CH-19-20 Climate Disruption and Ozone Depletion – Living in the Environment: Principles, Connections, and Solutions : Book Guide

This Document Contains Chapters 19 to 20 Chapter 19 Climate Disruption and Ozone Depletion Summary 1. The earth’s average surface temperature and climate has changed in the past. The changes include prolonged periods of global cooling and global warming. 2. There is a natural greenhouse effect in the earth’s atmosphere caused by the presence of gases that trap long-wave radiation (water, CO2, and others). Human emissions of carbon dioxide, methane, and nitrogen oxide increase the concentrations of greenhouse gases and cause additional warming of the earth’s surface. 3. Factor’s influencing changes of earth’s average surface temperature include changes in the solar output, the earth’s reflectivity, the ability of oceans and land ecosystems to store carbon dioxide, the ocean currents, the average sea level, cloud cover, and air pollution. 4. Possible effects from a warmer earth include shifts in plant-growing areas, crop yields and pests, extinction of some species, loss of habitats, prolonged heat waves and droughts, increased flooding, changes in water supplies, decreased water quality, changes in forest composition, increased fires, rising sea levels, beach erosion, contamination of aquifers, spread of tropical diseases into temperate zones, increased respiratory diseases and allergies, increased deaths, and migration. 5. To prevent or slow global warming we can limit fossil fuel use, shift from coal to natural gas use, place energy efficient technologies in developed and developing countries, improve energy efficiency, shift to renewable resources, reduce deforestation, use sustainable agriculture, limit urban sprawl, reduce poverty, and slow population growth. 6. Human activities that cause ozone depletion include emissions of chlorofluorocarbons, methyl bromide, hydrogen chloride, carbon tetrachloride, methyl chloroform, and others. The stratosphere contains high concentrations of ozone that absorbs UV radiation as it enters the atmosphere. Ozone depletion can lead to sunburns, cataracts, skin cancers, immune suppression, and reduced crop yields, particularly in the Southern Hemisphere. Note that students often confuse tropospheric ozone (air pollution) and stratospheric ozone (UV absorption), and confuse ozone depletion with global warming. Key Questions and Concepts 19-1 How Might the Earth’s Temperature and Climate Change in the Future? CORE CASE STUDY: Greenland’s ice is melting at a slow and accelerating rate. If Greenland’s glaciers melt, it could raise sea level dramatically. The IPCC projects that global sea level is likely to rise by 7-23 inches this century. Other scientists suggest that sea level rise will be much greater. A. Temperature and climate have been changing throughout the earth’s history. Climate shifts have occurred due to volcanic emissions, changes in solar input, continents moving on shifting plates, meteor strikes, and other factors. Alternating cycles of freezing and thawing are known as glacial and interglacial periods. B. Geologic records and atmospheric measurements provide a wealth of information about past atmospheric temperatures and climate. On average, over the past 900,000 years, there has been a cycle of global cooling and global warming. The cycles are known as glacial and interglacial periods. C. Certain gases in the atmosphere absorb heat and warm the lower atmosphere. A natural process called the greenhouse effect warms the lower troposphere and surface. D. The four major greenhouse gases in the lower atmosphere are water vapor, carbon dioxide, methane, and nitrous oxide. E. Climate change and human activities. 1. Humans have increased levels of greenhouse gases in the troposphere by use of fossil fuels, farming, use of inorganic fertilizers, burning forests, etc. Burning of fossil fuels has generated much of the CO2 increase. Methane emissions have risen as a result of raising livestock, extracting fossil fuels, creating landfills, and creating reservoirs. Nitrous oxide has risen because if increased use of nitrogen fertilizers. 2. There is evidence that the earth’s troposphere is warming, mostly because of human actions. The Intergovernmental Panel on Climate Change (IPCC) was formed in 1988 to evaluate possible future climate changes. The major findings of the IPCC are: a. The earth’s lower atmosphere is warming. b. Most of the increase in greenhouse gases is due to human activities. c. Changes in the atmosphere are beginning to change the climate. d. If greenhouse gas concentrations continue to rise, there will likely be rapid climate disruption. e. This disruption will likely cause ecological, economic, and social disruption. SCIENCE FOCUS: The IPCC brings together 2,500 scientists from around the world. The 2007 IPCC report is based on 18,000 peer reviewed publications by 2,500 scientists and researchers. 450 lead authors of the report took into account 90,000 comments by reviewers before issuing a final report of 30,000 pages. F. Carbon dioxide concentrations play an important role in determining the average temperature of the atmosphere. SCIENCE FOCUS: To make predictions about how temperature will change in the future, scientists develop complex mathematical models to simulate many factors. These are projections of what is likely, as opposed to predictions. 