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1.
Measured by weight, copper is the third most important metal used by man. The annual value of its 2007 output was on a par with the GDP of e.g. Ukraine. Copper is also one of the oldest metals, its employment going back 7000 years. For millennia, it was predominantly employed for decorative purposes, coinage and in warfare. Technical breakthroughs in antiquity, like smelting and alloying, expanded its production and enhanced its utility. Copper's true heyday occurred after 1850, with the usage of electricity. In the period since then, volumes increased 300-fold, while costs and prices declined. With impressive progress in the technology of its production and consumption, the red metal has been able to hold its own, despite the emergence over history of formidable substitutes like iron, aluminum, plastics and optic fiber. 相似文献
2.
Environmental site assessment criteria were originally developed by organizations that focused, almost exclusively, on surface,
subsurface, and pollution source contamination. Many of the hazards associated with indoor environments and building structures
were traditionally not considered when evaluating sources and entities of environmental pollution. Since a large number of
building materials are potentially hazardous, careful evaluation is necessary. Until recently, little information on building
inspection requirements of environmental problems has been published. Traditionally, asbestos has been the main component
of concern. The ever-changing environmental standards have dramatically expanded the scope of building surveys. Indoor environmental
concerns, for example, currently include formaldehyde, lead-based paint, polychlorinated biphenyls, radon, and indoor air
pollution. Environmental regulations are being expanded and developed that specifically include building structures. These
regulatory standards are being triggered by an increased awareness of health effects from indoor exposure, fires, spills,
and other accidents that have resulted in injury, death, and financial loss. This article discusses various aspects of assessments
for building structures. 相似文献
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4.
How consumers might switch from gasoline and diesel to alternative energy sources is not known, since the availability of alternatives is currently very limited. To bridge this gap, we exploit exogenous variation in ethanol prices at Brazil's pumps and uncover substantial consumer heterogeneity in the choice between long-established gasoline and an alternative that is similarly available and usable: sugarcane ethanol. We observe roughly 20% of flexible-fuel motorists choosing gasoline when gasoline is priced 20% above ethanol in energy-adjusted terms ($/mile) and, similarly, 20% of motorists choosing ethanol when ethanol is priced 20% above gasoline. We use transaction-level data to explore “non-price” characteristics which differentiate the two goods in the minds of different groups of consumers. Our findings suggest—and a counterfactual illustrates—that switching away from gasoline en masse, should this be desired, would require considerable price discounts to boost voluntary adoption, in the US and elsewhere. 相似文献
5.
夏治强 《城市环境与城市生态》1993,6(4):37-42
本文简介了臭氧层的破坏及耗损对生物和人类所造成的危害.描述了氯氟烃(CFC),氮氧化物(NO_x)与臭氧的反应,井详细论述了CFC,NO_x及火山爆发对臭氧层的破坏作用.对有关保护臭氧层的国际公约进行了扼要介绍.提出了防止臭氧耗损应来取的措施;执行保护臭氧层的国际公约;寻找CFC替代品;加强对臭氧层的科学研究 相似文献
6.
We investigate whether positive framing increases cooperation in three social dilemmas with slightly different properties: a linear public goods (PG) game, a non-linear PG game, and a common pool resource (CPR) game. Results from our laboratory experiments show that contributions to a linear PG are higher if the externality is framed positively, rather than negatively, corroborating earlier findings by Andreoni (1995). By contrast, we find no such framing effects in the non-linear PG game or the CPR game. In these games, the best response in the material payoffs is to contribute less if others contribute more, counteracting effects of pro-social preferences. Positive framing therefore does not help to solve the tragedy of the commons. 相似文献
7.
