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Abstract The evaluation of mining and other natural resource projects is made particularly difficult by the high degree of uncertainty attaching to output prices. It is shown that the techniques of continuous time arbitrage and stochastic control theory may be used not only to value such projects but also to determine the optimal policies for developing managing. This paper describes a model for evaluating natural resource investments under uncertainty from a new perspective. The previous works in this field mostly regard the movements of natural resource prices as a continuous GBM process, which pays few attentions to the shock of unexpected bad news. Our model provides the first theoretical method to analyze the impact of such “jump” on investment decisions. It concludes that the more frequently bad news happens, the earlier a project will be invested. 相似文献
435.
Surface mining is a global phenomenon. When dealing with the land disturbances caused by surface mining operations, the terms remediation, reclamation, restoration and rehabilitation (R4) are commonly used interchangeably or otherwise vaguely defined. Expectations associated with these terms may differ significantly from one stakeholder to another, however. Regulators, industry, environmental practitioners, local communities and the general public therefore stand to benefit from a precise terminology based on agreed-upon end-goals. The latter range from the avoidance of exposure to pollutants (remediation) to the full recovery of the original ecosystem (restoration). Although frequently claimed as the end-goal, restoration may often not be unachievable, because of altered hydrology, habitat fragmentation, contamination, climate change, prohibitive costs and other environmental and socio-economic boundary conditions. Mostly, the definitions of reclamation and rehabilitation may overlap in their definitions and approaches. Here we attempt the creation of a road-map that can clearly translate end-goals for each of the R4 terms. According to the definitions encountered and exposed here, reclamation, which aims to recover key ecosystem services and biogeochemical functions within a replacement ecosystem or rehabilitation, which implies a repurposing of the landscape, may be the best approaches to deal with surface mining legacies. 相似文献
436.
Watersheds are under increasing pressure worldwide, as expanding human activities coupled with global climate change threaten the water security of people downstream. In response, some communities have initiated investments in watershed services (IWS), a general term for policy-finance mechanisms that mitigate diverse watershed threats and promote ecosystem-based adaptation. Here, we explore the potential for increasing the uptake and impact of IWS, evaluating what limits its application and how institutional, financial, and informational barriers can be overcome. Our analysis complements the growing literature on individual programs by identifying levers at regional and global scales. We conclude that mainstreaming IWS as a cost-effective strategy alongside engineered approaches will require advances that (i) lower institutional barriers to implementation and participation in IWS; (ii) introduce structural market changes and standards of practice that account for the value of watersheds’ natural capital; (iii) develop practical tools and metrics of IWS costs and benefits; and (iv) share success stories of replicable institutional and financial models applied in varied contexts. 相似文献
437.
This article considers the environmental impacts and the governance framework of the domestic and international supply of iron, zinc, copper and nickel concentrates smelted and refined in Finland. The metals industry in the country is heavily dependent on imported concentrates, and the research is thus focused on defining the level of impacts related to mining and mineral processing abroad, and the change in the impacts between 2000 and 2010. The estimations of environmental impacts are based on waste minerals and CO2eq emissions, and the quality of governance in the set of indicators measuring different aspects of governance. The total amount of waste minerals and CO2eq emissions related to metal concentrates decreased over the ten-year period. At the same time, the quality of governance improved in all concentrate groups except nickel. Ore grade, mine type and transportation distance appear to be the most influential factors on environmental impacts. The results suggest that the country of origin can have a noticeable effect on the environmental impacts and the quality of governance of the mining and processing of metal concentrates. 相似文献
438.
为达到减少零被引论文发表数量、提高期刊质量与影响力的目的,在中国知网中检索了《自然资源学报》1986—2015年发表的论文作为研究的源数据,从刊文量及零被引率的变化、下载频次分布、作者情况、基金资助情况、所属学科领域等5个方面对零被引论文进行了详细的分析。研究结果表明:1)从季刊到双月刊和月刊,刊文量增加了,但零被引论文比例却没有随刊文量的增加而增加;2)零被引论文虽暂未被引用,但仍然存在一定程度的下载量,将来有可能被引,但也是低被引论文;3)作者分布方面,学生占比较大,因博士研究生是发文主流导致零被引论文中博士研究生人数多于硕士研究生,初、中级职称多于副高级、高级职称,由于高等院校和研究院所是投稿主力,因发文基数大导致零被引论文中高等院校和研究院所多于地方机构,作者群人数以1人为主,机构数量以1个为主;4)论文被引与否和基金资助数量和类别相关性不大;5)零被引论文学科分布以土壤学、地学、气象学和环境生物学为主。最后提出相应对策,建议通过“作者-审稿专家-编辑协同控制”过程,减少科技期刊零被引论文的产生,从而提高科技期刊的学术水平和影响力。 相似文献
439.
This article seeks to explain how and why church congregations mobilise on environmental issues and what – if anything – is distinctive about that mobilisation. Building on and adapting Resource Mobilisation Theory (RMT), we develop the idea of “spiritual resources” to help explain how a collection of spiritual identities, values, symbols and narratives can facilitate distinctive collective action on environmental issues. Our analysis draws on data derived from an in-depth case study of climate active groups in Scotland. It includes content analysis of websites, news stories as well as ethnographic observation of selected church and secular groups engaged in climate activity. We find church groups do enjoy a distinct set of resources – comprising tradition, rituals and symbols shaped by theology and doctrine – which are not wholly captured by other explanations of climate mobilisation. While these spiritual resources do not directly translate into specific environmental or climate action they can, especially when combined with other resources, lead to environmental activities distinctly motivated, and distinctly practised at the individual and community level. 相似文献
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