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OUR IMPACT ON THE ENVIRONMENT

One of the best ways to gain a sense of environ­mental science is to examine some of the problems that today's environmental scientists identify and attempt to solve. Some of the problems are truly global in scope, such as destruction of the Earth's ozone shield; others are more regional, such as acid precipitation; and still others are local, such as the pollution of a river. Some problems are cases of upsetting the delicate balance of nature by intro­ducing foreign animals or plants; the invasions of fire ants and killer bees are problems of this sort. Other problems involve the complete destination of ecosystems, such as filling in the coastal wet lands of the Atlantic and Gulf of Mexico coasts or clear-cutting the old-growth forests of the Pacific North-

Nuclear Energy Disaster: Chernobyl

The man is testing for radioactivity. A month earlier, at 1:24 in the morning of April 26, 1986, one of the four reactors of the Chernobyl nuclear power plant, which you see in the background, exploded. Located in the former Soviet Union, Chernobyl was one of the largest nuclear power plants in Europe.

Before dawn on April 26 workers at the planet hurried to complete a series of test and they took a foolish shortcut: they shut u power surge occurred during nothing to dampen it. Power zoom to hundreds of times the maximum safe blast with the force of melted the fuel rods and heated steam, which blew the reactor apart.

Agricultural land was contaminated by radioactive isotopes, particularly downwind from the reactor, and many other serious effects occurred. (See Chapter 11 for further discus­sion of Chernobyl.) One lesson the nuclear disaster at Chernobyl teaches us is that, as our technology advances, so does the impact we have on the environment. It is a theme you will encounter repeatedly as you pro­ceed through this text.

Water Pollution: Fighting to Save the Rhine

The river in Figure 1-5 is the Rhine, a broad rib­bon of water running through the soul of Europe. From high in the Alps that separate Italy and Swit­zerland, it flows north across the heart of industrial Germany before it reaches the Netherlands and the sea. On the first day of November, 1986, the Rhine almost died.

The blow that struck the Rhine did not seem so deadly at first. That morning firemen were fighting a blaze in Basel, Switzerland. The fire was gutting a huge warehouse belonging to a giant chemical company, Sandoz, and the firefighters aimed streams of water into the building to dampen the flames. In the rush to contain the fire, no one thought to ask what chemicals were stored there. By the time the fire was out, the water that had quenched the fire had also washed about 30 tons of mercury and pesticide into the Rhine.

Flowing down the river, the deadly wall of poi­son killed everything it passed. For hundreds of ki­lometers, the surface of the river was blanketed with dead fish. Even the aquatic plants in the river seemed to die. Many cities that use the waters of the Rhine for drinking had little time to make other arrangements. All across Europe, from Swit­zerland to the sea, the river reeked of rotting fish, and not one drop was safe to drink or even touch. Nothing could be done except to wait until the poison had washed out of the river ecosystem.

By 1990, Swiss and German environmental sci­entists monitoring the effects of the accident were able to report that the blow to the Rhine was not mortal. Enough small invertebrate water life and plants had survived to provide the basis for a vigor­ous return of fish and other aquatic organisms. A lesson difficult to ignore, the spill on the Rhine has caused the governments of Germany and Switzer­land to intensify efforts to protect the river from future industrial accidents and to regulate the growth of chemical and industrial plants on its shores.

The Rhine is examined again in Chapter 13, in the context of international management of impor­tant water resources. The member governments of the European Economic Community are now coop­erating to solve many of Europe's environmental problems. A major challenge looms ahead in Cen­tral and Eastern Europe, including Russia, Byelorus­sia, and the Ukraine, where substantial environ­mental damage has been done and must soon be addressed.

Vanishing Species: Our National Parks

In January 1987, William Newmark, a graduate stu­dent of biology, published his doctoral thesis results in the journal Nature. For several years Newmark had visited the national parks of the United States and Canada to see what species of mammals were found in each. He reviewed sighting records going back decades, and came to a startling conclusion: in all but the very largest of the parks, a high propor-

No animals were entirely lost, because those extinct in one park were still found in another. However, the pattern is clear: only the two largest parks {Yellowstone and Banff-Jasper) have not lost from one fourth to more than one third of their mammal species since they were founded around the turn of the century.

