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排序方式: 共有451条查询结果,搜索用时 750 毫秒
121.
122.
123.
Takamitsu Otake Yoshie Aoyagi Takashi Yarita 《Journal of environmental science and health. Part. B》2013,48(5):423-427
The aim of this study was to assess the performance of a method of analyzing pesticides in rice by using pressurized liquid extraction (PLE) and to perform a preliminary monitoring by using that method. The instrumental quantification limit, instrumental detection limit, method quantification limit, and method detection limit were determined. PLE temperature was also optimized for 6 target pesticides. Mean recoveries of spiked rice with target pesticides (4 ng/g and 40 ng/g) were 83%–109% with the repeatability of the analysis, represented as relative standard deviations, ranged from 1.3% to 11% (n = 5) for PLE at 130°C. These results were satisfactory according to the method of positive list in Japan. In a preliminary analysis of 10 target pesticides in 54 commercial rice samples, ferimzone was detected in only one unpolished rice sample. 相似文献
124.
Junichi Okuyama Takashi Kitagawa Kei Zenimoto Shingo Kimura Nobuaki Arai Yoshikazu Sasai Hideharu Sasaki 《Marine Biology》2011,158(9):2055-2063
We used Lagrangian numerical simulations to examine the trans-Pacific dispersal processes of loggerhead turtle hatchlings.
Ten thousand simulated particles were released from each of the three nesting regions in Japan and tracked for 5 years. Results
showed many particles moving eastward, drifting in the Kuroshio Current followed by the Kuroshio Extension Current. However,
no particles reached Baja California, a known feeding area, through passive processes, indicating that trans-Pacific transportation
requires active swimming by turtles. The duration of the trans-Pacific dispersal was estimated to be at least 1.6–3.4 years,
with some turtles drifting in the Kuroshio Countercurrent and remaining in the western Pacific even after 5 years. This indicates
that as revealed by previous genetic studies, not all loggerheads always disperse along a trans-Pacific route. The findings
showed that survival and expected growth rates varied widely according to ambient temperatures during drifting, which in turn
depended on nesting location. 相似文献
125.
Spatial variability of nitrous oxide emissions and their soil-related determining factors in an agricultural field 总被引:1,自引:0,他引:1
Yanai J Sawamoto T Oe T Kusa K Yamakawa K Sakamoto K Naganawa T Inubushi K Hatano R Kosaki T 《Journal of environmental quality》2003,32(6):1965-1977
To evaluate spatial variability of nitrous oxide (N2O) emissions and to elucidate their determining factors on a field-scale basis, N2O fluxes and various soil properties were evaluated in a 100- x 100-m onion (Allium cepa L.) field. Nitrous oxide fluxes were determined by a closed chamber method from the one-hundred 10- x 10-m plots. Physical (e.g., bulk density and water content), chemical (e.g., total N and pH), and biological (e.g., microbial biomass C and N) properties were determined from surface soil samples (0-0.1 m) of each plot. Geostatistical analysis was performed to examine spatial variability of both N2O fluxes and soil properties. Multivariate analysis was also conducted to elucidate relationships between soil properties and observed fluxes. Nitrous oxide fluxes were highly variable (average 331 microg N m(-2) h(-1), CV 217%) and were log-normally distributed. Log-transformed N2O fluxes had moderate spatial dependence with a range of >75 m. High N2O fluxes were observed at sites with relatively low elevation. Multivariate analysis indicated that an organic matter factor and a pH factor of the principal component analysis were the main soil-related determining factors of log-transformed N2O fluxes. By combining multivariate analysis with geostatistics, a map of predicted N2O fluxes closely matched the spatial pattern of measured fluxes. The regression equation based on the soil properties explained 56% of the spatially structured variation of the log-transformed N2O fluxes. Site-specific management to regulate organic matter content and water status of a soil could be a promising means of reducing N2O emissions from agricultural fields. 相似文献
126.
The basic properties of poly(lactic acid) produced by the direct condensation polymerization of lactic acid 总被引:8,自引:0,他引:8
M. Ajioka K. Enomoto K. Suzuki A. Yamaguchi 《Journal of Polymers and the Environment》1995,3(4):225-234
Poly(lactic acids) with high molecular weights have been synthesized by direct condensation polymerization of lactic acid. These polymers have good mechanical properties and can be processed into products such as cups, film, and fiber, which can be used as compostable materials. This polymerization method can be applied to the synthesis of copolymers of lactic acid and other hydroxyacids. The properties of poly(lactic acid) and copolymers synthesized by the direct process are different from those of polymers obtained by the conventional lactide process. 相似文献
127.
Measurements of aerosol size-separated number concentrations were performed in March 2001 on the Tama Hills of Japan, located
near regions of heavy industry. The concentrations of particles larger than 1.0 μ m in diameter dramatically increased during
the Kosa phenomena on 6–8 and 18–24 March. The number concentrations of coarse particles (> 3.0 μm) showed distinct diurnal
variations, especially during the Kosa events. Fine particles smaller than 0.5 μm increased when the relative humidity was
high and the wind speed was low. On the other hand, the coarse particles concentrations were well correlated with wind speed
and temperature. The dry deposition velocity of the coarse particles at the forest canopy was estimated from the nighttime
decrease in the number concentrations. 相似文献
128.
Marwan A. Hassan Dan L. Hogan Stephen A. Bird Christine L. May Takashi Gomi David Campbell 《Journal of the American Water Resources Association》2005,41(4):899-919
This paper synthesizes information on the spatial and temporal dynamics of wood in small streams in the Pacific Northwest region of North America. The literature on this topic is somewhat confused due to a lack of an accepted definition of what constitutes “small” streams and what is the relative size of woody debris contained within the channel. This paper presents a matrix that defines woody debris relative to channel size and then discusses the components of a wood budget. Headwater streams are in close proximity to wood sources and, in steeplands, are often tightly constrained by steep hillslopes. Special consideration is given to ecosystem characteristics and to management practices that affect the wood dynamics in this context. Knowledge gaps and uncertainties that can be used to guide future research are identified. Very little is currently known about the role of mass wasting in wood recruitment and storage relative to other processes, such as bank erosion and mortality, in larger streams. Further, very little work has addressed the relative importance of different wood depletion processes, especially those associated with wood transport. The effect of other ecosystem variables on wood dynamics locally across a watershed (from valley bottom to mountaintop) and regionally across the landscape (from maritime to continental climates) is not addressed. Finally, the scientific community has only begun to deal with the effects of management practices on wood quantity, structure, and movement in small streams. 相似文献
129.
Satoru Fujita Kenzi Suzuki Yasuo Shibasaki 《Journal of Material Cycles and Waste Management》2002,4(1):41-45
In this study, an attempt was made to synthesize hydrogrossular, a group of garnet minerals, under hydrothermal conditions
at temperatures below 180°C, using coal ash, which is the solid waste from thermal power plants, as a starting material. A
single phase corresponding to hydrogrossular was found at around 120°C, and the hydrogrossular coexisted with 11-Å tobermorite
above 140°C. The hydrogrossular phase decreased with increasing reaction temperature, while that of 11-Å tobermorite increased
concurrently. The physicochemical properties of the hydrogrossular obtained from the hydrothermal synthesis was characterized
by X-ray diffraction thermogravimetry/differential thermal, analysis, scanning electron microscopy, Fourier transform infrared
spectroscopy, and X-ray fluorescence spectroscopy.
Received: September 4, 2000 / Accepted: March 7, 2001 相似文献
130.