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1.
Sanae Unoki 《Journal of Oceanography》1973,29(6):276-284
2.
Sanae Koizumi Takehiko Hiraga Chihiro Tachibana Miki Tasaka Tomonori Miyazaki Tamio Kobayashi Asako Takamasa Naoki Ohashi Satoru Sano 《Physics and Chemistry of Minerals》2010,37(8):505-518
Synthesized mineral powders with particle size of <100 nm are vacuum sintered to obtain highly dense and fine-grained polycrystalline
mantle composites: single phase aggregates of forsterite (iron-free), olivine (iron containing), enstatite and diopside; two-phase
composites of forsterite + spinel and forsterite + periclase; and, three-phase composites of forsterite + enstatite + diopside.
Nano-sized powders of colloidal SiO2 and highly dispersed Mg(OH)2 with particle size of ≤50 nm are used as chemical sources for MgO and SiO2, which are common components for all of the aggregates. These powders are mixed with powders of CaCO3, MgAl2O4, and Fe(CO2CH3)2 to introduce mineral phases of diopside, spinel, and olivine to the aggregates, respectively. To synthesize highly dense
composites through pressureless sintering, we find that calcined powders should be composed of particles that have: (1) fully
or partially reacted to the desired minerals, (2) a size of <100 nm and (3) less propensity to coalesce. Such calcined powders
are cold isostatically pressed and then vacuum sintered. The temperature and duration of the sintering process are tuned to
achieve a balance between high density and fine grain size. Highly dense (i.e., porosity ≤1 vol%) polycrystalline mantle mineral
composites with grain size of 0.3–1.1 μm are successfully synthesized with this method. 相似文献
3.
Carlos Moreira Souza Jr. Kátia Pereira Victor Lins Sanae Haiashy Daniel Souza 《Earth Science Informatics》2009,2(4):205-215
A web GIS (WGIS) system for the Brazilian Amazon, named ImazonGeo and based on open source and public domain data, is presented.
ImazonGeo was built following three principles. First, the system is based on Spatial Data Infrastructure architecture and
web interface built using free software and public domain data. Second, we went beyond visualization of maps and spatial queries
by providing information obtained with spatial analysis models. To do that, we designed a database that stores the results
of previously defined spatial analyses and developed customized reports and query tools to facilitate fast access of information
by end-users. Finally, the system is application-oriented in the areas of forest monitoring, conservation and forest law enforcement,
meaning that it aims to contribute to support the protection of Brazilian Amazon forests. We illustrate these principles by
presenting ImazonGeo’s technology, architecture, content and tools. Moreover, we present two successful cases to demonstrate
how the system is being used. We conclude the paper discussing the challenges and potential solutions to turning our WGIS-SDI
system into an internet hub of geo-information about the Brazilian Amazon. 相似文献
4.
The R/V Mirai conducted hydrographic surveys in the western Arctic Ocean during summer 2004 (Mirai04) over wide east-west
ranges from Alaska to eastern Siberia, where sea-ice cover has been greatly reduced in recent summers. The obtained data reveal
differences in silicate profiles between shelf slope areas east and west of the Chukchi Plateau, the ridge that divides the
Canada Basin into the Alaskan and east Siberian sides. East of the plateau, a single silicate maximum was found in a layer
of Pacific-origin winter water, as examined in many previous studies. In contrast, west of the plateau, we found vertical
double silicate maxima, which are reported for the first time in this study. The shallower silicate maximum corresponded to
an N** minimum, signaling denitrification at the shelf bottom. This suggests that the shallower silicate maximum was caused
by the spreading of shelf water. In contrast, the deeper silicate maximum corresponded to an oxygen minimum and a maximum
silicate/phosphate ratio (Si/P), suggesting that this deeper maximum resulted from the decomposition of opal-shelled organisms.
We also compared a silicate profile from Mirai04 to aprofile from the Arctic Ocean Section 94 (AOS94) expedition of 1994,
a heavy ice year. The results suggest that sea-ice loss has enhanced biological activities, likely resulting in the appearance
of the deeper silicate maximum. 相似文献
5.
Noboru Okami Motoaki Kishino Shigehiko Sugihara Sanae Unoki 《Journal of Oceanography》1982,38(5):300-306
A method for evaluating the radiance due to sky light reflected by the sea surface and radiance emerging from the sea is described. The calculation is made as a function of the sun altitude, sky condition and sea state for varying optical properties of sea water. As a result of the contribution of reflected sky light, the shape of the spectral distribution for radiance just below the surface is considerably distorted above the surface, especially when chlorophyll concentrations are high. Special attention is paid to the ratio of radiance emerging from the sea to total upwelling radiance at the wavelength of 670 nrn. The variation in the ratio with wind-speed is small and the ratio decreases with increase in the atomospheric turbidity factor. 相似文献
6.
Noboru Okami Motoaki Kishino Shigehiko Sugihara Sanae Unoki 《Journal of Oceanography》1982,38(4):208-214
By using the two-flow optical model, the variation in the irradiance reflectance of the ocean just below the surface has been calculated for varying water optical properties, for the interpretation of remotely-sensed ocean color data. The input variables used in our model are the concentration of phytoplankton (chlorophyll-a), the absorption coeffiicient of yellow substance, the particle scattering coefficient, the ratio of the back-scattering coefficient to the total scattering coefficient of particles, and the ratio of the absorption to scattering coefficients for particles.The irradiance reflectance increases monotonically with the ratio of the back-scattering coefficient to the total scattering coefficient. Spectral changes occur in the irradiance reflectance for increases in chlorophyll-a concentration and yellow substance as well as the ratio of the absorption to scattering coefficients.Because slightly different mathematical expressions have been derived by other investigators using the two-flow model, an evaluation of the resulting calculation differences is presented and discussed. 相似文献
7.
