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411.
Garcés-Ordóñez Ostin Espinosa Luisa F. Costa Muniz Marcelo Salles Pereira Larissa Borba Meigikos dos Anjos Roberto 《Environmental science and pollution research international》2021,28(32):43431-43442
Environmental Science and Pollution Research - Microplastic pollution has become a global concern due to its distribution, high abundance, and negative impacts on aquatic ecosystems. These... 相似文献
412.
413.
Poliana Cardoso-Gustavson Francine Faia Fernandes Edenise Segala Alves Mariana Pereira Victorio Barbara Baesso Moura Marisa Domingos Caroline Albuquerque Rodrigues Andreza Portella Ribeiro Catarina Carvalho Nievola Ana Maria G Figueiredo 《Environmental science and pollution research international》2016,23(2):1779-1788
414.
Graham W. Prescott William J. Sutherland Daniel Aguirre Matthew Baird Vicky Bowman Jake Brunner Grant M. Connette Martin Cosier David Dapice Jose Don T. De Alban Alex Diment Julia Fogerite Jefferson Fox Win Hlaing Saw Htun Jack Hurd Katherine LaJeunesse Connette Felicia Lasmana Cheng Ling Lim Antony Lynam Aye Chan Maung Benjamin McCarron John F. McCarthy William J. McShea Frank Momberg Myat Su Mon Than Myint Robert Oberndorf Thaung Naing Oo Jacob Phelps Madhu Rao Dietrich Schmidt‐Vogt Hugh Speechly Oliver Springate‐Baginski Robert Steinmetz Kirk Talbott Maung Maung Than Tint Lwin Thaung Salai Cung Lian Thawng Kyaw Min Thein Shwe Thein Robert Tizard Tony Whitten Guy Williams Trevor Wilson Kevin Woods Alan D. Ziegler Michal Zrust Edward L. Webb 《Conservation biology》2017,31(6):1257-1270
Political and economic transitions have had substantial impacts on forest conservation. Where transitions are underway or anticipated, historical precedent and methods for systematically assessing future trends should be used to anticipate likely threats to forest conservation and design appropriate and prescient policy measures to counteract them. Myanmar is transitioning from an authoritarian, centralized state with a highly regulated economy to a more decentralized and economically liberal democracy and is working to end a long‐running civil war. With these transitions in mind, we used a horizon‐scanning approach to assess the 40 emerging issues most affecting Myanmar's forests, including internal conflict, land‐tenure insecurity, large‐scale agricultural development, demise of state timber enterprises, shortfalls in government revenue and capacity, and opening of new deforestation frontiers with new roads, mines, and hydroelectric dams. Averting these threats will require, for example, overhauling governance models, building capacity, improving infrastructure‐ and energy‐project planning, and reforming land‐tenure and environmental‐protection laws. Although challenges to conservation in Myanmar are daunting, the political transition offers an opportunity for conservationists and researchers to help shape a future that enhances Myanmar's social, economic, and environmental potential while learning and applying lessons from other countries. Our approach and results are relevant to other countries undergoing similar transitions. 相似文献
415.
416.
Optimal parameters to eliminate machining chatter may be identified using analytical stability models which require the dynamics of the tool-holder-spindle-machine assembly. Receptance coupling substructure analysis (RCSA) provides a useful analytical tool to couple measured spindle-machine dynamics with tool-holder models to predict the tool point frequency response function for the assembly. Previous research has demonstrated a procedure to determine all required spindle receptances from a single measurement, where each mode within the measurement bandwidth was modeled as a fixed-free Euler–Bernoulli beam and fit using a manual, iterative procedure. Here, a particle swarm optimization technique is described for fitting the spindle-machine measurement using a fixed-free Euler–Bernoulli beam model for each mode. The performance of the optimization process and RCSA in predicting the tool tip frequency response is evaluated and the results are presented. 相似文献
417.
Interactive effects of water and controlled release urea on nitrogen metabolism,accumulation, translocation,and yield in summer maize 总被引:1,自引:0,他引:1
Guanghao?Li Bin?ZhaoEmail author Shuting?DongEmail author Jiwang?Zhang Peng?Liu Tony?J.?Vyn 《Die Naturwissenschaften》2017,104(9-10):72
To investigate the interactive effects of water and N from controlled release urea (CRU) on N metabolism, accumulation, translocation, and yield in Zhengdan958 (a summer maize cultivar planted widely in China), three water levels (adequate water W3, mild water stress W2, severe water stress W1) and four amounts of CRU (N) (N0, N1, N2, and N3 were 0, 105, 210, and 315 kg N ha?1, respectively) were carried out under the waterproof shed and soil column conditions. The results showed that yield, N metabolism, accumulation, and translocation were significantly affected by water, CRU, and their interactions after tasseling. Yields showed an increasing trend in response to N rates from 100.2 to 128.8 g plant?1 under severe water stress (W1), from 124.7 to 174.6 g plant?1 under mild water stress (W2), and from 143.7 to 177.0 g plant?1 under adequate water conditions (W3). There was an associated optimum amount of N for each water level. Under W1 and W2, N3 treatments showed significant advantages in three N metabolism enzymes’ activities and the N accumulations, and yield and its components were highest. But the nitrogen harvest index (NHI) of N3 had no significant difference with other nitrogen treatments. Under W3, the N translocation efficiency (NTE) and N translocation conversion rate (NTCR) of N2 in stem and leaf were higher than those of N3, but the N metabolism enzymes’ activities and yields of N2 and N3 had no significant difference, which indicated that N2 was superior to N3. The N3 treatment under W2 and N2 under W3 increased the N accumulation capacity in maize grain as well as the N translocation to grain that contributed to the increase of 1000-gain weight and grains per ear after tasseling. Under this experimental condition, a CRU rate of 225 kg ha?1 was the best treatment when the soil moisture content was 75 ± 5% of field capacity, but an N rate of 300 kg ha?1 was superior when soil moisture content was maintained at 55 ± 5% of field capacity during the entire growing season. 相似文献
418.
