FREE ESSAY ON ACID RAIN

ACID RAIN

ACID RAIN
Pollution comes in various forms. Whether it's toxic waste, CFC's, or sewage, they are
all hazardous, to the earth. These can deplete the earth and it's inhabitants of
resources, causing a harmful change. A product of pollution is acid rain. We shall see
that acidification is harmful to all forms of life.
Acid rain is any form of precipitation that is polluted by sulphur dioxide (SO2), and
nitrogen oxides (NOX). This acid precipitation can be in the form of rain, snow, sleet,
fog, or cloud vapors. The acidity of substances dissolved in water are measured by their
pH levels. Normal precipitation pH levels fall between 5.0-5.6.2 When levels fall below
these numbers, then the precipitation is said to be acidic. 
There are two ways in which acid deposition can form. The first way occurs when nitrogen
oxides and sulphur dioxide land on the Earth's surface, and interact with frost or dew.
The second way takes place due to the oxidation of nitrogen oxides or sulphur dioxide
gases that are released into the air.3 Since it may take up to several days for the gases
to be altered into their acid counter-parts, the pollutants can travel miles away from
their original source. 
Emissions of (SO2) are responsible for the majority of the acid deposition, which falls
to Earth. When we burn coal, we are releasing (SO2), into the air, since coal is slight
made up of sulphur. Volcanic eruptions can add a great deal of sulphur into the
atmosphere. Everyday organic decay adds sulphur into the air as well. (SO2) can hit the
Earth's surface in dry forms or wet forms, by undergoing the following reactions:
(SO2 + H20 *** H2SO3) (SO2 + ?O2 *** SO3 + H2SO4)2
Human activity is the major cause for nitrogen oxides' presence in our atmosphere, such
as forest fires and the combustion of oil, coal, and gas. The other causes are due to
nature. Lightning, volcanic action, and bacteria in soil are just to name a few. The
following chemical reactions show how acids of nitrogen form:
(NO2 + ?O2 *** NO2) (2NO2 + H2O *** HNO2 + HNO3) 
(NO2 + OH *** HNO3)2
Acid rain can affect plant life directly when the surface of leaves and needles come into
contact with acid vapor or fog. This causes a reduction in the tree's ability to
withstand the cold. A direct result would be the tree's incapability of reproduction.
It can also harm plant life indirectly, by the acidification of soils. Acid rain can
cause soil to loose nutrients such as calcium, potassium, and magnesium. In very acid
conditions, aluminum becomes soluble, and is released from the soil. At high enough
concentrations, aluminum can cause damage to roots. 
Acid rain causes a nutrient imbalance, in soil. Although it is true that nitrogen
promotes forest growth, plant life also needs other nutrients. Precipitation polluted by
nitrogen can contain heavy metals, such as mercury, cadmium, and lead. This process is
known as nitrogen saturation.1 These too, can cause damage to tree roots. 
Besides trees, plants are also affected by acid rain. Reductions in pH levels can cause
seed germination to be inhibited. Plant structures become weak, due to the loss of
nutrients to the plant's tissues.4 Flowering of certain plants may not occur due to lack
of essential minerals.
Marine life is also greatly affect by acid rain. Acid water can leach high levels of
aluminum from the bedrock. Rocks that contain great amounts of calcium or magnesium can
act as a neutralizer. Those rocks and soils that lack some sort of buffers can cause
grave damage to marine fish and plants.
There are two ways in which aluminum can harm aquatic environments. It can cause a fish
to suffocate, because aluminum precipitates in gills, thus interfering in the transport
of oxygen. Secondly, fish produce mucus to combat the aluminum, in their gills. The mucus
then builds up a clogs the fish's gills.5
In middle latitudes many bodies of water experience what is called "acid shock."4 Over
the winter acid deposits can build up on snow. As the snow melts, the acids are released.
Most fish can survive shock, but their eggs cannot adapt to acidification.
When there is a change in the chemistry of water, the ecology of the water begins to
change. The number and variety of species are altered. At a pH level of 6.0 certain types
of zooplankton and green algae begin to disappear. The loss of green plants allows more
UV light to penetrate to further depths, so certain types of snails and phyto-plankton
disappear. Frogs, toads, and salamanders are also affected by acid rain.5 The low pH
stunts their growth.
Not only does acid rain kill species, but also it alters the food supply for higher
fauna. If there is a decrease in the number of bottom dwelling organisms (benthos), there
can be a decline in the number of insects, such as mosquitoes and flies. This puts a
stress on carnivorous fish. Birds that eat these fish, which may contain high levels of
aluminum, will then produce eggs with soft-shells. Their young will most likely not
survive.
Humans are not immune to the effects of acid rain. People that are exposed to high
concentrations of acidic pollution are known to have respiratory problems. SO2 can react
with water vapor to form fine particles of sulphate. If inhaled, these particles can
cause severe damage to lung tissue. The affect can be a simple cough or chest cold, or as
dangerous as asthma or chronic bronchitis.
Humans can consume aluminum by drinking water or eating crops that have contaminated by
acid precipitation. If ingested in large quantities, it can have toxic effects on human
health. Many doctors believe that aluminum consumption can lead to Alzheimer's disease.1
We see the effects of acidification everyday. All forms of acid precipitation may damage
automotive coatings. The damaged is mostly observed on newly painted vehicles. It is the
evaporation of acidic moisture that causes the damage. Many headstones and buildings and
statues, such as the Statue of Liberty, are affected in the same way. Acid deposition can
cause fading of these structures. Churches and cathedrals also suffer.3
The United States is trying to take care of this problem through environmental
legislation. Title IV of the Clean Air Act Amendments of 1990, calls for a 10 million ton
reduction in the number of emissions of sulfur dioxide.3 One way of reducing emissions is
lowering the production of sulphate aerosol cans. Since this act was passed, hospitals
have witnessed a significantly lower number of cases of respiratory problems. 
There are other ways that we can alleviate the problems of acid deposition. A process
known as liming can increase the pH levels of bodies of water.2 Large quantities of
hydrated lime are added to the water. 
The best way to solve the problems caused by acid deposition is for industries to try to
limit the emissions of pollutants. There has been two ways in which industries have done
this. Several companies have switched to using fuels that have a low sulphur content.
Other industries have used buffers on the tops of their smokestacks, to reduce the amount
of (SO2) in the air.4
There is no way that we can totally eliminate acid deposition. We as humans, are not the
only creators of this problem. Over the years, there has been an increase in the amount
of annual precipitation. We can change our ways of production to help decrease the amount
of acid precipitation, but then that would be greatly affecting our way of life. More
then the acid rain itself does. Just like the cycle of affects the acid rain has on
aquatic and terrestrial systems, there is the same type of cycle viewed when it comes to
human life.