排序方式: 共有58条查询结果,搜索用时 125 毫秒
51.
Nicole Schütze Xiaoyin Zhong Stefan Kirschbaum Iustinian Bejan Ian Barnes Thorsten Benter 《Atmospheric environment (Oxford, England : 1994)》2010,44(40):5407-5414
Relative kinetic studies have been performed on the reactions of Cl atoms with a series of methyl alkyl esters in a 405-liter borosilicate glass chamber at (298 ± 3) K and one atmosphere of synthetic air using in situ FTIR spectroscopy to monitor the reactants. Rate coefficients (in units of cm3 molecule?1 s?1) were determined for the following compounds: methyl acetate (2.48 ± 0.58) × 10?12; methyl propanoate (1.68 ± 0.36) × 10?11; methyl butanoate (4.77 ± 0.87) × 10?11; methyl pentanoate (7.84 ± 1.15) × 10?11; methyl hexanoate (1.09 ± 0.31) × 10?10; methyl heptanoate (1.56 ± 0.37) × 10?10; methyl cyclohexane carboxylate (3.32 ± 0.76) × 10?10; methyl-2-methyl butanoate (9.41 ± 1.39) × 10?11.In addition rate coefficients (in units of 10?11 cm3 molecule?1 s?1) have been obtained for the reactions of OH radicals with the following compounds: methyl butanoate (3.55 ± 0.71), methyl pentanoate (5.41 ± 1.08), and methyl-2-methyl butanoate (4.08 ± 0.82).Using the kinetic rate data tropospheric lifetimes for the methyl alkyl esters with respect to their reactions with OH, and Cl have been estimated for typical ambient air concentrations of these oxidants. 相似文献
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Even after 30 years of strict de jure protection, today's de facto extraction of products from Nepal's Royal Chitwan National Park (RCNP) and their great economic importance to local households suggests that this reality should be explicitly internalised in managing this world heritage park. Several studies have quantified local people's use of protected areas and estimated the value of such areas to them. However, few studies incorporate economic analyses to investigate the effect of management interventions on local communities' resource use and collection behaviour. In Nepal, buffer zones and especially buffer zone community forestry are seen as means to define and demarcate places, where local people may legally extract goods that are either identical to or relevant substitutes for products that are collected in protected areas. The intention is to resolve park-people conflicts over resource use. This article presents the findings of an in-depth study of the importance of natural resources to the livelihoods of 18 households. One village was located inside RCNP with no realistic alternatives to Park resources, while the other is located in the buffer zone with equal distance to the Park, a national forest and their community forest. For each household, the collection of products, allocation of time, and purchase and sale of goods were recorded daily through 12 consecutive months and economic values were calculated on the basis of local market prices and recorded quantities. The study shows that products from RCNP are of great importance to the livelihoods of local people. Furthermore, we find that products collected in the national forest substitute products from the Park, while the substitution effect of the community forest is small. Accordingly, the study illustrates that, irrespective of buffer zone community forestry, there is still a gap between local people's need for supplementing natural resources and their rights to satisfy them on a legal basis, which is likely to be unsustainable in the longer term. This calls for a thorough evaluation of actual park-people relations and how these may be improved through local participation that goes beyond the current form of buffer zone community forestry and the admitted 7-14 annual days of open access grass cutting within the park. 相似文献
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Thorsten Zellmann Alexandra S. B?uerle Reiner Doluschitz Dietmar Jahnke und Detlef Marell 《Umweltwissenschaften und Schadstoff-Forschung》1999,11(3):181-186
Zusammenfassung Die Erfassung der Ist-Situation im Rahmen der Umweltprüfung bildet die Grundlage für effiziente Schritte im Rahmen der Implementierung
von Umweltmanagementsystemen (UMS). Diese Basis-analyse stützt sich auf die Elemente Wirkungsaudit, Management-audit und Rechtsaudit.
Durch die optimale Ausgestaltung einer Umweltprüfung wird bei der Implementierung eines UMS auch in der Landwirtschaft die
Basis für einen maximalen Nutzen des Anwenders geschaffen. Dieser Nutzen ist etwa für den Betrieb in seinen Innenbeziehungen,
die Transparenz der Betriebsabl?ufe, ?konomische Gesichtspunkte, wie z.B. Einsparpotentiale, Informationsgewinnung sowie Effizienzgesichtspunkte
durch die Dokumentation der Ablauforganisation. Darüber hinaus nutzt ein UMS bei externen Anforderungen, wie z.B. beim Umgang
mit der ?ffentlichkeit, Marktpartnern, der Stellung gegenüber Beh?rden, Deregulierung oder Haftungsminimierung.
相似文献
56.
André Sceia Juan-Carlos Altamirano-Cabrera Laurent Drouet Thorsten F. Schulz Marc Vielle 《Environmental Modeling and Assessment》2012,17(3):193-207
The residential sector presents a great potential for greenhouse gases (GHG) mitigation. We perform an integrated assessment
of different mitigation policies for Switzerland focusing on the residential sector. We analyze the case of pure incentive
taxes and technical regulations. For our analysis, we have coupled a general equilibrium model with a Swiss residential energy
model. We find that a progressive GHG tax of more than 200 USD2000/tCO2 eq is necessary to reach a target of 50% reduction of GHG emissions in 2050. Finally, we also find that efficiency-based
technical regulations provide limited additional abatement incentives. 相似文献
57.
Extreme events associated with global change will impose increasing stress on coastal organisms. How strong biological interactions
such as the host–parasite arms-race are modulated by environmental change is largely unknown. The immune system of invertebrates,
in particular phagocytosis and phenoloxidase activity response are key defence mechanisms against parasites, yet they may
be sensitive to environmental perturbations. We here simulated an extreme event that mimicked the European heat wave in 2003
to investigate the effect of environmental change on the immunocompetence of the mesograzer Idotea baltica. Unlike earlier studies, our experiment aimed at simulation of the natural situation as closely as possible by using long
acclimation, a slow increase in temperature and a natural community setting including the animals’ providence with natural
food sources (Zostera marina and Fucus vesiculosus). Our results demonstrate that a simulated heat wave results in decreased immunocompetence of the mesograzer Idotea baltica, in particular a drop of phagocytosis by 50%. This suggests that global change has the potential to significantly affect
host–parasite interactions. 相似文献
58.
Metal speciation in landfill leachates with a focus on the influence of organic matter 总被引:2,自引:0,他引:2
Claret F Tournassat C Crouzet C Gaucher EC Schäfer T Braibant G Guyonnet D 《Waste management (New York, N.Y.)》2011,31(9-10):2036-2045
This study characterises the heavy-metal content in leachates collected from eight landfills in France. In order to identify heavy metal occurrence in the different size fractions of leachates, a cascade filtration protocol was applied directly in the field, under a nitrogen gas atmosphere to avoid metal oxidation. The results of analyses performed on the leachates suggest that most of the metals are concentrated in the <30 kDa fraction, while lead, copper and cadmium show an association with larger particles. Initial speciation calculations, without considering metal association with organic matter, suggest that leachate concentrations in lead, copper, nickel and zinc are super-saturated with respect to sulphur phases. Speciation calculations that account for metal complexation with organic matter, considered as fulvic acids based on C1(s) NEXAFS spectroscopy, show that this mechanism is not sufficient to explain such deviation from equilibrium conditions. It is therefore hypothesized that the deviation results also from the influence of biological activity on the kinetics of mineral phase precipitation and dissolution, thus providing a dynamic system. The results of chemical analyses of sampled fluids are compared with speciation calculations and some implications for the assessment of metal mobility and natural attenuation in a context of landfill risk assessment are discussed. 相似文献