Effects of alpine hydropower operations on primary production in a downstream lake     

David Finger  Peter Bossard  Martin Schmid  Lorenz Jaun  Beat Müller  Daniel Steiner  Erwin Schäffer  Markus Zeh  Alfred Wüest 《Aquatic Sciences - Research Across Boundaries》2007,69(2):240-256

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Comparison of large-area land cover products with national forest inventories and CORINE land cover in the European Alps     

Lars T. Waser  Markus Schwarz 《International Journal of Applied Earth Observation and Geoinformation》2006

Considerable efforts have recently resulted in the development of global land cover data at large spatial scales. The main objective of this study is a comparison of different AVHRR- and MODIS-based forest and land cover products at the scale of the European Alps: a large natural ecosystem that is exposed to both natural environmental threats and human impacts and exploitation. In a first test, the accuracy of land cover products in predicting the overall amount of forest across national boundaries was assessed using national forest inventory statistics. Both variants of forest class combinations resulted in a general overestimation of the forest area. The IGBP 2.0 cover performed best with an overall mean absolute error of 13% and a bias of 0%. In a second test, large-area land cover products were tested for accuracy in predicting 13 aggregated land cover types in a spatially explicit manner using CORINE land cover as reference dataset. Due to data inconsistencies, partly insufficient spatial resolution, steep terrain and land use heterogeneity of the European Alps, only partly satisfactory results were obtained.  相似文献   

Species diversity of the Okavango Delta, Botswana   总被引：4，自引：0，他引：4  

Lars Ramberg  Peter Hancock  Markus Lindholm  Thoralf Meyer  Susan Ringrose  Jan Sliva  Jo Van As  Cornelis Vander Post 《Aquatic Sciences - Research Across Boundaries》2006,68(3):310-337

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G. M. Simnett,C. E. Alissandrakis,and L. Vlahos (eds.), Solar and Heliospheric Plasma Physics,Proceedings of the 8th European Meeting on Solar Physics     

Aschwanden  Markus 《Solar physics》1998,179(2):441-442

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A Good Climate for Clean Air: Linkages between Climate Change and Air Pollution. An Editorial Essay     

Rob Swart  Markus Amann  Frank Raes  Willemijn Tuinstra 《Climatic change》2004,66(3):263-269

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Restructuring Governance of New Zealand Seaports: Geographical Impacts of Corporatisation     

Ali Memon  Markus J. Milne  John W. Selsky 《New Zealand geographer》2004,60(2):15-27

This study examines the rationales for and geographical outcomes of the post 1988 changes in port governance in New Zealand and their implications from a policy perspective. The study offers insights into the interrelationship between global processes and local places in the context of economic deregulation, a devolved infrastructure planning mandate and intra‐industry competitive dynamics. A trend towards port concentration consequent on globalisation has been long recognised in the international literature. In New Zealand, the trend towards port concentration can be described as selective, limited primarily to import trade while export trade is more dispersed. This new port geography is part of wider political and socio‐economic development geographies of the national and global hinterlands and forelands these ports interact with.  相似文献   

Plume-Ridge Interaction: a Geochemical Perspective from the Reykjanes Ridge   总被引：2，自引：0，他引：2  

MURTON  BRAMLEY J.; TAYLOR  REX N.; THIRLWALL  MATTHEW F. 《Journal of Petrology》2002,43(11):1987-2012

Plume–ridge interaction in the Reykjanes Ridge and Icelandregion is graphically demonstrated by several V-shaped ridgessurrounding the spreading axis, indicating mantle flow awayfrom Iceland. It also has significant geochemical effects. Regionally,incompatible element concentrations increase northwards coincidingwith decreasing depth and increasing crustal thickness, depthof melting and proximity to Iceland. Major and trace elementdata show that isolated magma bodies feed individual volcanicsystems along the ridge. Fractionation within these systemsincreases towards 60–61°N, where it coincides withthe intersection of a V-shaped ridge, thicker crust and moreabundant seamounts. Trace element, Nd and Sr isotopic data revealdynamic melting and mixing within a southward-thinning, heterogeneousmantle wedge beneath the Reykjanes Ridge. Melting is variableand locally enhanced at 58°N, 59°N, 60°N and 61°N.A total of six mantle components are identified. Some are specificto Iceland whereas others are found only beneath the ridge axis.The geographical distribution of these components reflects theirorigin within the deep upper and lower mantle and subsequenttranslation by plume outflow along the entire length of theridge. KEY WORDS: plume–ridge interaction; Iceland; Reykjanes Ridge; dynamic mantle mixing and melting  相似文献   

