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