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针对当前认为电-袋复合除尘器是一种新的除尘技术的观点,分析探讨了目前国内采用的电-袋复合除尘器的功效,指出电-袋复合除尘器实际为前电后袋式的电-袋结合除尘器,因而存在许多弊端,并不能克服电除尘器和袋式除尘器各自的缺点。 相似文献
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针对电-袋复合式除尘器的特点,分析了电-袋复合式除尘器在运行过程中应注意的事项,提出了电-袋复合式除尘工艺过程的运行管理要求,探讨了电-袋复合除尘器设备管理以及现场运行参数的设定,以实现提高电-袋复合式除尘器使用寿命及降低能耗的目的。 相似文献
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目前国家批建的火力发电燃煤机组主要为600MW及以上的大型机组,结合新的粉尘浓度≤30mg/Nm3的排放标准要求,本文根据大型燃煤机组主流配套的三种高效除尘设备(电除尘器、袋式除尘器、电袋复合除尘器)的设计经验,对其技术经济性进行了对比分析,结果表明,电袋复合除尘器的综合技术经济性优势明显。 相似文献
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以出口首台实现烟尘超低排放的土耳其泽塔斯三期2×660MW机组超净电袋复合除尘器为研究对象,分析超净电袋复合除尘技术的原理和措施,并介绍了该工程的工艺方案,通过运行情况、测试结果及电厂反馈,证明超净电袋复合除尘技术大型化出口应用的可行性和稳定性。 相似文献
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A. U. Mallik 《Environmental management》1995,19(5):675-684
Fire and logging in nutrient-poor temperate forests with certain ericaceous understory plants may convert the forests into
heaths. The process of disturbance-induced heath formation is documented by using examples ofCalluna in western Europe,Kalmia in Newfoundland, andGaultheria (salal) in coastal British Columbia. In a cool, temperate climate, rapid vegetative growth ofCalluna, Kalmia, and salal following disturbance results in increasing organic accumulation (paludification), nutrient sequestration, soil
acidification, and allelochemicals. These are thought to be the main reasons to conifer regeneration failure in disturbed
habitats.
If continuation in forest is a land-use objective, then temperate forests with an ericaceous understory should not be logged
unless effective silvicultural methods are devised to control the ericaceous plants and restore forest regeneration. Preharvest
vegetation control may be considered as an option. Failure to control the understory plants may lead to a long-term vegetation
shift, from forest to heathland, particularly in nutrient-poor sites. Successful methods of controllingKalmia andGaultheria, however, have yet to be developed. While theKalmia- andGaultheria- dominated heathlands are undesirable in Canada and the Pacific Northwest, a wide range ofCalluna heathlands of western Europe are being conserved as natural and seminatural vegetation. 相似文献
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Carl J. Sindermann 《Journal of the American Water Resources Association》1988,24(5):931-939
ABSTRACT: Sustained interest in and concern about the health status of the aquatic environment has resulted in extensive research focused on (1) effects of pollution on survival, growth, and reproduction of resource species at all life stages; (2) diseases of fish and shellfish, as they may be related to pollution and as they may serve as indicators of environmental stress; and (3) contaminant body burdens in fish and shellfish - their effects on the aquatic animals and their potential effects on humans. Effects, lethal and sublethal, of pollutants on life history stages of fish and shellfish have been documented, as have impacts on local stocks in badly degraded habitats, but as yet there has been no adequate quantitative demonstration of effects on entire aquatic species - probably because of the difficulty in sorting out relative effects of the many environmental factors that influence abundance. Sublethal effects, especially those that result in disease, have been examined intensively, and some diseases and disease syndromes have been associated statistically with pollution. Other pollution indicators (biochemical, physiological, genetic, behavioral, and ecological) have also received some attention, as have body burdens of contaminants in aquatic species. Research, especially that conducted during the past decade, has done much to clarify the many pathways and toxic effects of contaminants on aquatic animals, and has also helped to identify mechanisms for survival of fish and shellfish in the presence of environmental changes caused by human activities. 相似文献
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Pickett ST Cadenasso ML Grove JM Boone CG Groffman PM Irwin E Kaushal SS Marshall V McGrath BP Nilon CH Pouyat RV Szlavecz K Troy A Warren P 《Journal of environmental management》2011,92(3):331-362