Degradation of chlorinated ethylenes by Fe0: inhibition processes and mineral precipitation   总被引：2，自引：0，他引：2  

Ralf Köber  Oliver Schlicker  Markus Ebert  Andreas Dahmke 《Environmental Geology》2002,41(6):644-652

. Granular zero-valent iron was used for the treatment of groundwater pollution caused by chlorinated ethylenes, mainly TCE, cis-DCE and VC at an industrial site. The rapidly decreasing rates of de-chlorination in the initial phase were attributed to the precipitation of carbonates and the development of hydrogen by anaerobic corrosion. After 70 pore volumes, sulphate was reduced by bacteria. From this point in time, the degradation of TCE was slightly accelerated whereas the de-chlorination rates of the other chlorinated ethylenes decreased only slowly. This relative improvement was assumed to be caused by the uptake of electron-transfer-blocking hydrogen by bacteria. Because the overall trend of the degradation rates is negative we conclude that the inhibitive effect of carbonate precipitation and hydrogen formation cannot be compensated for by the positive influence of the activity of sulphate-reducing bacteria.  相似文献   

Variations of O/O in plants from temperate peat bogs (Switzerland): implications for paleoclimatic studies     

Guillemette Ménot-Combes  Stephen J. Burns  Markus Leuenberger 《Earth and Planetary Science Letters》2002,202(2):419-434

Despite the great potential of peat bogs as climatic archives, to date only few studies have focused on the climatic controls on cellulose isotopic composition in modern bog plants. This study attempts to calibrate plant-climate relationships by sampling a set of modern plant species (both vascular plants and mosses) and bog surface waters along an altitude transect in Switzerland. Isotopic analyses of water samples show that the δ¹⁸O-values of surface bog waters follow the trend of precipitation despite significant scatter in the data set. Detailed sampling of surface waters within one bog shows that δ¹⁸O-values vary widely and are closely related to the micro-topography of the bog surface. More enriched ¹⁸O/¹⁶O ratios in water samples collected from small raised hummocks than the ones collected from hollows are documented in both horizontal and vertical profiles. A δ¹⁸O-δD plot indicates that the process leading to the isotopic enrichment of the uppermost surface waters is evaporation, greater above Sphagnum covered hummocks than above open pools. To investigate the implications of such high variability of source water for plant α-cellulose δ¹⁸O-values, a detailed study of both surface water and α-cellulose δ¹⁸O-values within one site is conducted. The large δ¹⁸O variability observed in surface waters is found to be considerably smoothed in α-cellulose (by a factor of 5-10 depending on the plant species). This indicates that the water used by plant photosynthetic processes reflects the isotopic composition of the average annual precipitation. This points to a source water level for plants of a few decimeters where the variations are smaller than at the air-water interface. The response of the α-cellulose δ¹⁸O to the environmental gradient along the altitude transect varies considerably from species to species. For most of the species studied, the δ¹⁸O-values decrease with altitude, following the trends of δ¹⁸O-values in precipitation and in surface water samples. Some species, the cotton sedge Eriophorum vaginatum and the moss Sphagnum capillifolium, show statistically significant δ¹⁸O relationships to an altitude of −1.8‰/km and −2.9‰/km respectively. However, some other plant species, Calluna vulgaris, Vaccinium uliginosum, Andromeda poliflora, Carex pauciflora, Sphagnum cuspidatum and Sphagnum magellanicum, do not, or only partially, reflect changes in climatic parameters associated with an altitude increase. Furthermore, changes in relative humidity, which are not correlated with altitude, are found to explain a large part of the variability in δ¹⁸O-values for the sedge Carex pauciflora and the moss Sphagnum cuspidatum. Therefore, this study confirms the importance of species-specific studies when interpreting ¹⁸O/¹⁶O ratios of macrofossils along a fossil peat sequence as a record of past climate changes. Our study allows to extend the mechanistic model that isotopically links source water and cellulose to the physiological specificities of sedges and mosses. A comparison of the modeled and calculated net biological fractionation factors for Eriophorum vaginatum and Sphagnum capillifolium reveals that these two species appear to have a more homogeneous leaf reservoir than trees.  相似文献   

A Mediterranean earthquake project     

Markus Bth 《Tectonophysics》1979,58(3-4)

Cumulative frequency and cumulative energy may vary from one sample of earthquakes to another either in the same or in the opposite sense. Conditions for the variations are deduced theoretically and illustrated by numerical examples.  相似文献