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111.
Direct measurements of the air-sea CO2 flux by the eddy covariance technique were carried out in the equatorial Indian Ocean. The turbulent flux observation system
was installed at the top of the foremast of the R/V MIRAI, thus minimizing dynamical and thermal effects of the ship body.
During the turbulent flux runs around the two stations, the vessel was steered into the wind at constant speed. The power
spectra of the temperature or water vapor density fluctuations followed the Kolmogorov −5/3 power law, although that of the
CO2 density fluctuation showed white noise in the high frequency range. However, the cospectrum of the vertical wind velocity
and CO2 density was well matched with those of the vertical velocity and temperature or water vapor density in this frequency range,
and the CO2 white noise did not influence the CO2 flux. The raw CO2 fluxes due to the turbulent transport showed a sink from the air to the ocean, and had almost the same value as the source
CO2 fluxes due to the mean vertical flow, corrected by the sensible and latent heat fluxes (called the Webb correction). The
total CO2 fluxes including the Webb correction terms showed a source from the ocean to the air, and were larger than the bulk CO2 fluxes estimated using the gas transfer velocity by mass balance techniques. 相似文献
112.
The ability of biodegradation for crude oil was examined for ten strains of marine bacteria. With regard to their degradation ability forn-alkanes the microorganisms tested could be divided into four groups, although the same result was not observed for microbial degradation of aromatic hydrocarbons obtained by the UV measurements. 相似文献
113.
Hydration of rhyolitic glass during weathering as characterized by IR microspectroscopy 总被引:1,自引:0,他引:1
Tadashi Yokoyama Satoshi Okumura Satoru Nakashima 《Geochimica et cosmochimica acta》2008,72(1):117-125
The mechanism and rate of hydration of rhyolitic glass during weathering were studied. Doubly polished thin sections of two rhyolites with different duration of weathering (Ohsawa lava: 26,000 yr, Awanomikoto lava: 52,000 yr) were prepared. Optical microscope observation showed that altered layers had developed along the glass surfaces. IR spectral line profile analysis was conducted on the glass sections from the surface to the interior for a length of 250 μm and the contents of molecular H2O (H2Om), OH species (OH) and total water (H2Ot) were determined. The diffusion profile of H2Om in Ohsawa lava extends beyond the layer observed by optical microscope. The content of H2Om in the hydrated region is much higher than that of OH species. Thus, the reaction from H2Om to OH appears to be little and H2Om is the dominant water species moving into the glass during weathering. Based on the concentration profiles, the diffusion coefficients of H2Om(DH2Om) and H2Ot(DH2Ot) were determined to be 2.8 × 10−10 and 3.4 × 10−10 μm2 s−1 for Ohsawa lava, and 5.2 × 10−11 and 4.1 × 10−11 μm2 s−1 for Awanomikoto lava, respectively. The obtained DH2Om during weathering are more than 2-3 orders of magnitude larger than the diffusion coefficient at ∼20 °C that is extrapolated from the diffusivity data for >400 °C. This might suggest that the mechanism of water transport is different at weathering conditions and >400 °C. 相似文献
114.
The responses of hydrological processes and sediment yield to land‐use and climate change in the Be River Catchment,Vietnam
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In this study, we investigated the responses of hydrology and sediment yield with impacts of land‐use and climate change scenarios in the Be River Catchment, using the Soil and Water Assessment Tool (SWAT) hydrological model. The calibration and validation results indicated that the SWAT model is a powerful tool for simulating the impact of environmental change on hydrology and sediment yield in this catchment. The hydrologic and sediment yield responses to land‐use and climate changes were simulated based on the calibrated model. The results indicated that a 16.3% decrease in forest land is likely to increase streamflow (0.2 to 0.4%), sediment load (1.8 to 3.0%), and surface runoff (SURQ) (4.8 to 10.7%) and to decrease groundwater discharge (GW_Q) (3.5 to 7.9%). Climate change in the catchment leads to decreases in streamflow (0.7 to 6.9%) and GW_Q (3.0 to 8.4%), increase in evapotranspiration (0.5 to 2.9%), and changes in SURQ (?5.3 to 2.3%) and sediment load (?5.3 to 4.4%). The combined impacts of land‐use and climate changes decrease streamflow (2.0 to 3.9%) and GW_Q (12.3 to 14.0%), increase evapotranspiration (0.7 to 2.8%), SURQ (8.2 to 12.4%), and sediment load (2.0 to 7.9%). In general, the separate impacts of climate and land‐use changes on streamflow, sediment load, and water balance components are offset each other. However, SURQ and some component of subsurface flow are more sensitive to land‐use change than to climate change. Furthermore, the results emphasized water scarcity during the dry season and increased soil erosion during the wet season. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
115.
Porosity strongly affects the overall ductile behavior of cohesive geomaterials undergoing plastic deformation. In the present paper, we proposed an original micromechanical approach that suitably couples Drucker–Prager‐type plasticity, evolving porosity under general triaxial loadings. The resulting model has the advantage to be based on a single macroscopic yield function, which also plays the role of plastic potential. It is shown that this yield function is particularly appropriate to account for the pore collapse and plastic shearing mechanisms that govern the mechanical behavior of the studied Lixhe chalk. Finally, the new model is implemented and validated by comparison to triaxial tests data, covering a wide range of confining pressures. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
116.
