摘要:

Fluorine is the 13th element in order of abundance and occurs throughout man's environment. Airborne fluorides in very low concentrations may be introduced into pristine atmospheres from sources such as volcanic actions, dusts picked up by winds blowing over surface soils and weathered rocks, and from sea spray. Urban and surburban atmospheres may contain higher concentrations derived from burning fossil fuels and from miscellaneous effluents disseminated from a variety of industrial point sources. A number of states now have standards regulating the concentrations of fluoride which may be present in the air or released to the ambient air. Higher concentrations may be encountered in the work place, but again, limits selected to protect the worker from significant effects are in force. The principal effect of industrial fluoride‐containing dust to be protected against is the excessive deposition of fluoride in the skeleton. This condition, skeletal fluorosis, was recognized in Danish cryolite workers in the mid‐1930s. While mild degrees of skeletal fluorosis are occasionally seen today, no case of crippling fluorosis has yet been reported in the U.S. Gaseous fluorides may cause irritation and inflammation of the skin and of the surfaces of the respiratory tract and, in acute episodes, may produce burns. Adequate air sampling and analytical techniques are now available to ensure that airborne fluoride concentrations are in compliance with existing standards. Reasonably good knowledge of the metabolism of fluoride in man has permitted the development of biological monitoring procedures for workers to ensure that the first signs of unusual fluoride exposure are promptly detected.

ISSN:0007-8999    

DOI:10.1080/10643387909381666

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Plants are sensitive to sulfur dioxide and they are affected by it both directly and indirectly. The direct effects may be acute or chronic, depending on the duration and intensity of the exposure. Sulfur dioxide inhibits photosynthesis by disrupting the photosynthetic mechanism. The opening of the stomata is promoted by sulfur dioxide, resulting in an excessive loss of water. The cumulative effect of sulferous pollution is to reduce the quantity and quality of plant yield. Generally, its impact is more severe when in combination with other pollutants such as oxides of nitrogen, fluorides, and ozone. At the ecosystem level, sulfur dioxide affects species composition by eliminating more sensitive species. This reduces primary productivity and alters trophic relationships which have far‐reaching implications for the animal and microbial populations in the community. Another indirect effect results from the acid rain which leaches out nutrients from plant canopy and soil. The acidic run‐off changes the pH of the receiving waters and adds large quantities of nutrients which disturb the equilibrium of aquatic communities. Plants vary widely in their tolerance to sulfer dioxide. Lichens and bryophytes are among the most sensitive and have been successfully used as indicators of sulfur dioxide pollution.

ISSN:0007-8999    

DOI:10.1080/10643387909381667

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

High‐energy accelerators are not generally regarded as potential sources of significant environmental radiation or radioactivity. Indeed, by comparison with nuclear reactors, they produce rather small quantitiesofradioactivity, even though some kilocuries of radioactive material may be produced by some of these machines. The environmental impact of high‐energy accelerators is different in character from that of most nuclear installations. With accelerators, the predominant source of radiation exposuretothe general population is duetothe leakage of radionuclides into the environment. Studies of the production of the prompt radiation field during accelerator operation are reviewed, together with the transport of the field at large distances from the accelerator. Models for the calculation of population exposure are described and the experience at several high‐energy facilities summarized. Population exposure from radionuclides released to the atmosphere as a result of accelerator operation are at least an order of magnitude lower than that from prompt radiation — long‐lived radionuclides such as3H and7Be are of greatest concern. The production of radionuclides in soil and ground water near accelerators and their possible migration away from the accelerator site in ground water systems are thoroughly discussed. No significant population exposure is expected to arise from this source of environmental contamination at presently existing energies and intensities.

ISSN:0007-8999    

DOI:10.1080/10643387909381668

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor