排序方式: 共有53条查询结果,搜索用时 156 毫秒
31.
Macedo-Sousa JA Gerhardt A Brett CM Nogueira AJ Soares AM 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):966-973
The drainage of abandoned mines leads to several ecological problems, particularly the acidification of surface freshwater systems and heavy metal contamination. In order to study the possibility of using the behavioural early warning responses of Portuguese indigenous benthic invertebrates to detect an acute short-term pulse of Acid Mine Drainage (AMD), experiments with the Multispecies Freshwater Biomonitor MFB™ were performed and locomotion and ventilation were measured as endpoints. AMD was collected from the “São Domingos” mine (Southeast Portugal) and the following species were selected: Echinogammarus meridionalis (Pinkster, 1973), Hydropsyche pellucidula (Curtis, 1834) and Choroterpes picteti (Eaton, 1870). For simulating the pulsed exposure, AMD was added to river water where invertebrates were collected and pH was lowered until reaching 3.5. The effects of H+ and heavy metals were discriminated using HCl positive controls. In addition to behaviour, mortality was registered. E. meridionalis was the most sensitive species in terms of mortality and behavioural endpoints, followed by C. picteti and H. pellucidula. E. meridionalis early warning responses consisted of increased locomotion with subsequent increase in ventilation, whereas for C. picteti only an increase in locomotion was observed. H. pellucidula showed no early warning responses. This work demonstrates the suitableness of using benthic invertebrates' behavioural early warning responses for detecting spikes of pollutants like AMD. 相似文献
32.
王利佳 《辽宁城乡环境科技》2004,24(2):22-23,25
介绍了CODCr在线自动监测仪器的测试原理及功能试验,得出该仪器测量结果与国家标准方法对CODCr的测定无显著差异的结论。 相似文献
33.
对web在线中文输入法网站进行了研究,报告了其存在的安全问题,提出了一种基于Servlet和Applet技术的安全的web在线中文输入法系统实现框架,并着重分析了安全策略机制和快速码表查找方法,达到了保护输入法知识产权和程序核心代码的目的. 相似文献
34.
J. Arteta S. Cautenet M. Taghavi N. Audiffren 《Atmospheric environment (Oxford, England : 1994)》2006,40(40):7983-8001
Air quality models (AQM) consist of many modules (meteorology, emission, chemistry, deposition), and in some conditions such as: vicinity of clouds or aerosols plumes, complex local circulations (mountains, sea breezes), fully coupled models (online method) are necessary. In order to study the impact of lumped chemical mechanisms in AQM simulations, we examine the ability of both different chemical mechanisms: (i) simplified: Condensed Version of the MOdèle de Chimie Atmosphérique 2.2 (CV-MOCA2.2), and (ii) reference: Regional Atmospheric Chemistry Model (RACM), which are coupled online with the Regional Atmospheric Modeling Systems (RAMS) model, on the distribution of pollutants. During the ESCOMPTE experiment (Expérience sur Site pour COntraindre les Modèles de Pollution et de Transport d’Emissions) conducted over Southern France (including urban and industrial zones), Intensive observation periods (IOP) characterized by various meteorological and mixed chemical conditions are simulated. For both configurations of modeling, numerical results are compared with surface measurements (75 stations) for primary (NOx) and secondary (O3) species. We point out the impact of the two different chemical mechanisms on the production of species involved in the oxidizing capacity such as ozone and radicals within urban and industrial areas. We highlight that both chemical mechanisms produce very similar results for the main pollutants (NOx and O3) in three-dimensional (3D) distribution, despite large discrepancies in 0D modeling. For ozone concentration, we found sometimes small differences (5–10 ppb) between the mechanisms under study according to the cases (polluted or not). The relative difference between the two mechanisms over the whole domain is only −7% for ozone from CV-MOCA 2.2 versus RACM. When the order of magnitude is needed rather than an accurate estimate, a reduced mechanism is satisfactory. It has the advantage of running faster (four times less than CPU time on SGI 3800 with 30 processors). Simplified mechanisms are really important to study cases for which an online coupling is necessary between meso-scale and chemistry models (clouds or aerosols plumes impacts, highly variable meteorology). 相似文献
35.
