Introduction to Environmental Science PDF

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T Introduction to Unit 1 E Environmental Chapter 1 a Science Science and the H Environment Chapter 2 Tools of Environmental Science Chapter 3 The Dynamic Earth (t) ©Michael Melford/Getty Images; (b) ©Earth Imaging/Stone/Getty Images; (c) ©Charlotte Main/Photo Researchers, Inc. Once hatched, these perch will continuously pump water through the mouth and over the gill arches to breathe, which makes them vulnerable to pollutants in their environment. Scientists monitor fish and amphibian species to determine the effects of pollution on the world’s ecosystems. 3 Chapter 1 Section 1 Understanding Our Environment Science and the Environment Section 2 The Environment and Society Why It Matters A biologist uses an aerial tramway to survey the rain forest canopy in Costa Rica. Many plants found in the canopy ecosystem seem better adapted for life in the desert than in the rain forest. Why? CASESTUDY Learn more about the delicate balance in an ecosystem and the ways humans can both harm and help an ecosystem in the case study Dam Removal on the Penobscot River on pages 12–13. Online Melford/Getty Images ENVironmental Science HMDScience.com Go online to access additional Image Credits: resources, including labs, ©Michael worksheets, multimedia, and resources in Spanish. 4  Section 1 Understanding Our Objectives Environment Define environmental science, and compare environmental science with ecology. List the five major fields When someone mentions the term environment, some people think of a beautiful scene, such as a stream flowing through a wilderness area or a rain forest canopy of study that contribute to alive with blooming flowers and howling monkeys. You might not think of your environmental science. backyard or neighborhood as part of the environment. In fact, the environment is everything around us. It includes the natural world as well as things produced by Describe the major humans. But the environment is also more than what you can see—it is a complex environmental effects of hunter- web of relationships that connects us with the world we live in. gatherers, the agricultural revolution, and the Industrial Revolution. What Is Environmental Science? Distinguish between renewable There is a growing need to understand the environment as a whole, and nonrenewable resources. including both its biological and physical features. A wide variety of people contribute to this understanding of the environment, including Classify environmental high school students. In the 1990s, students from Keene High School problems into three major in Figure 1.1 studied dwarf wedge mussels in the Ashuelot River of New categories. Hampshire. The mussels, which were once abundant in the river, were in danger of disappearing, and the students wanted to know why. The students tested water samples from different parts of the river, conducted experiments, and asked questions. Key Terms environmental science The students’ efforts were highly praised and widely ­recognized. ecology More importantly, their work contributed to an ongoing community effort that still works toward the preservation of the endangered dwarf agriculture wedge mussel. The students’ work is just one example of a field called natural resource environmental science, the study of the environment that includes the pollution physical, biological, and social sciences. biodiversity Figure 1.1 Student Scientists These students are counting the dwarf wedge mussels in part of the Ashuelot River. Chapter 1: Science and the Environment 5  Figure 1.2 Environmental Scientists Scientists from a variety of fields use different methods to study how humans Connect to HISTORY interact with and impact the environment. Connect to HISTORY The Goals of Environmental Science Rachel Carson Environmental scientists have found that the environment is influenced Alarmed by the increasing levels of by people and that people are influenced by the environment. A major pesticides and other chemicals in the goal of many environmental scientists is to understand and solve envi- environment, biologist Rachel Carson ronmental problems. To address this goal, environmental scientists study published Silent Spring in 1962. two main types of interactions between humans and the environment. Carson imagined a spring morning One area of study focuses on how we use natural resources, such as water that was silent because the birds and and plants. The other area of study focuses on how our actions alter our frogs were dead after being poisoned environment. Environmental scientists must gather and analyze informa- by pesticides. Carson’s carefully tion from many different disciplines. Even though environmental scien- researched book was enthusiastically tists want to solve environmental problems, they are not the same as en- received by the public and was read vironmentalists. Scientists study the environment to accurately describe by many other scientists, as well environmental systems and determine how they work. Scientists also can as policy makers and politicians. use data and mathematical models to predict how