A method involving high resolution gas chromatography combined with ion trap (HRGC-MS/MS) and negative chemical ionisation
(NCI) was developed for the determination of nitrated or oxygenated polycyclic aromatic hydrocarbons (nitro-PAHs, oxy-PAHs)
and other electrophilic substitutes in soil samples. Efficient clean-up was achieved by a combination of methods for the determination
of PAHs in soil and nitro-PAHs in aerosol using solid phase extraction (SPE) and semipreparative high performance liquid chromatography
(HPLC). In samples of surface soil from the city of Basle (Switzerland), nitro-PAHs (mainly 3-nitrofluoranthene and 1-nitropyrene)
were found in concentrations between 30 and 800 ng/kg dry weight. Oxy-PAHs and parent PAHs revealed 102-104-fold higher levels. Nitro-PAHs which are up to 105 times more mutagenic seem to be less persistent in soil than the parent forms, although their entire mutagenic potential
has to be estimated as being on the same order of magnitude. In urban air particulate matter, the amounts of nitro-PAHs (2–62
pg/m3) were 10–100 times lower than oxyPAHs and parent PAHs which were both found in a similar range. 3-nitrobenzanthrone, a recently
described suspected human carcinogen has not yet been detected. Using multivariate statistical analysis, it was possible to
elucidate similarities or special characteristics of substances in a given matrix reflecting their chemical properties or
specific emission sources. 相似文献
8.
PFOS及其4种替代品对两栖动物非洲爪蟾和黑斑蛙蝌蚪的急性毒性结果为:用调聚法合成的织物三防整理剂对非洲爪蟾蝌蚪和黑斑蛙蝌蚪的96h-LC50分别为8和21mg·L-1,而PFOS对两种蝌蚪的96h-LC50分别为92和81mg·L-1。此实验结果说明织物三防整理剂的急性毒性高于PFOS。用电解氟化法合成的C4、C6织物三防整理剂和50%的全氟丁基有机铵盐阳离子表面活性剂浓度在100mg·L-1时,对两种蝌蚪都没有毒性。这说明,从急性毒性的角度,C4、C6织物三防整理剂和表面活性剂可作为PFOS的替代品使用,但是织物三防整理剂的急性毒性比PFOS大,作为替代品使用应慎重考虑。另外,PFOS和织物三防整理剂对黑斑蛙蝌蚪的急性毒性与对非洲爪蟾蝌蚪的急性毒性存在差异。出于保护我国本土两栖动物的目的,使用黑斑蛙开展毒性评价比使用非洲爪蟾更有现实意义。 相似文献
9.
一次性塑料是指生产生活中使用一次或几乎不重复利用的塑料,约占塑料总消费量的50%,是塑料制品的重要构成部分.近年来,随着电子商务的兴起,一次性塑料的生产和消费量迅速增长.随着人们对塑料以及由此引起的微塑料污染危害的认识不断提高,国际社会对削减一次性塑料污染的呼声日益高涨,迫切需要开发可持续、环境友好的替代品以减少一次性塑料的消费量.从全球范围来看,一次性塑料制品替代主要包括非塑料材料替代和可生物降解塑料材料替代两大类.建议我国尽快完善相关立法和标准,鼓励一次性塑料制品替代并加强替代产品的质量监管;为一次性塑料制品替代提供差别化的产业政策,提高环境友好替代产品的市场竞争力,同时还应将一次性塑料制品的环境治理成本纳入其价格成本;鼓励科技创新,研发更具市场竞争力的替代材料和产品;最后,还要唤起社会公众的共同参与,主动选择替代产品并减少一次性塑料制品的使用,才能从源头上解决塑料垃圾的污染问题. 相似文献
10.
利用煤矸石熔制岩棉的机理与工艺研究 总被引:3,自引:0,他引:3
合理利用废弃物资源,防止环境污染是世界各国急待解决的问题.本文介绍了国内第一条煤矸石岩棉生产线的工艺设计及其年产万吨的生产性试验,表明该产品的主要技术性能已达到国家规定的优等品标准;并探讨了煤矸石熔制岩棉的机理,为煤矸石资源的高效益深度开发利用提供了新的途径. 相似文献