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331.
The aim of this study was to assess the potential for coexistence between rural people (living adjacent to a protected area)
and predators (from the same area) ranging onto communal land. Ninety members of local communities bordering Manyeleti Game
Reserve, which is contiguous with Kruger National Park, South Africa were interviewed. Respondents expressed diverging attitudes
toward predators, which were more favorable among participants with higher education. Negative views were particularly due
to fear of human and livestock losses, especially to lions, Panthera leo. Lions were thought to be the most abundant predator both within and outside the reserve. Lions were also the best known
predator and were most often held responsible for killing livestock. Despite these livestock losses and a lack of conservation
education, most participants voiced favorable opinions about large carnivore conservation, as predators were considered an
integral part of the respondents’ natural heritage. Thanks to this cultural tolerance and also because of a largely accepted
management policy regarding predator control, large carnivores and people can coexist in the vicinity of Kruger National Park. 相似文献
332.
Off-line solid phase extraction and direct injection analysis were evaluated for the determination of traces of explosives such as TNT and its mono and diamino metabolites, HMX, RDX, nitroglycerin and PETN in lake water and tributaries applying liquid chromatography-electrospray tandem mass spectrometry. Improved chromatographic separation was achieved on a phenyl based stationary phase with baseline resolution of the mono- and diamino metabolites of TNT. Identification and quantification of the target compounds was performed by multiple reaction monitoring applying electrospray ionization in either the positive mode for the diaminometabolites of TNT or the negative mode for all other compounds. An extensive method validation was performed and limits of quantification were obtained for the explosives in preconcentrated lake water samples from 0.03 to 1 ng l(-1) and 0.1 to 5 ng l(-1) in river water. Direct injection analysis revealed comparable results to preconcentrated water samples for the most persistent explosives. Analysis of lake water samples collected at different depths showed the presence of HMX, RDX and PETN at concentrations from 0.1 to 0.4 ng l(-1). The analysis of main tributaries revealed concentrations from 0.1 to 0.9 ng l(-1) of the same compounds. They seem to be responsible for the contamination of the explosives in the lakes. 相似文献
333.
Usnic acid controls the acidity tolerance of lichens 总被引:2,自引:0,他引:2
The hypotheses were tested that, firstly, lichens producing the dibenzofuran usnic acid colonize substrates characterized by specific pH ranges, secondly, this preferred pH is in a range where soluble usnic acid and its corresponding anion occur in similar concentrations, and thirdly, usnic acid makes lichens vulnerable to acidity. Lichens with usnic acid prefer an ambient pH range between 3.5 and 5.5 with an optimum between 4.0 and 4.5. This optimum is close to the pKa1 value of usnic acid of 4.4. Below this optimum pH, dissolved SO2 reduces the chlorophyll fluorescence yield more in lichens with than without their natural content of usnic acid. This suggests that usnic acid influences the acidity tolerance of lichens. The putative mechanism of the limited acidity tolerance of usnic acid-containing lichens is the acidification of the cytosol by molecules of protonated usnic acid shuttling protons through the plasma membrane at an apoplastic pH < pKa1. 相似文献
334.
Environmental risks of farmed and barren alkaline coal ash landfills in Tuzla, Bosnia and Herzegovina 总被引:2,自引:0,他引:2
Dellantonio A Fitz WJ Custovic H Repmann F Schneider BU Grünewald H Gruber V Zgorelec Z Zerem N Carter C Markovic M Puschenreiter M Wenzel WW 《Environmental pollution (Barking, Essex : 1987)》2008,153(3):677-686
The disposal of coal combustion residues (CCR) has led to a significant consumption of land in the West Balkan region. In Tuzla (Bosnia and Herzegovina) we studied previously soil-covered (farmed) and barren CCR landfills including management practises, field ageing of CCR and the transfer of trace elements into crops, wild plants and wastewaters. Soil tillage resulted in mixing of cover soil with CCR. Medicago sativa showed very low Cu:Mo ratios (1.25) which may cause hypocuprosis in ruminants. Total loads of inorganic pollutants in the CCR transport water, but not pH ( approximately 12), were below regulatory limits of most EU countries. Arsenic concentrations in CCR transport water were <2microgl(-1) whereas reductive conditions in an abandoned landfill significantly enhanced concentrations in leachates (44microgl(-1)). The opposite pattern was found for Cr likely due to large initial leaching of CrVI. Public use of landfills, including farming, should be based on a prior risk assessment due to the heterogeneity of CCR. 相似文献
335.
336.
Kathrin Baumann Harald Maurer Gabriele Rau Martin Piringer Ulrike Pechinger Andr Prvt Markus Furger Bruno Neininger Umberto Pellegrini 《Atmospheric environment (Oxford, England : 1994)》2001,35(36):897
During the Mesoscale Alpine Programme (MAP) special observation period (SOP) between 7 September and 15 November 1999, ground-based and airborne measurements have been conducted in the Rhine valley south of the Lake of Constance to investigate the unstationary aspects of Foehn and related phenomena, like the impact of Foehn on the ozone concentrations in the valley. Foehn events occurred with above-average frequency and high diversity. Foehn induced ozone peaks in October and November are found to be much lower than the September Foehn case of the period. An inversion layer in the lake area with ozone concentrations below 10 ppb often shields the monitoring stations from the Foehn air aloft. Trajectory calculations for the Foehn period between 19 and 24 October 1999 reveal that the Foehn air originated from below 1 to 1.5 km above the Po Basin and the Mediterranean Sea. Tethered balloon soundings in the source area south of the Alps, ozone measurements at the mountain station Jungfraujoch (3580 m a.s.l.) and airborne measurements across the Alpine crests reveal that the ozone levels found in the Foehn air correspond to the concentrations just above the mixing height in the Po Basin and are transported across the Alpine crest within the lowest flow layer. 相似文献
337.
