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31.
Richard Arthur Reyment Isao Motoyama Miyuki Ota Yuichiro Tanaka 《Natural Resources Research》2008,17(3):187-195
A statistical analysis of two consecutive sequences of observations on radiolarian abundances in the western North Pacific,
by methods appropriate to data on the simplex (i.e., compositional data), show that although the overall graphical presentations
of the frequencies appear similar, there are substantial differences in the earlier part of each of the series. The results
of the multivariate analyses are used for identifying those species that contribute most to the analysis. A brief guide to
the mathematical properties of compositional data is given. 相似文献
32.
Assessing flood disaster impacts in agriculture under climate change in the river basins of Southeast Asia 总被引:1,自引:0,他引:1
Shrestha Badri Bhakta Perera Edangodage Duminda Pradeep Kudo Shun Miyamoto Mamoru Yamazaki Yusuke Kuribayashi Daisuke Sawano Hisaya Sayama Takahiro Magome Jun Hasegawa Akira Ushiyama Tomoki Iwami Yoichi Tokunaga Yoshio 《Natural Hazards》2019,97(1):157-192
Natural Hazards - This study focused on flood damage assessment for future floods under the impact of climate change. Four river basins of Southeast Asia were selected for the study. They included... 相似文献
33.
34.
The concentrations of Cu, Ni and Cd were determined in Funka Bay during a spring phytoplankton bloom, consisting of diatoms.
Just after the bloom, both dissolved Cd and nutrients were removed in the euphotic zone. However, the removal ratio of Cd
to phosphate was very different from that in seawater. The removal of Cd took place at a Cd/phosphate ratio of 0.07×10−3, which was lower than in seawater before the bloom (0.25×10−3), leading to an increase in this ratio in seawater exceeding 0.7×10−3 at the end of the bloom. Elevated concentrations of Cd and phosphate were observed in the deeper layer after the bloom due
to the decomposition of detrital materials produced in the bloom. The ratio of Cd/phosphate in the regeneration step was 0.24×10−3 which was different from the removal ratio of 0.07×10−3. These observations suggest that the high Cd/phosphate ratio in the regeneration would reflect a relatively high regeneration
rate of Cd than that of phosphate. No significant decrease in Cu and Ni concentrations was observed during the development
of the bloom, suggesting that biological removal of these metals was not so significant during the spring bloom. The concentrations
of Cd, Cu and silicate in surface waters increased after the bloom with decreasing salinity due to the influence of a spring
thaw. 相似文献
35.
We used wind-tunnel experiments to investigate velocity-field adjustment and scalar diffusion behaviour in and above urban canopies located downwind of various roughness elements. Staggered arrays of rectangular blocks of various heights H and plan area ratios λp were used to model the urban canopies. The velocity field in the roughness sublayer (height \({z \lesssim 2H}\)) reached equilibrium at distances proportional to \({\sqrt{L_{\rm c}H}}\) where L c is the canopy-drag length scale determined as a function of λp and the block side length L. A distance of about \({20\sqrt{L_{\rm c}H}}\) was required for adjustment at z = H/2 (in the canopy), and a distance of about \({10\sqrt{L_{\rm c}H}}\) was required at z = 2H (near the top of the roughness sublayer). Diffusion experiments from a ground emission source revealed that differences in upwind roughness conditions had negligible effects on the plume growth near the source (up to a few multiples of L from the source) if the source was located at a fetch F larger than about \({10\sqrt{L_{\rm c}H}}\) from the upwind edge of the canopy. However, at locations farther downwind (more than several multiples of L from the source), upwind conditions had considerable effects on the plume growth. For a representative urban canopy, it was shown that a much larger fetch than required for velocity-field adjustment in the roughness sublayer was necessary to eliminate the effects of upwind conditions on plume widths at 24L downwind from the source. 相似文献
36.
Lidong Dai Yuki Kudo Kei Hirose Motohiko Murakami Yuki Asahara Haruka Ozawa Yasuo Ohishi Naohisa Hirao 《Physics and Chemistry of Minerals》2013,40(3):195-201
The sound velocities of two aluminum-rich phases in the lower mantle, hexagonal new Al-rich phase (NAL) and its corresponding high-pressure polymorph orthorhombic Ca-ferrite-type phase (CF), were determined with the Brillouin scattering method in a pressure range from 9 to 73 GPa at room temperature. Both NAL and CF samples have identical chemical composition of Na0.4Mg0.6Al1.6Si0.4O4 (40 % NaAlSiO4–60 % MgAl2O4). Infrared laser annealing in the diamond anvil cell was performed to minimize the stress state of the sample and obtain the high-quality Brillouin spectra. The results show shear modulus at zero pressure G 0 = 121.960 ± 0.087 GPa and its pressure derivative G’ = 1.961 ± 0.009 for the NAL phase, and G 0 = 129.653 ± 0.059 GPa and G’ = 2.340 ± 0.004 for the CF phase. The zero-pressure shear velocities of the NAL and CF phases are obtained to be 5.601 ± 0.005 km/sec and 5.741 ± 0.001 km/sec, respectively. We also found that shear velocity increases by 2.5 % upon phase transition from NAL to CF at around 40 GPa. 相似文献
37.
