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141.
142.
Comparative study of microbial community structure in different filter media of constructed wetland 总被引:3,自引:0,他引:3
Comparisons of microbial community structure, in eight filter media of zeolites, anthracite, shale, vermiculite, ceramic filter media, gravel, steel slag and bio-ceramic, were undertaken by analyzing the phospholipid fatty acid (PLFA) composition. A total of 20 fatty acids in the range of C_(11) to C_(20) were determined but only 13 PLFAs were detected in steel slag. They consist of saturated fatty acids, branched fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids. The variation of fatty acids was revealed in the relative proportions of these fatty acids in different media. The aerobic prokaryotes were the predominant group in all media. The PLFA composition showed significant differences among the eight different media by Tukey's honestly test. It was found that steel slag was significantly different in the microbial community as compared to other filter media, probably due to its alkaline effluent. Steel slag alone is probably not a good choice of substratum in constructed wetlands. The principle components analysis (PCA) showed that zeolites, bio-ceramic, shale and vermiculite had a similar microbial community structure while steel slag and ceramic filter media were distinct from other media. 相似文献
143.
填料对曝气生物滤池影响的概述 总被引:1,自引:0,他引:1
曝气生物滤池因为其优越的自身条件,逐渐成为世界各国首选的处理各种污水的处理装置。而填料作为曝气生物滤池最关键影响因素引起广泛关注。文章简单介绍了填料的研究进展,对填料上生物膜的形成以及其填料净化机理等方面进行了研究;填料的选择是滤池设计和出水水质的关键因素。填料的类型、粒径、密度、高度对曝气生物滤池的效能有重要影响。尽管目前填料种类繁多,但由于曝气生物滤池除磷能力较弱,希望开发更多新型曝气生物滤池填料类型,更好地满足各种类型废水的处理。 相似文献
144.
Analytical solutions of three-dimensional contaminant transport in uniform flow field in porous media: A library 总被引:1,自引:0,他引:1
Hongtao Wang Huayong Wu 《Frontiers of Environmental Science & Engineering in China》2009,3(1):112-128
The purpose of this study is to present a library of analytical solutions for the three-dimensional contaminant transport
in uniform flow field in porous media with the first-order decay, linear sorption, and zero-order production. The library
is constructed using Green’s function method (GFM) in combination with available solutions. The library covers a wide range
of solutions for various conditions. The aquifer can be vertically finite, semi-infinitive or infinitive, and laterally semi-infinitive
or infinitive. The geometry of the sources can be of point, line, plane or volumetric body; and the source release can be
continuous, instantaneous, or by following a given function over time. Dimensionless forms of the solutions are also proposed.
A computer code FlowCAS is developed to calculate the solutions. Calculated results demonstrate the correctness of the presented
solutions. The library is widely applicable to solve contaminant transport problems of one- or multiple- dimensions in uniform
flow fields. 相似文献
145.
滤料表面的ζ电位是评价滤料颗粒表面性质的重要指标之一,研究滤料表面的ζ电位对于提高过滤效率以及开发改性滤料是十分重要的.根据流动电位与ζ电位的关系自制了一套测定ζ电位的装置,经测定计算出了4种常用水处理滤料表面的ζ电位,结果表明:当滤料的粒径范围在0.45~0.9mm之间时,使用该装置测得的磁铁矿、无烟煤、核桃壳和陶粒表面ζ电位分别为-27.64mV、-6.54mV、-5.87mV、-2.30mV.电子能谱和红外光谱分析结果证明磁铁矿、无烟煤、核桃壳和陶粒滤料表面ζ电位的差异主要归因于其表面化学结构的不同. 相似文献
146.
根据Matlab软件和数值计算前处理软件Gambit中的Journal文件建立了多层复合纤维滤料模型,利用计算流体动力学(CFD)技术对沿气流方向具有不同纤维填充密度及直径分布的滤料内部的气-固两相流动特性进行了数值研究,计算了不同运行条件下滤料的压力损失及过滤效率,并将数值计算值和经典模型及实验关联式的计算值进行了比较.结果表明,压力损失的数值计算预测值和实验关联式计算值吻合较好,误差在2%以内.随着迎面风速的增加,压力损失呈线性增加.相对于填充密度,纤维直径对压力损失和过滤效率的影响更显著.不同结构滤料过滤效率的数值计算结果和理论模型的计算值变化趋势基本一致.不同迎面风速下,过滤效率都是先减小后增大,对于颗粒直径dp≤0.05μm的颗粒,随着风速的增大,过滤效率减小;对于dp≥0.5μm的颗粒,过滤效率变化趋势正好相反.迎面风速不同,过滤效率最低点出现的位置也不同.对于小颗粒,风速越小,扩散作用起主导作用;而对于大颗粒,风速越大,惯性作用越明显.过滤效率最低点出现在扩散作用逐渐弱化,惯性作用刚刚开始加强的区域.多层复合滤料在结构上采用纤维直径逐层加大的梯次结构时,能够获得较高的过滤效率.而在多层复合滤料表面覆膜后过滤效率平均增加约13%. 相似文献
147.
