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Cycling of pollutants

Fig. 5. Receding angle on a pollution layer of fumed silica af lied to a silicone rubber sample, measuring new samples with different LMW contents (left) and repeated measuring during cycles of pollution and cleaning (right). Fig. 5. Receding angle on a pollution layer of fumed silica af lied to a silicone rubber sample, measuring new samples with different LMW contents (left) and repeated measuring during cycles of pollution and cleaning (right).
If weekly cycles of polluting and cleaning of specimens are performed, some of the LMW is taken away with the pollution layer. It is shown in Fig. 5 (right), that with the number of performed cycles the transfer process becomes slower (compare 1st and 8th cycles). After the 8th cycle a recovery period of 4 weeks was performed. It was found that the transfer of LMW into the pollution layer occurs significantly faster in the 9th cycle, but not as fast as in the 1st cycle. This shows that LMW from the bulk needs time to diffuse to the surface of the specimen. Even after 14 cycles a transfer effect can be proved. A lifetime for this process cannot be estimated from these curves. This should be the object of further investigations (see also Ref [10]). [Pg.775]

Cycles of pollution and cleaning of silicone rubber samples show that hydrophobicity transfer is a dynamic process that depends on the amount of freely diffusible fluid components. It seems probable that the transfer effect is present during the whole lifetime of a silicone rubber for high-voltage insulators. [Pg.778]

Table 5-1 Processes Affecting Cycling of Pollutants in Aquatic Systems... Table 5-1 Processes Affecting Cycling of Pollutants in Aquatic Systems...
Tables 5.29 and 5.30 show an example of the effects of hydrotreated diesel fuels on a diesel passenger car already having a low level of pollution owing to technical modifications such as sophisticated injection and optimized combustion. In the standard European driving cycle (ECE + EUDC), between... Tables 5.29 and 5.30 show an example of the effects of hydrotreated diesel fuels on a diesel passenger car already having a low level of pollution owing to technical modifications such as sophisticated injection and optimized combustion. In the standard European driving cycle (ECE + EUDC), between...
Human civilization interferes more and more with the cycles that cormect land, water, and atmosphere, and pollution seriously affects water quahty. In order to assess the stresses caused to aquatic ecosystems by chemical perturbation, the distribution of pollutants and their fate in the environment must be investigated (see Air pollution). [Pg.207]

The application of waste-management practices in the United States has recently moved toward securing a new pollution prevention ethic. The performance of pollution prevention assessments and their subsequent implementation will encourage increased activity into methods that 1 further aid in the reduction of hazardous wastes. One of the most important and propitious consequences of the pollution-prevention movement will be the development of life-cycle design and standardized hfe-cycle cost-accounting procedures. These two consequences are briefly discussed in the two paragraphs that follow. Additional information is provided in a later subsection. [Pg.2163]

As air pollution management moves forward, economics has a major role in reducing pollution. Multimedia considerations are forcing a blend of traditional emission reduction approaches and innovative methods for waste minimization. These efforts are directed toward full cost accounting of the life cycle of products and residuals from the manufacturing, use, and ultimate disposal of materials. [Pg.71]

Laboratory studies have also investigated the interaction of air pollutants and the reproductive cycle of certain plants. Subtle changes in reproduction in a few susceptible species can render them unable to survive and prosper in a given ecosystem. [Pg.113]

The interactions of air pollutants with forests at low-dose concentrations result in imperceptible effects on the natural biological cycles of these species. In some instances, these interactions may be beneficial to the forest ecosystem. Forests, as well as other natural systems, act as sinks for the removal of trace gases from the atmosphere. [Pg.117]

Elimination or Reduction of Pollutants 7. Use nonchrome-based additives in cooling water. 8. Use long-life catalysts and regeneration to extend the cycle. [Pg.59]

If hydrogen is made from decarbonized fossil fuels, fuel-cycle emissions can be cut by up to 80 percent. With renewable energy sources such as biomass, solar, or wind, the fuel cycle greenhouse gas emissions are virtually eliminated. It is possible to envision a future energy system based on hydrogen and fuel cells with little or no emissions of pollutants or greenhouse gases in fuel production, distribution, or use. [Pg.657]

In order to understand the impact of pollution on Earth, we must realize that the planet itself is not stagnant, but continually moving material around the system naturally. Any human (anthropogenic) redistribution in the elements is superimposed on these continuous natural events. Energy from the sun and radioactive decay from the Earth s interior drive these processes, which are often cyclic in nature. As a result, almost all of the rocks composing the continents have been processed at least once through a chemical and physical cycle involving... [Pg.3]

Perhaps because the unpolluted atmosphere can appear to be perfectly free of turbidity, it is not immediately obvious that it is a mixture of solid, gaseous, and liquid phases - even in the absence of clouds. Particles in the aerosol state constitute only a miniscule portion of the mass of the atmosphere - perhaps 10 or 10 ° in im-polluted cases. However, the condensed phases are important intermediates in the cycles of numerous elements, notably ammonia-N, suT... [Pg.152]


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