systems might change However, many people in the chemical under different scenarios. It is up to the public, special interest groups, industry saw Silent Spring as a threat and politicians to make decisions about how to manage the environment. to their pesticide sales and launched Environmentalism is a social movement that seeks to protect the environ- a $250,000 campaign to discredit ment and, because we all depend on the environment, people. Carson. Carson’s research prevailed, although she died in 1964—unaware that the book she had written was Many Fields of Study instrumental in the birth of the modern Environmental science is an interdisciplinary science, which means it environmental movement. involves many fields of study. Ecology is the study of how living things interact with each other and with their nonliving environment. Chemistry helps us understand how organic matter is transformed and the nature of pollutants. Geology helps us model how water and air move around the globe. Botany and zoology provide information needed to preserve species. Paleontology, the study of fossils, helps us understand how Earth’s climate has changed in the past. Using such information about the past can help us predict how future climate changes could affect life on Earth. Often, teams of environmental scientists work together to understand and solve environ- mental problems. Studying the environment also involves studying human populations. Environmental scientists may use the social sciences, which include eco- nomics, law, politics, and geography. Social sciences can help us answer questions such as How does human migration from rural to urban areas ©Matt Meadows Check for Understanding affect the local environment? Or how can economic incentives change Compare How is ecology related to people’s decisions to protect the environment? Figure 1.3 lists some of the environmental science? major fields of study that contribute to the study of environmental science. 6 Unit 1: Introduction to Environmental Science  Figure 1.3 Major Fields of Study That Contribute to Environmental Science Biology is the study of living Zoology is the study of animals. organi­sms. Botany is the study of plants. Microbiology is the study of microorganisms. Ecology is the study of how organisms interact with their environment and each other. Earth science is the study Geology is the study of Earth’s surface, interior processes, and history. of Earth’s nonliving systems Paleontology is the study of fossils and ancient life. and the planet as a whole. Climatology is the study of Earth’s atmosphere and climate. Hydrology is the study of Earth’s water resources. Physics is the study Engineering is the science by which matter and energy are made useful to humans in structures, of matter and energy. machines, and products. Chemistry is the study Biochemistry is the study of the chemistry of living things. of chemicals and their Geochemistry, a branch of geology, is the study of the chemistry of materials such as rocks, soil, interactions. and water. Social sciences are the Geography is the study of the relationship between human populations and Earth’s features. study of human populations. Anthropology is the study of the interactions of the biological, cultural, geographical, and historical aspects of humankind. Sociology is the study of human population dynamics and statistics. ©Douglas Faulkner/Photo Researchers, Inc. Chapter 1: Science and the Environment 7  Figure 1.4 Environmental Science and Public Life Scientists at a conference discuss climate change. Students study the movements of box turtles. Scientists as Citizens, Citizens as Scientists Governments, businesses, and communities recognize that studying our environment is vital to maintaining a healthy and productive society. Thus, environmental scientists are often asked to share their research with the world. Figure 1.4 shows scientists meeting to discuss climate change at a United Nations conference. Often, the observations of nonscientists are the first step toward addressing an environmental problem. For example, middle-school (b) ©North Wind Picture Archives; (tr) Courtesy of Gardner Watkins; (tl) ©Xu Jinquan/Xinhua Press/Corbis Figure 1.5 students first noticed the appearance of deformed frogs in Minnesota Change Three hundred years ago, lakes. Similarly, the students at Dublin Scioto High School in Ohio, Manhattan was a very different place. shown in Figure 1.4, have studied the habitat of endangered box turtles. A This painting shows an area where Native habitat is a place where an organism usually lives. The students wanted Americans hunted and fished. to find out how the turtles live and what factors affect their nesting and hibernation sites in their habitat. The students tracked and mapped the turtles’ movements, measured atmospheric conditions, and analyzed soil samples. These efforts are important because the box turtle habitat is threatened. The students have presented their findings to city planners, in an effort to protect the most sensitive turtle habitats. Our Environment Through Time Wherever humans have hunted, grown food, or settled, they have changed the environment. For example, the land where New York City now stands was once an area where Native Americans hunted game and gathered food, as shown in Figure 1.5. The environmental change that has occurred on Manhattan Island over the past 300 years is immense, yet this period of time is just a “blink” in human history. 