There is much concern nationwide about air quality. The following is from a 1985 report by the Tennessee Valley Authority. Sulfur Dioxide a colorless and odorless gas in typical outdoor concentrations, is formed naturally through biological decay and volcanic eruptions. Natural background levels are intensified by manmade emissions from fossil-fueled power plants, industrial and commercial boilers, ore smelters, cement plants and petroleum refineries. When a blanket of pollution enveloped the Meuse Valley, Belgium in 1993, 60 people died and 6,000 people became ill. When similar events occurred in Donora, Pennsylvania in 1948 and London, England in 1952, the scientific community was forced to locate and identify the culprit. During these incidents the estimated excessive concentrations of sulfur dioxide and particulate matter (many times greater than today’s standards) made them obvious choices as the problem pollutants. Sulfur dioxide becomes most dangerous to people when, clinging to small particulates, it is carried into the lungs. When this happens, as it did in the deadly incidents of the mid-1900’s, it may kill or incapacitate sensitive individuals such as the very young or very old or those with serious preexisting heart or lung problems. It can also cause increased illness in normally healthy people. The harmful effects of elevated sulfur dioxide concentrations on sensitive vegetation have been widely acknowledged and researched. Sulfur dioxide can injure plants growing near large emission sources and sometimes may reduce crop yield. Sulfur dioxide can also cause corrosive damage when it combines with water to form acids. Many of the problems associated with sulfur dioxide emissions (such as acid rain, inhalable particles and visibility impairment) are not a result of the sulfur dioxide itself but rather the secondary compounds it forms in the atmosphere. Particulates are small liquid droplets or solid particles or airborne “dust,” which range in size from those visible as soot or smoke to those too small to be seen without a high powered microscope. While large particles remain in the air for only a few minutes, falling our near their source, small particles often remain aloft for several days, traveling great distances and dispersing over a wide area. Particulates can be emitted directly from their source as liquid droplets or solid particles (primary particulates) or they can be formed in the atmosphere where gaseous pollutants can be chemically transformed (secondary particulates). Particulates have both natural and man made sources. Natural sources include the sea, volcanoes, forest fires, and wind blown silt. Important manmade sources include incinerators, manufacturing and industrial processes, fossil-fueled power plants, mining and materials processing, the internal combustion engine, and agricultural activities. On a global scale, natural emissions of particulates far exceed manmade emissions, but manmade emissions are predominant in industrialized or urban areas. The health effects of particulates depend on their size and composition. The larger particulates are usually filtered out in the nose and throat and rapidly cleared from the body. Smaller particles may be carried deeper into the lungs. Particles reaching sensitive deep lung areas are considered relatively more important for health purposes. Particle composition is also important because some compounds are relatively harmless whereas others – such as asbestos and beryllium – can result in serious health problems. Welfare effects caused by particulates have to do with soiling clothes and surfaces, and in combination with some gases, such as sulfur dioxide, corroding materials. Acid rain, or more accurately, acidic deposition (which refers to both wet and dry deposition of acidifying compounds), is one of the most controversial and important environmental issues of the day. It is the subject of both international concern and worldwide research. The principle causes of high rainfall acidity are sulfuric, nitric, and hydrochloric acids. The major manmade sources of pollutants that cause these acids are fossil-fueled utility and industrial boilers and the internal combustion engine. Proposed efforts to control man’s contributions to acid rain concentrate on controlling these acidifying pollutants, especially sulfur dioxide. Acidity is measured using a logarithmetic scale of 0 to 14 called the pH scale. On this scale, a neutral substance has a pH of 7. An acidic substance, like vinegar, has a pH value less than 7. An alkaline or basic substance, like baking soda, has a pH value higher than 7. Theoretically, pure rainfall has a pH of 5.6 and is acidic because the water has combined with carbon dioxide in the air to form weak carbonic acid. Rain with a lower pH than 5.6 is called acid rain. There is no reliable way to estimate what the acidity of rainfall may have been at various times and places throughout history. Preserved as ice in glaciers, arctic snows that fell in the 1800’’s were generally above pH 5, and some in Greenland even range from 6 to 7.6. Because of the remote location, however, these values might not be typical, and because snow and acid rain form by different processes and at different temperatures, values for rain and snow may not be directly comparable. Recent evidence suggests that natural rain (in the absence of manmade pollution) is several times more acidic than previously thought. In several remote areas of the globe, rainfall pH’s of 4.5 to 5.0 are routinely encountered. Some scientists suggest that these low pH values indicate the global extent of the acid rain problem. An important factor in determining the impact of acid rain on the environment is the ability of the natural ecosystem to neutralize or buffer incoming acidity. For a variety of reasons this capacity is different for each geographic area. Generally speaking, it is thought that most sensitive areas overlie crystalline rock whereas the least sensitive overlie limestone rock. Calcium carbonate and other alkaline substances dissolved from limestone rock act as neutralizing agents which raise the pH toward neutral. In some areas, there have been fishkills associated with acidic stream runoff following heavy rains. If the water in the streams, rivers, and lakes become too acidic, fish cannot survive. Spring snowmelt or heavy rain may abruptly change the water acidity level. Scientists are also studying the effects of acid rain on crops, plants, and land animals. For sensitive environments, an increase in the acidity of rainfall could be very serious. Clearly something must be done. However, it would be unwise to investigate every aspect of acid rain before action is taken.