The plant you however, is not blooming, because it has been killed by salt. Irrigation, which is responsible for the rich agricul­tural harvest of the San Joaquin Valley, is slowly killing the valley. Irrigation water contains dis-solved salts, and the continued application of such water, season after season, year after year, leads to the gradual accumulation of salt. When the water evaporates, the salts are left behind, particularly in the upper layers of the soil—the layers that are most important for agriculture. Given enough time, the salt concentration can rise to such a high level that plants are poisoned or their roots dehydrated. In the San Joaquin Valley the problem is wor­sened by local geology. A layer of clay 6 to 30 m (20 to 100 ft) below the surface lay down beneath the valley when it was still a lake, keeps water from draining out. Like an enormous bathtub, the valley slowly fills as irrigation water is added. Beneath some 73.000 hectares (about 180,000 acres) of land, the water level sits within 3 m (10 ft) of the surface. This water has already become very salty because it has been dissolving salts from the soil for many thousands of years. With continued irrigation rises closer and closer to the surface, posing a very serious threat to continued agriculture. There it, no easy solution to the problem of soil salinization.

Acid Precipitation

The smokestacks are those of the Four Corners Power Plane in New Mexico. This facility hums coal, sending the smoke high into the atmosphere with the stacks, each of which is more than 60 m (200 ft) tall. The smoke belched out by the stacks contains high concentrations of sulfur, which smells bad (like rotten eggs) and produces acid when it combines with the water vapor in air. The intent of those who designed the plant was to release the sulfur-rich smoke high up in the atmos­phere, where the winds would disperse and dilute it. This sort of solution to the problem of burning high-sulfur coal was first introduced in Great Brit­ain in the mid-1950s mid rapidly became popular in the United States and Europe. There are now about 800 such stacks in the United States alone.

Environmental scientists first noted in the 1970s that the exporting of industrial smoke into the upper atmosphere was producing acid rain andsnow. Sulfur introduced into the atmosphere com­bines with water vapor to produce sulfuric acid, and when the water later falls as rain or snow, the pre­cipitation is acid. Because the Earth spins counter­clockwise (from west to cast), the atmosphere passes from west to east across the Earth's surface, and the sulfur emissions released in the midwestern states return to the surface in the precipitation that falls on the eastern states. Similarly, the many tall stacks of the Ruhr Valley in Germany are responsi­ble for the often strongly acid precipitation that falls over broad areas of Northern Europe.

Among its other effects, acid precipitation de­stroys aquatic life. Thousands of the lakes of Swe­den and Norway no longer support fish. Many of the lakes in the northeastern United States and in eastern Canada also appear to have been acidified to death. Acid precipitation may also be a factor in the decline of forests. The Black Forest in Ger­many, for example, has suffered enormous damage.

At first, the solution seems obvious: capture and remove the emissions instead of releasing them into the atmosphere. There are, however, both eco­nomic and political blocks to such a solution. The economic problem is that it is expensive: reliable estimates of the cost of installing and maintaining the necessary scrubbers in smokestacks in the United States are on the order of $4 to $5 billion a year. The political problem is that the polluter and the recipient of the pollution are often far from one another, and neither is eager to pay so much for what is seen as someone else's problem. Canada, which is suffering from acid rain produced by the United States, has urged the United States to clean up its sulfur emissions. Encouragingly, the United States in 1990 passed clean-air legislation that should significantly improve the situation.

The Introduction of Exotic- Species: We Are Being Invaded

In the mid-1980s, Tampa, Florida, had a new kind of visitor—a cockroach that had arrived on a ship from Asia. Unlike its cousin, the common German cockroach, which lives in houses and scurries away from light, this new immigrant lives outdoors, is attracted to light, and flies. German cockroaches have wings but, like chickens, don't often use them. Asian cockroaches come buzzing in through open windows and land on television screens and lampshades. The Asian cockroach is now firmly established in Florida, and it is not known how rap­idly it will spread through the Southeast, although it seems almost certain that it will.

In 1992 another unwanted visitor entered out country. Several crates marked "Reptiles" were shipped from Lagos, Nigeria, to animal dealers in the United States. In fact, what they contained was a far more dangerous cargo—1,000 giant African snails. This species is considered by biologists to be the most environmentally destruc­tive snail in the world. As large as baseballs, the snails were sold as pets by dealers in 25 states. Weighing up to 0.45 kg (1 Ib) and with 80,000 rasping teeth, one giant African snail is able to eat almost anything and, if it escapes into the wild, can give rise to as many as 16 quadrillion descendants in five years. Federal officials are trying to collect the snails before an escape leads to disastrous con­sequences.

