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171.
A new assessment system for macrophytes and phytobenthos in German lakes according to the Water Framework Directive of the European Community is described. Based on biological, chemical and hydromorphological data from about 100 lake sites covering the main ecoregions, hydromorphological lake types and degradation forms, biocoenotic types could be defined. For developing a classification system the quality element macrophytes and phytobenthos was divided into two components: macrophytes and benthic diatoms. For macrophytes 4 and for benthic diatoms 4 lake types were identified. The benthic vegetation at reference conditions is described and degradation is characterised as deviation in benthic vegetation species composition and abundance from the reference biocoenosis. For classification in five ecological status classes, several metrics were developed and used in combination with existing indices. For a few of the described lake types further investigations are necessary before a classification can be developed.  相似文献   
172.
Biotic structures and processes of the comparatively large and deep Lake Constance are dominated by pelagic water bodies. Therefore, much more attention has thus far been paid to the carbon cycle of pelagic habitats as compared to littoral areas. Nevertheless, there is also an ongoing debate on the importance of littoral areas for the carbon cycle in this lake. Although actually existing data are certainly insufficient for a realistic carbon budget, investigations made during the past decade provide at least a rough basis for a first evaluation. Accordingly, littoral areas appear to contribute overproportionally (related to surface) both to production as well as to degradation of organic carbon in the lake. However, the relative effect seems to be more pronounced for heterotrophic activities, mostly due to intense degradation processes in littoral sediments. Related to volume, littoral water bodies exhibited similar or slightly higher microbial activities as compared to epilimnetic pelagic water bodies, while microbial abundances and activities observed for littoral sediments exceeded the corresponding overlying water layers by one to three orders of magnitude. As was confirmed by in situ measurements microbial oxygen consumption frequently exceeded photosynthetic oxygen production in the investigated littoral sites. Moreover, significant qualitative differences between water and sediment were found for the degradation potentials of xenobiotics as was exemplified for phenol and nitrilo-triacetic acid (NTA). Overall, a buffer function at the landwater interface may be ascribed to littoral areas due to which the large pelagic water bodies of the lake may become additionally protected against loads of undesired organic substances due to high littoral degradation capacities.  相似文献   
173.
Zusammenfassung Durch die Tiefbohrung Orth 1 der ÖMV-AG wurde in den Laaer Schichten (Helvet) des Wiener Beckens eine Latit-Tuffitlage durchfahren. Nach der Untersuchung ist das Gestein dem leicht kalibetonten, miozänen Vulkanismus des Alpenostrandes (Oststeiermark) zuordenbar. Eine chemische Analyse bestätigt dieses Ergebnis.
A latite-tuffite layer in the Laa beds (Helvetian) of the Vienna Basin
Summary In the Laa beds (Helvetian) of the Vienna Basin a latite-tuffite-layer was penetrated by a drill hole of the ÖMV-AG (Österreichische Mineralölverwaltung-AG). According to this investigation the rock is closely related to the Miocene volcanism of the Eastern End of the Alps (Eastern Styria). A chemical analyse confirms this.


Mit 6 Abbildungen  相似文献   
174.
Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air–sea interactions and convective organization.  相似文献   
175.
The ChemCam instrument on the Mars Science Laboratory (MSL) rover, Curiosity, observed numerous igneous float rocks and conglomerate clasts, reported previously. A new statistical analysis of single‐laser‐shot spectra of igneous targets observed by ChemCam shows a strong peak at ~55 wt% SiO2 and 6 wt% total alkalis, with a minor secondary maximum at 47–51 wt% SiO2 and lower alkali content. The centers of these distributions, together with the rock textures, indicate that many of the ChemCam igneous targets are trachybasalts, Mg# = 27 but with a secondary concentration of basaltic material, with a focus of compositions around Mg# = 54. We suggest that all of these igneous rocks resulted from low‐pressure, olivine‐dominated fractionation of Adirondack (MER) class‐type basalt compositions. This magmatism has subalkaline, tholeiitic affinities. The similarity of the basalt endmember to much of the Gale sediment compositions in the first 1000 sols of the MSL mission suggests that this type of Fe‐rich, relatively low‐Mg#, olivine tholeiite is the dominant constituent of the Gale catchment that is the source material for the fine‐grained sediments in Gale. The similarity to many Gusev igneous compositions suggests that it is a major constituent of ancient Martian magmas, and distinct from the shergottite parental melts thought to be associated with Tharsis and the Northern Lowlands. The Gale Crater catchment sampled a mixture of this tholeiitic basalt along with alkaline igneous material, together giving some analogies to terrestrial intraplate magmatic provinces.  相似文献   
176.
