Study of polluted soil remediation based on freezing and thawing cycles   总被引：1，自引：0，他引：1  

DaHu Rui  BaiYang Song  Yuzuru Ito  Li Wang 《寒旱区科学》2014,6(4):0322-0330

It is generally known that soil pollution poses a terrible hazard to the environment, but the present techniques of contaminated soil remediation cannot control this growing threat. This paper compares the pollutant extraction efficiency of traditional pumping and treating, which is a typical washing technology for the remediation of contaminated soils, with methods that utilize freeze-thaw cycles. In the soil freezing process, water shifts from unfrozen soils to the freezing front, and the permeability of soil will be enhanced under certain temperature gradients and water conditions. Therefore, this paper discusses the purification of contaminated soil through freeze-thaw action. We conducted a cleansing experiment on clay and silica sand infused with NaCl（simulation of heavy metals） and found that the efficiency of purification was enhanced remarkably in the latter by the freeze-thaw action. To assess the effective extraction of DNAPLs in soil, we conducted an experiment on suction by freezing, predicated on the different freezing points of moisture and pollutants. We found that the permeability coefficient was significantly increased by the freezing-thawing action, enabling the DNAPL contaminants to be extracted selectively and effectively.  相似文献   

考虑系统柔度影响的水压致裂法测量深部岩石应力     

Ito T  Satoh T  Kato H  甄宏伟 《国际地震动态》2011,(1):25-32

为了有效测量水压致裂方法中的重张压力,必须使用具有足够小柔度的试验设备,否则无法从重张压力估计垂直钻孔平面的最大水平应力.仅通过替换水压致裂系统中的某一部件来大幅度降低系统柔度是很难的.但如果流量计尽可能安装在靠近跨接式封隔器隔离出的钻孔测试区.那么系统柔度就会大大降低.为此,我们研制出配有井下流量计的试验系统,并在野...  相似文献   

Compressibility of strontium orthophosphate Sr<Subscript>3</Subscript>(PO<Subscript>4</Subscript>)<Subscript>2</Subscript> at high pressure     

Shuangmeng Zhai  Weihong Xue  Daisuke Yamazaki  Shuangming Shan  Eiji Ito  Naotaka Tomioka  Akira Shimojuku  Ken-ichi Funakoshi 《Physics and Chemistry of Minerals》2011,38(5):357-361

High pressure in situ synchrotron X-ray diffraction experiment of strontium orthophosphate Sr₃(PO₄)₂ has been carried out to 20.0 GPa at room temperature using multianvil apparatus. Fitting a third-order Birch–Murnaghan equation of state to the P–V data yields a volume of V ₀ = 498.0 ± 0.1 Å³, an isothermal bulk modulus of K _T  = 89.5 ± 1.7 GPa, and first pressure derivative of K _T ′ = 6.57 ± 0.34. If K _T ′ is fixed at 4, K _T is obtained as 104.4 ± 1.2 GPa. Analysis of axial compressible modulus shows that the a-axis (K _a  = 79.6 ± 3.2 GPa) is more compressible than the c-axis (K _c  = 116.4 ± 4.3 GPa). Based on the high pressure Raman spectroscopic results, the mode Grüneisen parameters are determined and the average mode Grüneisen parameter of PO₄ vibrations of Sr₃(PO₄)₂ is calculated to be 0.30(2).  相似文献   

Was the 2011 Tohoku-Oki earthquake preceded by aseismic preslip? Examination of seafloor vertical deformation data near the epicenter     

R. Hino  D. Inazu  Y. Ohta  Y. Ito  S. Suzuki  T. Iinuma  Y. Osada  M. Kido  H. Fujimoto  Y. Kaneda 《Marine Geophysical Researches》2014,35(3):181-190

Ocean-bottom pressure records obtained near the epicenter of the 2011 Tohoku-Oki earthquake were examined to test whether the earthquake was preceded by substantial precursory crustal deformation. The seafloor data enabled us to search for small-scale preslip near the epicenter that would be difficult to identify from terrestrial geodetic data. After treating the data to reduce nontectonic fluctuations, we obtained a time series of seafloor vertical deformation in the epicentral region with a noise level of 2–4 cm. No significant crustal deformation related to preslip was detected in the period of roughly a day before the mainshock, whereas postseismic deformation associated with the largest foreshock 2 days before the mainshock was apparent. From our quantitative estimate of the sensitivity of the seafloor network in detecting slip on the plate interface, we conclude that the Tohoku-Oki earthquake was not preceded by preslip with moment release greater than moment magnitude (Mw) 6.2 in the vicinity of the hypocenter or greater than Mw 6.0 along the subduction interface near the trench.  相似文献   

Detection of small earthquakes along the Pacific-Antarctic Ridge from T-waves recorded by abyssal ocean-bottom observatories     

Aki Ito  Hiroko Sugioka  Daisuke Suetsugu  Hajime Shiobara  Toshihiko Kanazawa  Yoshio Fukao 《Marine Geophysical Researches》2012,33(3):229-238

