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大地震在主破裂前往往行成地壳变形,高应力作用下进入峰值后的变形阶段,反映到地倾斜观测日均值曲线上,表现为固体潮形变趋势异常,这些异常能否指示远距离的地震,近年来不少研究者发现,远场前兆往往出现在对应力、应变变化反应灵敏的特殊构造部位。佳木斯台可能处于这种特殊的构造部位,对东北地区浅源地震短期前兆异常“场兆”的趋势性变化具有一定的意义。 相似文献
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Assessment of Water Supply as an Ecosystem Service in a Rural-Urban Watershed in Southwestern Mexico City 总被引:1,自引:0,他引:1
Jujnovsky J González-Martínez TM Cantoral-Uriza EA Almeida-Leñero L 《Environmental management》2012,49(3):690-702
Studies from the ecosystem services perspective can provide a useful framework because they allow us to fully examine the
benefits that humans obtain from socio-ecological systems. Mexico City, the second largest city in the world, has faced severe
problems related to water shortages, which have worsened due to increasing population. Demand for space has forced changes
in land cover, including covering areas that are essential for groundwater recharge. The city has 880 km2 of forest areas that are crucial for the water supply. The Magdalena River Watershed was chosen as a model because it is
a well-preserved zone within Mexico City and it provides water for the population. The general aim of this study was to assess
the ecosystem service of the water supply in the Magdalena River Watershed by determining its water balance (SWAT model) and
the number of beneficiaries of the ecosystem services. The results showed that the watershed provides 18.4 hm3 of water per year. Baseflow was dominant, with a contribution of 85%, while surface runoff only accounted for 15%. The zone
provides drinking water to 78,476 inhabitants and could supply 153,203 potential beneficiaries. This work provides an example
for understanding how ecosystem processes determine the provision of ecosystem services and benefits to the population in
a rural–urban watershed in Mexico City. 相似文献
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Patricia Miretzky Carolina Mu?oz Enrique Cantoral-Uriza 《Environmental Chemistry Letters》2011,9(1):55-63
Naturally occurring diatomaceous earth was modified by alkaline pretreatment, and its effectiveness for Cd2+ removal from contaminated water was investigated. Batch experiments were carried out to determine Cd2+ adsorption capacity and the efficiency of the sorption process under different experimental conditions. Experimental data
showed good fitting to Langmuir and Freundlich isotherms models. The Cd2+ maximum adsorption capacity was 0.058 mmol g−1 for raw diatomite and increased to 0.195 mmol g−1 for alkaline-pretreated diatomite with efficiency higher than 96% (diatomite dose 2.5 g L−1, pH 6). Adsorption of Cd2+ to alkaline-pretreated diatomite increased as the temperature increased. Thermodynamic parameters were calculated to evaluate
the feasibility of the adsorption process at different temperatures. The adsorption process was spontaneous and endothermic.
The interaction between Cd2+ ions and diatomite surface was weak enough to be considered as physical sorption, confirmed by the low value of activation
energy. 相似文献
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