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71.
We reconstructed the flora of a European region at a historical point in time from historical topographical maps that contain rather precise information about the condition and composition of habitats. The ecological information obtained from these maps can be enriched through the potential of broadly diversified archival information. This study is confined to grassland communities. Considerations in terms of phytosociology make historical lists of plant species a good starting point for the reconstruction of grassland communities. The combination of historical and scientific methods proves suitable for reconstructing specific historical environmental conditions. Taking into account the frequency of relevant historical sources in European archives as well as in archives abroad, this approach claims for far-reaching application to ecosystem restoration matters, especially if ecological information from natural sources is missing. 相似文献
72.
Herman Friedl Smidt Stefan Englisch Michael Grtner Manfred Jandl Robert Mutsch Franz Gattermayr Wolfgang 《Environmental science and pollution research international》2002,9(2):3-9
In the framework of this study, nitrogen fluxes on a limestone site are investigated. The major goals are the assessment of the nitrogen status, the estimation of the nitrogen budget and the evaluation of the nitrogen saturation. The investigation area, the intensive investigation plot and the research equipment are described. 相似文献
73.
Significance of platinum group metals emitted from automobile exhaust gas converters for the biosphere 总被引:1,自引:0,他引:1
Intention, Goal, Scope, Background Following the introduction of automobile catalytic converters the platinum group metals (PGM) platinum (Pt), palladium (Pd)
and rhodium (Rh) gain on increasing interest in environmental research as these metals are emitted with exhaust fumes into
the environment. Consequently, elevated PGM levels were found in different environmental matrices uch as road dusts, soils
along heavily frequented roads, sediments of urban rivers etc. Accordingly, the effects of increasing PGM emissions on the
biosphere are controversially discussed.
Objective This paper summarizes the present knowledge on the biological availability of PGM to plants and animals. As biological availability
is one of the most decisive factors determining the toxicologi-cal potential of xenobiotics, this information is very important
to evaluate the possible threat of the noble metals to ecosystems.
Results and Discussion The availability of soluble as well as particle bound PGM to terrestrial plants was demonstrated in several studies. Experimental
investigations revealed uptake of Pt, Pd and Rh also by aquatic plants. Additionally, the biological availability of the noble
metals for animals has been verified in experimental studies using soluble metal salts, catalytic converter model substances,
sediments of urban rivers, road dust or tunnel dust as metal sources. These studies refer mainly to aquatic animals. Beside
of free living organisms, in particular worms parasitizing fish demonstrated a high potential to accumulate PGM. This could
be of great interest in respect of biomonitoring purposes. Generally, for plants as well as for animals Pd turns out to be
the best available metal among the PGM. Compared to other heavy metals, the biological availability of PGM from road dust
to zebra mussels(Dreissena polymorpha) ranged between that of Cd and Pb.
Conclusion Especially chronic effects of PGM on the biosphere can not be excluded due to (1) their cumulative increase in the environment,
(2) their unexpected high biological availability and bioaccumulation and (3) their unknown toxicological and ecotoxicological
potential. However, it appears that acute effects on ecosystems due to anthropogenic PGM emission are not likely.
Recommendation and Outlook Research on environmental PGM contamination of the biosphere, especially the fauna, and on long-term toxiciry of low PGM concentrations
is highly appreciated. These studies require very sensitive analytical techniques to determine PGM even in low sample amounts.
Research has to be done in particular on reliable determination of (ultra) trace levels of Pd and Rh as the lack of data on
these two metals is mainly due to analytical problems. 相似文献
74.
Bernd U Wiese María C Palancar José M Aragón Fernando Sánchez Roberto Gil 《Water environment research》2006,78(8):781-791
The Entrepe?as Reservoir is a monomictic reservoir located in River Tagus (Spain). The aim of this work is to establish a feasible model to predict the depth of the thermocline that is developed in the reservoir during the period of natural thermal stratification. Entrainment, eddy diffusion, inflow of external energy, and other factors are considered to calibrate the parameters of the model. The methodology involves the measure of actual temperature and electrical conductivity profiles, use of meteorological data and reservoir parameters, and selection and application of several models from the literature. The calculations and predictions are integrated to a software packet that is able to predict thermocline depth and water temperature profile during a 1-year period on a day-by-day basis. In the thermocline depth, the prediction error, on the basis of real data, is less than 6% and, in the water temperature, it is 2 degrees C. 相似文献
75.