Ayako?ShinozakiEmail author Hisako?Hirai Hiroyuki?Kagi Tadashi?Kondo Taku?Okada Daisuke?Nishio-Hamane Shin-ichi?Machida Tetsuo?Irifune Takumi?Kikegawa Takehiko?Yagi 《Physics and Chemistry of Minerals》2012,39(2):123-129
High pressure and temperature reactions of a mixture of forsterite and hydrogen molecules have been carried out using a laser
heated diamond anvil cell at 9.8–13.2 GPa and ~1,000 K. In situ X-ray diffraction measurements showed no sign of decomposition
or phase transitions of the forsterite under these experimental conditions, indicating that the olivine structure was maintained
throughout all runs. However, a substantial expansion of the unit cell volume of the forsterite was observed for samples down
to ~3 GPa upon quenching to ambient pressure at room temperature. The Raman spectroscopy measurements under pressure showed
significant shifts of the Raman peaks of the Si–O vibration modes for forsterite and of the intramolecular vibration mode
for H2 molecules toward a lower frequency after heating. Additionally, no OH vibration modes were observed by Raman and FT-IR spectroscopic
measurements. These lines of evidence show that the observed volume expansion in forsterite is not explained by the incorporation
of hydrogen atoms as hydroxyl, but suggest the presence of hydrogen as molecules in the forsterite structure under these high
pressure and temperature conditions. 相似文献
117.
This article focuses on the dynamics of using numbers to construct an image of social reality in disaster areas. Numbers are
neither objective nor value-neutral but are rather generated, transmitted and shared with social signification. In other words,
numbers can be thought of as simply socially constructed information. Statistics and other numbers usually work in positive
ways. However, it is also possible that using numbers in the media can lead to unintended messages that could produce negative
consequences. We conducted field studies in disaster-stricken areas of the 2008 Wenchuan earthquake in China and compared
findings to the case of the 1995 Kobe earthquake in Japan in order to examine how numbers—in terms of the amount of donations,
the timeline of reconstruction projects and casualty figures—construct social reality and cause a variety of social dysfunctions. 相似文献
118.
Satoru Kojima Tamotsu Nozaki Hidehisa Nagata Ryota Tanahashi Ryoich Kondo Noriaki Okamura Kazuhiro Suzuki Akiko Ikeda Toshio Nakamura Tomoyuki Ohtani 《Environmental Earth Sciences》2014,71(6):2753-2763
Large-scale landslides along the Kubusu and Besso rivers in Toyama Prefecture are developed in the Miocene Iwaine Formation, which is composed of andesitic lava, tuff, and tuff breccia. In the middle member of this formation, the tuff is easily altered to montmorillonite-bearing rock, and subsequently plays an important role in the development of landslides events, which tend to be large-scale events, as the massive lava of the upper member forms a cap rock over the tuff. The Kiritani and Koinami basins, which are flat intermontane basins located along the Kubusu and Besso rivers, respectively, are interpreted as landslide-dammed lakes, later filled with sediment. Accelerator mass spectrometry 14C ages show that the landslides forming each dam occurred simultaneously, at approximately 2500 BP. These ages were measured from wood fragments embedded in the landslide material of Kiritani, and from an in situ stump drowned during the impoundment of Koinami. If the trigger of these landslides was an earthquake, it is most likely to have been the penultimate event along the Atotsugawa fault zone. 相似文献
119.
We monitored acoustic emission (AE) events during an in-situ direct shear test on a specimen composed of a slate-dominant alternation of slate and sandstone, measuring 0.5 m long, 0.5 m wide and 0.2 m high. The test was conducted in a survey tunnel for an underground powerhouse in central Japan. The AE epicenters located on a fractured plane are compared with the locations of joints and a loosening seam, the height distribution of the fractured plane, and the horizontal movement of the test block prior to failure. We conclude that an initially intact region of rock bounded by the joints and the seam is fractured, generating the AE. Considering these results in connection with asperity models of seismogenic faulting for a subduction-zone earthquake, the significant contrast of stress conditions derived from the geological inhomogeneity and the uneven fractured plane is analogous to that due to subducted seamounts and horst-graben structures on a subducted oceanic plate. For an inland earthquake, the intact regions on an expected shear plane can be considered to be a portion of the fault asperity that causes strong ground motion, while the weakened portion can be considered to correspond to a region of aseismic creep. Consequently, large-scale inhomogeneous rock fracturing experiments such as the in-situ direct shear test may provide useful insights as analog models of seismogenic faulting. Furthermore, understanding of inhomogeneous rock-mass fracturing obtained from such experiments will not only contribute to a better understanding of the mechanism of earthquakes but also provide valuable knowledge for AE monitoring applications in rock engineering, such as the predictions of rockbursts in mines and the monitoring of fractures around large underground chambers. 相似文献
120.
In order to provide a physical interpretation of the variation of the mechanical properties of Callovo-Oxfordian argillite with mineral composition, we implement three linear homogenization schemes. The argillite is modeled as a three phase material composed of a clay matrix and inclusions of quartz and calcite. It is shown that, unlike the dilute scheme and the self-consistent scheme, the Mori-Tanaka model describes the in situ experimental data well. The determined properties are finally used in a finite element computation. The aim is to evaluate the effect of mineral composition on the elastic response of the excavation of a vertical shaft in the context of the underground laboratory of Meuse/Haute Marne. 相似文献