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排序方式: 共有191条查询结果,搜索用时 15 毫秒
1.
S. Kojima S. Ohta T. Yamamoto T. Miura Y. Fujiwara K. Fujikura J. Hashimoto 《Marine Biology》2002,141(1):57-64
The nucleotide sequence of part (624 bp) of a mitochondrial gene for cytochrome oxidase I was determined for 46 escarpiid vestimentiferans collected from seven sites in the western Pacific and 49 individual specimens of Arcovestia ivanovi from two sites in the Manus Basin. Phylogenetic analysis, based on the newly obtained and previously reported sequences, indicated that escarpiids in the western Pacific can be divided into two tentative species, as we proposed in a previous report. While members of the first tentative species have been collected exclusively from a seep area at a depth of 300 m off the coast of central Japan, the members of the second species inhabit some sites at depths greater than 1,100 m, namely, seep areas in Japanese and Papua-New Guinean waters as well as hydrothermal vent fields in the Okinawa Trough and the Manus Basin. We detected no genetic structure among populations of the second tentative species. The first tentative species was more closely related to a species in the eastern Pacific, Escarpia spicata, and to a species in the Gulf of Mexico, Escarpia laminata, than to the second tentative species in the western Pacific. Sequences obtained from all arcovestiids were identical with the exception of those from three individuals, each of which included a single synonymous nucleotide substitution relative to the dominant haplotype, and no genetic differences were detected between specimens from the two sites in the Manus Basin. 相似文献
2.
Hiroshi Yamamoto Yudai Nakamura Yuki Nakamura Chise Kitani Tetsuya Imari Jun Sekizawa Yuji Takao Naoyuki Yamashita Narisato Hirai Shigeto Oda Norihisa Tatarazako 《Environmental sciences》2007,14(4):177-193
Eight pharmaceuticals were selected on the basis of their domestic consumption in Japan, the excretion ratio of the parent compound and the frequency of detection in the aquatic environment or wastewater treatment plant effluent. Toxicity tests on these pharmaceuticals were conducted using Japanese medaka (Oryzias latipes), daphnia (Daphnia magna), and green algae (Psuedokirchneriella subcapitata). Predicted no effect concentration (PNEC) was calculated using lethal or effect concentration 50 (LC50 or EC50) values and no effect concentration (NOEC) obtained in the toxicity tests for these compounds. Predicted environmental concentration (PEC) was also calculated from annual consumption, the excretion rate of the parent compound, and removal rate in the preliminary batch activated sludge treatment performed in this study. Maximum concentrations found in the aquatic environment or sewage effluent in Japan or foreign countries were also used for another calculation of PEC. Initial risk assessment on the selected pharmaceuticals was performed using the PEC/PNEC ratio. The results of initial risk assessment on the eight selected pharmaceuticals suggest neither urgent nor severe concern for the ecological risk of these compounds, but further study needs to be conducted using chronic toxicity tests, including reproduction inhibition and endocrine disruption assessments. 相似文献
3.
Atsuyoshi Nakayama Norioki Kawasaki Ioannis Arvanitoyannis Seiichi Aiba Noboru Yamamoto 《Journal of Polymers and the Environment》1996,4(3):205-211
Biodegradable polyesters were synthesized by ring-opening copolymerization of -butyrolactone (BL) and its derivatives withl-lactide (LLA). Although tetraphenyl tin was the main catalyst used, other organometallic catalysts were used as well.1H and13C NMR spectra showed that poly(BL-co-LLA)s were statistical and that their number-average molecular weights were as high as 7×104. The maximum BL content obtained from copolymerization BL/LLA was around 17%. TheT
m andT
g values of the copolymers showed a gradual depression with an increase in BL content. NoT
m was obtained for the copolymers containing more than 13 mol% BL. The biodegradability of the copolyesters was evaluated by enzymatic hydrolysis and nonenzymatic hydrolysis tests. The enzymatic hydrolysis was carried out at 37°C for 24 h using lipases fromRhizopus arrhizus andR. delemar. Hydrolyses by both lipases showed that an increase in BL content of the copolymer resulted in enhanced biodegradability. Nonenzymatic accelerated hydrolysis of copolymers at 70°C was found to increase proportionally to their exposure time. The hydrolysis rate of these copolymers was considerably faster than that of PLLA. The higher hydrolyzability was recorded for the BL-rich copolymers. The copolymerization of -methyl--butyrolactone (MBL) or -ethyl--butyrolactone (EBL) with LLA resulted in relatively LA-rich copolymers. 相似文献
4.