8 Unit 1: Introduction to Environmental Science  Hunter-Gatherers ECOFACT For most of human history, people were hunter-gatherers, or people who The Fall of Troy obtain food by collecting plants and by hunting wild animals or scaveng- Environmental problems are nothing ing their remains. Early hunter-gatherer groups were small, and they new. Nearly 3,000 years ago, the migrated from place to place as different types of food became available at Greek poet Homer wrote about the different times of the year. Even today there are hunter-gatherer societies ancient seaport of Troy, which was in the Amazon rain forests of South America and in New Guinea, as shown located beneath a wooded hillside. in Figure 1.6. The Trojans cut down all the trees on Hunter-gatherers affected their environment in many ways. For the surrounding hills. Without trees example, some Native American tribes hunted bison that live in grass- to hold the soil in place, rain washed lands. The tribes set fires to burn the prairies and prevent the growth the soil into the harbor. So much of trees. This kept the prairies as open grassland where the tribes could silt accumulated in the harbor that hunt bison. large ships could not enter and Troy’s economy collapsed. Today, the ruins of In North America, rapid climate changes and overhunting by hunter- Troy are several miles from the sea. gatherers may have contributed to the disappearance of some species of large mammals. These species include giant sloths, giant bison, mast- odons, cave bears, and saber-toothed cats. Large piles of bones have been found where meat was possibly stored during the winter. In Australia and Check for Understanding New Zealand, hunter-gatherers caused the extinction of many large spe- Identify Name two ways that hunter- cies of mammals and birds. gatherers affected their environment. Figure 1.6 Hunter-Gatherers This modern hunter-gatherer group lives in New Guinea, a tropical island off the north coast of Australia. ©David Gillison Chapter 1: Science and the Environment 9  The Agricultural Revolution FieldStudy Eventually many hunter-gatherer groups began to collect the seeds of Go to Appendix B to find the field study the plants they gathered and to domesticate some of the animals in their Measure Up. environment. Agriculture is the practice of growing, breeding, and caring for plants and animals that are used for food, clothing, housing, transpor- tation, and other purposes. The practice of agriculture started in many different parts of the world over 10,000 years ago. This change had such a dramatic impact on human societies and their environment that it is often called the neolithic agricultural revolution. The agricultural revolution allowed human populations to grow at an unprecedented rate. An area of land can support up to 100 times as many people by farming as it can by hunting and gathering. As populations grew, they began to concentrate in smaller areas. These changes placed increased pressure on local environments. The agricultural revolution also changed the food we eat. The plants we grow and eat today are descended from wild plants. During harvest season, farmers collected seeds from plants that exhibited the qualities they desired. The seeds of plants with large kernels or sweet and nutri- tious flesh were planted and harvested again. Over the course of many generations, the domesticated plants became very different from their wild ancestors. For example, the grass shown in Figure 1.7 may be related to the grass from which corn was bred. As grasslands, forests, and wetlands were replaced with farmland, habitats were destroyed. Slash-and-burn agriculture, shown in Figure 1.7, is one of the earliest ways by which land was converted to farmland. Replacing forest with farmland on a large scale caused soil loss, floods, and water shortages. In addition, much of this converted land was farmed poorly and is no longer fertile. The loss of fertile farmland had far-reach- ing effects. For example, the early civilizations of the Tigris-Euphrates River basin collapsed, in part, because the overworked soil became infer- tile through salt contamination. Figure 1.7 The Agricultural Revolution (bl) ©A. Murray/University of Florida; (br) ©Still Pictures This grass, called Eastern gama grass, is thought to be a relative For thousands of years humans have burned forests to create fields for of the modern corn plant. Native Americans may have selectively agriculture. In this photo, a rain forest in Thailand is being cleared for farming. bred a grass like this to produce corn. 10 Unit 1: Introduction to Environmental Science  Figure 1.8 Industrial Revolution During much of the Industrial Revolution, few limits were Quality of Life The invention of computers placed on the air pollution caused by burning fossil fuels. Locomotives such as these has improved the ways that people