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_acid rain _
By: jerry
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 acidicThere 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 + ½O2 * 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 + ½O2 * 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 rootsAcid 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.
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