黄河源区新构造运动对生态环境恶化的影响   总被引：7，自引：0，他引：7  

张森琦李永国  尚小刚辛元红王占昌  石维栋庄永成 周金元 《地质通报》2006,25(1):213-220

基于黄河源区1:25万生态环境地质调查新获得的大量实际资料,通过分析和研究发现,黄河源区早更新世-中更新世处于走滑伸展的大陆动力学背景,在整体隆升中,形成断块山与拉分盆地,湖泊广布;晚更新世,大陆动力学机制过渡为挤压收缩,在整体抬升中,断块山显著崛起,湖盆萎缩、变形;全新世,大陆动力学环境反转为走滑挤压,持续隆升,黄河扩展源头到达本区,扎陵湖、鄂陵湖外泄,闭流盆地水环境转向开放.近代,特别是20世纪70年代以来,新构造活化与寒冻风化岩屑坡扩大、沙质荒漠化蔓延、湖泊和沼泽湿地萎缩、区域地下水位下降、源区黄河频繁断流、生态环境日益恶化响应关系密切.因此,新构造运动在黄河源区生态环境恶化中起主导作用,而其他因素则起到促进与加速的作用.  相似文献   

优质淡水珍珠的体色及其与拉曼光谱的关系   总被引：2，自引：0，他引：2  

秦作路  马红艳  木士春  童张法 《矿物学报》2007,27(1):73-76

对不同颜色的优质淡水养殖珍珠进行激光拉曼光谱的研究,并试图从中找出珍珠颜色与其中的有机物以及和拉曼光谱的关系。结果发现,和纯白色系列优质珠相比,粉红色系列优质珠多了1134和1526 cm-1两个峰;紫色系列优质珠中的1017,1295,2231,2609 cm-1在纯白色珍珠和粉红色系列中均未曾出现;在有色珍珠中探测到某有机物的拉曼峰:由C—C伸缩振动引起的1121,1134 cm-1及C=C伸缩振动引起的1503,1526 cm-1,推测此有机物为聚乙炔类物质,不同于以前的研究者所认为的类胡萝卜素。不同色系的珍珠,其拉曼光谱有着明显的区别;随着同色系颜色的加深,有机物拉曼谱峰的强度也越来越强。  相似文献   

福州市表层土壤农业生态环境质量评价   总被引：3，自引：0，他引：3       下载免费PDF全文

魏为兴 《中国地质》2007,34(2):354-358

本文用地球化学指标和分级聚类模型中的积分值法,选取了N、P、K2O等16个指标对福州市表层土壤的农业生态环境质量进行了初步的评价分类。共划分为5个级别农业生态环境区。其中一般生态环境区面积最大,占全部面积58%。优良与良好生态环境区所占面积相对较小,两者合计面积同极差生态环境区面积相当,约占3%。各环境区多数富钾元素,贫中量、微量元素。并根据各个生态环境区的特点,对福州市农业规划与布局提出了建议。  相似文献   

四川九寨沟景观形成演化趋势分析及评价   总被引：3，自引：0，他引：3  

张瑞英  何政伟 《中国地质灾害与防治学报》2007,18(1):54-58

九寨沟风景名胜区是世界级旅游精品,正确认识九寨沟风景名胜区自然和人为的影响因素的发展变化,对景区的保护意义重大。首先,文章从地层岩性、地质构造、地形条件、第四纪冰川作用和地质灾害等方面详细阐述了地质环境条件对九寨沟景观的形成作用。然后,笔者从地下水岩溶通道的发育、钙华景观演化和湖泊泥沙沉积等方面分析了九寨沟地质环境演化趋势,九寨沟的地下水岩溶通道发育和钙华景观演化处于青壮年期,湖泊泥沙沉积缓慢。最后,作者分析了九寨沟景区的降水变化趋势和周期变化、生态环境的改变状态。通过上述分析,得出了九寨沟风景名胜区景观变化处于相对稳定状态的结论,证实了目前的一些景观退化与大自然的变化趋势是一致的,九寨沟核心景区的生命力尚处于青壮年阶段。  相似文献   

Economic gains of liberalising access to fishing quotas within the European Union     

Jesper L. Andersen  Max Nielsen  Erik Lindebo 《Marine Policy》2009

This paper analyses the extent to which specialisation gains can be achieved by liberalising access to fishing quotas within the European Union (EU). Fishing quotas are today exchanged between EU member states at a rate of 4% of total turnover in EU fisheries. Germany, Belgium, Denmark and the Netherlands are the most active. Only one fourth of these exchanges are permanent. With the management systems in EU fisheries differing among countries, comparative advantages in fisheries exist in member states with the best management practices. Hence, although positive but small specialisation gains exist in EU fisheries today, these gains might potentially be increased by liberalising access to fishing quotas and allowing transferability of quotas between individuals from different countries on a permanent basis. Increasing the gains might, however, affect relative stability.  相似文献   

The infusion of sustainability into bilateral fisheries agreements with developing countries: The European Union example     

Emma Witbooi   《Marine Policy》2008,32(4):669-679

The EU's bilateral fishing policy towards developing third countries has evolved over the years to increasingly emphasise sustainability, culminating in 2002 with the release of a ‘fisheries partnership approach’. The Community has begun to operationalise the policy in various West African coastal states, where its new fisheries partnership agreements are intended to function as ‘development vectors’. This paper introduces the EU's new policy, examines its potential implications for the role of sustainability in future bilateral fishing relations and highlights the impetus for it with reference to analysis of the EU's most recent agreement with Senegal based on empirical research.  相似文献   