Connectivity is a critical property of marine populations, particularly for species with segregated juvenile and adult habitats. Knowledge of this link is fundamental in understanding population structure and dynamics. Young adults of commercially important fish species Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax were sampled off the Portuguese coast in order to establish preliminary evidence of estuarine nursery origins through otolith elemental fingerprints. Concentrations of Li, Na, Mg, K, Mn, Cu, Zn, Sr, Ba and Pb in the otolith section corresponding to juvenile's nursery life period were determined through laser ablation inductively coupled plasma mass spectrometry. Element: Ca ratios in coastal fish differed significantly amongst collection areas, except for Platichthys flesus, and were compared with the elemental fingerprints previously defined for age 0 juveniles in the main estuarine nurseries of the Portuguese coast. Identification of nursery estuaries was achieved for four of the species. Assigned nursery origins varied amongst species and differences in the spatial scale of fish dispersal were also found. Diplodus vulgaris was not reliably assigned to any of the defined nurseries. Overall, results give evidence of the applicability of estuarine habitat tags in future assessments of estuarine nursery role. Research developments on the links between juvenile and adult habitats should contribute for the integrated management and conservation of nurseries and coastal stocks.  相似文献   
177.
High-resolution simulations with a mesoscale model are performed to estimate heat and moisture budgets of a well-mixed boundary layer. The model budgets are validated against energy budgets obtained from airborne measurements over heterogeneous terrain in Western Germany. Time rate of change, vertical divergence, and horizontal advection for an atmospheric column of air are estimated. Results show that the time trend of specific humidity exhibits some deficiencies, while the potential temperature trend is matched accurately. Furthermore, the simulated turbulent surface fluxes of sensible and latent heat are comparable to the measured fluxes, leading to similar values of the vertical divergence. The analysis of different horizontal model resolutions exhibits improved surface fluxes with increased resolution, a fact attributed to a reduced aggregation effect. Scale-interaction effects could be identified: while time trends and advection are strongly influenced by mesoscale forcing, the turbulent surface fluxes are mainly controlled by microscale processes.  相似文献   
178.
179.
Against the background of a recent shift in growth dynamics from export-oriented activities towards the domestic market in Chinese regions, it is the aim of this paper to demonstrate how the spatial organization of the electronics industry in Hong Kong and the Pearl River Delta has evolved over time and to assess the impact of the institutional setting and differences between Hong Kong and the Pearl River Delta on localization and upgrading of the industry. The empirical findings suggest a strong trend towards the localization of business activities in China and a differentiated perspective regarding the kinds of activities that are more likely to be localized. An advanced front shop, back factory model with complementary, but intertwined assets has been identified. The institutional interpretation of spatial processes has proven its potential to further develop contextually sensitive concepts for the economic geography of China.  相似文献   
180.
ABSTRACT

This paper reports on a controlled experiment evaluating how different cartographic representations of risk affect participants’ performance on a complex spatial decision task: route planning. The specific experimental scenario used is oriented towards emergency route-planning during flood response. The experiment compared six common abstract and metaphorical graphical symbolizations of risk. The results indicate a pattern of less-preferred graphical symbolizations associated with slower responses and lower-risk route choices. One mechanism that might explain these observed relationships would be that more complex and effortful maps promote closer attention paid by participants and lower levels of risk taking. Such user considerations have important implications for the design of maps and mapping interfaces for emergency planning and response. The data also highlights the importance of the ‘right decision, wrong outcome problem’ inherent in decision-making under uncertainty: in individual instances, more risky decisions do not always lead to worse outcomes.  相似文献   
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