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71.
A pollution transport problem is formulated in a limited area. As the pollution sources we take emissions from industrial plants. Physically and mathematically suitable conditions are prescribed on the open boundaries. We show that the problem (as well as its adjoint) is well posed in the sense that a weak solution exists, is unique and depends continuously on its data. Direct and adjoint estimates of the average pollution concentration in an ecologically important zone are given, and the sensitivity of these estimates to perturbations in model parameters is analyzed.  相似文献   
72.
Rewilding is increasingly recognized as a conservation tool but is often context specific, which inhibits broad application. Rewilding in Australia seeks to enhance ecosystem function and promote self-sustaining ecosystems. An absence of large-bodied native herbivores means trophic rewilding in mainland Australia has focused on the restoration of functions provided by apex predators and small mammals. Because of the pervasive influence of introduced mesopredators, predator-proof fences, and establishment of populations on predator-free islands are common rewilding approaches. This sets Australian rewilding apart from most jurisdictions and provides globally relevant insights but presents challenges to restoring function to broader landscapes. Passive rewilding is of limited utility in arid zones. Although increasing habitat extent and quality in mesic coastal areas may work, it will likely be necessary to undertake active management. Because much of Australia's population is in urban areas, rewilding efforts must include urban areas to maximize effectiveness. Thus rewilding is not synonymous with wilderness and can occur over multiple scales. Rewilding efforts must recognize human effects on other species and benefit both nature and humans. Rewilding in Australia requires development of a shared vision and strategy and proof-of-concept projects to demonstrate the benefits. The repackaging of existing conservation activities as rewilding may confuse and undermine the success of rewilding programs and should be avoided. As elsewhere, rewilding in Australia should be viewed as an important conservation tool.  相似文献   
73.
中国防治荒漠化对策   总被引:7,自引:0,他引:7  
我国防治荒漠化的体制障碍是:由荒漠化定义的多样性导致的政出多门、数据多元、职责不明、功能不彰。本文对症下药给出了治标-调整职责和治本-重组机构两套方案。  相似文献   
74.
职业危害现状与对策分析   总被引:8,自引:11,他引:8  
本文陈述了我国职业危害作业场所多、涉及面广、职业病患者多的现状,阐述了职业病防治技术和能力落后、有毒有害工种和工序转移、预防性工作审核不严等产生职业危害的原因;论述了职业病危害由城市向农村、由东部向西部、由大企业向小企业的转移倾向和职业病发病年龄呈现年轻化及新兴职业相关疾病发生的特点,提出相应的预防和控制职业危害的对策。  相似文献   
75.
就高职院校英语科差生所存在的问题和原因进行了剖析,既有个人内在因素又有教学中的外在因素,对于如何深挖学生潜力,作好学生思想工作,培养学生学习英语兴趣提出了一些具体的解决办法.  相似文献   
76.
ABSTRACT: Access to clean and sufficient amounts of water is a critical problem in many countries. A watershed approach is vital in understanding pollution pathways affecting water resources and in developing participatory solutions. Such integration of information with participatory approaches can lead to more sustainable solutions than traditional “crisis‐to‐crisis” management approaches. This study aims at applying a watershed based joint action approach to manage water resources. Since most watersheds have urban and rural sources of pollution and a wide disparity in access to and use of water, alternative solutions need to take an integrated approach through cooperative actions. An institutional model was applied to seven subwatersheds in Honduras to evaluate various sources and effects of water contamination and water shortages. Two specific pathways of water resources degradation were studied (contamination from coffee pulp manufacturing and urban nonpoint sources) to develop alternative solutions that mitigate downstream impacts of access to clean water. A locally driven joint mechanism to reuse coffee pulp in farming systems is proposed. Such an institutional solution can maximize benefits to both farms and the coffee pulp industry. A combination of education and investment in sanitary facilities in urbanizing areas is proposed to minimize urban sources of water contamination.  相似文献   
77.
汶川地震后主要农业环境污染事故分析与防治   总被引:1,自引:0,他引:1  
农业环境污染事故威胁着农产品产量和质量。文章结合四川汶川县地震后的实际情况与多起农业环境污染事故处理经验,分析了地震后震区可能出现农业环境污染事故的类型、途径以及危害,提出了相应的预防和处理的建议与对策,为灾区应急处理以及灾后重建规划与实施等方面提供参考。  相似文献   
78.
汽车生命周期全过程存在的环境问题及解决措施   总被引:1,自引:0,他引:1  
介绍了汽车全生命周期过程产生的污染物情况并提出解决问题的措施,以减少对环境造成的影响。汽车制造、运行、报废的生命周期过程中,每一个环节都涉及到环境问题,当汽车数量增加到一定程度,其制造、运行、招废后各阶段所产生的污染物可能会超出有限的环境所能承受的容量,将给人们的生活环境造成巨大困扰。  相似文献   
79.
固废拆解业是一项将废旧电器及废旧五金等电子垃圾进行资源化处理的产业.然而,目前我国国内电子固废的回收网络的缺失、以及拆解企业的技术水平落后大大制约了这个行业的健康发展,同时带来的环境隐患也不容忽视.本文结合当地的实际情况,分析了制约固废拆解业发展的主要两人问题,并探索性的提出了相应的解决对策.  相似文献   
80.
目的 分析某气田井下管柱失效的根本原因,并提出有效的解决措施,以减少同类事故的再次发生。方法 采用宏观分析、拉伸性能、化学成分分析、金相分析、腐蚀产物分析、水质分析及结垢预测等方法,对可能造成某气田井下管柱腐蚀的原因进行深入分析。结果 失效件的拉伸性能、化学成分及金相显微组织均满足标准要求,排除因材质缺陷引起腐蚀。宏观分析表明,油管外螺纹与接箍内螺纹及镗孔处存在缝隙,且在缝隙处未预涂丝扣螺纹脂,因此在含有大量 Cl?的腐蚀性环境中发生了缝隙腐蚀。此外,由于该地层水易结垢,当 Ca CO3垢及砂样沉积在缝隙处时,再次构成缝隙腐蚀发生的条件,从而加速腐蚀的进行。结论 在下管柱作业中,在接箍与油管旋合处有必要预涂螺纹脂,防止服役环境中的腐蚀介质在缝隙处造成缝隙腐蚀而减少井下管柱的服役寿命。  相似文献   
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