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acid deposition

acid deposition Acid deposition is a huge problem in our world today. It contaminates our waters causing the deaths of plants, trees, and fish as well as other animals. This is not a problem that only affects wildlife, as humans, we depend on this wildlife for our own sources of food and shelter. It is a problem we must face together in order to solve it. However, acid rain by itself is not the biggest problem. It causes many other deadly problems such as aluminum poisoning. What is acid deposition? Acid deposition, also known as acid rain, is all the rain, snow, mist, etc. that falls from the sky onto the Earth that contains unnatural acids. It is not to be concerned with uncontaminated rain that falls, even though all rain is naturally slightly acidic. Acid rain is caused by contaminates emitted by today's industries as well as by automobiles. These poisons are released into our atmosphere because of the difficulty and cost of properly disposing of them. Therefore, the sulfur dioxides and nitrogen oxides reach our atmosphere virtually untreated. "Eventually, raindrops that fall through heavily-polluted air scavenge a load of airborne materials, and included in their load are acid gases and acid particles. Acid deposition was first considered to be a serious threat around 20 years ago when scientists in Norway and Sweden first believed that acidic rain might be causing great ecological damage to the planet. This was a monumental discovery. However, it was discovered too late. Detecting acidic lakes is often quite difficult. A lake does not become acidic overnight. It happens over a period of many years, or even over decades of deposition. The changes are usually too gradual for them to be detected early (Acid Deposition, 1983, p.128). Sulfuric acid is composed of two parts known as ions. They are hydrogen (H2) and sulfate (SO4) (Luoma, 1984, p.147). When it rains and the rivers overflow onto their banks the river passes through the soil. Since the Industrial Revolution there has been an increasing amount of sulfur in the soil. The river does not have enough sulfur in it to complete the reaction until it filters through the sulfur rich soil. This in part aids in the reaction creating sulfuric acid. When it joins with the water the pH rises dramatically (Louma, 1984, 148). This is how acid enters our waters, and its affects are devastating. The natural water does not contain the right amounts of sulfur to create the acid but with a little help from man the cycle is complete. At the beginning of the 20th century most rivers and lakes, like the river in Tovdal, 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 on the banks of rivers. As the winter ice and snow began to thaw, the fish kills rose dramatically. River trout was one of the hardest hit of fish populations (Pearce, 1987, p.23). It was at this time that scientists began to search for a reason. As the scientists continued their investigations, the fish kills rose. They found that the fish were dying at an alarming rate; they even found masses of up to 5,000 dead fish in some areas. When divers were sent to examine the bottom of the river all they found were more dead fish. The live and dead specimens were taken to laboratories across Norway for further examination. When the live specimens were examined they were found to have very low sodium levels in their bloodstreams. This is a typical symptom of acid poisoning. The acid had entered the fish's gills and poisoned them so that they were unable to extract salt from the water in order to maintain their body's normal sodium level (Pearce, 1987, p.34). Some scientists theorized that the acid poisoning was due to natural acidic runoff from the spring thaw. They felt that the snow had been exposed to natural phenomena that gave the snow its high acid content. Other scientists did not believe this theory to be correct. At the time the snow was added to the lakes and streams the pH levels changed from 5.2 to 4.6. They felt that such a marginal increase could not be attributed to natural causes. The scientists believed air pollution was the culprit. They were right. Since the beginning of the Industrial Revolution in England pollution had been affecting the trees, soils, and rivers all over Europe and North America (Pearce, 1987, p.38). However, until recently the losses of fish was contained to the southernmost parts of Europe. After a constant onslaught of acidic lakes and rivers began to lose their ability to counteract their affects. Much of the alkaline elements; such as calcium and limestone; in the soil have been totally washed away. It is these lakes and rivers that we must focus on, for they will shortly become extinct if drastic measures are not taken immediately (Pearce, 1987, p.37). One interesting fact that fishermen will enjoy is the fact that they will be catching older and larger fish at this present time. This may please them now, but in the long run, these rivers and lakes will be depleted of fish and the waters will become extinct. This is because the acid present in the water causes difficulties in the fish's reproductive system. Often, fish born in acidic lakes do not survive. They are often born with birth defects such as deformed spinal columns. This is a sign that they are unable to extract enough calcium from the water in order to fully develop their bones. With virtually no young, the older, stronger fish can live and grow easily. However, the acid in the water contaminates their food. Soon they do not have food to survive and the fish resort to cannibalism (Howells, 1990, p.99). With only