《Environmental Communication: A Journal of Nature and Culture》2013,7(6):713-722
ABSTRACTThe media play a vital role in framing the narrative on climate change, however little work exists to assess the extent to which local media outlets increase public engagement on climate change through interaction and engagement with local academics. As temperatures rise and concerns mount that we have passed the tipping point, local media play a potentially critical role in communicating how climate change exacerbates their impact. Based on a review of extant literature on this topic, and a small pilot email survey, this article argues that scientists could be more active in increasing local salience of climate change by building trusted relationships with local media. Coverage of science in the media could benefit from closer engagement with local scientists as environmental stories often get more coverage in local media (compared to national media) which constitute an important source of knowledge on climate change. This would enable constructive discussions between local media and scientists, better translation of science to publics, increased awareness and interest of science production locally, and ultimately creating a trusted intermediary in the science-public interface. 相似文献
148.
《Environmental Communication: A Journal of Nature and Culture》2013,7(8):1108-1127
ABSTRACTThis article analyzes the emergence of a new environmental issue in the German press. Since the 1990s, scientists have detected traces of pharmaceuticals, hormones and chemicals in all segments of the water cycle. These micropollutants have negative effects on aquatic life and might affect human health. Their sources are manifold and include private households. Yet although micropollutants of are direct concern to media audiences, they are a challenging topic for news reporting. Although this issue is systemic and fraught with uncertainty, it does not easily translate into news stories. Our content analysis of 444 articles (1995–2015) reveals that the societal risk was rarely presented as a stand-alone topic. Instead, the issue was mostly covered as part of local routine reporting and framed as a challenge for experts to solve. Over time, the reporting became more managerial, while media framings of micropollutants gained more substance and scope. We contend that local routine reporting should receive more attention as a public forum for addressing emerging environmental concerns. 相似文献
149.
《Environmental Communication: A Journal of Nature and Culture》2013,7(3):269-287
It is 30 years since the Australian environmental movement enlisted the term “wilderness” to protect Tasmania's remote Franklin River from hydroelectric development. Environmentalists deployed “wilderness” strategically during the conflict to build public support for their no-dam campaign, aided by national and international media who used the term liberally, while Tasmanian news media and pro-development elites acknowledged the term's inherent political qualities by suppressing its use. Our interest is in the political and media framing of “wilderness” since the concept was “branded” by government and industry at the turn of the twenty-first century. Drawing on continuing environmental conflict over Tasmania's remote Tarkine region as a case study, we ask to what extent media portrayals of “wilderness” have changed since the Franklin dam was stopped and the Tasmanian World Heritage Wilderness Area was created in 1982. Using content analysis of related articles in the local media and qualitative analysis of international travel journalism about Tasmania published over an extended period, we find that place branding has contributed to the routinization of “wilderness” and to a shift in the focus of mediated conflict from “wilderness” to “tourism.” The Tasmanian experience demonstrates that while the actions of the environmental movement can valorize place, branding can depoliticize contested natural areas. Yet brands that incorporate or allude to “wilderness” may have the unanticipated consequence of valorizing “wilderness” transnationally, in a manner that the environmental movement would struggle to emulate. 相似文献
150.
《Environmental Communication: A Journal of Nature and Culture》2013,7(3):307-325
There is strong evidence that a meat and dairy-based diet is a very important contributor to climate change. However, the correlation between the production and consumption of livestock and anthropogenic climate change has received minimal media coverage. The literature for English-speaking countries shows a sort of media blind spot for meat in that the news media barely address, or do not address, the responsibility of individuals' dietary choices with regard to this issue. In this paper, we provide data for press coverage in Southern Europe from a sample of the top 10 Spanish and Italian newspapers for a seven-year period (2006–2013). Data from our samples correlate with findings from previous studies. However, our comparative study suggests that there are also meaningful differences between both countries studied while their alleged Mediterranean dietary background makes no difference in terms of ethical or dietary sensitivity. 相似文献