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501.
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503.
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
504.
Degradation of chlorinated ethylenes by Fe0: inhibition processes and mineral precipitation 总被引:2,自引:0,他引:2
505.
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
506.
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
507.
508.
Markus Båth 《Pure and Applied Geophysics》1967,68(1):19-23
Summary In an earlier paper the author developed mathematical expressions for the longitudinal and transverse wave velocities in the lower mantle in the form of power functions of the radius. In the present paper we shall instead develop the velocities as power series or polynomials of the radius. The two procedures are compared with regard to accuracy and convenience in applications. The power series expansion can permit higher accuracy in the representation of the velocities, but often entails greater complications in applications. 相似文献
509.
Markus Båth 《Pure and Applied Geophysics》1966,64(1):19-30
Summary
Sn andPn waves propagated to teleseismic distances are investigated by means of short-period seismograph records of the Swedish network.Sn is found in the distance range of 2400 to 4600 km andPn in the range 3500 to 3900 km, but only provided the path is exceptionally homogeneous. Almost all paths are restricted to the Russian platform. There are probably very few areas in the world offering similar propagation paths. The velocities just under the Mohorovii discontinuity are found to be 4.72 km/sec and 8.26 km/sec for transverse and longitudinal waves respectively. In addition, other properties of the teleseismicSn andPn are investigated, such as periods, dispersion, amplitudes, particle motions, propagation mechanisms, and comparisons are made withPa, Sa, withLi, Lg1, Lg2 and withP. The fact that teleseismicPn occurs much more seldom than teleseismicSn could be explained by different velocity profiles just under the crust. 相似文献
510.
Markus Båth 《Physics of the Earth and Planetary Interiors》1985,37(4):228-234
The small amplitudes of surface waves for intermediate and deep-focus earthquakes lead to too low values of the surface-wave magnitudes. On the basis of available material, average magnitude corrections are deduced, which increase with focal depth and amount to 0.1–0.5 for focal depths of 50 100 km and to 0.5–0.7 for depths of 100–700 km. 相似文献