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171.
Not only the nutritional status and biological activity but also the soil ecological functioning or soil health has been impacted profoundly by land degradation in the karst area of southwest China where the karst ecosystems are generally considered as extremely vulnerable to land degradation under intensified land-use changes. The objectives of this study are to elucidate the changes in overall soil quality by a holistic approach of soil nutritional, biological activity, and soil health indicators in the karst area as impacted by intense cultivation and vegetation degradation. Topsoil samples were collected on selected eco-tesserae in a sequence of land degradation in a karst area of southwest Guizhou in 2004. The soil nutrient pools of organic carbon (Corg), extractable extracellular carbon (Cext), total soil nitrogen (Nt), alkali-hydrolyzable nitrogen (Nah), total phosphorus (Pt), available phosphorus (Pa) were analyzed by wet soil chemistry. The soil biological properties were studied by means of measurements of microbial biomass carbon (both by fumigation–extraction, FE-Cmic, and by calculation from substrate-incubation respiration, SIR-Cmic) of respiration [respiration without addition of substrates, basal respiration (BR), and potential respiration (PR) with substrate-incubation] and of soil enzyme activities (invertase, urease, and alkaline phosphatase). Soil health status was assessed by simple indices of Cmic/Corg and BR/Cmic in conjunction with bacterial community structures determined by polymerase chain reaction and denaturing gradient gel electrophoresis. While the nutritional pool parameters, such as Corg and Cext, described basically the changes in soil life-supporting capacity with cultivation interference and vegetation declined, those parameters of biological activity such as FE-Cmic, SIR, and SIR-Cmic as well as bacterial community structures measured by molecular method evidenced well the changes in soil functioning for ecosystem health with the land degradation. 相似文献
172.
A new earthquake catalogue for central, northern and northwestern Europe with unified Mw magnitudes, in part derived from chi-square maximum likelihood regressions, forms the basis for seismic hazard calculations
for the Lower Rhine Embayment. Uncertainties in the various input parameters are introduced, a detailed seismic zonation is
performed and a recently developed technique for maximum expected magnitude estimation is adopted and quantified. Applying
the logic tree algorithm, resulting hazard values with error estimates are obtained as fractile curves (median, 16% and 84%
fractiles and mean) plotted for pga (peak ground acceleration; median values for Cologne 0.7 and 1.2 m/s2 for probabilities of exceedence of 10% and 2%, respectively, in 50 years), 0.4 s (0.8 and 1.5 m/s2) and 1.0 s (0.3 and 0.5 m/s2) pseudoacclerations, and intensity (I0 = 6.5 and 7.2). For the ground motion parameters, rock foundation is assumed. For the area near Cologne and Aachen, maps
show the median and 84% fractile hazard for 2% probability of exceedence in 50 years based on pga (maximum median value about
1.5 m/s2), and 0.4 s (>2 m/s2) and 1.0 s (about 0.8 m/s2) pseudoaccelerations, all for rock. The pga 84% fractile map also has a maximum value above 2 m/s2 and shows similarities with the median map for 0.4 s. In all maps, the maximum values fall within the area 6.2–6.3° E and
50.8–50.9° N, i.e., east of Aachen. 相似文献
173.
Karst groundwater protection in the Kupa River catchment area and sustainable development 总被引:1,自引:0,他引:1
One of the most significant water resources in the Republic of Croatia is the catchment area of the Kupa River, located in
the region bordering the Republic of Slovenia. About 88% of the total amount of water in this catchment originates in Croatia
and just 12% from Slovenia; therefore, the largest part of the catchment area (about 1000 km2) is on the Croatian side of the border. It is a typical karst area of the Dinarides with aquifers characterized by a relatively
rapid water exchange, high groundwater flow velocities and aquifers open to human impact from the surface. Consequently, the
aquifers are highly vulnerable and at risk. Due to the availability of large quantities of high-quality spring water (about
6 m3/s), the entire area has a strategic importance within the context of any future development strategy pertaining to the western
part of Croatia. The catchment area on the Croatian side was investigated using a wide range of research methods that included
a classical hydrogeological approach, the detailed hydrologic calculation of water balance to the hydrogeochemical analyses
and modelling. The objective was to determine protection zones and protection measures for the whole area. The difficulties
are increased due to the fact that the karst catchment area is crossed by major traffic corridors, oil pipelines and a railway
and that many settlements and a highly developed wood industry are present. The combination of protecting water resources
with adequate prevention measures and necessary remedial activities that should satisfy the very strict requirements necessary
for the protection of the karst aquifers while still allowing for present and future human activities is difficult – but not
impossible – to achieve. One good example is the present highway with a closed dewatering system and waste water treatment
before the water passes into the karst underground system. 相似文献
174.
