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971.
972.
We analyze the bipartisan call to ban US exports of commodity mercury. An export ban can generate positive environmental benefits by increasing the scarcity of mercury in developing economies where significant toxic releases occur. We show, however, that a direct mercury purchase and retirement policy can achieve the same foreign environmental goals without adverse impacts on domestic environmental quality. We present qualitative and quantitative evidence that highlight the potential inefficiencies of a mercury export ban as a method of achieving environmental objectives. 相似文献
973.
含硫油品储罐腐蚀产物自燃及其防治理论研究 总被引:1,自引:0,他引:1
含硫油品储罐内壁腐蚀产物(Fe2O3、Fe3O4、Fe(OH)3)与H2S反应生成硫化铁,硫化铁的氧化放热是引起储罐火灾的主要原因.实验模拟了油品储罐中硫化铁的生成,研究了在无氧条件下H2S气体与油品储罐内壁腐蚀产物的反应以及生成的硫化铁在自然环境下的氧化自燃性.结果表明,Fe2O3、Fe3O4、Fe(OH)3,以及它们的混合物经硫化后生成的硫化铁具有很高的自然氧化活性,在自然环境中,常温下能迅速和空气中的氧气反应并放出大量的热,热量积聚引起储罐火灾爆炸事故.在实验结论的基础上,提出了一些行之有效的安全防范措施. 相似文献
974.
《环境科学学报(英文版)》2023,35(3):544-552
Ammonia nitrogen (NH4+-N) is a ubiquitous environmental pollutant, especially in offshore aquaculture systems. Electrochemical oxidation is very promising to remove NH4+-N, but suffers from the use of precious metals anodes. In this work, a robust and cheap electrocatalyst, iron single-atoms distributed in nitrogen-doped carbon (Fe-SAs/N-C), was developed for electrochemical removal of NH4+-N from in wastewater containing chloride. The Fe-SAs/N-C catalyst exhibited superior activity than that of iron nanoparticles loaded carbon (Fe-NPs/N-C), unmodified carbon and conventional Ti/IrO2-TiO2-RuO2 electrodes. And high removal efficiency (> 99%) could be achieved as well as high N2 selectivity (99.5%) at low current density. Further experiments and density functional theory (DFT) calculations demonstrated the indispensable role of single-atom iron in the promoted generation of chloride derived species for efficient removal of NH4+-N. This study provides promising inexpensive catalysts for NH4+-N removal in aquaculture wastewater. 相似文献
975.
976.
977.
978.
SHANNON M. BARBER‐MEYER 《Conservation biology》2010,24(4):918-923
Abstract: Illegal international trade in wildlife (excluding fisheries and timber) has been valued at more than US$20 billion. A more precise figure has not been determined in part because of the clandestine nature of the trade, and for this same reason even regional and local levels of wildlife trade are difficult to assess. The application of recent developments in wildlife field‐survey methods (e.g., occupancy) now allows for a more‐accurate estimation of wildlife trade occurrence, including its hidden components at a variety of scales (e.g., regional, local) and periods (e.g., single season, 1 year, multiple years). Occupancy models have been applied in wildlife field studies to address the problem of false absences when conducting presence–absence surveys. Occupancy surveys differ from traditional presence–absence surveys because they incorporate repeat surveys, allowing for the likelihood of detecting a species (the probability of detection) to be estimated explicitly (in contrast to traditional surveys that often incorrectly treat this probability as close to one to allow for estimation of presence). Occupancy methods can be applied to a variety of wildlife‐trade surveys, including, for example, single‐species availability, links between two illegally traded species (i.e., co‐occurrence), and disease occurrence in live trade. In addition, free user‐friendly software (i.e., PRESENCE) allows even nonstatisticians to adequately address this issue. I simulated a hypothetical wildlife‐trade market survey that resulted in an apparent 20% decline in naïve occupancy (proportion of surveyed towns engaged in the trade) over 2 years, but when I accounted for change in probability of detection over the years the difference in occupancy was not statistically significant. As more sophisticated methods, such as occupancy, are applied to wildlife‐trade market surveys, results will be more robust and defensible and therefore, theoretically, more powerful when presented to conservation policy and decision makers. 相似文献
979.
2012和2013年的废纸市场让很多企业一筹莫展,全球经济不振,国内需求不足,产能过剩,直接影响了造纸行业的生产和销售,作为原料供应商的废纸回收利用行业,必然受到连带影响,整个产业进入低迷阶段.除了外部经济环境的影响,行业内部应该如何调整,产业政策又该怎样引导行业健康发展,将是未来需要持续探讨的课题. 相似文献
980.
介绍了"十五"和"十一五"时期国内废钢行业发展概况,重点阐述废钢行业的回收供应以及消耗情况,并对影响废钢价格的因素进行数学建模,对关联程度大小进行量化,对更好地分析废钢市场走势有较好的指导意义。 相似文献