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11.
In order to improve the efficiency and cost-effectiveness of the PCB analysis, the DMSO partition and SPE extraction were applied to clean up the PCB-contaminated transformer oils and PCB level was determined by means of the quadrupole GC/MS. The analysis data obtained from this method were compared statistically to that from the standard method. 相似文献
12.
Takeo Kurihara Hideki Takami Takeharu Kosuge Susumu Chiba Masatsugu Iseda Takenori Sasaki 《Marine Biology》2011,158(9):2095-2107
Increases of low-latitude species in various sea areas and poleward shifts of ranges of many species have been reported and
linked to warming environments. To examine the generality of these trends for mollusks, we conducted 7 quadrat surveys during
1978–2006 on Pacific rocky shores in Japan (26.6–45.0°N). Results showed that the dominance of southern species increased
on 11 of the 15 shores in a southern, warming sea area but on only 1 of the 6 shores in a northern area with no warming trend.
The latitudes of species ranges increased on average but showed large interspecific variations which showed a weak, positive
correlation with interspecific taxonomic distance. The differences of these results from the previously reported trends are
discussed in relation to the unique current patterns in our study area and the phylogenetic constraints of species-specific
responses to a warming environment. 相似文献
13.
Jun Kobayashi Takeo Sakurai Kaoruko Mizukawa Kyoko Kinoshita Nozomi Ito Shunji Hashimoto Daisuke Nakajima Toru Kawai Yoshitaka Imaizumi Hideshige Takada Noriyuki Suzuki 《Chemosphere》2013
We investigated the respiratory uptake kinetics of polychlorinated biphenyls (PCBs), organohalogen pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and 2,2′,4,4′-tetrabrominated diphenyl ether (BDE #47) in a marine benthic fish, Pseudopleuronectes yokohamae. The respiratory uptake efficiencies (EW) of the chemicals, of which there have been no reports for the majority of persistent organic pollutants (POPs), were obtained by measuring the respiratory uptake rate constants (k1) and the oxygen consumption rates of fish. Fish were exposed to water in which these chemicals were dissolved at environmentally relevant concentrations for 28 d, followed by 168 d of depuration in clean seawater. The k1 and EW values for 99 compounds were obtained, and they ranged from 2000 to 42 000 L kg-lipid−1 d−1 and from 0.060 to 1.3, respectively. The EW values of the chemicals, except for PAHs, tended to increase with increasing values of the log octanol–water partition coefficients (KOW) of the chemicals up to a log KOW of 5. For log KOW in the range 3–5, the EW values in this study were much lower than those in a published study (about one-third). As a result of analysis by a two-phase resistance model, the resistance of transport rates to the lipid phase in this study was lower than was the case in the published study. These findings indicate that the EW predicted by the published study for log KOW in the range 3–5 may differ among fish species and water temperature, and further study is needed. 相似文献
14.
Isobe T Serizawa S Horiguchi T Shibata Y Managaki S Takada H Morita M Shiraishi H 《Environmental pollution (Barking, Essex : 1987)》2006,144(2):632-638
A monitoring survey was conducted to investigate the distribution of steroid estrogens and their conjugates in surface sediments of Tokyo Bay for the first time, which is known as one of the most heavily polluted marine embayments in the world. The surface sediment samples were collected at 20 locations covering the whole area of Tokyo Bay and analyzed for steroid estrogens and their conjugates using liquid chromatography-tandem mass spectrometry. The concentrations of 17beta-estradiol (beta-E2) and estrone (E1) ranged from ND (below the detection limit; <0.07) to 0.59 and from 0.05 to 3.60 ng g-1 dry, respectively. Those concentrations were higher in the northern part of the bay, which is directly receiving huge quantities of pollutants from adjacent rivers containing a large amount of municipal and industrial wastewater. 17alpha-Estradiol (alpha-E2) and estrone-3-sulfate (E1-3S) were detected in some of the samples, whereas neither of the other conjugates, estriol (E3) or 17alpha-ethynylestradiol (EE2), was found. 相似文献
15.
Although provisioning of habitat by ecosystem engineers is one of the most common biological interactions, previous studies have mostly focused on facilitative or bottom-up processes. Here we show that engineering effects can indirectly strengthen top-down effects mediated by predator abundance. We conducted a small-scale manipulative field experiment and broad-scale field observations of the plant, web spider, and detrital insect system in forest understory habitats. In the field experiment, artificially increasing architectural elements enhanced the abundance of spiders by providing physical support for web building. Moreover, aerial insects derived from the detrital food web decreased in response to increased spider abundance. As artificial architecture per se did not affect aerial detritivores, these results indicate that ecosystem engineering indirectly strengthens top-down effects mediated by predators. In field observations conducted in 12 cedar forests, path analyses supported the importance of an indirect pathway originating from understory vegetation complexity to spider abundance and to aerial detritivores. The effect size of spiders on detrital insects was similar in the field experiment and in the observations. These results indicate that the engineering effects of plants cascade to detrital insects through web spiders across different scales. 相似文献
16.
