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141.
化石燃料的大量使用所排放的温室气体使得全球气候日益变暖,低碳经济的提出成为了目前全球应对气候变暖的主要策略,而发展中国家在进行低碳技术引进时常常面临来自发达国家的知识产权贸易壁垒。本文从"公地悲剧"角度解析气候变暖的经济学根源,从"反公地悲剧"角度揭示低碳技术转让过程中发达国家以知识产权为借口制造技术壁垒的经济学缘由。 相似文献
142.
为了研究近场脉冲地震下桥梁结构的时变抗震性能,以一座常规连续梁桥为研究对象,引入氯离子侵蚀模型,在考虑多种不确定性因素基础上,采用拉丁超立方抽样建立不同服役时期的时变模型样本,运用增量动力分析方法,从能力、需求以及倒塌等方面对算例桥梁的时变抗震性能进行了研究和评价。结果表明:近场脉冲型地震下结构的抗震需求明显大于远场地震;氯离子侵蚀导致钢筋锈蚀后力学性能发生改变,箍筋对核心混凝土约束能力减弱,锈蚀纵筋屈服强度及极限拉应变都降低,导致桥墩的变形能力下降;与地面运动的不确定性相比,模型参数的不确定性对结构的抗震需求均值及离散性影响均不大;随着服役时间延长,钢筋锈蚀加剧,桥墩出现倒塌破坏的概率加大。 相似文献
143.
1961-2012 年西藏极端降水事件的变化 总被引:2,自引:0,他引:2
利用18 个气象站点1961-2012 年逐日降水量资料,计算了10 个极端降水指数,采用滑动平均、线性回归、Mann-Kendall 非参数检验和Morlet 小波分析等方法,分析了西藏极端降水事件的变化规律。结果表明:西藏近52 a 连续干旱日数(CDD)呈显著减少趋势,最大5 d 降水量也趋于减少但不显著,大雨日数和强降水量的线性趋势不明显,其他6 个极端降水指数都表现为增加趋势且不显著。与全球、青藏高原及其周边地区比较,西藏CDD和连续湿日的变幅明显偏大,最大1 日降水量、强降水量和极强降水量的变幅明显偏小。除CDD外,极端降水指数的变化趋势与海拔高度呈显著的二次曲线关系,仅有中雨日数的变化趋势与经度呈显著的正相关。在近52 a 的时间尺度上各项极端降水指数都存在3~4 a 显著周期,多数指数也存在12a、15 a 和16 a 的周期。在时间转折上,CDD的突变点时间较早,从1974 年开始;中雨日数、连续湿日和年总降水量的突变点发生在20 世纪80 年代末。从空间分布来看,那曲地区西部是极端降水指数变化最为显著的区域,雅鲁藏布江中游大部的多数极端降水指标趋于下降,而山南地区南部、林芝地区东南部的降水极值和降水强度都在增加。 相似文献
144.
马洪艳 《安全.健康和环境》2014,14(5):1-3
介绍了模块化施工的概念、原则及主要做法,以实例证明录取模块化施工可大大降低安全风险,提高施工效率。 相似文献
145.
为进一步加强建设项目施工期的环境管理,中国在生态环境影响突出的国家13个重点建设项目中开展工程环境监理试点。石化工程相比其它工程项目具有建设规模大,对周边生态环境影响大,污染物排放总量大,潜在安全隐患大等特点。本文结合作者自身的工作体会对石化工程开展环境监理工作进行了探讨。包括石化工程在施工组织设计、施工准备阶段、施工期、试生产及竣工等各阶段的环境监理工作内容,并提出了工作中存在的一些问题及建议,为石化项目环境监理工作提供理论及实践依据。 相似文献
146.
Newton M Cole EC Tinsley IJ 《Environmental science and pollution research international》2008,15(7):573-583
Background, aim, and scope Large-scale deforestation is occurring in subarctic North America following clearing by salvage logging or insect attack.
Numerous shrubs, herbs, and deciduous tree species tend to dominate areas on which stands of white spruce have grown. In the
absence of economically advantageous mechanical methods, several herbicides have value in efforts to reforest by planting
white spruce. Glyphosate, imazapyr, triclopyr, and hexazinone are all capable of selectively removing many competing species,
but there is concern about whether they would degrade naturally or persist owing to the frigid climate.
Materials and methods We established test plots with all four herbicides in upland and river bottom sites at 65°N and 58°N latitudes. The northern
site has extremely cold winters, with soils that freeze to a depth of 1–2 m, and precipitation of 275 mm/year. The southern
site has heavy rain and snowfall, amounting to 2,250 mm/year evenly distributed. Soil seldom freezes deeply. On each test
plot, one of the four herbicides was applied at twice the normal operational use rate to facilitate detection. They were applied
at the normal timing, with hexazinone, imazapyr, and triclopyr applied in June and glyphosate applied in fall. Soils were
sampled immediately after treatment and those samples used as references for dissipation data gathered over the next 11–14 months
from soil 0- to 15- and 15- to 45-cm depths.
Results Dissipation rates did not follow first-order rates because freezing conditions slowed most microbial activity. All products
dissipated to close to or below detection limits within the time of the study. Dissipation from vegetation was substantially
more rapid and depended on the nature of the plants treated as well as the product used. While soil residues dissipated more
slowly than in temperate regions, they did display consistent dissipation patterns during above-freezing conditions and also
the influence of microbial activity. Mobility was very limited with all products but hexazinone.
Discussion These products dissipate during summer in high latitudes much as they would in temperate climates. Winter changes are small,
but are not unlike some changes reported elsewhere under freezing conditions. Unlike many other studies, soil water did not
influence dissipation heavily, but the high latitude and semi-arid climate also did not create severely droughty soils. Residues
in plants were much higher than those in soils, but denatured the vegetation quickly, leading to unsuitability for forage
in any case.
Conclusions Low toxicity of these products and their metabolites combined with consistent dissipation and low mobility suggest that toxic
hazard of their use at high latitudes need not be a matter of serious concern to humans, terrestrial wildlife, or aquatic
systems. They are safe for use in management and rehabilitation of boreal forests when used properly.
Recommendations and perspectives Dissipation at rates approaching those in warmer climates offer a hypothesis that microflora native to high latitudes may
be adapted to destruction of such molecules at lower temperatures than may be indicated by experiments with microflora adapted
to warmer climates. Residues pose no observable risk to wildlife or humans in the area of use when products are applied properly.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available for authorized users. 相似文献
147.
148.
149.
150.
After introducing soft defence techniques as an alternative to hard defence techniques, the need is emphasized to consider
the coastal area as an integral system. By recalling the main driving factors for coastal management: conflict resolution,
resilience and sustainability, we logically arrive at the concepts of ecological engineering and ecotechnology, which are
increasingly acknowledged as possible solutions to achieve sustainable use of coastal space as a resource. In this context,
we refer to the principles of self design and of ecosystem conservation.
In order to deal with real situations we are in need of fundamental ‘tools’ for the application of the soft intervention technology
approach. We therefore introduce the concept of physiographic units and develop an initial elaboration for a coastal stretch
and for coastal wetlands. The latter deserve more attention because of the already established practices of ecotechnology,
at least as far as water and soil quality are concerned, but certainly also concerning morphology, especially in the future.
We conclude by briefly discussing how activities undertaken in two research projects currently being conducted under the framework
of the Marine Science and Technology Program of the Commission of the European Communities are expected to contribute to the
concepts introduced here. 相似文献