Unfortunately, such invasions are the rule, not the exception. Most of us have read of the recent invasions of fire ants, Africanized killer bees, water hyacinths, kudzu, and others. Each of these incur­sions seems a unique accident when it happens, but the overall problem is general and very serious: our highly mobile society has facilitated the movement of foreign animals and plants, often with disastrous consequences.

Vanishing Species: Destroying the Tropical Forests

The fire you see in Figure 1-10 is in a tropical forest in the Amazon Basin of Brazil. The fire will burn for weeks; turning thousands of acres of forest trees into charred stumps, for no one will try to halt its relentless destruction. This fire was not started by a dropped cigarette or a careless camper, it was set deliberately in order to clear the forest and pro­duce grazing land. All over the world, the tropical forests are being cleared—cut for timber or fire­wood or burned to make pasture or agricultural land. More than half of the entire world's tropical ev­ergreen forests had been destroyed by 1991. What is left, some 6 million square kilometers (about 2.3 million square miles), is less than the area of the United States, and each year another T I W.OOO km" (65,000 mi²), an area larger than size of Wash­ington state, is cleared. In the early I990h, we are destroying tropical forests at the rate of 0.54 hec­tares (1.3 acres) per second.

Tropical forests are among the richest and most diverse of the Earth's biological communities, but when they are cut down or burned, they are very slow to return. We will not see the forest in Figure 1-10 again in our lifetime. The destruction of the world's tropical forests is a tragedy, for count­less species of plants and animals occur in those forests, many of them unique forms only now being described by scientists, and many others awaiting discovery. None of the organisms that have inhab­ited the forest burning in Figure 1-10 will be dis­covered, however. Everything that lived there is gone now. And this same story is repeated every day for hundreds of square kilometers. Who knows which of these plants and animals might have been of great use to future generations of humans?

Damage to the Atmosphere: Ozone Depletion

The swirling colors are a view of the South Pole from a satellite. This is not the picture your eye would see, but rather a computer recon­struction, in which the colors represent different concentrations of ozone, a form of oxygen gas. As you can easily see, there is -a large ozone "hole" over

The Environmental Movement in Brazil

The highly visible environmental movement in the United States, which tackles problems both at home and abroad, may make some consciousness. In actuality, people in developing countries ace increasingly aware of their environmental problems and are working hard to solve them.

Consider Brazil, the world’s fifth largest country and one of the richest in natural resources, particularly fresh water, fore-sis, wild­life, and minerals. Hundreds of Brazilian environmental groups are working to preserve Brazil’s forests, wildlife, and coasts. These Organizations may not have been existence for as long as many environmental groups in the United States, but they have accom­plished a great deal in a relatively short pe­riod of rime. Many of them cosponsor proj­ects with environmental organizations in the United Slates as well as with international corporate sponsor. Some Brazilian environmental organizations are: The Pro-Nature Institute, founded in 1986, which administers programs in several rain forests and has established a wildlife sanctuary. Funatura, founded in 1986, which over sees a wildlife sanctuary in the Atlantic coastal forest as well as conservation program in the Grand Sertau Veredas National Park. The Blue Wave Foundation was founded in 1989, which conducts a national television campaign to clean and protect the beaches of Brazil. Although their funds are often limited, several environmental organizations have produced radio and television ads to educate Brazilians about the destruction of their natu­ral heritage. The fact that grass-roots environmental organizations are continually being founded in Brazil attests to the heightened environmental awareness of that society.

Antarctica is, within which the ozone concentration is much lower than elsewhere. It covers an area about the size of the United States. This ozone hole was first reported in 1985 by British environmental scientists. This is looking buck at earlier satellite data, we now sec that the zone of thinning ozone appeared for the first time in 1975. The hole is not a perma­nent feature but a seasonal phenomenon, evident only for a few months at the onset of the Antarctic winter in September. Every September from 1975 to the present, the ozone hole has reappeared, and each year the layer of ozone has been thinner. In 1990 the minimum ozone concentration in the hole was 50 percent lower than the minimum ten years earlier. And by 1992 there was clear evidence that the ozone was also being depleted over the Arctic,

Environmental scientists are worried about the Antarctic ozone hole because it seems to portend a thinning of the ozone layer worldwide. In the heav­ily populated mid-latitudes of the planet, winter ozone levels dropped by as much as 4 to 6 percent during the 1980s. Why is this worrisome? In the upper atmosphere, ozone absorbs harmful ultravio­let radiation from sunlight; without its protection, human skin cancers caused by ultraviolet radiation would become far more common. The increased ultraviolet radiation might also damage other plant and animal species.