Manfred Kiese 《Die Naturwissenschaften》1942,30(38-39):587-588
76.
The Science of Nature - 相似文献
77.
78.
Christian Reichle Stefan Jarau Ingrid Aguilar Manfred Ayasse 《Die Naturwissenschaften》2010,97(5):519-524
The ability to learn food odors inside the nest and to associate them with food sources in the field is of essential importance for the recruitment of nestmates in social bees. We investigated odor learning by workers within the hive and the influence of these odors on their food choice in the field in the stingless bee Scaptotrigona pectoralis. During the experiments, recruited bees had to choose between two feeders, one with an odor that was present inside the nest during the recruitment process, and one with an unknown odor. In all experiments with different odor combinations (linalool/phenylacetaldehyde, geraniol/eugenol) a significant majority of bees visited the feeder with the odor they had experienced in their nest (χ 2-tests; p?<?0.05). By contrast, the bees showed no preference for one of two feeders when they were either baited with the same odor (linalool) or contained no odor. Our results clearly show that naïve workers of S. pectoralis can learn the odor of a food source during the recruitment process from the nest atmosphere and that their subsequent food search in the field is influenced by the learned odor. 相似文献
79.
80.
An overview of the application of organic geochemistry to the analysis of organic matter on aerosol particles is presented
here. This organic matter is analyzed as solvent extractable bitumen/ lipids by gas chromatography-mass spectrometry. The
organic geochemical approach assesses the origin, the environmental history and the nature of secondary products of organic
matter by using the data derived from specific molecular analyses. Evaluations of production and fluxes, with cross-correlations
can thus be made by the application of the same separation and analytical procedures to samples from point source emissions
and the ambient atmosphere. This will be illustrated here with typical examples from the ambient atmosphere (aerosol particles)
and from emissions of biomass burning (smoke).
Organic matter in aerosols is derived from two major sources and is admixed depending on the geographic relief of the air
shed. These sources are biogenic detritus (e.g., plant wax, microbes, etc.) and anthropogenic particle emissions (e.g., oils,
soot, synthetics, etc.). Both biogenic detritus and some of the anthropogenic particle emissions contain organic materials
which have unique and distinguishable compound distribution patterns (C14-C40). Microbial and vascular plant lipids are the dominant biogenic residues and petroleum hydrocarbons, with lesser amounts
of the pyrogenic polynuclear aromatic hydrocarbons (PAH) and synthetics (e.g., chlorinated compounds), are the major anthropogenic
residues.
Biomass combustion is another important primary source of particles injected into the global atmosphere. It contributes many
trace substances which are reactants in atmospheric chemistry and soot paniculate matter with adsorbed biomarker compounds,
most of which are unknown chemical structures. The injection of natural product organic compounds into smoke occurs primarily
by direct volatilization/steam stripping and by thermal alteration based on combustion temperature. Although the molecular
composition of organic matter in smoke particles is highly variable, the molecular tracers are generally still source specific.
Retene has been utilized as a tracer for conifer smoke in urban aerosols, but is not always detectable. Dehydroabietic acid
is generally more concentrated in the atmosphere from the same emission sources. Degradation products from biopolymers (e.g.,
levoglucosan from cellulose) are also excellent tracers. An overview of the biomarker compositions of biomass smoke types
is presented here. Defining additional tracers of thermally-altered and directly-emitted natural products in smoke aids the
assessment of the organic matter type and input from biomass combustion to aerosols. The precursor to product approach of
compound characterization by organic geochemistry can be applied successfully to provide tracers for studying the chemistry
and dispersion of ambient aerosols and smoke plumes.
Presented at the 6th FECS Conference on Chemistry and the Environment, Atmospheric Chemistry and Air Pollution, August 26–28,
1998, Copenhagen. 相似文献