Essay/Term paper: Acid rain

Essay, term paper, research paper:  Science

Acid Rain


INTRODUCTION: Acid rain is a great problem in our world. It causes fish and
plants to die in our waters. As well it causes harm to our own race as well,
because we eat these fish, drink this water and eat these plants. It is a
problem that we must all face together and try to get rid of. However acid rain
on it's own is not the biggest problem. It cause many other problems such as
aluminum poisoning. Acid Rain is deadly.

WHAT IS ACID RAIN?

Acid rain is all the rain, snow, mist etc that falls from the sky onto our
planet that contains an unnatural acidic. It is not to be confused with
uncontaminated rain that falls, for that rain is naturally slightly acidic. It
is caused by today's industry. When products are manufactured many chemicals are
used to create it. However because of the difficulty and cost of properly
disposing of these products they are often emitted into the atmosphere with
little or no treatment.

The term was first considered to be important about 20 years ago when
scientists in Sweden and Norway first believed that acidic rain may be causing
great ecological damage to the planet. The problem was that by the time that the
scientist found the problem it was already very large. Detecting an acid lake is
often quite difficult. A lake does not become acid over night. It happens over a
period of many years, some times decades. The changes are usually to gradual for
them to be noticed early.

At the beginning of the 20th century most rivers/lakes like the river
Tovdal in Norway had not yet begun to die. However by 1926 local inspectors were
noticing that many of the lakes were beginning to show signs of death. Fish were
found dead along the banks of many rivers. As the winters ice began to melt off
more and more hundreds upon hundreds more dead fish (trout in particular) were
being found. It was at this time that scientist began to search for the reason.
As the scientists continued to work they found many piles of dead fish, up to
5000 in one pile, further up the river. Divers were sent in to examine the
bottom of the rivers. What they found were many more dead fish. Many live and
dead specimens were taken back to labs across Norway. When the live specimens
were examined they were found to have very little sodium in their blood. This is
typical a typical symptom of acid poisoning. The acid had entered the gills of
the fish and poisoned them so that they were unable to extract salt from the
water to maintain their bodies sodium levels.

Many scientist said that this acid poising was due to the fact that it was
just after the winter and that all the snow and ice was running down into the
streams and lakes. They believed that the snow had been exposed to many natural
phenomena that gave the snow it's high acid content. Other scientists were not
sure that this theory was correct because at the time that the snow was added to
the lakes and streams the Ph levels would change from around 5.2 to 4.6. They
believed that such a high jump could not be attributed to natural causes. They
believed that it was due to air pollution. They were right. Since the beginning
of the Industrial revolution in England pollution had been affecting all the
trees,soil and rivers in Europe and North America.

However until recently the loses of fish was contained to the southern
parts of Europe. Because of the constant onslaught of acid rain lakes and rivers
began to lose their ability to counter act their affects. Much of the alkaline
elements; such as calcium and limestone; in the soil had been washed away. It is
these lakes that we must be worried about for they will soon become extinct.

A fact that may please fishermen is that in lakes/rivers they tend to catch
older and larger fish. This may please them in the short run however they will
soon have to change lakes for the fish supply will die quickly in these lakes.
The problem is that acid causes difficulties the fish's reproductive system.
Often fish born in acid lakes do not survive for they are born with birth
defects such as twisted and deformed spinal columns. This is a sign that they
are unable to extract enough calcium from the water to fully develop their bone.
These young soon die. With no competition the older,stronger can grow easily.
However there food is contaminated as well by the acid in the water. Soon they
have not enough food for themselves and turn to cannibalism. With only an older
population left there is no one left to regenerate themselves. Soon the lake
dies.

By the late 1970s many Norwegian scientists began to suspect that it was
not only the acid in the water that was causing the deaths. They had proved that
most fish could survive in a stream that had up to a 1 unit difference in PH.
After many experiments and research they found that their missing link was
aluminum.

Aluminum is one of the most common metals on earth. It is stored in a
combined form with other elements in the earth. When it is combined it cannot
dissolve into the water and harm the fish and plants. However the acid from acid
rain can easily dissolve the bond between these elements. The Aluminum is then
dissolved into a more soluble state by the acid. Other metals such as Copper
(Cu), iron (Fe) etc can cause such effects upon the fish as well however it is
the aluminum that is the most common. For example: CuO + H2SO4 ---------->
CuSO4 + H2O

In this form it is easily absorbed into the water. When it comes in contact
with fish it causes irritation to the gills. In response the fish creates a film
of mucus in the gills to stop this irritation until the irritant is gone.
However the aluminum does not go always and the fish continues to build up more
and more mucus to counteract it. Eventually there is so much mucus that it clogs
the gills. When this happens the fish can no longer breath. It dies and then
sinks to the bottom of the lake. Scientists now see acid, aluminum and shortages
of calcium as the three determining factors in the extinction of fish.

