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21.
Nakashima Y Nakano T Nakamura K Uesugi K Tsuchiyama A Ikeda S 《Journal of contaminant hydrology》2004,74(1-4):253-264
The diffusion pathways of porous sandstone were examined by a three-dimensional (3-D) imaging technique based on X-ray computed tomography (CT) using the SPring-8 (Super Photon ring-8 GeV, Hyogo, Japan) synchrotron radiation facility. The analysis was undertaken to develop better understanding of the diffusion pathways in natural rock as a key factor in clarifying the detailed mechanism of the diffusion of radionuclides and water molecules through the pore spaces of natural barriers in underground nuclear waste disposal facilities. A cylindrical sample (diameter 4 mm, length 6 mm) of sandstone (porosity 0.14) was imaged to obtain a 3-D image set of 450(3) voxels=2.62(3) mm(3). Through cluster-labeling analysis of the 3-D image set, it was revealed that 89% of the pore space forms a single large pore-cluster responsible for macroscopic diffusive transport, while only 11% of the pore space is made up of isolated pores that are not involved in long-range diffusive transport. Computer simulations of the 3-D diffusion of non-sorbing random walkers in the largest pore cluster were performed to calculate the surface-to-volume ratio of the pore, tortuosity (diffusion coefficient in free space divided by that in porous rock). The results showed that (i) the simulated surface-to-volume ratio is about 60% of the results obtained by conventional pulsed-field-gradient proton nuclear magnetic resonance (NMR) laboratory experiments and (ii) the simulated tortuosity is five to seven times larger than the results of laboratory diffusion experiments using non-sorbing I(-) and Br(-). These discrepancies are probably attributed to the intrinsic sample heterogeneity and limited spatial resolution of the CT system. The permeability was also estimated based on the NMR diffusometry theory using the results of the random walk simulations via the Kozeny-Carman equation. The estimated permeability involved an error of about 20% compared with the permeability measured by the conventional method, suggesting that the diffusometry-based NMR well logging with gradient coils is applicable to the in-situ permeability measurement of strata. The present study demonstrated that X-ray CT using synchrotron radiation is a powerful tool for obtaining 3-D pore structure images without the beam-hardening artifacts inevitable in conventional CT using X-ray tubes. 相似文献
22.
So Kazama Toshiki Aizawa Toru Watanabe Priyantha Ranjan Luminda Gunawardhana Ayako Amano 《Sustainability Science》2012,7(1):45-54
Flooding and inundation are annual events that occur during the rainy season in Cambodia, and inundation has a strong relationship
with human health. This study simulated the coliform bacteria distribution using a hydraulic model and estimated the impact
of inundation on public health using a dose–response model. The model parameters were calibrated using field survey data from
Cambodia and obtained good agreement with the coliform group count distribution. The results suggest that the impact of inundation
on human health is most noticeable in residential areas. The annual average risk of infection during medium-sized flood events
is 0.21. The risk due to groundwater use ranges from 0.12 to 0.17 in inundation areas and reaches as high as 0.23 outside
the inundation areas. The risk attributed to groundwater use is therefore higher than that for surface water use (0.02–0.06),
except in densely populated areas at the city center. There is a high risk for infection with waterborne disease in residential
areas, and the annual average risk during small flood events is 0.94. An assessment of possible countermeasures to reduce
the risk shows that the control of inundation may bring more risk to public health in Cambodia. Shallower inundation water
(<0.3 m) leads to a higher risk of infection, but if the depth is greater than 2 m, the risk is low in residential areas.
The simulated results explain the spatial distributions of infection risk,, which are vitally important for determining the
highest priority places with relatively high risk and will be helpful for decision makers when considering the implementation
of countermeasures. 相似文献
23.
Koike Kentaro Yamaji Toru Nishida Takahiro Yonamine Kazuhide Adachi Akihiro Nakagawa Kozo 《Journal of Material Cycles and Waste Management》2022,24(4):1368-1377
Journal of Material Cycles and Waste Management - Copper slag fine aggregate (CUS) is 30% denser than normal aggregate is an effective material for port and harbor structures demanding high-density... 相似文献
24.
