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51.
Antje Stokman 《中国勘察设计》2007,(3):63-63
考虑一下我们城市的发展,我们在建立自己生活空间的同时,使得城市不断地发展和扩大。城市的规模在不断地增加,结构与以前也有了很大的不同,城市的建筑和景观不像过去那么密集,那么,为什么城市有了这样一个结构?因为人们在追求更好的生活环境和更高的生活质量,而且他们也希望能够在城市当中有更多的空间和时间。这样一来,城市不再以密集的方式发展,而是出现了这种零散化、片段化的趋势。中国城市发展的速度是非常快的,现在人们越来越多地注意到城市的边缘在不断地扩大,城市的景观和农村也在不断地融合,看起来,它既不是城市的景观, 相似文献
52.
In this study the influence of land-surface parameters on latent heat fluxes simulated with the numerical weather prediction model Lokalmodell (LM) of the German Meteorological Service is investigated. The area of interest is the LITFASS area during the LITFASS-2003 campaign. Based on simulations with varying soil and vegetation properties, we confirm that simulated latent heat fluxes strongly depend on soil moisture and leaf area index. Both parameters are difficult to obtain from in situ measurements with sufficient spatial resolution over heterogeneous land surfaces. Therefore, a procedure is proposed to determine area average values of soil moisture from time domain reflectometer measurements performed at a limited number of sites. The area averages cover the 7 × 7 km2 grid cells of the LM around Lindenberg (south-east of Berlin). Furthermore, satellite inferred plant parameters from NOAA–AVHRR are used to initialise model runs; the derived vegetation parameters show notable differences with those in the standard input of LM. The latent heat fluxes from the LM are compared with the aggregated eddy-covariance-measurements, and while the operational LM shows a strong overestimation of latent heat fluxes, it is demonstrated that the application of land-surface parameters derived from measurements can significantly reduce the deviation between the simulated and measured latent heat fluxes. 相似文献
53.
Polybaric differentiation of alkali basaltic magmas: evidence from green-core clinopyroxenes (Eifel,FRG) 总被引:5,自引:0,他引:5
The Quaternary foidites and basanites of the West Eifel (Germany) contain optically and chemically heterogeneous clinopyroxenes, some of which occur as discrete zones within individual crystals: Most clinopyroxene phenocrysts are made up of a core and a normally zoned comagmatic titanaugite mantle. Most cores are greenish pleochroic and moderately resorbed (fassaitic augite). Some are pale green and strongly resorbed (acmitic augite). Cores of Al-augite composition and of Cr-diopside derived from peridotite xenoliths are rare. The fassaitic augites are similar in trace element distribution pattern to the titanaugites, but are more enriched in incompatible elements. The acmitic augites, in contrast, are clearly different in their trace element composition and are enriched in Na, Mn, Fe and depleted in Al, Ti, Sr, Zr. A model for polybaric magma evolution in the West Eifel is proposed: Primitive alkali basaltic magma rises through the upper mantle precipitating Al-augite en route. It stagnates and differentiates near the crust/mantle boundary crystallizing Fe-rich fassaitic augites. The magma differentiated at high pressure is subsequently mixed with new pulses of primitive magma from which the rims of pyroxene are crystallized. Sporadic alkali pyroxenite xenoliths are interpreted to represent cumulates of cognate phases formed within the crust and not metasomatized upper mantle material (Lloyd and Bailey 1975). 相似文献
54.