Markus Frischknecht 《Behavioral ecology and sociobiology》1996,38(3):159-166
Where prey arriving in a patch are not consumed immediately, they will accumulate. Predators are then presented with a prey
density or standing crop that increases through further input, and decreases through the consumption by predators. Firstly,
I show that the switching rule of predators has a significant influence on the expected predator equilibrium distribution
in such a dynamic system. Three rules are compared; for all rules, analytical solutions are calculated (where possible). To
test their plausibility for natural situations, predator distributions are simulated given the assumption that each predator
obtains individual patch profitability estimates by using a common learning rule. As long as prey arrive in the patches in
constant numbers per time unit, the first rule leads to input matching because predators stop switching when consumption in
the two patches is equal. The other two rules, where predators continue to sample both patches even in the equilibrium state,
lead to predator distributions where the more profitable patch is underused. The final equilibrium depends on the exact assumptions
of the switching rule; however, it is independent of interference. But if the input delivered into a patch is a function of
the current prey standing crop (for example in a reproducing prey population), predator and prey distributions will not reach
an equilibrium in most cases: either standing crops increase indefinitely, or they approach zero, with all predators concentrating
on the better patch. Only a small number of parameter sets show intermediate crops that are reasonably stable. With this input
type, only up to 54% of the simulations reach the expected distribution. In a system with competition for dynamic standing
crop, it is therefore essential to know the type of input and the switching-rule used by predators to be able to predict equilibrium
predator distributions.
Received: 17 March 1995/Accepted after revision: 5 November 1995 相似文献
338.
Summary. Tracer feeding studies with radioactively labeled pyrrolizidine alkaloids (PAs) were performed to attain experimental information
about the specificity and mechanisms of uptake, metabolism and storage of PAs in the alkaloid sequestering ithomiine butterfly
Mechanitis polymnia. Adult butterflies easily ingest the tracers offered dissolved in a saturated sugar solution. Feeding of [14C]rinderine (free base) confirmed that M. polymnia is well adapted to sequester and maintain PAs of the lycopsamine type. Approximately 80% of the ingested radioactivity can
be recovered in methanol extracts of the butterflies over a period of at least 6 hours. Labeled rinderine is efficiently N-oxidized and transformed into a metabolite of still unknown structure. These two metabolites are formed in almost equal amounts
and account for more than 90% of total radioactivity. After four hours the toxic free base is only detectable in traces. Radioactively
labeled senecioylretronecine (free base), a PA that often accompanies PAs of the lycopsamine type in plants, is metabolized
in a different manner. The toxic free base disappeared as fast as the tertiary rinderine, but the final products which accumulated
in a stable ratio after 12 hours were mainly two polar metabolites of unknown structure; senecioylretronecine N-oxide accounts for less than 10% of total PAs. Labeled senecionine a macrocyclic PA, which never has been found in wild caught
M. polymnia is only slowly N-oxidized. In females ca 50% of the ingested senecionine is still present as free base after 24 hours, whereas under the same
conditions in males this percentage is only ca 20%. This difference in N-oxidation was the only significant sex-specific difference observed in various experiments. Larvae of M. polymnia which feed on Solanum tabacifolium, a plant that does not contain PAs, are able to sequester and partly N-oxidize labeled senecioylretronecine and senecionine. However, the storage is not very efficient; with the two tracers less
than 5% of radioactivity remained in the bodies after 24 hours.
Received 19 October 1999; accepted 24 November 1999 相似文献
339.
Germany seems to be one of the leading nations in solid waste management, especially in the case of packaging waste; success
stories about the ongoing increase in recycling strengthen this impression. However, enormous costs and questionable ecological
benefits are the result of Germany's packaging ordinance and the formation of the recycling organization Duales System Deutschland
(DSD). This article shows that similar progress in the reduction and recycling of packaging could have been realized without
the packaging ordinance and dual system, with lower costs. This regulatory impact analysis of the German packaging ordinance
covers all the effects on the different life-cycle stages of packaging, from production to recycling or disposal. The conclusion
is that a fragmentary solid waste management approach – one that is based, like the German packaging ordinance, more on ideology
than on facts – leads to enormous costs and questionable ecological benefits. To improve this situation, there is a need for
an integrated solid waste management approach, based on evaluation of the economic, environmental, and social effects of different
waste management options for the materials involved.
Received: February 4, 1999 / Accepted: April 30, 1999 相似文献
340.
Lars T. Waser Meinrad Kuechler Markus Schwarz Eva Ivits Silvia Stofer Christoph Scheidegger 《Environmental Modeling and Assessment》2007,12(4):315-328
The present study focuses on developing models to predict lichen species richness in a UNESCO Biosphere Reserve of the Swiss
Pre-Alps following a gradient of land-use intensity combining remote sensing data and regression models. The predictive power
of the models and the obtained r ranging from 0.5 for lichens on soil to 0.8 for lichens on trees can be regarded as satisfactory to good, respectively. The
study revealed that a combination of airborne and spaceborne remote sensing data produced a variety of ecological meaningful
variables. 相似文献