work, learn, were powered by burning coal. communicate, and entertain themselves. The Industrial Revolution For about 2.5 million years the tools of human societies were powered mainly by humans or animals. This pattern changed in the middle of the 1700s with the Industrial Revolution, which involved a shift from energy sources, such as animal muscle and running water, to fossil fuels, such as coal and oil. The increased use of fossil fuels and machines, such as the steam engines shown in Figure 1.8, changed society and greatly increased the efficiency of agriculture, industry, and transportation. During the Industrial Revolution, the large-scale production of goods (tl) ©Lambert/Archive Photos/PictureQuest/Getty Images; (tr) ©Color Blind Images/Blend Images/Getty Images in factories became less expensive than the local production of goods. Machinery reduced the amount of land and human labor needed for farming. As fewer people grew their own food, populations in urban areas steadily grew. Fossil fuels and motorized vehicles allowed food and other goods to be transported cheaply across great distances. Improving Quality of Life The Industrial Revolution introduced many positive changes. Inventions such as the light bulb greatly improved our quality of life. Agricultural productivity increased, and sanitation, nutrition, and medical care vastly improved. Technologies such as the telephone and the portable com- puter, shown in Figure 1.8, enabled people to work and communicate more easily from any location. Yet with all of these advances, the Indus- trial Revolution introduced many new environmental problems. In the 1900s, modern societies began to use artificial substances in place of raw animal and plant products. Plastics and many other artificial ma­terials have made life easier. However, we now understand some of the environmental problems they present. Much of environ- Check for Understanding mental science is concerned with the problems associated with the Identify Identify three ways that the Industrial Revolution. Industrial Revolution changed society. Chapter 1: Science and the Environment 11  Figure 1.9 Spaceship Earth Earth, shown from space in Figure 1.9, has been compared to a ship travel- Space This photograph was taken in ing through space, unable to dispose of waste or take on new supplies as 1968 by the crew of Apollo 8. Photographs such as this helped people realize the it travels. Earth is essentially a closed system—the only thing that enters uniqueness of the planet we share. Earth’s atmosphere in large amounts is energy from the sun, and the only thing that leaves in large amounts is heat. A closed system has potential problems. Some resources are limited, and as the population grows, the resources will be used. In a closed system there is also the chance that we will produce wastes more quickly than we can dispose of them. Although Earth can be thought of as a complete system, envi­ ronmental problems can occur on different scales: local, regional, or global. For example, your community may be discussing where to build a new landfill, or local developers may be arguing with environmental- ists about the importance of a rare bird or insect. On a regional level, the drinking water in your area may be affected by a polluted river hundreds of miles away. Other environmental problems are global. For example, carbon dioxide released in one part of the world can contribute to climate change around the globe. CASESTUDY Dam Removal on the Penobscot River Dams on rivers help to produce much-needed electricity fisheries have been lost and the Penobscot population without continuously burning fossil fuels. These benefits, of salmon was listed under the Endangered Species Act however, are accompanied by some environmental, in 2009. Scientists determined that the primary cause of economic, and social costs. The large geographic areas of decline is obstruction of fishes’ migratory paths by dams. watersheds (the land area that drains into a river) and the Dams reduce the environmental benefits of a free- diverse mix of interest groups present challenges to making running river in many ways. These benefits include food, fair and sustainable decisions about hydropower. How can recreation, cultural enrichment, and clean water. Varying the right balance be achieved? depths and currents that come with natural flow create diverse habitats that promote diverse wildlife. Periods of The Penobscot River, Maine fast flow remove silt from gravel beds, which is necessary The watershed of the Penobscot River is the largest in for many aquatic insects. These insects are food for fish. Maine, and the major streams extend over 8,800 km (about Many species of fish need sand or gravel to reproduce. 