中国草畜平衡状态时空演变指示的草地生态保护格局   总被引：2，自引：0，他引：2  

黄麟  翟俊  祝萍  郑瑜晗 《地理学报》2020,75(11):2396-2407

中国草原牧区作为重要生态安全屏障和草地畜牧业生产基地,其草畜平衡状态直接影响草地退化与恢复,进而影响草地生态系统服务能力的强弱。本文分析了2000—2015年主要草原牧区草地植被覆盖、牧草供给、草畜平衡状态的时空变化特征,深入探讨草地退化与恢复及载畜压力下草地生态系统保护与恢复空间格局。结果表明：过去16年主要草原牧区草地面积净减少约163万hm²,6.7%的草地出现植被覆盖退化,而5.4%的草地呈现植被覆盖明显恢复。天然草地牧草供给量以增加为主,年增率约0.3 kg/hm²,然而其载畜压力亦持续增加,不考虑补饲的载畜压力指数高达3.8,除内蒙古东北部、青藏高原中部仍有载畜潜力,其余多处于超载状态;考虑实际冷季补饲的载畜压力指数约3.1,内蒙古中东部有所缓解;假设冷季全额补饲则载畜压力指数减至1.9,内蒙古、青藏高原等区域明显缓解。叠加上述数据,本文针对自然保护地、牧区、半农半牧区和农区等不同区域的草地生态保护格局,提出了平衡草地生态保护与畜牧生产利用的不同发展策略。  相似文献   

广盐性鱼类渗透压适应性与生理可塑性机制研究     

马爱军  崔文晓  刘志峰  张金生  黄智慧  杨双双  刘晓菲  杨凯  张薇 《海洋与湖沼》2018,49(6):1308-1317

拥有强大的渗透压调节能力对广盐性鱼类的生存至关重要。目前,关于鱼类渗透压调节机制已有不少研究,但均存在较大的局限性。本文从广盐性鱼类渗透压信号转导机制、渗透胁迫的细胞调控机制、渗透调控的内分泌调节机制和无机离子通道和转运蛋白介导的渗透调控等方面对广盐性鱼类的渗透压适应性和生理可塑性机制进行分析,以期从分子、细胞、通路和生理等层次初步探索广盐性鱼类盐度胁迫后的可塑性表型变化和不同盐度条件下的应答机制,为广盐性鱼类的渗透压调节机制的深入研究奠定基础。对广盐性鱼类渗透压适应性与生理可塑性机制研究,有助于研究其环境适应机理,促进野生鱼种的人工化养殖以及新品种的育种从而提高经济效益、社会效益和生态效益,对促进水产养殖学进步以及养殖业的发展具有重要意义,同时,为研究广盐性鱼类的渗透压调节机制开辟新的研究方向。  相似文献   

隧道工程地质评价的内容和方法   总被引：2，自引：0，他引：2  

陈新建  孙琳  李新星  孙巧银 《地球科学与环境学报》2004,26(1):41-45

结合工程隧道实际,首先阐述了隧道工程的基本地质环境和工程地质条件,然后针对隧道工程可能出现的不良地质现象和可采取的工程措施,从大气降水、围岩稳定、围岩压力、洞口稳定、隧道比选等角度探讨隧道工程地质评价的主要方法和一般内容,进行隧道工程地质评价,为隧道施工、支护提供了依据.  相似文献   

Modelling of deformation response and chemo‐mechanical coupling in chalk     

S. Pietruszczak  D. Lydzba  J. F. Shao 《国际地质力学数值与分析法杂志》2006,30(10):997-1018

A constitutive relation is derived for describing the mechanical response of chalk. The approach is based on a phenomenological framework which employs chemo‐plasticity. The properties of the material are assumed to be affected by the physico‐chemical processes that occur through the interaction between the skeleton and the pore fluid. The underlying mechanism is discussed by invoking a micromechanical analysis. The performance of the framework is illustrated by examining the evolution of mechanical characteristics in the presence of different pore fluids. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

地下洞库勘察中的深斜孔钻探和压水试验技术          下载免费PDF全文

吉孟瑞  孙桂明  吴昌庆  原华山 《山东国土资源》2001,17(2):56-60

青岛市黄岛区拟建设海底地下油气储藏库,前期地质勘察工作要求施工倾角45°、深220m的取心钻孔4个,并在孔内分段进行压水试验.本文介绍了如何利用XY-4型金刚石小口径钻机施工基岩深斜孔及压水试验技术.  相似文献   

Formation Pressure Evaluation Method for Single Well     

WANG Yachun 《东北亚地学研究》2002,(1)

The paper deals with the methods of formation pressure evaluation for a single well by using the very common ac-cepted parameters, such as drilling exponent , and flowline temperature , etc. which is part of compiling the end well report.  相似文献   

Viscoelastodynamics of A Stratified, Compressible Planet: Incremental Field Equations and Short- and Long-Time Asymptotes     