A number of seismoacoustic T-wave events were observed between January 2003 and January 2004 by broadband ocean-bottom seismometers installed on the French Polynesia seafloor at depths of 4,000?C5,000?m, well below the conjugate depth of the SOFAR channel. Using T-wave arrival times, we located 89 T-wave events along the Pacific-Antarctic Ridge. Among these, 63 events were not detected by land-based seismic observations of the United States Geological Survey (USGS), which was nearly twice the number of earthquakes reported by the USGS in the area during the observation period. We used a simple method to estimate earthquake magnitude from T-wave energy. The magnitudes of the events unidentified by the USGS ranged from 2.3 to 5.5, whereas magnitudes of the earthquakes reported by the USGS ranged from 4.1 to 6.2. Our study suggests that T-wave observations with abyssal ocean-bottom seismometers can improve the detection of small earthquakes and help our understanding of the seismotectonics of remote oceanic areas.  相似文献   

Multiple temporal scale variability during the twentieth century in global carbon dynamics simulated by a coupled climate–terrestrial carbon cycle model     

Tomomichi Kato  Akihiko Ito  Michio Kawamiya 《Climate Dynamics》2009,32(7-8):901-923

A coupled climate–carbon cycle model composed of a process-based terrestrial carbon cycle model, Sim-CYCLE, and the CCSR/NIES/FRCGC atmospheric general circulation model was developed. We examined the multiple temporal scale functions of terrestrial ecosystem carbon dynamics induced by human activities and natural processes and evaluated their contribution to fluctuations in the global carbon budget during the twentieth century. Global annual net primary production (NPP) and heterotrophic respiration (HR) increased gradually by 6.7 and 4.7%, respectively, from the 1900s to the 1990s. The difference between NPP and HR was the net carbon uptake by natural ecosystems, which was 0.6 Pg C year^?1 in the 1980s, whereas the carbon emission induced by human land-use changes was 0.5 Pg C year^?1, largely offsetting the natural terrestrial carbon sequestration. Our results indicate that monthly to interannual variation in atmospheric CO₂ growth rate anomalies show 2- and 6-month time lags behind anomalies in temperature and the NiNO₃ index, respectively. The simulated anomaly amplitude in monthly net carbon flux from terrestrial ecosystems to the atmosphere was much larger than in the prescribed air-to-sea carbon flux. Fluctuations in the global atmospheric CO₂ time series were dominated by the activity of terrestrial vegetation. These results suggest that terrestrial ecosystems have acted as a net neutral reservoir for atmospheric CO₂ concentrations during the twentieth century on an interdecadal timescale, but as the dominant driver for atmospheric CO₂ fluctuations on a monthly to interannual timescale.  相似文献   

Changes of seawater quality in Ofunto Bay,Iwate, after the 2011 off the Pacific coast of Tohoku Earthquake     

Yuichiro Yamada  Shinnosuke Kaga  Yoshimasa Kaga  Kimiaki Naiki  Shiho Watanabe 《Journal of Oceanography》2017,73(1):11-24

Ofunato Bay was a semi-closed area because of the breakwater effect at the entrance; however, the breakwater was destroyed by a massive tsunami generated by the 2011 off the Pacific coast of Tohoku Earthquake. Consequently, the physical environment of Ofunato Bay has been changed significantly, i.e., the modification of the stratified structure of seawater inside the bay and the intermittent intrusion of seawater outside the bay. These alterations of physical environment are considered to have an influence on the chemical and biological environment in Ofunato Bay. To elucidate the influence of the tsunami on the aquatic environment, we measured dissolved nutrients, chlorophyll a and dissolved oxygen concentrations, and heterotrophic bacteria abundance inside and outside of Ofunato Bay from 2012 to 2014, and compared these data with those obtained before the earthquake. As compared with before the earthquake, significant changes after the earthquake were (1) decrease of ammonium and phosphate concentrations, (2) increase of chlorophyll a concentration, (3) increase of dissolved oxygen concentration in the bottom, and (4) decrease of heterotrophic bacteria abundance. The collapse of the breakwater and consequential enhanced water exchange were considered to have brought the decrease of nutrient concentration inside the bay. Furthermore, washout of shellfish mariculture rafts by the tsunami decreased the shellfish biodeposits along with the elution of nutrients by heterotrophic bacteria. Decrease of cultivated shellfish further caused a decline in feeding pressure on phytoplankton and, subsequently, increased the phytoplankton biomass that contributed to the decrease of nutrients inside the bay.  相似文献   

