Experimental study of migration of potassium ion through a two-layer soil system     

Yan Jun Du  Shigenori Hayashi  Song Yu Liu 《Environmental Geology》2005,48(8):1096-1106

A barrier system based on the hydraulic trap design concept for a landfill was proposed. To study the field scenario in which a clay liner is underlain by a granular layer functioning as a secondary leachate drain layer, a laboratory advection–diffusion test was performed to investigate factors controlling the transport of contaminants in a two-layer soil system. The soils used for this study were Ariake clay and, the underlying layer, Shirasu soil from the Kyushu region of Japan. Potassium (K⁺) was selected as the target chemical species with an initial concentration of 905 mg L⁻¹. The effective diffusion coefficients (D _e) of K⁺ for Ariake clay and Shirasu soil were back-calculated using an available computer program, Pollute V 6.3. Values of D _e derived from this experiment are consistent with previously published ones. The Ariake clay has lower D _e than the Shirasu soil. The hypothesis that mechanical dispersion can be considered negligible is reasonable based on both the observation that the predicted values well fit the experimental data and the analyses of two dimensionless parameters. Parametric analyses show that transport of K⁺ through soils is controlled by advection–diffusion rather than diffusion only, whereas at low Darcy velocity (i.e., ≤10⁻⁹ m s⁻¹), transport of K⁺ will be controlled by diffusion. Applications of the test results and parametric analysis results in practical situations were reviewed.  相似文献   

Observational aspects on a dominant spectral frequency in an airflow over a weeping-lovegrass stand     

Yousay Hayashi 《Boundary-Layer Meteorology》1986,36(3):239-243

Mean and fluctuating wind velocities were measured above a flexible stand (weeping-lovegrass). A waving phenomenon Honami appeared over the stand during the observation period. Some spectral parameters were derived from the vertical wind fluctuations. A dependency of frequency on mean horizontal wind velocity was found. The result, n _m = 0.66u, was obtained under the range of wind speeds from 0.9 m s^-1 to 3.1 m s^-1 just above the canopy.  相似文献   

Discharge of H2 from the Atotsugawa and Ushikubi Faults,Japan, and its relation to earthquakes     

Hiroshi Satake  Masahiko Ohashi  Yoshimitsu Hayashi 《Pure and Applied Geophysics》1984,122(2-4):185-193

The concentration of H₂ in soil gases has been measured weekly at five stations on the Atotsugawa and Ushikubi faults in northern central Main Island, Japan, since 1981 in search of possible relationship with earthquakes. The observed H₂ concentration varies from lower than 1 ppm to 7.8% in time and place. When a large earthquake (M: 7.7, epicenter distance: 486 km) occurred on 26 May 1983, an outstanding discharge of H₂ was observed at all five stations, preseismically at three of them, and coseismically at the other two. Simultaneous H₂ emission was also observed at some stations in seven other occasions. These periods of unusual H₂ discharge nearly coincided with occurrences of major earthquakes in Japan, but not of local minor earthquakes along the Atotsugawa fault. This fault, being a deep fracture zone, may be sensitive to large-scale crustal stress changes which incidentally cause the major earthquakes. Increased H₂ may be produced by rock fracture caused by the increased stresses on the fault and by the earthquakes themselves. Local minor earthquakes along Atotsugawa fault with magnitude lower than 3 may be unable to cause sufficient rock fracture to produce significant H₂.  相似文献   

Role of Stress-controlled Flow Pathways in HDR Geothermal Reservoirs     

T. Ito  K. Hayashi 《Pure and Applied Geophysics》2003,160(5-6):1103-1124

— We addressed effects of in situ stress on the formation of flow pathways in fractured rocks in geothermal reservoirs, especially for HDR projects. Here we focused on fractures which are critically-stressed, causing shear slip in a current stress field. The sliding is likely to break sealing in the fractures and, as a result, to increase their permeability. Such a mechanism is possibly significant under high-temperature conditions at geothermal fields because of temperature enhancement on chemical reactions for the sealing. We present a procedure to estimate the orientation of the critically-stressed fractures relative to axes of in situ principal stress with the aid of the Mohr diagram. The procedure allows us to evaluate intuitively how the orientation changes with factors such as magnitude of in situ principal stresses and pore pressure. We applied the procedure to estimate possible orientations of the critically-stressed fractures in major HDR test sites. Results show that overall alignments of microseismicity during hydraulic stimulation are within predicted ranges for possible orientations of the critically-stressed fractures. Furthermore, it was found that if the state of in situ stress is not favorable to cause sliding of natural fractures, it tends to lead a high wellhead pressure at hydraulic stimulation and a high recovery rate at circulation. On the other hand, if the state of in situ stress is favorable for sliding, it tends vice versa to lead a low wellhead pressure at hydraulic stimulation and a low recovery rate at circulation.  相似文献   

Ore mineralogy,fluid inclusion,and stable isotopic characteristics of stratiform copper deposits in the coastal Cordillera of northern Chile     

Shoji Kojima  José Astudillo  Juan Rojo  Dania Tristá  Ken-ichiro Hayashi 《Mineralium Deposita》2003,38(2):208-216

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Is there horizontal phase propagation of 5-min oscillations at high velocities?     