Probing the cause of the ozone hole with high­flying aircraft, environmental scientists in 1987 reported significant amounts of chlorine in the upper atmosphere, suggesting that the ozone in the ozone hole had reacted chemically with chlorine. The main source of the chlorine is a human-made group of chemicals called chlorofluorocarbons (CFCs), familiar to many of us as aerosol propellants in spray cans (now banned in the United States) and as the Freon cooling agent in refrigera­tors and air conditioners.

As a direct result of public awareness of the problem, strong laws were passed restricting use of CFCs in the United States and Canada. In 1990, some 90 other nations agreed to a total ban on CFC production by the year 2000, and in 1992 efforts were made by the United States to move up that

deadline. Because CFCs are very stable, they can survive in the atmosphere 120 years or more, so the changes in Earth's atmosphere initiated by the re­lease of CFCs may not be quickly reversible.

Oil Spills: Killing Sea Otters

On March 24, 1989, the oil supertanker Exxon Valdez ran aground on a reef in the northern part of Prince William Sound, Alaska, discharging 260,000 barrels (11 million gallons) of crude oil that quickly covered thousands of square kilome­ters. The spill proved to be one of the most devas­tating to wildlife, and sea otters were among the most severely hurt. In the first week, 250 dead ot­ters were collected, and 135 live, oil-coated otters were captured and cleaned (Figure 1-12); only 55 of the cleaned otters survived. Post-mortem exami­nations revealed that the oil had poisoned most of them, severely damaging their livers, kidneys, and lungs. All told, several thousand sea otters and more than 30,000 birds arc known to have died.

As a result of the extensive publicity given this natural disaster, new oil tankers are being con­structed with double hulls. A reef might tear the

Outer hull but would not he likely to damage [he inner one. The first such "environmental" canker was launched in Japan in 1991.

It is important to understand that, although oil spills are spectacular environmental disasters, the major forces driving many marine organisms to ex­tinction are not spills, hut fertilizers, pesticides, soil erosion, and other effects of onshore human opera­tions, including the general input of chemicals of all kinds into the open oceans. Less visible than oil spills, this "quiet" pollution is, in the final account­ing, far more deadly, for it has a much greater im­pact un the global marine' ecosystem.

Global Climate Change: Carbon Dioxide Levels

During the past two centuries, as the world's popu­lation has grown to ten times its former size, the level of carbon dioxide (CO_:) in the Earth's atmos­phere has increased dramatically. The causes of the increase in atmosphere CO2 are no mystery: the burning of fossil fuel (coal, oil, and natural gas) and the clearing and burning of forests by farmers. Environmental scientists are growing increasingly concerned that the rising levels of CO₂ may change the Earth's climate. Carbon diox­ide levels rose from315 parts per million (ppm) in 1958 to 354 ppm in 1990 (latest data available). Just as the panes of glass in a greenhouse let light in but do not allow heat out, so CO; in the atmos­phere allows solar radiation to pass through but does not allow heat to radiate back into space. In­stead, the heat is reflected back to the Earth's sur­face. As CO; accumulates in the Earth's atmos­phere, enough heat may be trapped to gradually warm the Earth.

The decade of the 1980s saw the six warmest years in U.S. weather records, and environmental scientists estimate that if trends are not changed, the Earth's mean temperature could rise 1.5 to 4.5°C (2.5 to 7-5^QF) by the middle of the next cen­tury, making the atmosphere warmer than it has' been at any time in the last 100,000 years. This might produce major shifts in patterns of rainfall, and might initiate melting of the West Antarctic ice sheet (as did the last warm period 120,000 years ago). This melting would cause ocean levels to rise. Such a rise is alarming, as it might put many of the Earth's major cities at least partly underwater. With each new warm year in the 1990s, the possibility seems more real that a significant warming trend has begun. Hard conclusions about long-term trends are difficult to reach, hut an increasing num­ber of environmental scientists are concerned.