Titan’s atomic hydrogen corona     

P. Hedelt  Y. Ito  L. Esposito 《Icarus》2010,210(1):424-435

Based on measurements performed by the Hydrogen Deuterium Absorption Cell (HDAC) aboard the Cassini orbiter, Titan’s atomic hydrogen exosphere is investigated. Data obtained during the T9 encounter are used to infer the distribution of atomic hydrogen throughout Titan’s exosphere, as well as the exospheric temperature.The measurements performed during the flyby are modeled by performing Monte Carlo radiative transfer calculations of solar Lyman-α radiation, which is resonantly scattered on atomic hydrogen in Titan’s exosphere. Two different atomic hydrogen distribution models are applied to determine the best fitting density profile. One model is a static model that uses the Chamberlain formalism to calculate the distribution of atomic hydrogen throughout the exosphere, whereas the second model is a Particle model, which can also be applied to non-Maxwellian velocity distributions.The density distributions provided by both models are able to fit the measurements although both models differ at the exobase: best fitting exobase atomic hydrogen densities of n_H = (1.5 ± 0.5) × 10⁴ cm⁻³ and n_H = (7 ± 1) × 10⁴ cm⁻³ were found using the density distribution provided by both models, respectively. This is based on the fact that during the encounter, HDAC was sensitive to altitudes above about 3000 km, hence well above the exobase at about 1500 km. Above 3000 km, both models produce densities which are comparable, when taking into account the measurement uncertainty.The inferred exobase density using the Chamberlain profile is a factor of about 2.6 lower than the density obtained from Voyager 1 measurements and much lower than the values inferred from current photochemical models. However, when taking into account the higher solar activity during the Voyager flyby, this is consistent with the Voyager measurements. When using the density profile provided by the particle model, the best fitting exobase density is in perfect agreement with the densities inferred by current photochemical models.Furthermore, a best fitting exospheric temperature of atomic hydrogen in the range of T_H = (150-175) ± 25 K was obtained when assuming an isothermal exosphere for the calculations. The required exospheric temperature depends on the density distribution chosen. This result is within the temperature range determined by different instruments aboard Cassini. The inferred temperature is close to the critical temperature for atomic hydrogen, above which it can escape hydrodynamically after it diffused through the heavier background gas.  相似文献   

Impacts of climate change on growth, migration and recruitment success of Japanese sardine (Sardinops melanostictus) in the western North Pacific     

Takeshi Okunishi  Shin-ichi Ito  Taketo Hashioka  Takashi T. Sakamoto  Naoki Yoshie  Hiroshi Sumata  Yumiko Yara  Naosuke Okada  Yasuhiro Yamanaka 《Climatic change》2012,115(3-4):485-503

We developed a multi-trophic level ecosystem model by coupling physical, biogeochemical-plankton and fish models. An oceanic general circulation model was coupled with a lower trophic level ecosystem model and a Japanese sardine migration model, and applied to the western North Pacific. To investigate the impact of global warming on the pelagic fish ecosystem, such as Japanese sardine, we conducted numerical experiments of growth and migration of Japanese sardine using physical fields for the present day and future with a global warming scenario simulated by a high-resolution climate model. The model results demonstrated possible impacts of global warming on the growth and migration pattern of Japanese sardine. The growths of fish in the current main spawning region under the global warming scenario were significantly slower than those under the present climate scenario. Fish in this region will be at disadvantage for their recruitment under the global warming condition. Prey conditions in the spawning region were projected not to markedly change under global warming condition while water temperature increased. As a result sardine spawning ground was projected to shift towards more north areas. During the feeding migration period in summer, geographical distribution of juveniles fish was projected to shift northwards by one to two degrees latitude under the global warming condition following the change in the distribution of optimal temperature region for feeding. However, this northwards shift of the optimal temperature for feeding was minimized adjacent to the western North Pacific by the cooler water supply by the intensification of the Oyashio.  相似文献   

High temperature infrared spectra of hydrous microcrystalline quartz   总被引：1，自引：0，他引：1  

Hiraku Yamagishi  Satoru Nakashima  Yuki Ito 《Physics and Chemistry of Minerals》1997,24(1):66-74

A series of in-situ high temperature infrared (IR) measurements of water in an agate sample and in a milky quartz has been conducted in order to understand the nature of water in silica at high temperatures (50–700?°C) and the dehydration behavior. IR absorption bands of water molecules trapped in the milky quartz showed a systematic decrease in intensities and a shift from 3425?cm^?1 at 50?°C toward 3590?cm^?1 at 700?°C without any loss of water. This indicates a change in IR absorption coefficients corresponding to different polymeric states of water at different temperatures. The broad 3430?cm^?1 band in the agate sample also showed a systematic decrease in IR intensity and a band shift toward higher frequency with increasing temperature (～700?°C). This indicates that the agate sample also contains fluid inclusion-like water. For this agate sample, a dehydration of loosely hydrogen-bonded molecular water occurred at lower temperatures (<200?°C). At higher temperatures (>400?°C), sharp bands around 3660 and 3725?cm^?1 (3740?cm^?1 at 50?°C) due to surface silanols, appeared. This indicates dehydration of H₂O molecules that are hydrogen bonded to surface silanols. SiOH species in the agate are divided into three groups, namely SiOH group located at structural defects, surface silanols hydrogen bonded to each other and free surface silanols. Former two dehydrate below 700?°C and the dehydration rate of the SiOH at structural defects is faster than the other. IR spectra show that SiOH species decrease continuously even after the dehydration of most of H₂O molecules. All these results provide realistic bases for the change in physicochemical states of different OH species in silica at high temperatures.  相似文献