5,500 miles). Historically, the Penobscot was home to Normal river flow helps rivers recover from pollution, and abundant fish and other wildlife. For example, more than coastal ocean ecosystems are productive because rivers 100,000 salmon per year migrated for reproduction from deliver nutrients from land to ocean. These benefits of the ocean to this watershed. Salmon and ten other species natural river flow have been revealed by the work of many of migratory fish enriched the watershed and provided food environmental scientists. and cultural value for the Wabanaki people, who occupied the area continuously for more than 9,000 years. The Penobscot River Restoration Trust European settlement of the area brought construction To reconcile the benefits and costs of dams, the Penobscot of many dams to provide power for mills and eventually to River Restoration Project brought together a wide variety of ©NASA produce electricity. In the past few decades all commercial groups to develop a plan that is now being implemented. 12 Unit 1: Introduction to Environmental Science  Population Growth: A Local Pressure Figure 1.10 One reason many environmental problems are so pressing today is that World Population The size of the the agricultural revolution and the Industrial Revolution allowed the human population in 2010 was nearly human population to grow much faster than it had ever grown before. The 14 times larger than it was in 1600. development of modern medicine and sanitation also helped increase the human population. As shown in Figure 1.10, the human population almost WorldÊPopulation:Ê quadrupled during the 20th century. Producing enough food for such 1600Ð2010 7.5 a large population has environmental consequences. Many of the envi- Population (in billions) 6.5 ronmental problems that affect us today, such as habitat destruction and 5.5 pesticide pollution, are the result of feeding the world in the 20th century. 4.5 Other problems, like climate change, are the result of filling the demand 3.5 for goods and transportation of so many people. 2.5 There are many different predictions of population growth for the 1.5 future. But most scientists think that the human population will almost 0.5 double in the 21st century before it will begin to stabilize. We can expect 1600 1700 1800 1900 2000 that the pressure on the environment will continue to increase as the hu- Year Source:ÊU.S.ÊCensusÊBureau,Ê man population and its need for food and resources grow. InternationalÊDatabase The Penobscot River, Maine today to millions of fish! This will revitalize the Penobscot Indian Nation’s culture and traditions and will promote sustainable economic development of communities within the watershed. The story of the Penobscot River is an example of how environmental science and public action work together to solve environmental problems. Good science These groups include a hydropower company, the revealed the causes for decline, needs for ecological Penobscot Indian Nation (a part of the Wabanaki people), Critical Thinking restoration, and the engineering solutions to implement seven conservation groups, and government agencies at large-scale projects. Science will continue to be applied the state and federal levels. As part of the plan, hydropower to evaluate the recovery of wildlife, and many groups with levels will be maintained, but two dams closest to the different interests working together will ensure the long-term mouth of the river will be removed, construction of a bypass health of the river and local communities. for migratory fish will occur at a third dam, and passages will be built for fish at four more dams. These actions Critical Thinking ©Edwin Remsberg/Alamy Images will be monitored by Maine and Federal agencies. Most 1. Analyzing Processes Why was the Penobscot importantly, the Penobscot River Restoration Trust was River Restoration Trust formed? formed to promote continued collaboration and oversight 2. Analyzing Relationships Describe how for all the participating groups. Increased access to proper environmental science helped the Trust decide habitat and improved water quality should allow populations that some dams should be removed. of many migratory fishes to grow from no more than 2,000 Chapter 1: Science and the Environment 13 QUICKLAB What Are Our Main Environmental Problems? Classifying Resources You may feel as though the world has an unlimited variety of environ- QUICKLAB Procedure mental problems. But many environmental problems fall into three 1. You and a partner will be given a categories: resource depletion, pollution, or loss of biodiversity. small container of objects by your teacher. 2. Working separately, you should Resource Depletion each create a data table with Any natural material that is used by humans is called a natural resource. the headings, “Renewable” and Natural resources can be classified as renewable or nonrenewable, as “Nonrenewable.” shown in Figure 1.11. A renewable resource is a resource that can be replaced 3. Without speaking, each of you relatively quickly by natural processes. Fresh water, air, soil, trees, and crops should look at the objects and are all resources that can be renewed. Energy from the sun is also a renew- decide in which of the two able resource. A nonrenewable resource is a resource that forms at a much categories they belong. slower rate than the rate that it is consumed. The most common nonre- 4. When you are both finished, compare your choices. Discuss newable resources are minerals and fossil fuels. Once a nonrenewable any differences, explaining why resource is used