Susana L. H. Rebelo A. Melo R. Coimbra M. Emília Azenha Mariette M. Pereira Hugh D. Burrows Mohamed Sarakha 《Environmental Chemistry Letters》2007,5(1):29-33
The photodegradation of the herbicides atrazine and ametryn with visible light in aerated neutral aqueous solutions and 5,
10, 15, 20-tetrakis (2,6-dichloro-3-sulfophenyl) porphyrin or 5, 10, 15, 20-tetrakis (4-sulfophenyl) porphyrin as sensitizers
are reported for the first time. Our findings show that the degradation percentage reached 30% for atrazine and 63% for ametryn.
The final photoproducts were characterized as dealkylated s-triazines. Photolysis of the pesticides in the presence of a singlet oxygen quencher showed only a minor contribution of
this type of mechanism, while a bimolecular quenching reaction between the triplet state of the sensitizer and the pesticides
is excluded by flash photolysis studies. It is proposed that the mechanism may involve the formation of a superoxide radical
anion from the triplet state of the sensitizer and molecular oxygen, followed by a radical decomposition pathway.
Selected article from 1st International Meeting on Photochemistry, Photocatalysis and Environmental Applications, Agadir,
2006, organised by Prof. Dr. Ait Ichou, University Ibn Zohr, Agadir, Morocco 相似文献
419.
Organic compounds derived from coal-tar wastes in a contaminated aquifer in St. Louis Park, Minnesota, were identified, and their partition coefficients between the tar phase and aqueous phase were determined and compared with the corresponding n-octanol/water partition coefficients. Coal tar contains numerous polycyclic aromatic compounds, many of which are suspected carcinogens or mutagens. Groundwater contamination by these toxic compounds may pose an environmental health hazard in nearby public water-supply wells. Fluid samples from this aquifer developed two phases upon settling: an upper aqueous phase, and a lower oily-tar phase. After separating the phases, polycyclic aromatic compounds in each phase were isolated using complexation with N-methyl-2-pyrrolidone and identified by fused-silica capillary gas chromatography/mass spectrometry. Thirty-one of the polycyclic aromatic compounds were chosen for further study from four different classes: 12 polycyclic aromatic hydrocarbons, 10 nitrogen heterocycles, 5 sulfur heterocycles, and 4 oxygen heterocycles. Within each compound class, the tar/water partition coefficients of these compounds were reasonably comparable with the respective n-octanol/water partition coefficient. 相似文献
420.
Fabíola Maria N. Nunes M.C.C. Veloso P.A. de P. Pereira J.B. de Andrade 《Atmospheric environment (Oxford, England : 1994)》2005,39(40):927
Biogenic emissions of volatile organic compounds (VOCs) play a fundamental role in atmospheric chemistry. Vegetation is the most abundant natural source of VOCs, while terpenoids, as limonene, α and β pinene and mircene, top the plants emission list. Much interest has been demonstrated in oxidation and photooxidation reactions of VOCs, particularly of monoterpenoids, owing to their diversity and to uncertainties regarding their mechanism of reaction. Quantification of primary carbonylic compounds, as well as of biradical reaction components, is highly relevant to the understanding of the major reactions. In this context, taking into account both structural factors and the fact that these compounds are found in the essential oils of plants typically found in Brazil and that they may be present in the atmosphere from emission by the plants, the monoterpenoids (S)-(+)-carvone, (R)-(−)-carvone, (−)-carveol, geraniol and citral (a mixture of the isomers geranial and neral) were selected for this study.The ozonolysis reactions of the monoterpenoids were carried out under dark conditions for all experiments, due to their photochemical reactivity. The analysis of the results lets us propose a mechanism by which these reactions occur. The observed results of the ozonolysis of S and R carvone suggest that the stereochemistry of asymmetric carbon does not affect either in the yields of both formaldehyde and of OH radicals produced in the reaction, or in the reactivity of these compounds, for which the rate constants were in the scale of 10−6 s−1.We found that, in the (−)-carveol's cis and trans mixture, even though the hydroxyl in the axial position—in the case of trans-(C) and cis-(D′) isomers—favors the attack by the ozone molecule on the external double bond, thus increasing the mixture's reactivity , it affects the average production of formaldehyde. The presence of geraniol and citral led to the production of formaldehyde, propanone, glyoxal, methyl–glyoxal and cyclohexanone (OH radicals) as reaction products. The influence of an electron attractor group bonded to the carbon of the double bond, on the reactivity of the double bond, could not be observed in the case of citral, due to strong interference occurring in the instrument in all experiments with this monoterpenoid. For this reason, only the kinetics of geraniol was monitored . 相似文献