Friday, June 29, 2012

Acid Rain an Environmental Scourge:

An acid rain damaged gargoyle
Photo by Nino Barbieri  

Acid rain is rain or any other form of precipitation that is unusually high in acid content from natural or demographic sources.  It is produced by burning sulfur containing fuel such as coal or petroleum or by nitrogen combining with oxygen during the process of combustion.  An associated source of acid rain can be found in the minerals found in the fuel.  This takes the form of toxic minerals of which many can be found in nature.  Acid rain is also produced from many different sources.  Volcanic activity is one of the many sources, so is ocean spray.  It is particularly damaging to animals, vegetation and buildings.  In the later 20th century many governments have taken steps to alleviate the problem by enacting laws to reduce these emissions.  The term acid rain has entered the popular language as any type of water particle carrying airborne acid.  A closely allied problem is the depositation of trace elements into the air from trace elements contained in the natural and demographic sources. 

Acid rain is a manifestation of a larger problem air pollution that becomes excessive in areas suffering from poor atmospheric circulation as the Los Angeles Basin.  Here a combination of a high range of mountains encircling Los Angeles allows stagnate air to accumulate over Los Angeles allowing the air to become heavily polluted.  Although draconian measures have been taken over the past half century air pollution is still a major problem.  The unfortunate for the residents of the city a good share of the air pollution is from the burning of fuel by those same residents.

As can be seen on Figure 1 the heaviest concentration of acid rain is in the northeastern part of the country and adjoining Canada.  Much of this is acid rain caused by the combustion of coal in coal fired electric generating plants located in the north central part of the country along the lower Great Lakes and east to the Atlantic Ocean.

Since the start of the industrial revolution in the 1700s acid rain has increased due to the emissions of sulfur dioxide and nitrogen oxides into the atmosphere.  Although acid rain was discovered in 1852 it wasn’t until the 1960s that scientists started to investigate the problem.  The name “Acid Rain” dates from 1972 when the Canadian Scientist Harold Harvey was one of the first scientists to study a “dead lake.”   The New York Times made the public aware of the problem through reports about the Hubbard Brook Experimental Forest in New Hampshire outlining the numerous deleterious effects on the forest as a result of Acid Rain.

Acid rain is measured by taking a series of samples throughout the suspected affected area and measuring their pH.  Neutral or distilled water has a pH of 7 anything below that level is acidic; anything above pH7 is alkaline.  By measuring a series of samples over a wide area then comparing the results a map of the affected area can be generated.  This map will help scientists to trace their way back to the source much as a prospector traces a placer gold deposit back to its source as a lode deposit.

The reason why there is such a concentration of acid rain in the Northeast is because caused by the concentration of cities, and the heavy industrialization of the Midwest and the Northeast.  Coal fired power plants located in the Midwest are blamed for much of this pollution.  This is combined with the prevailing soil and bedrock in the Northeast being unable to generate enough dust to neutralize the acid rain.  The reason the Northeast receives so much acid rain from the Midwest is because of the prevailing
Westerly winds.   

There is no easy solution to this problem except to try to discover methods to decrease pollutants in the atmosphere.  To address this problem there have been concerted efforts by both government and private institutions. 


Acid Rain, Wikipedia, the free encyclopedia,

What is Acid Rain, USGS,

Manahan, Stanley E., Environmental Chemistry Fourth Edition, © Lewis Publishers, 1990, Pages, 9, 10, 48, 286, 327, 336, 427, 486

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