Seasonal and interannual change in mesozooplankton community structure in the offshore Tsushima Current area of the Japan/East Sea was studied in relation to climatic events and temporal variability of the upper water column environment from 1991 to 1999. We observed a clear seasonal succession in zooplankton community structure from a cold-water copepod-dominated community in winter and spring to a gelatinous, carnivorous and warm-water copepod-dominated community in summer and autumn. The mean abundance (inds. m−3) of the spring community was 3–4-fold higher than that of the other season. The spring community structure varied considerably between years: the community characterized by the summer–autumn type zooplankton assemblage appeared in 1991–1993 and 1998, while the community characterized by high abundance of cold-water copepods appeared in the mid 1990s. Time series profiles of water density and nutrients showed the thickness of the surface warm Tsushima Current and the cold subsurface water increased and decreased, respectively, limiting nutrient supply to the surface water in 1992 and 1998. These results suggest that a thick, warm surface layer might reduce the reproductive success and survival ratio of the cold-water copepods both directly and indirectly, by hindering their upward migration to the surface where food is available, and by limiting phytoplankton growth due to nutrient depletion, respectively. A Monsoon Index (MOI) showed weaker winter wind stress in 1992 and 1998, which might have attenuated formation of the cold subsurface layer in the northern Japan/East Sea and been responsible for surface warming of the study area. Since 1992 and 1998 were El Niño years, this study revealed that ENSO related climatic variability on an interannual time scale considerably influenced the lower trophic level ecosystem in the Japan/East Sea. 相似文献
8.
Issa Sakho Jean-Paul Dupont Mohamed Talla Cisse Sanae El Janyani Soda Loum 《Environmental Earth Sciences》2017,76(6):253
The understanding of the spatial and temporal dynamic of river systems is essential for developing sustainable water resource management plan. For the Senegal River, this subject is very complex according to the context of (1) transboundary basin, (2) several contrasted climatic zones (Guinea, South Sudanian, North Sudanian and Sahelian) with high rainfall variability and (3) high human pressures (dam construction and water uses). From 1954 to 2000, 80% (mean value) of the Senegal River flows recorded downstream part of the basin are provided by three majors tributaries (Bafing, Bakoye and Faléme) located in the upstream part. Then, in our study, this upper Senegal River basin was chosen in order to investigate the hydrological responses to rainfall variability and dam construction. Two nonparametric statistical methods, Mann–Kendall and Hubert test, were used to detect the long-term changes in the time series of precipitation and water discharge (1954–2000) at the annual and seasonal scales. The continuous wavelet transform (Morlet Wavelet) was employed to characterize the different mode in the water discharge variability. Flow duration curve and cumulative curve methods were used to assess the impact of dams on the hydrological regime of the Senegal River. Results showed that the Senegal River flows have been changing under the influence of both rainfall variation and dam construction. The long-term evolution of water discharge depend on long-term rainfall variability: The wet periods of the 1950s and 1960s correspond to periods of higher river flows, while the droughts of the 1970s and 1980s led to unprecedented river flows deficits. The new period, since 1994, show a high inter-annual variability of rainfall and discharge without clear trend. At seasonal scale, the results showed also a strong relationship between rainfall and runoff (R 2 > 0.8) resulting from alternating wet and dry seasons and rapid hydrological responses according to annual rainfall. Nevertheless, the observed flows during dry seasons highlighted the influence of water storage and restitution of infiltrated waters in soils and surficial formations during wet seasons. In the dry seasons, the water budget of the three upstream tributaries showed a water deficit at the downstream gauging station. This deficit was characterized by water loss to underlying aquifers and highlighted the influence of geological setting on water balance. However, in this context, water restitution during the dry season remained dependent on climatic zone and on the total annual rainfall volume during the previous wet season. The results have highlighted an impact of the Manantali dam previously obscured: The dam has no effect on the regulation of high river flows. That is what explains that since its construction in 1988, flooding of coastal cities, like Saint-louis, by seasonal river floods has not ceased. The flooding risk in coastal cities is not avoided, and the dams caused hyper-salinization of the Senegal lower estuary. The breach created in the coastal barrier of the Langue of Barbary in October 2003 promotes direct export of excess floodwater to the sea and reduces this risk of flooding in the delta area. But, this solution led to considerable loss of potential water resources, and the authors recommend a new water management plan with a global focus. However, this study shows the positives impacts of the two dams. They allow the availability of freshwater in order to support agricultural irrigation in the valley and delta zone, in particular during low flows periods. 相似文献
9.
Tokumoto T Ishikawa K Furusawa T Ii S Hachisuka K Tokumoto M Tsai HJ Uchida S Maezawa A 《Marine environmental research》2008,66(3):372-377
Sonolysis and photolysis often exhibit synergistic effects in the degradation of organic molecules. An assay of fish oocyte maturation provides an appropriate experimental system to investigate the hormonal activities of chemical agents. Oocyte maturation in fish is triggered by maturation-inducing hormone (MIH), which acts on receptors on the oocyte surface. A synthetic estrogen, diethylstilbestrol (DES), possesses inducing activity of fish oocyte maturation, and a widely used biocide, pentachlorophenol (PCP), exhibits a potent inhibitory effect on fish oocyte maturation. In this study, the effects of the combined treatment by sonolysis with photolysis (sonophotocatalysis) to diminish the hormonal activity of DES and the maturation preventing activity of PCP was examined. By sonophotocatalysis, hormonal activity of DES was completely lost within 30min and the inhibiting activity of PCP was lost within 120min. These results demonstrated that sonophotocatalysis is effective for diminishing the endocrine-disrupting activity of chemical agents. 相似文献
10.