Polychlorodibenzothiophenes (PCDTs) are sulfur analogues of polychlorodibenzofurans (PCDFs) and have been detected in environmental samples. We used density functional theory calculations (Gaussian 98W) to predict the photodechlorination pathways of octachlorodibenzothiophene (OCDT) and octachlorodibenzofuran (OCDF) in hexane, and we compared the predicted pathways with those observed during UV irradiation experiments. OCDT and OCDF were observed to degrade through first-order dechlorination processes, and the rate constant for OCDT was less than one-third that for OCDF. The main experimental photodechlorination pathways of OCDT and OCDF led to hexachlorinated and tetrachlorinated congeners, respectively; that is, the photodechlorination pathway of OCDT differed from that of OCDF. On the assumption that the dechlorination mechanisms involved radical reactions, we used DFT calculations to estimate bond-dissociation energies and single-point energies of OCDT and OCDF and their dechlorinated congeners, and we used the resulting information, along with hypotheses regarding the rate-controlling step of the degradations, to predict theoretical degradation pathways. We propose that reaction of dechlorinated radicals with a hydrogen donor was the rate-controlling step for OCDT and that C-Cl bond dissociation by UV light was the rate-controlling step for OCDF. 相似文献
17.
Takeshi Osawa Kazuhisa Yamasaki Ken Tabuchi Akira Yoshioka Mayura B. Takada 《Ambio》2018,47(7):806-815
Detecting dispersal pathways is important both for understanding species range expansion and for managing nuisance species. However, direct detection is difficult. Here, we propose detecting these crucial pathways using a virtual ecology approach, simulating species dynamics using models, and virtual observations. As a case study, we developed a dispersal model based on cellular automata for the pest insect Stenotus rubrovittatus and simulated its expansion. We tested models for species expansion based on four landscape parameters as candidate pathways; these are river density, road density, area of paddy fields, and area of abandoned farmland, and validated their accuracy. We found that both road density and abandoned area models had prediction accuracy. The simulation requires simple data only to have predictive power, allowing for fast modeling and swift establishment of management plans. 相似文献
18.
Photodegradation of hexachlorobenzene and theoretical prediction of its degradation pathways using quantum chemical calculation 总被引:2,自引:0,他引:2
Experimentally determined photodegradation pathways of hexachlorobenzene (HCB), a chlorinated aromatic compound, in hexane, 2-propanol (IPA), and methanol were compared with those predicted by quantum chemical calculation based on density functional theory (DFT), and the adequacy of the prediction method was evaluated. The experimental main degradation pathways of HCB were virtually the same for the three solvents and also agreed with the predicted main degradation pathways. In the DFT method, the main degradation product was the dechlorinated benzene at the position where the C-Cl bond was predicted to have the lowest bond dissociation energy. This result suggested that the photodechlorination pathways of chlorinated aromatic compounds could be predicted by comparing the bond dissociation energies calculated with the DFT method. 相似文献
19.
Nobuyuki Tsuji Anthony R. Chittenden Takuya Ogawa Takenori Takada Yan-Xuan Zhang Yutaka Saito 《Sustainability Science》2011,6(1):97-107
Since the late 1980s, spider mite pests have caused serious damage to many moso bamboo (Phyllostachys pubescens) forests in China’s Fujian province. The culms of this plant are an essential component of the building and handicraft industries,
and the shoots are a prized food item in many Asian countries. Furthermore, bamboo forests play an important soil conservation
role in mountainous areas. We examined pest mite outbreaks in several moso bamboo plantations in Fujian, and could show that
a change in cultivation style from polyculture (a kind of mixed forest) to monoculture (all plants other than bamboo were
removed) was primarily responsible for the local extinction of an important predaceous mite species. This phenomenon is due
to the periodic shedding of leaves by the bamboo, which forces the predator mites occurring on bamboo to switch to prey mite
species that occur on other plants. We then tried to elucidate the factors that resulted from such a cultivation change. Adopting
a computer simulation approach, we could successfully show that at least two plants, moso bamboo and Chinese silvergrass,
are necessary to maintain stable predator–prey interactions in moso forests. That is, systems consisting of one common predator
and two host-specific pest mites on different host plant species frequently became stable when the pest mites were at low
density. This finding indicates clearly that bio-diversity, even when it consists of only two plants and three mite species
as in this study, is necessary for the sustainable regulation of large-scale forests, such as moso bamboo plantations. 相似文献
20.
Kazuhiko Sakamoto Hisae Takada Kazuhiko Sekiguchi 《Atmospheric environment (Oxford, England : 1994)》2004,38(40):6961
To evaluate the influences of O3, relative humidity (RH), and flow rate on the reaction between yellow sand and SO2, the SO2 deposition velocity and the oxidation state of sulfur were investigated by means of exposure experiments in a cylindrical flow reactor. Early in the reaction, the deposition velocity was not influenced by the RH or the presence of O3; as the reaction progressed, however, the deposition velocity increased in the presence of O3 and at high humidity. The oxidation of sulfur from S(IV) to S(VI) was also enhanced under these conditions. The amount of sulfur oxidation was positively correlated with the amount of deposited O3. Furthermore, the SO2 deposition velocity increased with increasing flow rate. However, changes in the flow rate had no noticeable effect on the amount of SO2 oxidation. 相似文献