Urban ecological studies, including focus on cities, suburbs, and exurbs, while having deep roots in the early to mid 20th century, have burgeoned in the last several decades. We use the state factor approach to highlight the role of important aspects of climate, substrate, organisms, relief, and time in differentiating urban from non-urban areas, and for determining heterogeneity within spatially extensive metropolitan areas. In addition to reviewing key findings relevant to each state factor, we note the emergence of tentative "urban syndromes" concerning soils, streams, wildlife and plants, and homogenization of certain ecosystem functions, such as soil organic carbon dynamics. We note the utility of the ecosystem approach, the human ecosystem framework, and watersheds as integrative tools to tie information about multiple state factors together. The organismal component of urban complexes includes the social organization of the human population, and we review key modes by which human populations within urban areas are differentiated, and how such differentiation affects environmentally relevant actions. Emerging syntheses in land change science and ecological urban design are also summarized. The multifaceted frameworks and the growing urban knowledge base do however identify some pressing research needs. 相似文献
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Justin D. Burdine 《Local Environment》2018,23(2):198-219
Urban gardens are important sources of sustenance for communities with limited access to food. Hence, this study focuses on food production in gardens in the Toledo metropolitan area in Northwest Ohio. We administered surveys to 150 garden managers from November 2014 to February 2015 in our attempt to better understand how neighbourhood racial composition and poverty levels are related to staffing and voluntarism, food production and distribution, the development of infrastructure, and the adoption of sustainability practices in urban gardens. The results from 30 gardens are presented in this paper. We used Geographic Information Systems to map the gardens and overlay the map with 2010 census data so that we could conduct demographic analyses of the neighbourhoods in which the gardens were located. Though the gardens were small – two acres or less – up to 46 varieties of food were grown in a single garden. Gardens also operated on small budgets. Food from the gardens was gifted or shared with friends, family, and neighbourhood residents. Gardens in predominantly minority neighbourhoods tended to have fewer institutional partners, less garden infrastructure, and had adopted fewer sustainable practices than gardens in predominantly White neighbourhoods. Nonetheless, residents of predominantly minority and high-poverty neighbourhoods participated in garden activities and influenced garden operations. Volunteering and staffing were racialised and gendered. 相似文献
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All major journalism ethical codes explicitly state that journalists should protect editorial copy from undue influence by
outside sources. However, much of the previous research on agricultural information has concentrated on what information various
media communicate (gatekeeping studies) or communication's role in increasing innovation adoption (diffusion studies). Few
studies have concentrated specifically on organizational and structural constraints that might adversely affect agricultural
journalists' ethical standards; those that have, focus largely on farm magazines. A study of newspaper reporters who cover
agricultural news found that the most pressing ethical concern is the effect of advertiser (agri-business) pressure on editorial
copy, and that their concerns in general parallel those of farm magazine writers and editors. The majority reported being
in situations in which they might be exposed to advertiser pressure, including pressures to change or withhold editorial copy.
Large minorities suggested that advertising pressures affect the overall environment in which agricultural journalists work,
and more than one in ten said they allow advertiser pressures to influence editorial decisions. The newspaper reporters who
cover agricultural beats showed slightly more resistance to advertiser pressure than did farm magazine editors in a parallel
study. 相似文献
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Mapped environmental classifications are defined using various procedures, but there has been little evaluation of the differences
in their ability to discriminate variation in independent ecological characteristics. We tested the performance of environmental
classifications of the streams and rivers of France that had been defined from the same environmental data using geographic
regionalization and numerical classification of individual river valley segments. Test data comprised invertebrate assemblages,
water chemistry, and hydrological indexes obtained from sites throughout France. Classification performance was measured by
analysis of similarity (ANOSIM). Geometric regions defined by a regular grid and without regard to environmental variables
and a posteriori classifications based on clustering the test datasets defined lower and upper bounds of performance for a
given number of classes. Differences in classification performances were generally small. The ANOSIM statistics for the a
posteriori classifications were around twice that of all environmental classifications, including geometrically defined regions.