Groundwater vulnerability assessment in shallow aquifer of Kathmandu Valley using GIS-based DRASTIC model 总被引:1,自引:0,他引:1
Dhundi Raj Pathak Akira Hiratsuka Isao Awata Luonan Chen 《Environmental Geology》2009,57(7):1569-1578
In this paper, groundwater aquifer vulnerability map has been developed by incorporating the major geological and hydro-geological
factors that affect and control the groundwater contamination using GIS based DRASTIC model. This work demonstrates the potential
of GIS to derive a map by overlying various spatially referenced digital data layers that portrays cumulative aquifer sensitivity
ratings across the Kathmandu Valley, Nepal, providing a relative indication of groundwater vulnerability to contamination.
In fact, the groundwater is the major natural resources in Kathmandu for drinking purpose. The decline in groundwater levels
due to the over exploitation and thus extracted water from shallow aquifer has been contaminated by the infiltration of pollutants
from polluted river and land surface is continuous and serious. As the demand for water for human and industrial use has escalated
and at the same time, the engineering and environmental costs are much higher for new water supplies than maintaining the
existing sources already in use. Management of groundwater source and protecting its quality is therefore essential to increase
efficient use of existing water supplies. Aquifer vulnerability maps developed in this study are valuable tools for environmental
planning and predictive groundwater management. Further, a sensitivity analysis has been performed to evaluate the influence
of single parameters on aquifer vulnerability assessment such that some subjectivity can be reduced to some extent and then
new weights have been computed for each DRASTIC parameters. 相似文献
38.
Taweewath NAKCHAIYA Toshio MITZUTA Daizo ISHIYAMA Isao TAKASHIMA Krit WON-IN Veerasak LUNWONGSA Punya CHARUSIRI 《地球学报》2009,30(Z1):48-48
Akara gold mine in north-central Thailand is situated within the Loei-Phetchabun-Nakhon Nayok volcanic belt. The roughly north-south trending, Permo-Triassic volcanic rocks earlier mapped by Thailand Department of Mineral Resources were re-mapped and samples were collected from the main active open pit. Forty-four samples were petrographi-cally classified and geochemically analyzed to docu-ment their stratigraphy. Two types of volcanic rocks are recognized, namely coherent and non-coherent units, in which the former is older on the basis of stratigraphic succession. Several lines of evidence suggest that the studied rocks occurred nearby the volcanic edifices and were dominated by debris flows of submarine environment. 相似文献
39.
Toshio Kataoka Eiji Yunoki Mitsuo Shimizu Tadashige Mori Osamu Tsukamoto Yukitaka Ohashi Ken Sahashi Toshihiko Maitani Koh’ichi Miyashita Toru Iwata Yoko Fujikawa Akira Kudo Roger H. Shaw 《Boundary-Layer Meteorology》2001,101(2):131-156
Concentrations of radon 222Rn andair pollutants, meteorological parametersnear the surface and vertical profiles of meteorological elements were measured atUchio (Okayama City, Okayama Prefecture, Japan) 12 km north from the coast ofthe Inland Sea of Japan. In the nighttime, the 222Rn concentration increased in the case of weak winds, but did not increase as much in the case of moderate or strong winds, as had been expected. In the daytime, the 222Rn concentrationheld at a slightly higher than average level for the period from sunrise to about 1100 JST. It is considered that this phenomenon is due to a period of morning calm, that is, a transition period from land breeze to sea breeze.NO, which is sensitive to traffic volume,brought information concerning advection.Oxidant concentrations,which reflect the availability of sunlight,acted in the reverse manner to 222Rnconcentrations. Thus, a set of 222Rn and air pollutants could provide useful information regarding the local conditions of the atmospheric boundary layer. 相似文献
40.
Hisayoshi YURIMOTO Isao SAKAGUCHI Norimasa NISHIDA Shigeho SUENO 《Geostandards and Geoanalytical Research》1991,15(1):155-159
Trace level determination of nickel in silicate rock samples has been achieved using secondary ion mass spectrometry (SIMS) with kinetic energy filtering. Standard rock references, issued by the Geological Survey of Japan, were fused into glass and used as standards for the SIMS analysis. Due to interferences from the glass matrix, the secondary ion of mass 60 was only useful for Ni, although the secondary ion was interfered mainly by CaO+. The contributions of these molecular ions were deconvolved by a least squares regression. Good linear correlation between results after the deconvolution and the Ni concentration in the glass standards was obtained. The uncertainties of the SIMS analysis depend strongly on the degree of contribution of CaO+ molecular ion. Such a method of SIMS analysis is especially useful to study the detailed behavior of Ni on a micro-scale in Ca-poor materials. 相似文献