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排序方式: 共有571条查询结果,搜索用时 15 毫秒
111.
Andreas Klumpp Wolfgang Ansel Gabriele Klumpp Vicent Calatayud Jean Pierre Garrec Shang He Josep Peuelas ngela Ribas Helge Ro-Poulsen Stine Rasmussen María Jos Sanz Phillippe Vergne 《Atmospheric environment (Oxford, England : 1994)》2006,40(40):7963-7974
In the frame of a European research project on air quality in urban agglomerations, data on ozone concentrations from 23 automated urban and suburban monitoring stations in 11 cities from seven countries were analysed and evaluated. Daily and summer mean and maximum concentrations were computed based on hourly mean values, and cumulative ozone exposure indices (Accumulated exposure Over a Threshold of 40 ppb (AOT40), AOT20) were calculated. The diurnal profiles showed a characteristic pattern in most city centres, with minimum values in the early morning hours, a strong rise during the morning, peak concentrations in the afternoon, and a decline during the night. The widest amplitudes between minimum and maximum values were found in central and southern European cities such as Düsseldorf, Verona, Klagenfurt, Lyon or Barcelona. In the northern European cities of Edinburgh and Copenhagen, by contrast, maximum values were lower and diurnal variation was much smaller. Based on ozone concentrations as well as on cumulative exposure indices, a clear north–south gradient in ozone pollution, with increasing levels from northern and northwestern sites to central and southern European sites, was observed. Only the Spanish cities did not fit this pattern; there, ozone levels were again lower than in central European cities, probably due to the direct influence of strong car traffic emissions. In general, ozone concentrations and cumulative exposure were significantly higher at suburban sites than at urban and traffic-exposed sites. When applying the newly established European Union (EU) Directive on ozone pollution in ambient air, it was demonstrated that the target value for the protection of human health was regularly surpassed at urban as well as suburban sites, particularly in cities in Austria, France, northern Italy and southern Germany. European target values and long-term objectives for the protection of vegetation expressed as AOT40 were also exceeded at many monitoring sites. 相似文献
112.
Schmid A 《Environmental science and pollution research international》2002,9(4):227-229
Mechanical oscillations as well as electrical oscillations (e.g. in an electrical oscillatory circuit) can lead to resonance conditions by external agitation with the natural frequency of the system. During the microbial protein synthesis, the induction and repression mechanisms also cause oscillations in the form of varying protein concentrations. The aim of this work concentrates on an induced resonance case of the biological system, comparable with physical resonance phenomena, by external periodic stimulations. For this, system theoretical computer simulations with a structured genetic model were carried out, which built the theoretical fundament for describing the effect of 'Biological Resonance'. Based on that, lab-scale experiments using a mixed microbial culture (activated sludge) and skimmed milk as an inducing substrate revealed an enhanced microbial productivity of around 60%-75% compared to values of the productivity under steady-state conditions in a narrow range of process parameters. The optimum (resonance case) was confirmed by a repetition of the variation experiments and is characterised by a substrate supply period of approx. 18 min and a following starvation period of about 9 min. Long-term investigations under optimised process conditions indicate adaptation mechanisms of the microorganisms to evade the imposed stress conditions. The productivity will not remain constant without additional stimulation and declines to its original level. However, temporal modulation of the starvation period permanently increases the productivity (elevated catabolism) to about 60%, which was observed over a period of several weeks. 相似文献
113.
A new way of detecting trace elements in water is developed by using charged article nduced -ray mission (PIXE) analysis of cell walls of , a fresh water alga. 相似文献
114.
The Science of Nature - 相似文献
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116.
Borhani Faezeh Shafiepour Motlagh Majid Stohl Andreas Rashidi Yousef Ehsani Amir Houshang 《Environmental geochemistry and health》2022,44(10):3615-3637
Environmental Geochemistry and Health - Air pollution and its effects on human health and the environment are one of the main concerns in urban areas. This study focuses on the distribution and... 相似文献
117.
Jovanne?Mevi-Schütz Marcel?Goverde Andreas?ErhardtEmail author 《Behavioral ecology and sociobiology》2003,54(1):36-43
The effects of larval diet on the nutritional preferences of butterflies has rarely been examined. This study investigates whether alterations in the larval diet result in changes in adult preferences for nectar amino acids. Larvae of Coenonympha pamphilus were raised on fertilized or unfertilized Festuca rubra, grown under ambient (350 ppm) or elevated (750 ppm) atmospheric CO 2environments. Fertilization led to marked increases in leaf nitrogen concentration. In plants grown under elevated CO 2conditions, leaf water and nitrogen concentrations were significantly lower, and the C/N-ratio increased significantly. Fertilization of the host plant shortened the development time of C. pamphilus larvae, and pupal weight increased. In contrast, larvae of C. pamphilus developed significantly slower on F. rubra grown under elevated CO 2, but adult emergence weight was not affected by CO 2treatment of the plant. C. pamphilus females showed a clear preference for nectar mimics containing amino acids, whereas males, regardless of treatment, either preferred the nectar mimic void of amino acids or showed no preference for the different solutions. Female butterflies raised on fertilized plants showed a significant decline in their preference for nectar mimics containing amino acids. A slight, but not significant, trend towards increased nectar amino acid preference was found in females raised on plants grown under elevated CO 2. We clearly demonstrate that alterations in larval host quality led to changes in butterfly nectar preferences. The ability of the butterfly to either rely less on nectar uptake or compensate for poor larval conditions represents a trade-off between larval and adult butterfly feeding. 相似文献
118.
119.
Climate change generally requires species to migrate northward or to higher elevation to maintain constant climate conditions, but migration requirement and migration capacity of individual species can vary greatly. Individual populations of species occupy different positions in the landscape that determine their required range shift to maintain similar climate, and likewise the migration capacity depends on habitat connectivity. Here, we demonstrate an approach to quantifying species vulnerabilities to climate change for 419 rare vascular plants in Alberta, Canada, based on a multivariate velocity of climate change metric, local habitat fragmentation, and migration capacity. Climate change velocities indicated that future migration requirements ranged from 1 to 5 km/year in topographically complex landscapes, such as the Alberta Foothills and Rocky Mountains. In contrast, migration requirements to maintain constant climate in relatively flat Boreal Plains, Parkland, and Grassland ranged from 4 to 8 km/year. Habitat fragmentation was also highest in these flat regions, particularly the Parkland Natural Region. Of the 419 rare vascular plants assessed, 36 were globally threatened (G1–G3 ranking). Three globally threatened species were ranked as extremely vulnerable and five species as highly vulnerable to the interactions among climate change velocity, habitat fragmentation, and migration capacity. Incorporating dispersal characteristics and habitat fragmentation with local patterns in climate change velocity improves the assessment of climate change threats to species and may be applied to guide monitoring efforts or conservation actions. 相似文献
120.