up, it may take millions of years to replenish it. you placed objects in a particular Resources are said to be depleted when a large fraction of the resource category. has been used up. Figure 1.11 shows a mine where copper, a nonrenew- 5. Participate in a class discussion able resource, is removed from the Earth’s crust. Some renewable re- about what resources the sources can also be depleted. For example, if trees are harvested faster objects represent and why they than they can grow naturally in an area, deforestation will result. are considered renewable or nonrenewable. Pollution Analysis With the Industrial Revolution, societies began producing wastes faster 1. Why are resources like air and water considered to be at risk, than the wastes could be disposed of. The wastes accumulate and cause even though they are considered pollution. Pollution is an undesired change in air, water, or soil that ad- renewable? versely affects the health, survival, or activities of humans or other organ- 2. Select one resource and hypothesize isms. Air pollution levels in Mexico City, as shown in Figure 1.12, are danger- what side effects might occur if ously high, mostly because of car exhaust and industrial pollutants. that resource is depleted. Biode­gradable pollutants can be broken down by natural processes. These pollutants include things such as human sewage and food wastes. Figure 1.11 Resources More than 12 million tons of copper have Renewable and been mined from the Bingham Nonrenewable Resources mine in Utah. Once all of the copper that can be profitably Renewable Nonrenewable extracted is used up, the copper energy from metals such as ©Gene Ahrens/Bruce Coleman, Inc./Photoshot in this mine will be depleted. the sun iron, aluminum, and water copper nonmetallic ma­terials wood such as salt, sand, soil and clay air fossil fuels 14 Unit 1: Introduction to Environmental Science  Biodegradable pollutants are a problem when they accumulate faster Figure 1.12 than they can be broken down. Nonbiodegradable pollutants, such as mercury, lead, and some types of plastic, cannot be broken down by Air Pollution The problem of air pollution in Mexico City is compounded natural processes. Because such pollutants do not break down easily, because the city is located in a valley that they can build to dangerous levels in the environment. traps air pollutants. Because carbon dioxide is generally not harmful to people’s health— we breathe it out when we exhale—people often don’t think of it as a pollutant. But the huge amounts of CO2 being released from the burning of fossil fuels are increasing the amount in the atmosphere and chang- ing the climate. Because of this undesirable effect, it may be considered pollution in some forms. Because climate change is a global problem that affects many other environmental problems, many scientists believe that it is the most pressing environmental issue. Loss of Biodiversity The term biodiversity refers to the number and variety of species that live in an area. Earth has been home to hundreds of millions of species. Only a fraction of those species are alive today. Extinction is a natural process, (cr) ©Nature Source/Photo Researchers, Inc; (tr) ©SPL/Photo Researchers, Inc. and several large-scale extinctions, or mass extinctions, have occurred through Earth’s history. Scientists believe that the pace of extinctions Figure 1.13 occurring today matches that of mass extinctions in the past. Why should Loss of Biodiversity The Tasmanian we be concerned about the modern extinction of individual species? tiger, native to Australia and the island of The organisms that share the world with us can be considered natural Tasmania, was declared extinct in 1986. resources. We depend on other organisms for food, for the oxygen we breathe, and for many other things. A species that is extinct is gone for- ever, so a species can be considered a nonrenewable resource. Scientists think that if current rates of extinction continue, it may cause problems for human populations in the future because the loss of too many species may cause significant disruption in ecosystems. If this happens, many of the services ecosystems provide to people may be lost. Many people also argue that all species have potential economic, ecological, scientific, aesthetic, and recrea­tional value, so it is important to preserve them. Section 1 Formative Assessment Reviewing Main Ideas Critical Thinking 1. Describe the two main types of interactions 5. Making Comparisons What is the difference that environmental scientists study. Give an between environmental science and ecology? example of each. 6. Making Inferences Fossil fuels are said to be 2. Describe the major environmental effects of nonrenewable resources, yet they are produced the agricultural revolution and the Industrial by the Earth over millions of years. By what time Revolution. frame are they considered nonrenewable? Write a paragraph that explains your answer. 3. Explain how environmental problems can be local, regional, or global. Give one example of each. 4. Explain why environmental science is an interdisciplinary science. Chapter 1: Science and the Environment 15