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61.
Characterization of bioactive plant ellagitannins by chromatographic, spectroscopic and mass spectrometric methods 总被引:1,自引:0,他引:1
Ellagitannins are widely distributed plant polyphenols showing potent anti-herbivore activities, but rather complex chemical structures. Here we show how ellagitannins with different structures can be efficiently characterized from plant extracts by utilizing the information obtained from four universal methods used for ellagitannin analysis: Sephadex LH-20 gel chromatography, high-performance liquid chromatography, ultraviolet spectroscopy, and mass spectrometry. We show that by combining the information obtained from the ellagitannins’ chromatographic elution order, specific shapes of the ultraviolet spectra, molecular masses and characteristic mass spectral fragmentations, it is possible to classify these polyphenols into different ellagitannin sub-groups, and even characterize the structures within the sub-groups. These findings aid in the fast screening of complex plant samples for their ellagitannin composition without having to isolate compounds for individual characterization. 相似文献
62.
Comparison of forest protection between regions in Europe is extremely difficult, because there is such wide variation of strategies, procedures and constraints; the way forests have been used historically and their present closeness to nature also varies, and furthermore so does the definition of what constitutes a forest. For the European Ministerial Conference on the Protection of Forests in Europe (MCPFE) in 2003, forest protection has been harmonised into three categories for the sake of comparison: protection to safeguard biodiversity, protection of landscape and specific natural features, and protective forest functions.There is no single, uniform and universal model and no internationally agreed target with respect to the percentage of forests which should be protected. What is more important than a fixed percentage level of forested area (e.g. 5 or 10%) is that the protection network should be biogeographically and ecologically representative and accordingly distributed on a regional basis. Long-term practical experience and research have proved that conservation of different species of organisms can be assured by appropriate silvicultural management of multifunctional production forests. Consequently, the focus of debate in Europe appears to shift more and more from total protection in segregated areas to 'precision protection' and to combining protection and timber production in the holistic, integrated concept of modern management of forest areas.Advances in regional ecological planning and the growing adoption of naturalistic forest management practices have slowed the decline of the biological diversity in the multifunctional production forests. However, this fact is not yet widely and sufficiently acknowledged and appreciated. There is consequently a political and scientific need for continued study of the effects of naturalistic silvicultural management on the biodiversity of forests. Information from such research is crucially needed before new and additional protection networks and schemes are set up on a large-scale. Protection by voluntary contracts between parties is a workable model concept for European forestry based on private forest ownership. In small private forests, patches of forest worth protecting are often small and located within production forests.Forest certification can contribute to the efforts of maintaining biodiversity in multifunctional production forests and offers an instrument of independently monitoring and verifying that forests are managed according to the agreed criteria. Forest certification is not an alternative or a means of increasing forest protection, because as a voluntary process it cannot guarantee the permanence of protected areas or deal with issues of finance and compensation. 相似文献
63.
Huttunen JT Alm J Saarijärvi E Lappalainen KM Silvola J Martikainen PJ 《Chemosphere》2003,50(2):247-250
The springtime methane (CH4) emission from a small, eutrophied boreal lake was assessed during the winter ice-cover by measurement of gas ebullition and CH4 accumulation in the water column in association with the development of oxygen depletion after ice formation. The winter CH4 production was estimated to result in a loss of 3.6-7.9 g CH4 m(-2) from the lake to the atmosphere during the short period of ice melt. This could account for 22-48% of the annual CH4 emission from the pelagic zone of the lake. The contribution of winter to the annual CH4 release can be similar or even higher in seasonally ice-covered northern aquatic ecosystems than in northern terrestrial wetlands, thus winter must be considered in any studies into the aquatic CH4 emissions. The trophic state and wintertime oxygen conditions, linked to the changes in land-use in the catchments and climate, are important factors controlling the springtime lake CH4 emissions. 相似文献
64.
Jari?Lyytim?kiEmail author 《Mitigation and Adaptation Strategies for Global Change》2011,16(6):649-661
Integration of climate change adaptation and mitigation measures into other policies is considered to be a precondition for
effective climate policies. This paper explores the role of mass media coverage as a potential obstacle or enhancing factor
in relation to this mainstreaming of climate policies. The paper presents a quantitative content analysis of the national-level
press coverage of climate change from 1990 to 2010, focusing on Finland. The empirical results indicate four major phases
of Finnish media coverage of climate change: a definition phase before the Kyoto meeting in 1997, a maturation phase after
the Kyoto meeting, climate hype in 2006–2008, and a phase of levelling off that started in late 2008. The results suggest
that climate issues have widely permeated various fields of newspaper coverage. This broad-based debate may create and sustain
a public agenda potentially favourable to attempts to bring climate policies into the mainstream of other policy domains.
However, it also may open doors for unexpected initiatives by various activists and lobbyists that employ climate concern
as a tool to advance other interests. The role of mass media has received little attention in studies focusing on the mainstreaming
of climate policies. This paper highlights the importance of taking media coverage into account as a key factor in the formulation
and implementation of environmental policies aimed at broad-based actions. 相似文献
65.
66.
Fluxes of methane,carbon dioxide and nitrous oxide in boreal lakes and potential anthropogenic effects on the aquatic greenhouse gas emissions 总被引:12,自引:0,他引:12
Huttunen JT Alm J Liikanen A Juutinen S Larmola T Hammar T Silvola J Martikainen PJ 《Chemosphere》2003,52(3):609-621
We have examined how some major catchment disturbances may affect the aquatic greenhouse gas fluxes in the boreal zone, using gas flux data from studies made in 1994-1999 in the pelagic regions of seven lakes and two reservoirs in Finland. The highest pelagic seasonal average methane (CH(4)) emissions were up to 12 mmol x m(-2) x d(-1) from eutrophied lakes with agricultural catchments. Nutrient loading increases autochthonous primary production in lakes, promoting oxygen consumption and anaerobic decomposition in the sediments and this can lead to increased CH(4) release from lakes to the atmosphere. The carbon dioxide (CO(2)) fluxes were higher from reservoirs and lakes whose catchment areas were rich in peatlands or managed forests, and from eutrophied lakes in comparison to oligotrophic and mesotrophic sites. However, all these sites were net sources of CO(2) to the atmosphere. The pelagic CH(4) emissions were generally lower than those from the littoral zone. The fluxes of nitrous oxide (N(2)O) were negligible in the pelagic regions, apparently due to low nitrate inputs and/or low nitrification activity. However, the littoral zone, acting as a buffer for leached nitrogen, did release N(2)O. Anthropogenic disturbances of boreal lakes, such as increasing eutrophication, can change the aquatic greenhouse gas balance, but also the gas exchange in the littoral zone should be included in any assessment of the overall effect. It seems that autochthonous and allochthonous carbon sources, which contribute to the CH(4) and CO(2) production in lakes, also have importance in the greenhouse gas emissions from reservoirs. 相似文献