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Free Essays > Science and Technology > Acid Rain
Acid Rain
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Word Count: 1983
Page Count: 8 Acid Rain
Acid Rain
INTRODUCTION: Acid rain is a great problem in our world. It causes fishand plants to die in our waters. As well it causes harm to our own race aswell, because we eat these fish, drink this water and eat these plants. Itis a problem that we must all face together and try to get rid of. Howeveracid rain on it's own is not the biggest problem. It cause many otherproblems 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 ontoour planet that contains an unnatural acidic. It is not to be confused withuncontaminated rain that falls, for that rain is naturally slightly acidic.It is caused by today's industry. When products are manufactured manychemicals are used to create it. However because of the difficulty and costof properly disposing of these products they are often emitted into theatmosphere with little or no treatment.
The term was first considered to be important about 20 years ago whenscientists in Sweden and Norway first believed that acidic rain may becausing great ecological damage to the planet. The problem was that by thetime that the scientist found the problem it was already very large.Detecting an acid lake is often quite difficult. A lake does not becomeacid over night. It happens over a period of many years, some timesdecades. The changes are usually to gradual for them to be noticed early.
At the beginning of the 20th century most rivers/lakes like the riverTovdal in Norway had not yet begun to die. However by 1926 local inspectorswere 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 icebegan to melt off more and more hundreds upon hundreds more dead fish(trout in particular) were being found. It was at this time that scientistbegan to search for the reason. As the scientists continued to work theyfound many piles of dead fish, up to 5000 in one pile, further up theriver. Divers were sent in to examine the bottom of the rivers. What theyfound were many more dead fish. Many live and dead specimens were takenback to labs across Norway. When the live specimens were examined they werefound to have very little sodium in their blood. This is typical a typicalsymptom of acid poisoning. The acid had entered the gills of the fish andpoisoned them so that they were unable to extract salt from the water tomaintain their bodies sodium levels.
Many scientist said that this acid poising was due to the fact that itwas just after the winter and that all the snow and ice was running downinto the streams and lakes. They believed that the snow had been exposed tomany natural phenomena that gave the snow it's high acid content. Otherscientists were not sure that this theory was correct because at the timethat the snow was added to the lakes and streams the Ph levels would changefrom around 5.2 to 4.6. They believed that such a high jump could not beattributed to natural causes. They believed that it was due to airpollution. They were right. Since the beginning of the Industrialrevolution in England pollution had been affecting all the trees,soil andrivers in Europe and North America.
However until recently the loses of fish was contained to the southernparts of Europe. Because of the constant onslaught of acid rain lakes andrivers began to lose their ability to counter act their affects. Much ofthe alkaline elements; such as calcium and limestone; in the soil had beenwashed away. It is these lakes that we must be worried about for they willsoon become extinct.
A fact that may please fishermen is that in lakes/rivers they tend tocatch older and larger fish. This may please them in the short run howeverthey will soon have to change lakes for the fish supply will die quickly inthese lakes. The problem is that acid causes difficulties the fish'sreproductive system. Often fish born in acid lakes do not survive for theyare born with birth defects such as twisted and deformed spinal columns.This is a sign that they are unable to extract enough calcium from thewater to fully develop their bone. These young soon die. With nocompetition the older,stronger can grow easily. However there food iscontaminated as well by the acid in the water. Soon they have not enoughfood for themselves and turn to cannibalism. With only an older populationleft there is no one left to regenerate themselves. Soon the lake dies.
By the late 1970s many Norwegian scientists began to suspect that itwas not only the acid in the water that was causing the deaths. They hadproved that most fish could survive in a stream that had up to a 1 unitdifference in PH. After many experiments and research they found that theirmissing link was aluminum.
Aluminum is one of the most common metals on earth. It is stored in acombined form with other elements in the earth. When it is combined itcannot dissolve into the water and harm the fish and plants. However theacid from acid rain can easily dissolve the bond between these elements.The Aluminum is then dissolved into a more soluble state by the acid. Othermetals such as Copper (Cu), iron (Fe) etc can cause such effects upon thefish as well however it is the aluminum that is the most common. Forexample: CuO + H2SO4 ----------> CuSO4 + H2O
..
...In this form it is easily absorbed into the water. When it comes incontact with fish it causes irritation to the gills. In response the fishcreates a film of mucus in the gills to stop this irritation until theirritant is gone. However the aluminum does not go always and the fishcontinues to build up more and more mucus to counteract it. Eventuallythere is so much mucus that it clogs the gills. When this happens the fishcan 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 threedetermining factors in the extinction of fish.
As well there is the problem of chlorine. In many parts of the worldit is commonly found in the soil. If it enters the fish's environment itcan be deadly. It affects many of the fish's organisms and causes it todie. 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 plantsin 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 withthe fish's nervous system.
Acid lakes are deceivingly beautiful. The are crystal clear and have aluscious carpet of green algae on the bottom. The reason that these lakesare so clear is because many of the decomposers are dead. They cannot breakdown that material such as leaves and dead animals. These materialseventually sink to the bottom instead of going through the natural processof decomposition. In acid lakes decomposition is very slow. "The wholemetabolism of the lake is slowed down."
During this same period of time the Canadian department of fisheriesspent eight years dumping sulfuric acid (H2SO4) into an Ontario lake to seethe effects of the decrease in the PH over a number of years. At the PH of5.9 the first organisms began to disappear. They were shrimps. They startedout at a population of about seven million, but at the pH of 5.9 they weretotally wiped out. Within a year the minnow died because it could no longerreproduce it's self.
At this time the pH was of 5.8. New trout were failing to be producedbecause many smaller organisms that served as food to it had been wiped outearlier. With not enough food the older fish did not have the energy toreproduce. Upon reaching the pH of 5.1 it was noted that the trout becamecannibals. It is believed this is due to the fact that the minnow wasnearly extinct.
At a pH of 5.6 the external skeletons of crayfish softened and theywere 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 theexperiment none of the major species had survived the trials of the acid.The next experiment conducted by the scientists was to try and bring thelake back to life. They cut in half the amount of acid that they dumped tosimulate a large scale cleanup. Soon again the cuckers and minnows began toreproduce 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 acidrain on it's own that was affecting the lakes in such a deadly way. Thisscientist was Dr Rosenqvist.
"Why is it that during heavy rain, the swollen rivers can be up tofifteen times more acid than the rain? It cannot be the rain alone that isdoing it, can it?" Many scientist shunned him for this however they couldnot come up with a better answer. Soon the scientists were forced to acceptthis theory.
Sulfuric acid is composed of two parts, know as ions. The hydrogen ionis what make a substance acid. The other ion is sulphate. When there aremore hydrogen ions then a substance is acid. It is this sulphate ion thatwe are interested in. When the rain causes rivers to overboard onto thebanks the river water passes through the soil. Since the industrialrevolution in britain there has been an increasing amount of sulphur in thesoil. In the river there is not enough sulphur for the acid to react ingreat quantities. However in the soil there is a great collection ofsulphur to aid the reaction. When it joins the water the pH becomes muchlower. This is the most deadly effect of acid rain on our water!!! Thewater itself does not contain enough sulphur to kill off it's population offish 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 problemsthat are very serious as well such as the release of aluminium and leadinto our water supplies. We are suffering because of it. In Scotland thereare many birth defects being attributed to it. We must cut down thereleases of chemicals that cause it. But it will take time, even if we wereto stop today we would have the problem for years to come because of thebuild 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.
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Related Keywords: acid, fish, rain, lakes, water, problem, causes, Acid, rivers, soil, +, dead, lake, pH, believed, free essays, free term papers, free college term papers
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