Kim J. Krahn Mario Tucci Brigitte Urban Julien Pilgrim Peter Frenzel Ingeborg Soulié-Märsche Antje Schwalb 《Boreas: An International Journal of Quaternary Research》2021,50(3):723-745
The archaeological sites in the open-cast mine of Schöningen, Germany, represent outstanding archives for understanding Middle Pleistocene interglacial–glacial transitions and human adaption. Aquatic microfossil and pollen assemblages from the ‘Reinsdorf sequence’, likely correlated to Marine Isotope Stage 9, document environmental changes from a thermal maximum to succeeding glacial conditions recorded in two sequences of excavation sites 12 II and 13 II. Multi-proxy analyses enable detailed reconstruction of lake-shore and landscape developments despite variable microfossil preservation in changing carbonate- and organic-rich deposits. Rich aquatic vegetation with abundant charophytes suggests repeated phases with water depths of 0.5–2 m at site 13 II, while even greater temporary depths are deduced for 12 II DB. Mesorheophilic and mesotitanophilic ostracod species indicate stream inflows with medium–low calcium contents of >18 mg Ca L–1 originating from nearby springs. Diatoms point to meso-eutrophic conditions and an alkaline pH of the lake water. Interglacial conditions with thermophile forests but no aquatic microfossils preserved, suggesting a dry or only temporarily flooded site, mark the beginning of the sequence. Continuous presence of aquatic organisms and overall dominance of small tychoplanktonic diatoms during a subsequent cool steppe phase provide evidence for increased water depths and unstable habitats characterized by erosion and probably prolonged periods of lake ice cover. During the succeeding boreal forest-steppe phase, surface runoff into the productive, shallow lake decreased due to a more extensive vegetation cover. Concurrently, intensified groundwater input in contact with the nearby salt wall caused elevated salinities. Following a lake level drop, stream inflows and lake levels increased again towards the end of the Reinsdorf sequence and promoted development of a diverse fauna and flora at the lake shore; thereby maintaining an attractive living and hunting environment for early humans during a phase of generally cooler temperatures and landscape instability at the transition into a glacial period. 相似文献
55.
Antje Missbach 《Singapore journal of tropical geography》2014,35(2):228-244
Although the partial outsourcing of state border control to non‐state actors is not a new phenomenon, Indonesia is an interesting case study. Border control in an archipelago consisting of more than 17 000 islands is particularly challenging for state authorities. In addition to contending with the exceptional geography, Indonesia's state authorities are also challenged by the political constellation with Australia in regard to irregular cross‐border movements of asylum seekers that has become a controversial issue in recent history. As an important transit country for asylum seekers and refugees en route to Australia, Indonesia's porous borders have rendered it possible to enter and exit the country relatively easily. Given Australia's political pressure and the financial incentives offered to Indonesia to act as a ‘final bulwark’ and control irregular migration flows more effectively, border control nowadays has gained more significance in Indonesia than in the past. Yet, financial constraints and, more importantly, a lack of political will to host asylum seekers in its own territories for the long term remain as obstacles. Fieldwork observations show that due to ongoing funding restrictions for state‐led border control, state‐society cooperation for border surveillance has increased. Civilians in many hotspots for irregular border crossings have been encouraged to report on ‘suspicious foreigners’. State‐society cooperation for border control, however, offers new opportunities for people smugglers to pay off civilian spies or corrupt border authorities. 相似文献
56.
Sediment cores recovered from Lago di Mezzano, central Italy, were petrographically and geochemically (dry densitity, total organic carbon) investigated. A floating chronology was established with sedimentation rates derived from varve thickness measurements, and this chronology was both supported and extrapolated with calibrated AMS-14C-datings. The profile has a length of 29.7 m and comprises a total of 34,000 years.Late Pleistocene sediments consist of minerogenic-organic mud with few benthic diatoms and an organic carbon content of 2%, thus suggesting a high allochthonous input. The onset of the Late Glacial at 14,580 cal BP is documented by a lithologic change to more organic-dominated sedimentation. The Younger Dryas cold event is recorded between 12,650 and 11,400 cal BP and exhibits higher dry densities and minerogenic input. These dates agree with records from other lacustrine archives in Europe and the Greenland ice cores.The early Holocene comprises a laminated organic diatom gyttja deposited at a time of climatic amelioration and increased primary productivity. The establishment of an anoxic hypolimnion enhanced the varve and organic matter preservation. Since 3700 varve years BP the sedimentation pattern has been strongly influenced by human impact, as documented by the increase in minerogenic sediments and turbidites as well as higher sedimention rates. The onset of this influence coincides with a Bronze Age settlement at the lake shore. 相似文献