Osamu Sawai Teppei Nunoura Kazuo Yamamoto 《Journal of Material Cycles and Waste Management》2014,16(1):82-92
Sewage sludge, a byproduct of municipal wastewater treatment, was gasified by supercritical water using a bench-scale batch reactor. Configuration of bench-scale batch reactor and operation procedures are discussed in detail. Experience and challenges that arose during the experiment are also shared. Using the bench-scale reactor under the condition of 600 °C, 23 MPa, and a reaction time of 60 min without catalyst presence, a total gas yield of 9.8 mol/(kg-sewage sludge) was obtained. Furthermore, investigations on operational parameters were conducted. Extension of reaction time up to 60 min increased the gasification, reaching a plateau thereafter. Investigation on pressure indicated the superiority of supercritical pressure. The addition of Ni as a catalyst also promoted gasification, although inorganic salts and char seemed to cover the catalyst surface. With regard to the prospect of future operation at a municipal waste water treatment plant, the effect of operational parameters on heavy metal concentration in the liquid phase is also discussed. 相似文献
5.
Evi Kurniati Novi Arfarit Tsuyoshi Imai Takaya Higuchi Ariyo Kanno Koichi Yamamoto Masahiko Sekine 《环境科学学报(英文版)》2014,26(6):1223-1231
The use of filamentous fungi in bioremediation of heavy metal contamination has been developed recently. This research aims to observe the capability of filamentous fungi isolated from forest soil for bioremediation of mercury contamination in a substrate. Six fungal strains were selected based on their capability to grow in 25 mg/L Hg2+-contaminated potato dextrose agar plates. Fungal strain KRP1 showed the highest ratio of growth diameter, 0.831, thus was chosen for further observation.Identification based on colony and cell morphology carried out by 18S rRNA analysis gave a 98%match to Aspergillus flavus strain KRP1. The fungal characteristics in mercury(Ⅱ) contamination such as range of optimum pH, optimum temperature and tolerance level were 5.5–7 and 25–35℃ and 100 mg/L respectively. The concentration of mercury in the media affected fungal growth during lag phases. The capability of the fungal strain to remove the mercury(Ⅱ) contaminant was evaluated in 100 mL sterile 10 mg/L Hg2+-contaminated potato dextrose broth media in 250 mL Erlenmeyer flasks inoculated with 108spore/mL fungal spore suspension and incubation at 30℃ for 7 days. The mercury(Ⅱ) utilization was observed for flasks shaken in a 130 r/min orbital shaker(shaken) and nonshaken flasks(static) treatments. Flasks containing contaminated media with no fungal spores were also provided as control. All treatments were done in triplicate. The strain was able to remove 97.50%and 98.73% mercury from shaken and static systems respectively. A. flavus strain KRP1 seems to have potential use in bioremediation of aqueous substrates containing mercury(Ⅱ) through a biosorption mechanism. 相似文献
6.
Yukiyo Yamamoto Thomas Oberthür Rod Lefroy 《Environment, Development and Sustainability》2009,11(3):639-654
In the mountainous regions of northern Laos, shifting cultivation, or slash-and-burn agriculture, is widely practiced. However,
the crop–fallow rotation cycle is becoming shorter owing to forest conservation policies and population pressure, causing
loss of productivity that deleteriously affects farmers’ livelihoods in the region. To investigate regional land use conditions,
we have developed a method of identifying the crop–fallow rotation cycle from Landsat Thematic Mapper (TM) and Enhanced Thematic
Mapper+ (ETM+) data. We assessed the impact of the identified cycle on plant production measured by Normalized Difference
Vegetation Index (NDVI). The study site was an area in Luang Prabang Province. Using eight TM and ETM+ images acquired annually
from 1995 to 2003, except for 1998, when cloud-free data were not collected, we classified land use in each year as crop or
fallow by the presence of vegetation in the late dry season. Conformity with fallow age determined by field investigation
was 69.1%. The cultivation frequency from 1995 to 2002 showed that 77,000 ha (17.3% of the study site) had not been used for
cropping during the period, but 41,000 ha (9.2%) had been used every year. Of the study site, 129,000 ha (29.1%) was cultivated
one or two times, 83,000 ha (18.7%) was three or four times, and 54,000 ha (12.2%) was five or six times. The NDVI of crops
in November did not provide sufficient evidence to prove the assumption that a longer fallow period would result in better
crop yields. Instead, the regeneration of fallow vegetation was evidenced by the higher NDVI values after longer fallow. More
than 8 years would be needed to reach the same NDVI as forest. From the produced maps indicating fallow age and cultivation
frequency, we found that areas with high potential for regeneration decreased as cultivation frequency increased. Areas near
rivers were intensively used, and fallow length was accordingly short. Low-potential areas were found in the western basin
of the Mekong River. This spatial information can be used to detect areas where biomass productivity is at high risk of deteriorating.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
7.
