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Mercury is released to the environment from various anthropogenic and natural sources. This work is a compilation of mercury emissions from anthropogenic sources in Ontario, Canada. The goal of our study was to identify all sources of mercury, and develop an emission inventory of anthropogenic mercury in Ontario. The result of our investigation revealed that combustion of fossil fuels and emissions from landfill sites are two primary sources of mercury to the atmosphere. Other sources of significance are emissions from waste incinerators, various industrial activities, and cement production. Total mercury emission in Ontario is estimated as 4100 kg per year. 相似文献
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Tarhule Aondover Woo Ming-ko 《Mitigation and Adaptation Strategies for Global Change》2002,7(3):215-237
Domestic and agro-economic activities in the semi-arid region of Nigeria rely exclusively on rainfall, streamflow and groundwater in deep and alluvial (fadama) aquifers. Such water supply systems are subject to considerable seasonal and inter-annual variability. However, a combination of the various sources may mitigate the effects of water scarcity. This study describes the dynamics of the water sources for a village in northeastern Nigeria as an example that demonstrates the linkages between rainfall, streamflow and groundwater. Such linkages are important for developing strategies to mitigate the effects of climatic variation. Long-term records of rainfall were not available at the site so that the short-term data was interpreted in the context of the long-term climatic experience of the region. The stratigraphic profile of the aquifer was developed from resistivity methods, to supplement information obtained from well level hydrographs. Field observations and analysis of the data reveal that the beginning of the rainy season is a precarious period because none of the water sources are reliable. Rainfall infiltration recharges the shallow aquifers while lateral water flux from the floodwater-saturated fadama also contributes to water level rises in the deep wells. A study of the water level changes in response to deepening of the wells suggests that the wells are fed by an assortment of water-bearing lenses, separated by layers of low transmissivity. One major finding of this study is that there exists a close association between the wells in this riparian community and the recharge processes within the fadama. Upstream diversion, abstraction or impoundment could therefore undermine the viability of aquifer exploitation by the communities in the riparian zone. Analysis of the interactions among the various sources of water leads to the identification of several potential adaptation strategies for confronting the problem of water scarcity. 相似文献
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以锦州化工二厂生产的2#环烷酸为原料,采用减压蒸馏──初馏分皂化萃取脱油工艺,可制得中性油含量分别低于10%和5%的一级品环烷酸.该工艺具有流程简单、物料消耗少、产品收率高等优点.通过实验,初步探讨了蒸馏真空度、氢氧化钠浓度及用量、乙醇用量、萃取剂用量等工艺条件对脱油效果及产品质量的影响。 相似文献
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根据现行的上海市和国家的超标污水征收标准的特点,提出制定新标准的5项原则。新标准的制定方案中,确定以y=a.x^β费用函数基础;用数理统计等方法,通过对污染排放标准,处理深度和处理费用3者关系的处理,得出二类污染物中,1级收费标准比现行2级收费标准上升30%、2级收费采用现行标准、3级收费标准比现行标准下降20-30%;并提出污染物收费的计算公式,经对方案的论证和测算,说明其有效好的可行性。 相似文献
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Fed-batch cultures of recombinantEscherichia coli strains were carried out for the production of poly(3-hydroxybutyric acid) (PHB) in a chemically defined medium. TheE. coli strains used were XL1-Blue, harboring pSYL105, a stable high-copy number plasmid containing theAlcaligenes eutrophus polyhydroxyalkanoate (PHA) genes, and XL1-Blue, harboring pSYL107, which is pSYL105 containing theE. coli ftsZ gene to suppress filamentation. With XL1-Blue(pSYL105) the final cell mass and PHB concentration obtained in 62 h were 102 and 22.5 g/L, respectively. Fed-batch culture of XL1-Blue(pSYL107) under identical conditions resulted in a final cell mass and PHB concentration of 127.5 and 48.2 g/L, respectively. The PHB contents obtained with XL1-Blue(pSYL105) and XL1-Blue(pSYL107) were 22.1 and 37.8%, respectively. Therefore, PHB was more efficiently produced in a defined medium by employing filamentation-suppressed recombinantE. coli. 相似文献
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Effect of amorphous silica and silica sand on removal of chromium(VI) by zero-valent iron 总被引:1,自引:0,他引:1
The effect of two surfaces (amorphous silica and silica sand) on the reduction of chromium(VI) by zero-valent iron (Fe(0)) was investigated using batch reactors. The amendment of both surfaces significantly increased the rate and extent of Cr(VI) removal. The rate enhancement by amended surfaces is presumed to result from scavenging of Fe(0)-Cr(VI) reaction products by the provided surfaces, which minimized surface deactivation of Fe(0). The rate enhancing effect was greater for silica compared to sand, and the difference is attributed to silica's higher surface area, greater affinity for reaction products and pH buffering effect. For a given mass of Fe(0), the reactivity and longevity of Fe(0) to treat Cr(VI) increased with increasing dose of silica. Elemental analyses of the reacted iron and silica revealed that chromium removed from the solution was associated with both surfaces, with its mass distribution being approximately 1:1 per mass of iron and silica. The overall result suggests reductive precipitation was a predominant Cr(VI) removal pathway, which involves initial reduction of Cr(VI) to Cr(III), followed by formation of Cr(III)/Fe(III) hydroxides precipitates. 相似文献
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Felton Adam Petersson Lisa Nilsson Oscar Witzell Johanna Cleary Michelle Felton Annika M. Björkman Christer Sang Åsa Ode Jonsell Mats Holmström Emma Nilsson Urban Rönnberg Jonas Kalén Christer Lindbladh Matts 《Ambio》2020,49(5):1035-1049
Ambio - The choice of tree species used in production forests matters for biodiversity and ecosystem services. In Sweden, damage to young production forests by large browsing herbivores is helping... 相似文献