There is much concern nationwide about air quality. The following is from a 1985 report by the Tennessee Valley Authority.
Sulfur Dioxide a colorless and odorless gas in typical outdoor concentrations, is formed naturally through biological decay and volcanic eruptions. Natural background levels are intensified by manmade emissions from fossil-fueled power plants, industrial and commercial boilers, ore smelters, cement plants and petroleum refineries.
When a blanket of pollution enveloped the Meuse Valley, Belgium in 1993, 60 people died and 6,000 people became ill. When similar events occurred in Donora,
Pennsylvania in 1948 and London, England in 1952, the scientific community was forced to locate and identify the culprit. During these incidents the estimated excessive concentrations of sulfur dioxide and particulate matter (many times greater than today’s standards) made them obvious choices as the problem pollutants.
Sulfur dioxide becomes most dangerous to people when, clinging to small particulates, it is carried into the lungs. When this happens, as it did in the deadly incidents of the mid-1900’s, it may kill or incapacitate sensitive individuals such as the very young or very old or those with serious preexisting heart or lung problems. It can also cause increased illness in normally healthy people.
The harmful effects of elevated sulfur dioxide concentrations on sensitive vegetation have been widely acknowledged and researched. Sulfur dioxide can injure plants growing near large emission sources and sometimes may reduce crop yield. Sulfur dioxide can also cause corrosive damage when it combines with water to form acids.
Many of the problems associated with sulfur dioxide emissions (such as acid rain, inhalable particles and visibility impairment) are not a result of the sulfur dioxide itself but rather the secondary compounds it forms in the atmosphere.
Particulates are small liquid droplets or solid particles or airborne “dust,” which range in size from those visible as soot or smoke to those too small to be seen without a high powered microscope. While large particles remain in the air for only a few minutes, falling our near their source, small particles often remain aloft for several days, traveling great distances and dispersing over a wide area. Particulates can be emitted directly from their source as liquid droplets or solid particles (primary particulates) or they can be formed in the atmosphere where gaseous pollutants can be chemically transformed (secondary particulates).
Particulates have both natural and man made sources. Natural sources include the sea, volcanoes, forest fires, and wind blown silt. Important manmade sources include incinerators, manufacturing and industrial processes, fossil-fueled power plants, mining and materials processing, the internal combustion engine, and agricultural activities. On a global scale, natural emissions of particulates far exceed manmade emissions, but manmade emissions are predominant in industrialized or urban areas.
The health effects of particulates depend on their size and composition. The larger particulates are usually filtered out in the nose and throat and rapidly cleared from the body. Smaller particles may be carried deeper into the lungs. Particles reaching sensitive deep lung areas are considered relatively more important for health purposes.
Particle composition is also important because some compounds are relatively harmless whereas others – such as asbestos and beryllium – can result in serious health problems.
Welfare effects caused by particulates have to do with soiling clothes and surfaces, and in combination with some gases, such as sulfur dioxide, corroding materials.
Acid rain, or more accurately, acidic deposition (which refers to both wet and dry deposition of acidifying compounds), is one of the most controversial and important environmental issues of the day. It is the subject of both international concern and worldwide research.
The principle causes of high rainfall acidity are sulfuric, nitric, and hydrochloric acids. The major manmade sources of pollutants that cause these acids are fossil-fueled utility and industrial boilers and the internal combustion engine. Proposed efforts to control man’s contributions to acid rain concentrate on controlling these acidifying pollutants, especially sulfur dioxide.
Acidity is measured using a logarithmetic scale of 0 to 14 called the pH scale. On this scale, a neutral substance has a pH of 7. An acidic substance, like vinegar, has a pH value less than 7. An alkaline or basic substance, like baking soda, has a pH value higher than 7. Theoretically, pure rainfall has a pH of 5.6 and is acidic because the water has combined with carbon dioxide in the air to form weak carbonic acid. Rain with a lower pH than 5.6 is called acid rain.
There is no reliable way to estimate what the acidity of rainfall may have been at various times and places throughout history. Preserved as ice in glaciers, arctic snows that fell in the 1800’’s were generally above pH 5, and some in Greenland even range from 6 to 7.6. Because of the remote location, however, these values might not be typical, and because snow and acid rain form by different processes and at different temperatures, values for rain and snow may not be directly comparable.
Recent evidence suggests that natural rain (in the absence of manmade pollution) is several times more acidic than previously thought. In several remote areas of the globe, rainfall pH’s of 4.5 to 5.0 are routinely encountered. Some scientists suggest that these low pH values indicate the global extent of the acid rain problem.
An important factor in determining the impact of acid rain on the environment is the ability of the natural ecosystem to neutralize or buffer incoming acidity. For a variety of reasons this capacity is different for each geographic area. Generally speaking, it is thought that most sensitive areas overlie crystalline rock whereas the least sensitive overlie limestone rock. Calcium carbonate and other alkaline substances dissolved from limestone rock act as neutralizing agents which raise the pH toward neutral.
In some areas, there have been fishkills associated with acidic stream runoff following heavy rains. If the water in the streams, rivers, and lakes become too acidic, fish cannot survive. Spring snowmelt or heavy rain may abruptly change the water acidity level. Scientists are also studying the effects of acid rain on crops, plants, and land animals. For sensitive environments, an increase in the acidity of rainfall could be very serious. Clearly something must be done.
However, it would be unwise to investigate every aspect of acid rain before action is taken.
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