Motoyuki Sugano Akihiro Komatsu Masanori Yamamoto Mika Kumagai Takayuki Shimizu Katsumi Hirano Kiyoshi Mashimo 《Journal of Material Cycles and Waste Management》2009,11(1):27-31
Most landfilled plastic waste is a mixture or is in the form of composites with incombustible wastes such as glass, metals,
and ceramics. After hydrothermal treatment, including a steam-explosion process, the separation of mixed waste (MW) into organic
and inorganic substances becomes easy. However, the effect of hydrothermal pretreatment on the subsequent liquefaction of
organic substances from MW is not obvious. In this study, the effects on the liquefaction of polystyrene and high-density
polyethylene are discussed. Moreover, optimum conditions for the liquefaction of organic substances from hydrothermally treated
MW are identified. By means of this hydrothermal pretreatment, including the steam-explosion process, polystyrene and high-density
polyethylene can be significantly converted to oil by liquefaction at 300°–400°C. In comparison with liquefaction of hydrothermally
pretreated mixed waste (HMW) at 300°–400°C with a batch type reactor, the yield of oil increases significantly on liquefaction
using a semi-batch type reactor. It is considered that the radical chain and termination reactions among the radicals from
HMW were inhibited in the semi-batch type reactor. On liquefaction of HMW in a semi-batch reactor, the conversion of HMW to
oil was enhanced on increasing the liquefaction temperature to 350°C and the holding time to 60 min.
Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6 相似文献
8.
Shinya Inazumi Hiroyasu Ohtsu Yu Otake Makoto Kimura Masashi Kamon 《Journal of Material Cycles and Waste Management》2009,11(1):55-64
An evaluation method that can express the local leakage of leachate from joint sections in steel pipe sheet pile (SPSP) cutoff
walls is discussed in this study. In particular, the evaluation of environmental feasibility (containment of leachates containing
toxic substances) considering a three-dimensional arrangement and hydraulic conductivity distribution of the joint sections
in the SPSP cutoff wall is compared with an evaluation that uses the equivalent hydraulic conductivity. This equivalent hydraulic
conductivity assumes that the joint section and the steel pipe are integrated; therefore, the hydraulic conductivity is substituted
with a uniform permeable layer. However, in an evaluation that employs the equivalent hydraulic conductivity, it is difficult
to consider the local leakage of leachate containing toxic substances from the joint sections in the SPSP cutoff wall. It
was established that evaluations of the environmental feasibility of SPSP cutoff walls with joint sections must take into
account the local leakage of leachates containing toxic substances from the joint sections. Also, it was clarified that technologies
that lower the hydraulic conductivities of joint sections in SPSP cutoff walls and also facilitate the use of sparser joint
arrangements contribute significantly to increasing the environmental feasibility of SPSP cutoff walls at landfill sites. 相似文献
9.
Effects of potassium alkalis and sodium alkalis on the dechlorination of o-chlorophenol in supercritical water 总被引:1,自引:0,他引:1
Effects of potassium alkalis and sodium alkalis on the dechlorination of o-chlorophenol (o-CP) in supercritical water (SCW) were studied in this paper under the conditions of 450 degrees C and 25 MPa. Experimental results indicated that the dechlorination of o-CP can be accelerated significantly by all alkalis investigated. The dechlorination of o-CP proceeded mainly via two pathways: hydrodechlorination and hydrolysis. Both of the two pathways can be promoted by alkalis, and the dechlorination of o-CP can be accelerated by both the cations and hydroxide ion dissociated from alkalis. The overall dechlorination of o-CP can be accelerated by cations via promoting the hydrodechlorination pathway, while, hydroxide ion via promoting the hydrolysis pathway. In addition, the hydrodechlorination can be accelerated faster by sodium alkalis than that by potassium ones, while, the hydrolysis can be promoted faster by potassium alkalis. This difference may be caused by the different charge density between potassium ion and sodium ion, and the different solubility and dissociation constant between potassium alkalis and sodium alkalis in SCW. Dechlorination of o-CP with addition of alkalis prior to supercritical water oxidation (SCWO) process not only can avoid the reactor corrosion caused by the generated hydrochloric acid in direct SCWO of o-CP, but also can reduce the formation of toxic chlorinated byproducts compared with direct SCWO process or SCWO of o-CP with addition of alkali. 相似文献
10.
The photochemical decomposition of short-chain (C(3)-C(5)) perfluorocarboxylic acids (PFCAs) was investigated. Direct photolysis in water proceeded slowly with the 220- to 460-nm light emission from a xenon-mercury lamp to form F(-), CO(2), and shorter-chain PFCAs. Addition of a small amount of Fe(3+) to the aqueous solutions of the PFCAs dramatically enhanced their photochemical decomposition under an oxygen atmosphere: when the (initial PFCA)/(initial Fe(3+)) molar ratio was 13.5 (initial PFCA concentration=67.3mM), the pseudo-first-order rate constants for the PFCA decomposition were 3.6-5.3 times those with photolysis alone, and the turnover number for the catalytic PFCA decomposition [i.e., (moles of decomposed PFCA)/(moles of initial Fe(3+))] reached 6.71-8.68 after 24h of irradiation. The catalysis can be explained by photoredox reactions between PFCA, Fe(3+)/Fe(2+) and oxygen via photo-induced complexation of Fe(3+) with the PFCAs. 相似文献