Detlef Wolf 《Geophysical Journal International》1991,104(2):401-417

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Ultrahigh pressure macro diamonds from Copeton (New South Wales, Australia), based on Raman spectroscopy of inclusions   总被引：1，自引：0，他引：1  

L.M. Barron  B.J. Barron  T.P. Mernagh  W.D. Birch 《Ore Geology Reviews》2008,34(1-2):76

Mining of Cenozoic alluvial deposits at Copeton and Bingara (Eastern Australia) has produced two million macrodiamonds (0.25 ct median size). Raman spectroscopy is used to identify included minerals within uncut Copeton diamonds, with sealed chamber remnant pressures of 31.7 to 35.6 kbar for coesite, 13.6 and 22.7 kbar for clinopyroxene, and 7.6 kbar for grossular garnet. Assuming elastic behaviour, these values generate inclusion entrapment PT loci which intersect, restricting diamond formation conditions: from 250 °C, 43 kbar to 800 °C, 52 kbar. Larger than error (± 100 °C and ± 4 kbar), this range shows a systematic variation in inclusion composition with diamond zoning and N properties. Published research shows 1) Copeton and Bingara diamonds are unique, and 2) modern alluvium in the Bingara district carries mantle-formed garnet, captured by post-tectonic alkali basalt from an extensive diamondiferous ultrahigh pressure (UHP) terrane that stalled at depth because it is dominated by mafic eclogite. The combined Raman and geological results indicate two sets of subduction UHP diamond formation conditions/protolith are required, firstly cooler oceanic slab and secondly including higher temperature continental crust. The Copeton and Bingara stones are UHP macrodiamonds, and Carboniferous ⁴⁰Ar/³⁹Ar age dates on clinopyroxene inclusions should be interpreted as ages of crystallisation, representing the termination of subduction. The characteristic features of ruptured inclusions and etched percussion marks on Copeton and Bingara diamond indicate volcanic delivery to the earth's surface. Alluvial deposits elsewhere in Eastern Australia may carry similar diamond along with diamond of different origin.  相似文献   

Impact evaluation on groundwater of the infiltration of an urban wastewater geopurification system placed over a detrital aquifer in a semiarid region (Spain)     

L. Moreno  J. J. Durán  M. A. Casermeiro  J. R. Quintana  Ma A. Fernández 《Environmental Geology》2008,54(3):465-477

Over a period of 4 years and 4 months, the geopurification installations at Dehesas de Guadix (Granada, Spain) were monitored to determine the impact on soil and groundwater of the controlled discharge of urban wastewater, and also to identify the best indicators of the entry of the recharged water into the aquifer. The installations are located in an area where the climate is Mediterranean sub-arid, with an average precipitation of less than 287 mm/year, and a rate of evapotranspiration that is almost three times greater. The system was controlled by determining the balance of majority nutrients and boron in the soil and in the groundwater, both at the points affected directly by the wastewater discharge and at others. The quantity of mass discharged was relatively large (COD 14,656 g/m², NO₃ 85 g/m², NO₂ 4 g/m², NH₄ 2,425 g/m², PO₄ 1,143 g/m², K 1,531 g/m², B 63 g/m²). It was observed that the elimination of nutrients within the soil (COD 97.5%, PO₄ 94.4%, K 59.17%, N _total 18.8%, B 12.69%) was very efficient except for the nitrogen, which nevertheless did not reach the groundwater, as it was eliminated at deep levels of the unsaturated zone. Only 12.69% of the boron was removed, and appreciable, increasing amounts of this element did reach the groundwater. Unexpectedly, none of the majority nutrients behaved as a reliable indicator of the impact on groundwater; despite this, the boron and the bicarbonate did clearly reflect the arrival of the recharged water, and are proposed as the best indicators.  相似文献   

Mapping susceptibility of rainfall-triggered shallow landslides using a probabilistic approach   总被引：2，自引：0，他引：2  

Chia-Nan Liu  Chia-Chen Wu 《Environmental Geology》2008,55(4):907-915

To prepare a landslide susceptibility map is essential to identify hazardous regions, construct appropriate mitigation facilities, and plan emergency measures for a region prone to landslides triggered by rainfall. The conventional mapping methods require much information about past landslides records and contributing terrace and rainfall. They also rely heavily on the quantity and quality of accessible information and subjectively of the map builder. This paper contributes to a systematic and quantitative assessment of mapping landslide hazards over a region. Geographical Information System is implemented to retrieve relevant parameters from data layers, including the spatial distribution of transient fluid pressures, which is estimated using the TRIGRS program. The factor of safety of each pixel in the study region is calculated analytically. Monte Carlo simulation of random variables is conducted to process the estimation of fluid pressure and factor of safety for multiple times. The failure probability of each pixel is thus estimated. These procedures of mapping landslide potential are demonstrated in a case history. The analysis results reveal a positive correlation between landslide probability and accumulated rainfall. This approach gives simulation results compared to field records. The location and size of actual landslide are well predicted. An explanation for some of the inconsistencies is also provided to emphasize the importance of site information on the accuracy of mapping results.  相似文献