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1.
贵州喀斯特生态环境脆弱性类型区及其开发治理研究   总被引:19,自引:0,他引:19  
贵州碳酸盐分布广,喀斯特强烈发育,人类赖以生存的喀斯特环境是一个脆弱的生态系统。本文根据综合性原则,主导因素原则,人地矛盾分析原则和区域完整性原则,从组成生态环境系统的因素入手,采用“灰色关联度”方法,通过指标筛选及权重的确定,求得以县(市)域为单元的生态环境脆弱度。经综合评判,将全省划分为强度脆弱区、中度脆弱区和轻度脆弱区等三大类喀斯特生态环境脆弱性类型区。最后,针对各类型区的基本特征提出了今后开发治理的方向和措施。  相似文献   

2.
通过分析福建省生态环境脆弱性的现状特征、影响因素及人类活动对脆弱生态环境的正、负面影响,建立反映人类活动对福建省脆弱生态环境影响的评价指标体系.根据生态环境脆弱性评价的相关方法 和理论,计算出人类活动对脆弱生态环境正、负面影响度及总影响度,再通过自然划分法,把福建省67个县市分成5种影响度类型.最后,将人类影响度指数与生态环境脆弱性指数进行相关性分析,得出其具有显著的相关关系.  相似文献   

3.
云南元谋干热河谷生态环境退化及恢复重建试验研究   总被引:6,自引:0,他引:6  
干热河谷是我国西南地区的一种特殊生态类型,元谋干热河谷是金沙江干热河谷的典型代表。该区气候炎热干燥、植被稀疏、生态环境脆弱,加之人类活动的干扰,生态环境退化严重。1992年以来,我们对该区的生态环境退化状况进行了研究,并进行了复合生态模式、岩土性质与土壤水分、植被恢复、农(林)业节水技术试验研究和推广。  相似文献   

4.
人类赖以生存和发展的生态环境越来越多地受到人类活动的干扰、破坏,形成诸多生态环境问题,生态环境愈显敏感、脆弱。通过对黔中地区生态环境敏感性的初步探讨。拟采用层次分析法计算各指标的权重,采用均匀分布函数确定各指标的隶属度,采用模糊综合评判方法对黔中地区34个县域单元的生态环境敏感性进行综合评价。  相似文献   

5.
利用Landsat遥感影像和MODIS数据集,得到和田河流域沙漠段河流水面面积和植被覆盖面积的时空分布特征.进一步分析归一化植被指数(NDVI)的季节变化特征与景观格局指数,得到和田河流域沙漠段生态环境的空间变化特征.结果表明:生态补水措施增加了流域的水体和植被面积,缓解了生态环境;并且生态补水后河流曲折系数下降,平均水面宽度增加,河流逐步朝平流化方向发展;NDVI的空间分布呈现河流两端植被覆盖量高,中间覆盖量低的特点.分析景观格局指数得到,生态应急补水使和田河流域沙漠段水体景观和植被景观分布呈现聚集分布,有效地缓解了生态环境.   相似文献   

6.
黄土高原是世界著名的高原 ,以深厚的黄土堆积和广阔的分布面积著称于世界。黄土高原地处半湿润、半干旱区域 ,生态稳定性差 ,是我国华北平原的生态屏障区 ,是黄河流域的主体。其独特的自然环境又孕育了我国早期的历史文明 ,6000年前的半坡文化更证明黄土高原是中华民族的发祥地。由此可以说明我国黄土高原曾经具有适宜于人类生存与发展的良好环境。而目前 ,生态环境十分脆弱 ,正在经历着一场生态退化、资源减衰、人类生存空间丧失的过程。其根源 ,在于人口数量增加与不合理利用资源环境所致。扭转这一被动局面的关键 ,在于有效防治水土…  相似文献   

7.
青南高原区因其幅员辽阔、海拔高、气候严寒、受人文活动干扰相对较少而成为全球变化研究的环境本底.近年来,自然和人类活动的双重作用使得目前青南地区生态环境趋于恶化,其中位于黄河源区的玛多县是草场退化、土地沙漠化、草原鼠虫害、湿地退化等环境问题比较集中的区域.本项研究选取多种生态环境问题较为集中的位于黄河源区的青海省果洛州玛多县作为研究区.  相似文献   

8.
目前荒漠化是西北干旱区最严重的现实也是人类生态环境面临的主要课题近50 年来由于人口迅速增长垦耕滥牧和樵伐导致植被严重受损与此同时河流流量减少流程缩短不少湖泊干枯固定沙丘活化环境的恶化已威胁到西北干旱区人民的正常生产和工作为此恢复生态平衡重建山川秀美的大西北成为一项刻不容缓的长期而艰巨的任务在此背景下利用恢复生态学理论去解决西北干旱区生态重建的有关问题具有重要的意义1 恢复生态学可作为西北干旱区生态环境建设的理论指导西北地区生态环境的恶化是自然灾害和人类活动双重压力下植被破坏而造成生态系统十分脆弱的…  相似文献   

9.
黄河流域生态环境变迁的主导因素分析   总被引:1,自引:1,他引:0  
1万年以来黄河流域生态环境发生了很大的变化,早期由亚热带森林草原景观演变为温带森林草原景观,后期森林草原景观逐渐被破坏,演变为现今天然植被几乎荡然无存,水土流失十分严重.黄河流域生态环境变迁的主导因素是气候和人类活动.气候自然波动是生态环境演变的基础,在冷干或暖干条件下,植被退化甚至死亡.人类活动主要是不合理的开垦加速植被破坏.人类活动叠加气候波动共同促使黄河流域生态环境的变迁.  相似文献   

10.
分析了长江上游森林生态环境脆弱的特点 ,根据生态环境的差异性 ,将长江上游森林生态脆弱带划为 3种类型 :道孚类型、翁达类型、炉霍类型。通过论述长江上游森林生态环境脆弱带环境质量退化的现状 ,说明保护、发展这一地段的森林资源对于长江上游防护林体系建设的重要作用 ,并对目前的研究工作提出了一些建议。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

15.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

19.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

20.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

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