Michihiro Kitagawa Kentaro Sugiura Hiroko Omi Yoshiaki Akiyama Kiyoko Kanayama Masaru Shinya Tadao Tanaka Hirobumi Yura Haruhiko Sago 《黑龙江环境通报》2002,22(1):17-21
To isolate fetal cells from maternal blood, we developed a new method based on galactose-bearing conjugation. Nucleated red blood cells (NRBCs), which highly express galactose on their surface, were selectively attached to a substrate coated with a galactose-containing polymer via soybean agglutinin (SBA), a galactose-specific lectin. Cord blood samples were used to evaluate enrichment efficacy of NRBCs by this method. Blood samples were obtained from 131 pregnant women between 6 and 27 gestational weeks. After preliminary condensation of fetal cells by Ficoll gradient centrifugation, NRBCs were enriched using galactose-positive selection by adjusting SBA concentration. We isolated one to severalhundred NRBCs (mean±SD, 7.8±8.5) in 2.3 ml of peripheral blood samples from 96% of pregnantwomen. The isolated NRBCs were analyzed by a Y-chromosome FISH probe in eight cases carrying male fetuses. Y-signals were detected in all eight cases and more than half of the NRBCs wereoffetal origin. The study demonstrates that our new method using galactose-specific lectin provides effective enrichment of fetal NRBCs allowing non-invasive prenatal diagnosis. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
25.
26.
Koji Tokimatsu Masahiko Aicha Kentaro Yoshida Masahiro Nishio Eiichi Endo Masaji Sakagami 《国际发展与全球生态学杂志》2016,23(6):541-552
We need a consistent methodology to measure the co-benefits of climate change mitigation across Asian countries. This study chose a strategy of modifying the Japan-specific life-cycle impact assessment method based on endpoint modeling (LIME) for wider application across countries. LIME has two dimensions. First, it is an environmental science that links the cause-and-effect chain. Second, it is an environmental valuation that weighs four endpoint damages in monetary terms through a conjoint analysis that is derived from an Internet-based questionnaire survey. This article describes the modification of the methodology for application of the conjoint analysis to weigh environmental impacts. We approached the investigation as follows. First, we conducted Internet surveys to measure marginal willingness-to-pay (MWTP). We used a sample of 112 respondents in their 20 s to 40 s, divided equally between men and women, in 11 cities across China, India, and Southeast Asia. The results obtained showed clear statistical significance and were comparable across the cities. Second, we attempted to develop functions (called benefit transfer functions) to simplify the measured MWTP in order to apply it across different Asian countries. The functions were derived through a stepwise meta-analytic method, a type of multiple regression analysis whose independent variable was MWTP and dependent variables were attributes of both respondents and surveyed cities. The functions showed that coal consumption and percentage of nature reserve were dependent variables. Then, the MWTPs estimated from the functions were compared with the measured MWTP for transfer error, which is calculated by the absolute value of the difference between the estimated value and the measured value divided by the latter. The transfer error was below 50% in about 90% of the 44 results (a combination of four endpoints and 11 cities), implying that the developed functions were statistically significant. 相似文献
27.
The atmospheric deposition of reactive nitrogen on turf grassland in Tsukuba, central Japan, was investigated from July 2003
to December 2004. The target components were ammonium, nitrate, and nitrite ions for wet deposition and gaseous ammonia, nitric
and nitrous acids, and particulate ammonium, nitrate, and nitrite for dry deposition. Organic nitrogen was also evaluated
by subtracting the amount of inorganic nitrogen from total nitrogen. A wet-only sampler and filter holders were used to collect
precipitation and the atmospheric components, respectively. An inferential method was applied to calculate the dry deposition
velocity of gases and particles, which involved the effects of surface wetness and ammonia volatilization through stomata
on the dry deposition velocity. The mean fraction of the monthly wet to total deposition was different among chemical species;
37, 77, and 1% for ammoniacal, nitrate-, and nitrite-nitrogen, respectively. The annual deposition of inorganic nitrogen in
2004 was 47 and 48 mmol m−2 yr−1 for wet and dry deposition, respectively; 51% of atmospheric deposition was contributed by dry deposition. The annual wet
deposition in 2004 was 20, 27, and 0.07 mmol m−2 yr−1, and the annual dry deposition in 2004 was 35, 7.4, and 5.4 mmol m−2 yr−1 for ammoniacal, nitrate-, and nitrite-nitrogen, respectively. Ammoniacal nitrogen was the most important reactive nitrogen
because of its remarkable contribution to both wet and dry deposition. The median ratio of the organic nitrogen concentration
to total nitrogen was 9.8, 17, and 15% for precipitation, gases, and particles, respectively. 相似文献
28.