为判断环境空气污染的程度,提出一种考虑道路扬尘特性的环境空气质量在线监测方法。通过前端数据监测模块采集大气环境数据,基于光全散射法监测道路扬尘的质量浓度和密度;通过监测通信模块将监测结果传送至云服务器;云服务器利用基于极限学习机神经网络的预测模型,采用自适应粒子群优化算法,获取最佳的环境空气质量在线监测结果。结果表明,该方法学习速率的取值为0.5时,能够完成颗粒物浓度和密度的准确检测,且解释方差<2%,同时能够监测扬尘颗粒的扩散时间,确定适合活动的区域。 相似文献
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伴随着我国社会现代化程度和城市化进程的不断加深,社会得到了非常好的发展,但同时也产生了大量的废气和废水,对生态环境造成了严重破坏。因此,为了将这个问题良好的解决,应建立一套具有较高科学性和合理性的废水废气污染源在线监测系统,并加大日常维护及故障处理的力度,从根源减少人们在工作生活中对生态环境造成的影响。因此,本文针对废水废气污染源在线监测系统日常维护及故障处理的有效措施,展开详细的分析,以期能够为我国生态环境可持续发展目标的实现贡献应有的力量。 相似文献
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《Environmental Communication: A Journal of Nature and Culture》2013,7(2):278-284
This article examines online discourse in 2011 surrounding the proposed Duke Energy and Progress Energy merger in the Carolinas. It explores how issues pertaining to the merger, including constructing new nuclear plants, are discussed in media coverage and by citizens using social media. Overall, we find that the merger discourse focuses on economic concerns rather than the environmental concerns we had anticipated. However, post-Fukushima discourse appears to have become more inclusive of environmental concerns. We conclude that environmental discussions and efforts are likely to be globally informed andlocally situated, discussing the implications for environmental communication research exploring online discourses, specifically through social media. Future research must address how to locate and delineate constellations of locally situated discourse to provide a clearer picture of environmentally focused social media communication. 相似文献
40.
Valto P Knuutinen J Alén R 《Environmental science and pollution research international》2009,16(3):287-294
Background, aim, and scope In papermaking, there is a continuous interest both to minimize fresh water consumption and to reduce discharges into the
environment. These general trends mean an increase in the amounts of detrimental substances, such as resin and fatty acids,
in papermaking process waters. Resin acids, in particular, are responsible for much of the toxicity typically present in paper
mill effluents and, for this reason, the routine and rapid monitoring of these compounds in various process streams is necessary.
This also means that there is a continuous need to develop straightforward offline and online techniques to clarify problems
occurring, for example, as a result of the introduction of more intensively closed systems of water circulation. In the present
study, we describe the use of a novel, online, sample enrichment technique followed by atmospheric pressure chemical ionization–mass
spectrometry (APCI-MS) suitable for monitoring the concentration levels of common resin and fatty acids in papermaking process
waters.
Materials and methods The representative process water samples were taken from the grinding zone of a thermomechanical pulping mill. The samples
were first preconcentrated in a precolumn C18, and the analytes were transferred online to MS. The high intensive [M–H]− ion was used for the identification of each analyte since, according to the present ionization method, no other fragmentation
was observed. Laboratory-scale, online measurements with an online sample feed were carried out by connecting a centrifugal
pump and a ceramic filter to the APCI-MS.
Results Quality parameters, such as repeatability, linearity, and limit of detection (LOD), were determined by using dehydroabietic
acid (DHAA) in order to evaluate the suitability of the method for the rapid screening of concentration levels. This method
provided satisfactory linearity and a good correlation between analyte concentration and peak area. The suitability of the
system for the continuous analysis of the same acids was evaluated in laboratory-scale, online experiments. In all cases,
the response to changes in the analyte concentration was linear, and the repeatability of the system was also satisfactory.
Discussion Only a few studies have been published on the analysis of resin and fatty acids with MS techniques. The present method was
applied to the monitoring of dehydroabietic, oleic, and stearic acids. The quality parameters were highly comparable with
those reported earlier, and the LOD values of the DHAA were below the levels usually encountered in process waters. The quality
parameters were only slightly higher than those obtained by the traditional methods of analysis, probably due to the absence
of an effective sample clean-up before analysis.
Conclusions The results of the laboratory-scale, online experiments indicated that the online enrichment APCI-MS system is a suitable
alternative for monitoring the concentration levels of selected resin and fatty acids in papermaking process waters. The method
can be used, for example, to provide useful information about the concentration levels of these acids in different stages
of the process, thus signaling possibly impending problems. In general, faster and simpler measurements are needed to meet
the requirements for a reduction in fresh water usage in papermaking.
Recommendations and perspectives Compared to the conventional methods used for this purpose, the main benefits of the method are rapidity of measurement, simplicity
of use, and absence of the need for multistage sample treatments (short analysis time). For this reason, this online method
is more suitable for the control of papermaking by analyzing the concentration levels of interfering substances (i.e., selected
resin and fatty acids) than an offline analysis detailing all the individual extractives-based compounds in process streams.
It is also obvious that the technique can easily be modified for other environmental pollutants as well. 相似文献