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671.
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673.
The effect of environmental conditions on the ability of a constructed wetland to disinfect municipal wastewaters 总被引:2,自引:0,他引:2
Zdragas A Zalidis GC Takavakoglou V Katsavouni S Anastasiadis ET Eskridge K Panoras A 《Environmental management》2002,29(4):510-515
Constructed wetlands are widely used all over the world for the treatment of municipal wastewaters, which are characterized
by high concentrations of pathogens. The objectives of this study were (1) to study the effect of solar radiation and temperature
on the ability of a constructed wetland to reduce the concentration of total coliforms (TC), and (2) to evaluate the relationship
between the presence of Salmonella spp. in the outflow and the concentration of TC. The results of this study showed that under Mediterranean environmental conditions,
the percentage reduction in coliforms was lower during winter compared to all other seasons. Maximum removal of coliforms
was achieved under conditions of high solar radiation and temperature. In addition, solar radiation was found to play a greater
role in coliform die-off at low temperatures than at high temperatures. Finally, it was found that the probability of Salmonella spp. appearance in the outflow of the wetland was related to the concentration of TC. The increase in coliform bacteria in the
effluents also increased the chances of Salmonella appearance. The risk of Salmonella spp. appearance in the outflow is minimized when the concentration of TC is below 102/100 mL. 相似文献
674.
Jorma K. Miettenen 《Environmental management》1988,12(1):1-3
Summary The risks of radioactivity are a really complicated matter, yet they are much better known than are the risks relating to thousands of chemical poisons that occur in our environment. The greatest mistakes are probably made in the definition of safety margins. Except for the bombs dropped in Japan and one other case in the Marshall Islands, there has always—luckily—been a wide safety margin between fallout radiation and doses dangerous to health; the margin has actually been about 1000-fold. The Chernobyl dose of 0.5 mGy/year that we received is only 1/1000 of the acute dose of 0.5 Gy which would cause a slight and nonpermanent change in the blood picture.There is no such safety margin with respect to many air pollutants. The safety standards for sulfuric or nitric oxides, ozone and so on, have been set only just below the level that already causes a health hazard, and these standards are exceeded once in a while. Otherwise, traffic would have to be forbidden and many industrial plants, especially power stations using coal, would have to stop working whenever a low-temperature inversion occurred. Environmental radioactivity does not represent a likely health risk in Finland unless a nuclear war breaks out. Air pollutants, on the contrary, are a real and almost daily health risk that should be carefully considered when decisions about our energy production are being made.In spite of what happened at Chernobyl, global consumption of nuclear power will double by the year 2000, since there are about 140 nuclear power plants presently under construction. It is not likely that another catastrophe like Chernobyl will happen, yet nuclear plant accidents are of course possible, even if their likelihood is diminished by improving reactor safety and even if any eventual damage could be expected to be smaller. If a reactor is hooded by a containment structure, no significant release of radioactive materials should be possible even in case of an accident. However, we must be prepared to protect the population with carefully planned civil defense and radiation protection measures.I would like to sum up all of this as follows: The risks of radiation are a fact, but the fear they arouse is often disproportionate. There are risks related to all other methods of energy production as well; nuclear power is no exception in that respect. It is good that we aim at greater safety, but I hope that false presumptions will not lead us to mistaking a less safe alternative for a safer one. 相似文献
675.
Ulf Roar Aakenes 《Chemistry and Ecology》1995,10(1):61-69
The principles and operation of a gamma radiation sensor mounted on oceanographic buoys are described. the sensor has proved rugged in severe weather conditions and has satisfactory detection limits and accuracy. Continuous monitoring of artificially produced γ-emitters such as 137Cs, 134Cs, 131I, 133I, 132Te, naturally occuring emitters such as 40k and 214Bi in open sea conditions can provide important information in critical situations. 相似文献
676.
677.
J. W. M. van de Staaij R. Huijsmans W. H. O. Ernst J. Rozema 《Environmental pollution (Barking, Essex : 1987)》1995,90(3)
Highland (altitude 1600 m above sea level) and lowland (altitude −2 m below sea level) populations of the perennial herb Silene vulgaris (Moench) Garcke, were tested on their response to elevated levels of UV-B radiation. Highland populations typically receive high natural UV-B fluxes, whereas lowland populations receive a lower natural UV-B dose. Adaptation to high UV-B levels of the highland population is to be expected. Experimental comparison of growth rates, gas exchange rates, transpiration and biochemical parameters using adult plants as well as seedlings did not show a difference in the response to elevated UV-B levels between the two populations. Individuals of both populations were relatively insensitive to elevated UV-B radiation. The response of alpine and lowland populations of Silene vulgaris is discussed in relation to the dispersal of this species after the last ice age. 相似文献
678.
人工电磁辐射源固有危险性指数法评价研究 总被引:1,自引:0,他引:1
在总结现有安全评价方法基础上,结合电磁辐射中对污染危害有影响的因素建立了电磁辐射源固有危险性评价的指数法评判模型.在该模型里,就电磁辐射源固有危险性评判的评价指标与等级选取、评价指标标准以及权重确定等进行了研究. 相似文献
679.
综述了手机辐射的原理、辐射危害、辐射场计算和辐射评价技术标准及其检测仪器,并提出了一些减小手机辐射的措施和建议. 相似文献
680.
阐述了电磁环境污染的特点及其危害,介绍了我国电磁环境保护标准并与国际非电离辐射防护委员会(ICNIRP)推荐标准进行了比较,提出我国在电磁辐射污染的管理和政策制定中应当考虑的原则. 相似文献