these results, the carbon isotopic ratio of CO₂ passed through the air/ sea interface is estimated to be about ?10 %. for air to sea and ?8 %. for sea to air when CO₂ exchange takes place between air (δ¹³C = ?8 %.) and surface sea water (δ¹³C = 2 %.) at 288.2 K.  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   

Structural and fabric analyses of basal slip zone of the Jin’nosuke-dani landslide, northern central Japan: its application to the slip mechanism of decollement     

Kiichiro Kawamura  Yujiro Ogawa  Norio Oyagi  Tetsuro Kitahara  Ryo Anma 《Landslides》2007,4(4):371-380

We describe in detail the deformation structures and textures of a large-scale landslide body that developed in the Betto-dani Valley in northern central Japan. We studied the shape-preferred orientation of clasts and clay flakes and the development of internal shear planes within the slip zone of the landslide. The slip has an average rate of 5–10 cm/year under the overburden pressure of approximately 1.6 MPa; these values are similar to those of the proto-decollement zone of the Nankai accretionary prism in SW Japan. The anisotropy of magnetic susceptibility of samples obtained from the slip zone reveals that the long axes of clay flakes define an imbricate structure. The slip was due to a long-term periodical creep, which occurs during the thaw seasons with an average slip rate of 0.16–0.32 μm/min. During the creep, the long axes of grains including clay flakes in the slip zone are developed from parallel to perpendicular to the slip direction. The observed textures provide a clue to elucidate the deformation textures and process in the decollement zone of the Nankai prism.  相似文献   

Analysis of Physical and Chemical Parameters for Discrimination of Water Origin in a Hydroelectric Reservoir     

Wagner José Barreto  Ieda Scarminio  Maria Cristina Solci  Dílson Norio Ishikawa  Melissa Tiemi Ogasawara  Sônia Naomi Nomi  Sônia Regina Giancoli Barreto 《洁净——土壤、空气、水》2007,35(3):239-245

Seventeen physical and chemical parameters were obtained from a hydroelectric reservoir located in a tropical region in the south of Brazil. Multivariate Principal Component Analysis (PCA) and Hierarchical Group Analysis (HGA) were used to identify the parameters discriminating the origin of water from the Tibagi and the Primeiro de Maio River, after it has passed the mixing region. The study was conducted during the dry and rainy seasons in July 2002 and February 2003 at three depths and three sampling sites located 0, 5, and 10 km away from the mixing region. The statistical methods showed to be appropriate for identifying the contribution of each tributary in the water mixing site of a complex water system. The most important discriminating parameter was the absorbance relation A(253 nm)/A(203 nm), followed by the concentrations of Fe(III), Mn(III), and Ni(II). An anthropogenic interference was found in the reservoir due to high Ni(II) and orthophosphate concentrations caused by a nearby town sewage discharge. The interference was more important during the dry periods due to the lower dispersion of the pollutants. Urgent initiatives should be taken from the state government to build treatment stations for the wastewater of the small cities around the Capivara hydroelectric reservoir to prevent the drinking water quality from deteriorating.  相似文献