The hydro-ecoregions performed slightly better for the invertebrate data and the network classification performed slightly
better for the chemistry and hydrological data. Our results indicate that environmental classifications that are defined using
different procedures can be comparable in terms of their ability to discriminate variation of ecological characteristics and
that alleged differences in performance arising from different classification procedures can be small relative to unexplained
variation. We conclude that definition procedures might have little effect on the performance of large-scale environmental
classifications and decisions over which procedures to use should be based primarily on pragmatic considerations. 相似文献
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Collisions with deer and other large animals are increasing, and the resulting economic costs and risks to public safety have made mitigation measures a priority for both city and wildlife managers. We created landscape models to describe and predict deer-vehicle collision (DVCs) within the City of Edmonton, Alberta. Models based on roadside characteristics revealed that DVCs occurred frequently where roadside vegetation was both denser and more diverse, and that DVCs were more likely to occur when the groomed width of roadside right-of-ways was smaller. No DVCs occurred where the width of the vegetation-free or manicured roadside buffer was greater than 40 m. Landscape-based models showed that DVCs were more likely in more heterogeneous landscapes where road densities were lower and speed limits were higher, and where non-forested vegetation such as farmland was in closer proximity to larger tracts of forest. These models can help wildlife and transportation managers to identify locations of high collision frequency for mitigation. Modifying certain landscape and roadside habitats can be an effective way to reduce deer-vehicle collisions. 相似文献
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Paul M. Bradley Jeffrey H. Writer 《Journal of the American Water Resources Association》2014,50(2):334-342
Biodegradation of [A‐ring 14C] Estrone (E1), 17β‐estradiol (E2), and 17α‐ethinylestradiol (EE2) to 14CO2 was investigated under light and dark conditions in microcosms containing epilithon or sediment collected from Boulder Creek, Colorado. Mineralization of the estrogen A‐ring was observed in all sediment treatments, but not epilithon treatments. No difference in net mineralization between light and dark treatments was observed for 14C‐E2. Net mineralization of 14C‐E1 and 14C‐EE2 was enhanced in light treatments. Extents of 14CO2 accumulation and rates of mineralization were significantly greater for E2 than E1 under dark conditions, but were comparable under light conditions. These results indicate substantial differences in the uptake and metabolism of E1 and E2 in the environment and suggest biorecalcitrance of E1 relative to E2 in light‐limited environments. The extent of 14CO2 accumulation and rate of mineralization for EE2 in dark treatments were less than half of that observed for E2 and generally lower than for E1, consistent with previous reports of EE2 biorecalcitrance. However, 14CO2 accumulation and rates of mineralization were comparable for EE2, E2, and E1 under light conditions. These results indicate photoactivation and/or phototransformation/photodegradation processes can substantially enhance heterotrophic biodegradation of estrogens in sunlit environments and may play an important role in estrogen transport and attenuation. 相似文献
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《International Journal of Green Energy》2013,10(3):301-312
Abstract Sustainable ecosystems can be designed to eliminate environmental toxins and reduce pathogen loads through the direct and indirect consequences of plant and microbial activities. We present an approach to the bioremediation of disturbed environments, focusing on petroleum hydrocarbon (PHC) contaminants. Treatment consists of incorporating a plant-based amendment to enhance ecosystem productivity and physiochemical degradation followed by the establishment of plants to serve as oxidizers and foundations for microbial communities. Promising amendments for widespread use are entire plants of the water fern Azolla and seed meal of Brassica napus (rapeseed). An inexpensive byproduct from the manufacture of biodiesel and lubricants, rapeseed meal is high in nitrogen (6% wt/wt), stimulates >100-fold increases in populations of resident Streptomyces species, and suppresses fungal infection of roots subsequently cultivated in the amended soil. Synergistic enzymatic and chemical activities of plant and microbial metabolism in root zones transform and degrade soil contaminants. Emphasis is given to mechanisms that enable PHC functionalization via reactive molecular species. 相似文献
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Zimbabwean provincial plans were instituted to help in the achievement of the national goal of the creation of an egalitarian, socialist and integrated society. The national goal itself was adopted as an antithesis to the dualist society characterised by spatial, economic, social, politican and technological inequalities that Zimbabwe inherited from colonialism. This meant that provincial plans had to play both a functional (or growth allocating/distribution) and a territorial (or redistribution) role.
This paper reviews their role in achieving the national goal by examining their functions, content, structure and methodology. The paper concludes that because of their nature, provincial plans are not suitable tools for the achievement of the national goal. 相似文献