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261.
The photocatalytic disinfection of Escherichia coli K-12 is investigated by the natural sphalerite (NS) under different spectra, wavelengths and intensities of visible light (VL) emitted by light-emitting-diode lamp (LED). The spectrum effect of VL on disinfection efficiency is studied by using white LED, fluorescent tube (FT) and xenon lamp (XE), which indicates that the “discreted peak spectrum” of FT is more effective to inactivate bacteria than “continuous spectrum” of LED and XE. Besides, the photocatalytic disinfection of bacteria is compared under different single spectrum (blue, green, yellow and red color) LEDs. The results show that the most effective wavelength ranges of VL for photocatalytic disinfection with the NS are 440-490 and 570-620 nm. Furthermore, a positive relationship is obtained between the disinfection efficiency and the VL intensity. The experiment shows that NS can completely inactivate 107 cfu mL−1E. coli K-12 within 8 h irradiation by white LED with the intensity of 200 mW cm−2 at pH 8. Moreover, the destruction process of the cell wall and the cell membrane are directly observed by TEM. Finally, no bacterial colony can be detected within a 96 h regrowth test of inactivated bacteria, which reveals that the VL-photocatalytic disinfection leads to an irreversible damage to the bacterial cells. 相似文献
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An earthworm assay was used to assess the toxicity of two main gasoline components. Ecotoxicities of toluene and methyl tert-butyl ether (MTBE) were compared for Asian earthworm Perionyx excavatus separately and in combination. Sum of toxic unit (TU) at 50% mortality for the mixture (LC50mix) was estimated from the dose (TU-based)-response relationships by the Trimmed Spearman-Karber method. Toluene was shown to be about five and two times more toxic to P. excavatus than MTBE in filter paper contact test and natural soil tests, respectively. This is primarily due to the adsorption of toluene to soil particles, leading to less bioavailability of toluene to the earthworm in soil. The combined effect of toluene and MTBE was investigated using toxic unit model, and it was found to be almost additive and synergistic responses to P. excavatus in filter paper contact test and soil tests, respectively. The combined effect of toluene and MTBE in filter paper contact test was not consistent with the results in soil toxicity tests. This phenomenon may be associated with the interaction of soil salts with pollutants. Treatment with toluene and MTBE also affected the behavior and morphology of P. excavatus. It indicates that the VOCs induce metabolic and functional damages in earthworms. Combined effects of gasoline components should be taken into account to soil risk assessment. 相似文献
264.
Evaluation of the thermal/optical reflectance method for quantification of elemental carbon in sediments 总被引:2,自引:0,他引:2
The IMPROVE thermal/optical reflectance (TOR) method, commonly used for EC quantification in atmospheric aerosols, is applied to soils and sediments and compared with a thermochemical method commonly applied to these non-atmospheric samples. TOR determines elemental carbon (EC) by an optical method, but it also yields thermally defined EC fractions in a 2% O2/98% He oxidizing atmosphere at 550 degrees C (EC1), 700 degrees C (EC2), and 800 degrees C (EC3). Replicate TOR TC, OC, and EC values exhibited precisions of approximately +/-10% as determined from multiple analyses of the same samples. EC abundances relative to total mass concentrations were within the ranges reported by other methods for diesel exhaust soot, n-hexane soot, wood and rice chars, and coals, as well as for environmental matrices. A direct comparison with the chemothermal (CTO) method of Gustafson et al. for ten soil and sediment samples demonstrated that almost all of the OC and EC1 are eliminated, as is part of the EC2. The CTO soot carbon is bounded by the EC3 and EC2+EC3 fractions of the IMPROVE TOR analysis. It might be possible to adjust these fractions to obtain better agreement between atmospheric aerosol and soil/sediment analysis methods. Given its linking the EC measurement in the atmosphere to sediments, the TOR method will not only provide useful information on the explanation and comparison between different environmental matrices, but also can be used to derive information on global cycling of EC. 相似文献
265.
Noppe H Ghekiere A Verslycke T Wulf ED Verheyden K Monteyne E Polfliet K Caeter Pv Janssen CR De Brabander HF 《Environmental pollution (Barking, Essex : 1987)》2007,147(3):668-676
As part of the Endis-Risks project, the current study describes the occurrence of the chlorotriazine pesticides atrazine, simazine and terbutylazine in water, sediment and suspended matter in the Scheldt estuary (B-Nl) from 2002 to 2005 (3 samplings a year, 8 sampling points). Atrazine was found at the highest concentrations, varying from 10 to 736 ng/l in water and from 5 up to 10 ng/g in suspended matter. Simazine and terbutylazine were detected at lower concentrations. Traces of the targeted pesticides were also detected in sediments, but these were below the limit of quantification. As part of an ecotoxicological assessment, we studied the potential effect of atrazine on molting of Neomysis integer (Crustacea:Mysidacea), a resident invertebrate of the Scheldt Estuary and a proposed test organism for the evaluation of endocrine disruption. Following chronic exposure ( approximately 3 weeks), atrazine did not significantly affect mysid molting at environmentally relevant concentrations (up to 1 microg/l). 相似文献
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通过对我国地震应急组织体系及财政应对地震类灾害的流程分析,结合国外应对地震类突发事件的成功经验,分析了我国公共财政应对地震类灾害事件中存在的不足,最后通过对应急管理主体机理特征的分析,提出了公共财政应对地震类突发事件的五大机制,即公共财政日常运行机制、震前预警防范机制、震时响应机制、震后恢复重建机制和财政监督检查机制. 相似文献
268.
隧道火灾,尤其是长大公路、铁路隧道火灾,往往是灾难性的。因此,基于性能化防火设计原理,对雪峰山特长公路隧道的横通道间距和车行间距进行了研究。对中等规模20 MW的火灾,按照规范建议的3 m/s的风速进行通风的情况下,先用CFD软件模拟计算火灾危险时间Tfire,然后由疏散模型中的经验公式计算人员疏散时间Tevac,比较分析不同横通道间距下人员疏散的安全性;同时为了避免隧道内车辆间的引燃,利用辐射换热原理,对车辆间的火灾蔓延性进行了分析。模拟结果为:最佳横通道间距约为290 m,最小引燃间距为6 m。考虑到建设成本的问题,建议雪峰山隧道的横通道间距改为300 m;同时,考虑到后继车辆的刹车及不同的行车速度等因素,建议特长隧道内车距最好要大于110 m; 相似文献
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利用 2 2 0辆某轻型客车制动性能台试检测所得大量样本数据 ,对其 6项制动性能指标进行了统计分析 ,并得出了各项制动性能指标的实测合格率。轻型客车的制动性能检测与分析 ,对发现存在的问题 ,指导设计制造和使用维修单位改进工作 ,确保道路交通安全及车辆的行驶安全性具有重要作用。 相似文献