以中国科学院盐亭紫色土农业生态试验站小流域为例,研究不同土壤侵蚀沉积地段(斜坡和沟谷不同部位)的土壤结构特征,以了解侵蚀沉积对土壤结构的影响。结果表明,在植被覆盖较好的坡体顶部,土壤侵蚀较弱,团聚度达到30.1%,MWD变化为3.4mm,土壤结构良好;沟谷底部由于沉积而有较多细土物质并具有适宜的水分条件,有利于土壤团聚体的形成,结构状况亦较好,团聚度达到50.3%,结构保持率为35.4%;而坡腰侵蚀较严重,团聚度仅为13.6%,结构保持率为14.1%,土壤结构状况较差。 相似文献
175.
Planning for source water protection in Ontario 总被引:2,自引:0,他引:2
Ontario began developing a drinking water source protection planning process in 2000, after a rural community's water supply was contaminated by pathogens from agricultural runoff. An expert committee report has recommended legislating a new source protection “sphere of jurisdiction” for municipalities; however, no specific new municipal tools or authorities have been proposed as yet. This paper reports findings from an evaluation of the extent to which existing institutional arrangements for land use planning and water management facilitate or constrain source protection by municipalities. A case study of the Regional Municipality of Waterloo suggests there is the potential to link land use planning more strongly to water management through creative use of existing tools, forgoing the need for major institutional changes. 相似文献
176.
Christine S McCulloch 《Area》2006,38(1):24-33
Public participation in transparent decisionmaking has been proposed as a panacea for environmental protection. Bargaining theory suggests drawbacks to transparency such as hardening of attitudes and intransigence. Yet achievement of consensus on environmental values for integrated water resource management demands public involvement. Historical study of attempts to prevent reservoir construction in upland valleys designated for protection of nature suggests that 'closed-door' bargaining proved more effective for environmentalists than open, public debate. Records now open for analysis of disputes over Teesdale and Farndale, 1950–1970, allow comparisons to be made between behind-the-scenes deliberations and 'open-door' public discussion. The ambition of progressing from public participation to devolution of environmental decisionmaking and responsibility to the local scale demands more conceptualization of the process of decisionmaking on water resource development. 相似文献
177.
IAN YEBOAH 《The Geographical journal》2006,172(1):50-65
This paper is concerned with subaltern actions providing alternatives to development practice. I use Ghana's attempt at urban water privatization to illustrate that Ghana's development practice is characterized by a dependence on foreign sources of capital and expertise that illustrates a psyche and mindset of Eurocentrism associated with the elite and decisionmakers of the country. The rationale for water privatization, the how of privatization, and the anti-development opposition to privatization not only demonstrate this dependency but also the extent to which decisionmakers are willing to sacrifice sovereignty and culturally sensitive ways of doing things, to global capital, in exchange for development funds. In the state's zeal for Western or Occidental development, subalterns in Ghana have devised hybridities that are post-traditional and Oriental in nature to solve their water problems. These development solutions are couched within structures provided to human agency and suggest that development practice should therefore listen to subalterns in terms of how they imagine and solve their problems. The concern with subaltern voices shows the relationship between postcolonial studies and development practice. 相似文献
178.
The Dahuiyeh (Zarand) earthquake of 2005 February 22 in central Iran: reactivation of an intramountain reverse fault 总被引:3,自引:0,他引:3
179.
Zoltán Wéber 《Geophysical Journal International》2006,165(2):607-621
180.
分析了洪山预测区西部洪山岩体地质特征及其向外围扩散的范围和程度,研究了北掌勘查区和焦窑煤矿两邻区煤层受岩浆岩影响的程度,认为洪山岩体对预测区煤系及煤层赋存的影响较小,岩体外围仍有煤系赋存。为下一步找煤指明了方向。 相似文献