Rethinking small-scale fisheries compliance   总被引：3，自引：1，他引：2  

Maria Hauck   《Marine Policy》2008,32(4):635-642

Fisheries compliance has been identified as key to sustainable fisheries management. However, it has been widely acknowledged that the approach by many governments worldwide to achieve compliance is largely through law enforcement efforts. Although theories of normative action have expanded compliance thinking from that of rationalist approaches, this paper takes the argument further. By drawing on criminology and security discourse, and on empirical research on small-scale fisheries in South Africa, this paper argues for a new approach to our understanding of compliance. Furthermore, it argues that rather than taking law as given, the formation of law and the power dynamics influencing such processes are critical aspects that need to be acknowledged and understood in fisheries compliance theory.  相似文献   

Impacts of trawling on benthic macro-fauna and -flora of the Spencer Gulf prawn fishing grounds     

Ib Svane  Zoe Hammett  Peter Lauer   《Estuarine, Coastal and Shelf Science》2009,82(4):621-631

The overall effects of trawling on benthic habitats and their assemblages are dependent on the distribution and intensity of trawl effort. The benthic habitats of the Spencer Gulf prawn trawling grounds are subjected to known variable levels of trawling disturbance recorded from fisher's logbooks. These habitats have not been quantitatively investigated. The aim of the study was firstly to characterise the macro-faunal and -floral assemblages and secondly, to comparatively assess trawl impact by testing the null hypothesis of no differences between five sites exposed to different intensity of trawl effort. The distribution and abundance of benthic macro-fauna and -flora were studied at two sampling resolutions by using beam trawl sampling (10,000 m²) and underwater stereophotography (4.5 m²) at five sites with different levels of trawl disturbance (effort). The results showed that the Spencer Gulf prawn trawling grounds are characterised by sandy sediments with a low content of silt and clay, with the exception of one site with very fine gravel. Biomass, abundance and cover of macro-fauna and -flora were generally low throughout, but with large differences among sites. Biomass, abundance and cover were found to be negatively correlated to both trawl hours from 1994–1998 and during the period of study. ANOSIM and SIMPER analyses using biomass, abundance and percentage cover as variables showed significant differences between sites with eight species or taxonomic groups contributing more than 10% to the observed similarity within sites. The two northern sites were dominated by sponges and the bearded mussel, Trichomya hirsutus, and the southern hammer oyster, Malleus meridianus. Other species that contributed to the similarity within sites were the ascidian, Polycarpa viridis, mobile epifauna (the blue swimmer crab, Portunus pelagicus, and the western king prawn, Penaeus (Melicertus) latisulcatus) and demersal fish species (Degens leatherjacket, Thamnaconus degeni, and the Melbourne silver belly, Parequula melbournensis). Simpson's Index of Diversity (1 − λ) and species richness in the beam trawl samples were fairly even across all sites, but a significant effect of site was found in the stereophotographic transect samples. It was concluded that prawn trawling has a strong influence on the structure of the benthic habitats of the Spencer Gulf prawn fishing grounds highlighted by the magnitude of change and the strength of the gradient of effects. Confounding factors linked to the biophysical attributes of the sites are believed to be minor.  相似文献   

Small-scale marine fisheries policy in Vietnam   总被引：1，自引：0，他引：1  

Robert Pomeroy  Kim Anh Thi Nguyen  Ha Xuan Thong 《Marine Policy》2009

Vietnam's marine fisheries are considered to be small scale and are concentrated in coastal near-shore waters. This has resulted in heavy pressure on near-shore fisheries resources. Near-shore fisheries are considered by fishers and the government to be over-exploited, causing hardship for many coastal communities. This paper reviews and analyzes changes in policy towards small-scale fisheries in Vietnam over the last two decades. The primary issues facing the small-scale fisheries in Vietnam are to restructure the near-shore fisheries and to address over-capacity. Recommended actions include improved fisheries statistics, resources for provincial fisheries staff, and a coordinated and integrated approach involving a mixed strategy of resource management; resource restoration; economic and community development; and new governance arrangements.  相似文献   

Numerical modelling of the potential effects of a dam on a coastal aquifer in S. Spain     

M. L. Calvache  S. Ibáñez  C. Duque  W. Martín‐Rosales  M. López‐Chicano  J. C. Rubio  A. González  C. Viseras 《水文研究》2009,23(9):1268-1281

This study presents the results of a three‐dimensional variable‐density numerical modelling of the Motril‐Salobreña coastal aquifer and the possible effects of the entry into service in May 2005 of the Rules Dam, located just 17 km from the coast. Present parameters of the Motril‐Salobreña aquifer show that the system's conditions are very similar to a natural regime. The dam will substantially alter aquifer recharge, as the entry flow through the alluvial sediments of the Guadalfeo River will be entirely cut off or drastically reduced. Different scenarios reproducing the possible evolution of the aquifer under operation of the Rules Dam have been modelled. In most cases, results indicate that the conditions of the aquifer would worsen, with a general advance of the freshwater–saltwater interface. The area with most risk of saltwater intrusion is the old mouth of the Guadalfeo River, where the mixing zone could advance 1200 m inland. It is proposed that maintaining a 5–6 Mm³ year^?1 ‘ecological flow’ in the Guadalfeo River could prevent this saline advance. This application demonstrates that variable‐density models are potentially useful tools for estimating the effects of dams on the hydrodynamic and hydrochemical conditions of a coastal aquifer. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献