Adapting cropping systems to climate change in Nepal: a cross-regional study of farmers’ perception and practices 总被引:4,自引:1,他引:3
Sujata Manandhar Dietrich Schmidt Vogt Sylvain R. Perret Futaba Kazama 《Regional Environmental Change》2011,11(2):335-348
Climate change is a global challenge that has a particularly strong effect on developing countries such as Nepal, where adaptive
capacity is low and where agriculture, which is highly dependent on climatic factors, is the main source of income for the
majority of people. The nature and extent of the effects of climate change on rural livelihoods varies across Nepal in accordance
with its highly diverse environmental conditions. In order to capture some of this variability, a comparative study was performed
in two different ecological regions: Terai (lowland) and Mountain (upland) in the western development region of Nepal. The
study focuses on perceptions of, and on adaptations to climate change by farmers. Information was collected from both primary
and secondary data sources. Climate data were analyzed through trend analysis. Results show that most farmers perceive climate
change acutely and respond to it, based on their own indigenous knowledge and experiences, through both agricultural and non-agricultural
adaptations at an individual level. The study also shows that there is a need to go beyond the individual level, and to plan
and provide support for appropriate technologies and strategies in order to cope with the expected increasing impacts of climate
change. 相似文献
29.
Kazuhide Matsuda Yoshifumi Fujimura Kentaro Hayashi Akira Takahashi Ko Nakaya 《Atmospheric environment (Oxford, England : 1994)》2010,44(36):4582-4587
In order to increase knowledge of aerosol dry deposition for the regional assessment of acid deposition and transboundary air pollution in East Asia, an experimental study on PM2.5 sulfate deposition was implemented in the early summer of 2009. The experimental field was located in a deciduous forest at the foot of Mt. Asama, central Japan. Aerosol fluxes were obtained using the aerodynamic gradient method. Three aerosol samplers were placed on an experimental tower at 21, 24 and 27 m above the ground surface, and collected PM2.5 on filters for chemical analysis. Vertical concentration differences between 21 m and 27 m of PM2.5 sulfate were detected significantly when the concentration exceeded 1 μg m?3. Mean deposition velocity was estimated to be 0.9 ± 1.0 cm s?1 in the daytime and 0.3 ± 0.3 cm s?1 in the nighttime. In the case that a height-dependent correction in the roughness sub-layer was taken into account, the deposition velocities increased more, especially in daytime. Higher deposition velocities in the daytime were associated with larger friction velocities and unstable conditions. The deposition velocities observed in this study were in agreement with other experimental results found in the literature. On the other hand, they were higher than those calculated by theoretical models. Two empirical parameterizations (Wesely, M.L., Cook, D.R., Hart, R.L., 1985. Measurement and parameterization of particulate sulfur dry deposition over grass. Journal of Geophysical Research 90, 2131–2143; Ruijgrok, W., Tieben, H., Eisinga, P., 1997. The dry deposition of particles to a forest canopy: a comparison of model and experimental results. Atmospheric Environment 31, 399–415) were validated by the observations. The general trend of higher daytime and lower nighttime deposition velocities was similar among the observation and the two parameterizations. The large variability found in the measurement was not reproduced by the parameterizations, because it is attributable to random error from the differences between the samplers. The observations were in accordance with the parameterization of Ruijgrok et al. (1997) for a forest, although much larger than that of Wesely et al. (1985) for grasslands. This indicates the large difference in aerosol deposition velocities between forests and grasslands. 相似文献
30.
Sujata Manandhar Vishnu Prasad Pandey Futaba Kazama 《Regional Environmental Change》2014,14(2):743-756
Mustang, a mountainous region in the Kali Gandaki River Basin in western Nepal, has been increasingly experiencing climatic changes (e.g., higher temperatures). Rising temperatures lead to ecological shifts, which, in turn, can lead to the expansion of the lower limit for the cultivation of apple trees in this area. Apple cultivation can provide opportunities for adaptations under climate change through vulnerability reduction, income source diversification, livelihood improvement, and capacity building for farmers. As there is a lack of a strong basis to justify the expansion of apple cultivation in Mustang, this study examines the biophysical and socioeconomic suitability of apple cultivation in the area. Necessary data and information were collected from both primary and secondary sources. Findings of biophysical suitability using variable and equal weights to the indicators showed that 5.2 and 4.1 % of the areas are highly suitable for apple cultivation, respectively. However, not all potential farming areas are currently in use. Thus, there is the possibility to expand apple cultivation into unplanted areas and to integrate apple crops with other crops on cultivated lands. Increasing temperature may increase the suitable areas for the cultivation of apples in the coming years. High, benefit–cost ratio for land use confirmed the economic suitability of apple farming when compared to other land uses. The social suitability assessment showed no social discords, conflicts, or disagreements with apple cultivation, which is a positive indicator for the expansion of apple cultivation in western Nepal. 相似文献