an older population left, there are no fish left to regenerate. Soon the lake dies. By the late 1970's many Norwegian scientists began to suspect that it was not solely the acid in the water that was causing the fish kills. They proved that most fish could survive in a stream that had up to a 1-unit difference in pH. After many experiments and research, the scientists came to the conclusion that aluminum was to blame (Howells, 1990, p.123). Aluminum is one of the most common metals on Earth. It is stored in a combined form with other elements. When combined it cannot be dissolved into water and harm fish or plants. However the acid from acidic 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) as well as others can cause similar effects to the fish as well. However, aluminum is the most common culprit. For example: CuO + H2SO4 ---à CuSO4 + H2O (Howells 124). In this form the aluminum is easily absorbed into the water. When it comes in contact wit fish it causes irritation of the gills. In response, the fish creates a film of mucus encasing the gills in order to stop the irritation. If the aluminum does not go away the fish will continue to build this layer of mucus to counteract it. Eventually, the amount of mucus gets so high that it ends up clogging the gills so that the fish can no longer breathe. Scientists now see acid, aluminum, and the lack of calcium as three determining factors in the extinction of fish (Howells, 1990, p.124). Just as aluminum is a major problem, the leeching of chlorine is also a threat. Chlorine is commonly found in the soil in many parts of the world. If it enters the fish's environment it can be deadly. It affects many of the fish's organs and causes the fish to die. The chloride bonds with sodium, which in part interferes with, the photosynthesis process in plants. NaOH + HCL --à NaCL + H2O (Howells, 1990, p.124). Acidic lakes are deceivingly beautiful. They are crystal clear and have a luscious carpet of green algae on their bottom. The reason these lakes appear so clear is because many of the lakes decomposers are dead (Howells, 1990, p.145). Therefore, materials such as leaves and dead animals cannot be broken down. 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." (Pearce, 1987, p.67) During this same period of time, the Canadian Department of Fisheries conducted an experiment over 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 a PH of 5.9 the first organisms, shrimp, began to disappear. The shrimp population began at about seven million, but at the pH of 5.9 they were totally wiped out. Within one year the minnow population was wiped out because it could no longer reproduce itself. At this time the pH was 5.8 and new trout were failing to be produced because the smaller organisms that served as food for them had been eliminated. Without sufficient food the trout did not have enough energy to reproduce. As the pH level reached 5.1 it is noted that the trout population resorted to cannibalism. This was due to the extinction of the minnow, the trout's main food source. By the end of the experiment none of the major species had survived the trials of the acid (Pearce, 1987, p.71). The next experiment conducted by the scientists was to try and bring the lake back to life. They cut the amount of acid present in the water in half in order to stimulate a large-scale cleanup. Soon the minnows began to reproduce again, and the lake eventually "came back to life" to an extent (Pearce, 1987, p. 71). Acid deposition is a major problem in our world today. It causes the death of our lakes, rivers, and if we do not find a solution soon, the death of life as we know it. As it poisons the fish by leeching aluminum and lead, it also poisons the human race, for we depend on these lakes as major food sources, and we are already starting to suffer because of it. In Scotland, there have been a rash of birth defects attributed to acid rain and its destructiveness (Pearce, 1987, p.149). It is imperative that we cut down on the emission of chemicals that cause it. All hope is not lost. Over the last 15 years, lakes and streams throughout many areas in the United States have experienced decreases in sulfate concentration in response to decreased emissions and deposition of sulfur. There is even evidence of recovery from acidification in some New England lakes. However, the majority of the Adirondack lakes have continued to acidify. Additional reduction of sulfur and nitrogen will be required to fully recover sensitive Adirondack lakes (Gibbons, 1996, p. 4). Now that we see that change is possible, and that these lakes are not too far-gone. Humans, as a whole, need to come together to help solve this problem. If it requires stricter regulations on power plants, so be it. Everyone can do their part; we can drive cleaner burning cars, or just simply drive less. The point is, acid deposition is a potentially deadly situation that can potentially be solved with hard work and time. The question is, do we have time or have we sat and stared at the clock for too long. Bibliography: Works Cited Acid Deposition. Washington, D.C. : National Academy Press, 1983. Howells, Gwyneth. Acid Rain and Acid Water. London: Ellis Horwood, 1989. Luoma, Jon. Troubled Skies, Troubled Waters. New York: The Viking Press, 1984. Gibbons, John. National Acid Precipitation Assessment Program Biennial Report to Congress: An Integrated Assessment. National Science and Technology Council, 1998. http://www.nnic.noaa.gov/CENR/NAPAP/_96.htm. Pearce, Fred. Acid Rain, What is it and What is it doing to us? New York: Penguin Publishing House, 1987.

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