As well there is the problem of chlorine. In many parts of the world it is
commonly found in the soil. If it enters the fish's environment it can be deadly.
It affects many of the fish's organisms and causes it to die. As well it
interferes in the photosynthesis process in plants.

NaOH + HCl ----> NaCl + H2O

The carbon in the water can become very dangerous for fish and plants in the
water if the following reaction happens:

CaCO3 + 2HCl ---> CaCl2 + H2CO3 then
H2CO3 ---> H2O + CO2

The salt created by this reaction can kill. It interferes directly with the
fish's nervous system.

Acid lakes are deceivingly beautiful. The are crystal clear and have a
luscious carpet of green algae on the bottom. The reason that these lakes are so
clear is because many of the decomposers are dead. They cannot break down that
material such as leaves and dead animals. These materials eventually sink to the
bottom instead of going through the natural process of decomposition. In acid
lakes decomposition is very slow. "The whole metabolism of the lake is slowed
down."

During this same period of time the Canadian department of fisheries spent
eight years dumping sulfuric acid (H2SO4) into an Ontario lake to see the
effects of the decrease in the PH over a number of years. At the PH of 5.9 the
first organisms began to disappear. They were shrimps. They started out at a
population of about seven million, but at the pH of 5.9 they were totally wiped
out. Within a year the minnow died because it could no longer reproduce it's
self.

At this time the pH was of 5.8. New trout were failing to be produced
because many smaller organisms that served as food to it had been wiped out
earlier. With not enough food the older fish did not have the energy to
reproduce. Upon reaching the pH of 5.1 it was noted that the trout became
cannibals. It is believed this is due to the fact that the minnow was nearly
extinct.

At a pH of 5.6 the external skeletons of crayfish softened and they were
soon infected with parasites, and there eggs were destroyed by fungi. When the
pH went down to 5.1 they were almost gone. By the end of the experiment none of
the major species had survived the trials of the acid. The next experiment
conducted by the scientists was to try and bring the lake back to life. They cut
in half the amount of acid that they dumped to simulate a large scale cleanup.
Soon again the cuckers and minnows began to reproduce again. The lake eventually
did come back; to a certain extent; back to life. THE NEW THEORY:

A scientist in Norway had a problem believing that it was the acid rain on
it's own that was affecting the lakes in such a deadly way. This scientist was
Dr Rosenqvist.



"Why is it that during heavy rain, the swollen rivers can be up to fifteen
times more acid than the rain? It cannot be the rain alone that is doing it, can
it?" Many scientist shunned him for this however they could not come up with a
better answer. Soon the scientists were forced to accept this theory.

Sulfuric acid is composed of two parts, know as ions. The hydrogen ion is
what make a substance acid. The other ion is sulphate. When there are more
hydrogen ions then a substance is acid. It is this sulphate ion that we are
interested in. When the rain causes rivers to overboard onto the banks the river
water passes through the soil. Since the industrial revolution in britain there
has been an increasing amount of sulphur in the soil. In the river there is not
enough sulphur for the acid to react in great quantities. However in the soil
there is a great collection of sulphur to aid the reaction. When it joins the
water the pH becomes much lower. This is the most deadly effect of acid rain on
our water!!! The water itself does not contain enough sulphur to kill off it's
population of fish and plants. But with the sulphur in the soil it does.

CONCLUSION:

Acid rain is a big problem. It causes the death of our lakes, our rivers, our
wild life and most importantly us. As well it causes other problems that are
very serious as well such as the release of aluminium and lead into our water
supplies. We are suffering because of it. In Scotland there are many birth
defects being attributed to it. We must cut down the releases of chemicals that
cause it. But it will take time, even if we were to stop today we would have the
problem for years to come because of the build up in the soil. Let's hope we can
do something.

BIBLIOGRAPHY

Penguin Publishing House, 1987 , Pearce Fred Acid Rain. What is it and
what is it doing to us?

New York Publishers, 1989, William Stone Acid Rain. Fiend or Foe?

Lucent books, Inc. 1990, Steward Gail Acid Rain.