Franz-Ludwig Deubner  Nobukazu Hayashi 《Solar physics》1973,30(1):39-46

New observations of the photospheric 5-min oscillations are presented which prove that the physical reality of the very high horizontal phase propagation velocities observed in connection with the oscillations cannot be maintained. Instead, a statistical model is proposed to explain the observed phase relations.Mitteilungen aus dem Fraunhofer Institut Nr. 119.  相似文献   

A Perspective on Water Resources in China: Interactions between Climate Change and Soil Degradation     

Fulu Tao  Masayuki Yokozawa  Yousay Hayashi  Erda Lin 《Climatic change》2005,68(1-2):169-197

Water is one of the most critical resources in China. Climate change and soil degradation will be two major, interrelated environmental challenges faced by managers of water resources in coming decades. In this study, we used a water-balance model and updated databases to assess the interacting impacts of climate change and soil degradation on Chinas future water resources. We plotted the spatial pattern of changes in actual and potential evapotranspiration, soil moisture deficits, and surface runoff across China in the 2020s using a resolution of 0.5° latitude and longitude under scenarios based on climate change, soil degradation, and a combination of the two. The results showed that climate change would affect the magnitude and spatial pattern of water resources on a national scale. Some regions in central, southwestern, and northeastern China would become more vulnerable to disastrous drought and floods as a result of soil degradation. Under the combined impacts of climate change and soil degradation, soil moisture deficits would increase most in central, western, and southwestern China; surface runoff would increase most in southeastern China. More detailed process-based models are needed to capture feedback mechanisms more effectively.  相似文献   

Numerical Simulation of Accretion Discs in Close Binary Systems andDiscovery of Spiral Shocks     

Takuya Matsuda  Makoto Makita  Hidekazu Fujiwara  Takizo Nagae  Kei Haraguchi  Eiji Hayashi  H.M.J. Boffin 《Astrophysics and Space Science》2000,274(1-2):259-273

The history of hydrodynamic numerical simulations for accretion disks in close binary systems is reviewed, in which emphasis is placed, in particular, on the facts that spiral shock waves were numerically found in 1986 by researchers including one of the present authors and that spiral structure was discovered in IP Pegasi in 1997 by Steeghs et al. The results of our two and three-dimensional numerical simulations in recent years are then summarized, with comparison being made with observations. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Effects of frozen soil and snow cover on cold‐season soil water dynamics in Tokachi,Japan     

Yukiyoshi Iwata  Tomoyoshi Hirota  Masaki Hayashi  Shinji Suzuki  Shuichi Hasegawa 《水文研究》2010,24(13):1755-1765

Despite the potential impact of winter soil water movements in cold regions, relatively few field studies have investigated cold‐season hydrological processes that occur before spring‐onset of snowmelt infiltration. The contribution of soil water fluxes in winter to the annual water balance was evaluated over 5 years of field observations at an agricultural field in Tokachi, Hokkaido, Japan. In two of the winters, soil frost reached a maximum depth of 0·2 m (‘frozen’ winters), whereas soil frost was mostly absent during the remaining three winters (‘unfrozen’ winters). Significant infiltration of winter snowmelt water, to a depth exceeding 1·0 m, occurred during both frozen and unfrozen winters. Such infiltration ranged between 126 and 255 mm, representing 28–51% of total annual soil water fluxes. During frozen winters, a substantial quantity of water (ca 40 mm) was drawn from deeper layers into the 0–0·2 m topsoil layer when this froze. Under such conditions, the progression and regression of the freezing front, regulated by the thickness of snow cover, controlled the quantity of soil water flux below the frozen layer. During unfrozen winters, 13–62 mm of water infiltrated to a depth of 0·2 m, before the spring snowmelt. These results indicate the importance of correctly evaluating winter soil water movement in cold regions. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

The Structure of Young Stellar Jets and Winds Revealed by High Resolution [Fe II] λ1.644μm Line Observations     

Tae-Soo Pyo  Masahiko Hayashi  Naoto Kobayashi  Alan T. Tokunaga  Hiroshi Terada  Miwa Goto  Takuya Yamashita  Yoichi Itoh  Hideki Takami  Naruhisa Takato  Yutaka Hayano  Wolfgang Gaessler  Yukiko Kamata  Yosuke Minowa  Masanori Iye 《Astrophysics and Space Science》2003,287(1-4):21-24

We present high angular resolution spectra taken along the jets from L1551 IRS 5 and DG Tau obtained with the Subaru Telescope. The position-velocity diagrams of the [Fe II] λ 1.644 μmemission line revealed remarkably similar characteristics for the two sources, showing two distinct velocity components separated from each other in both velocity and space with the entire emission range blueshifted with respect to the stellar velocity. The high velocity component (HVC) has a velocity of –200 ––300 km s^-1 with a narrow line width, while the low velocity component (LVC) is around –100 km s^-1 exhibitinig a broad line width. The HVC is located farther away from the origin and is more extended than the LVC. Our results suggest that the HVC is a well-collimated jet originating from the region close to the star, while the LVC is a widely-opened wind accelerated in the region near the inner edge of the accretion disk.  相似文献