1. Exceeding carbon dioxide levels of 450 ppm may push us beyond an irreversible tipping point. 2. The largest carbon dioxide emitters are China, the United States and the European Union. G. It is thought that most of the rise in temperature since 1980 could not be the result of increased solar output. H. Oceans lose some of their ability to remove carbon from the atmosphere as their temperatures rise. Oceans are also becoming more acidic because of increasing levels of carbon dioxide. I. The role of clouds in warming the atmosphere is largely unknown. J. Aerosols may temporarily slow warming by reflecting sunlight and serving as condensation nuclei for clouds. 19-2 What Are Some Possible Effects of a Warmer Atmosphere? A. Most historic changes in the temperature of the lower atmosphere took place over thousands of years. Today we face a rapid projected increase. B. Severe droughts may increase. This may cause an increase in wildfires, declines inaccessible surface water and declining biodiversity. C. The melting of some of the world’s ice means that less sunlight is reflected back into space, and helps warm the troposphere further. Mountain glaciers are a major source of fresh water and they are shrinking. D. Permafrost will likely melt, emitting significant amounts of methane and carbon dioxide into the atmosphere. E. Sea levels are rising faster than expected, and will likely rise 3-6.5 feet by the end of the century. This will cause severe flooding and destruction of habitat. F. Atmospheric warming will increase the incidence of extreme weather events, including droughts, floods and tropical storms. G. A warmer troposphere will change the distribution and population sizes of wild species, shift locations of ecosystems, and threaten some protected reserves and coral reefs. H. Climate change will lead to a decline in agriculture in some areas, particularly those that emphasize monoculture production, whereas productivity will increase for other areas. I. Health implications are likely as insects, microbes and other organisms begin to expand their ranges. 19-3 What Can We Do to Slow Projected Climate Disruption? A. Climate change is hard to deal with because it has many causes, its effects are uneven and long-term, and there is disagreement over what should be done. 1. The problem is global. 2. The problem is a long-term political issue. 3. The harmful and beneficial impacts of climate change are not spread evenly. 4. Many actions that might reduce the threat of climate change, such as phasing out fossil fuels, are controversial because they can disrupt economics and lifestyle. 5. Humans may not be hardwired to respond to long-term threats. SCIENCE FOCUS: At a time when the IPCC achieved unprecedented agreement about climate change, the percentage of the general public that believes this issue is over-exaggerated has increased. This is due to deliberate politicizing, as well as playing on the public’s lack of knowledge about how science works and their lack of knowledge of the difference between weather and climate. B. Four major prevention strategies that could reduce carbon dioxide emissions dramatically are: 1. Improve energy efficiency 2. Shift to low-carbon renewable energy resources 3. Stop deforestation 4. Shift to more sustainable agriculture C. There are several strategies for removing carbon dioxide from the atmosphere. These include: 1. A massive tree-planting program 2. Wetland restoration 3. Plant large areas with fast growing perennial plants 4. Preservation and restoration of forests 5. Seeding oceans to promote growth of marine algae 6. Carbon capture and storage D. Geoengineering provides another option. 1. Launching sulfates into the atmosphere may lead to cooling. 2. Using pipes to pump nutrient-rich water from the deep oceans to fertilize algae on the surface would also remove carbon dioxide from the atmosphere. SCIENCE FOCUS: Carbon capture and storage refers to schemes to remove carbon dioxide from power plants and industrial facilities and store it underground. Large scale leaks could potentially lead to severe climate disruption. Many contend that this is a risky output solution. E. Governments can use six methods to deal with climate change. 1. Strictly regulate carbon dioxide and methane as air pollutants 2. Impose carbon taxes or fees 3. Place a cap on total emissions and institute cap-and-trade 4. Increase subsidies to energy efficient technologies 5. Fund the transfer of green technologies from more-developed to less-developed countries 6. Create programs to help curb population growth F. The Kyoto Protocol, developed in 1997, would require 38 developed countries to cut emissions of some gases by about 5.2% below 1990 levels by 2012. SCIENCE FOCUS: Carbon dioxide is an important part of the carbon cycle. It is only considered a pollutant because of its concentration in the atmosphere. G. Costa Rica aims to be the world’s first carbon neutral nation. Analysts urge rapidly developing nations such as China and India to make a shift toward sustainability. H. There needs to be 50-85% reductions in emissions by 2050 to avoid projected harmful effects. As this is unlikely, we must prepare for the harmful effects. I. The no-regrets strategy for dealing with climate change suggests that actions directed at addressing the issue will have important environmental, health, and economic benefits. 19-4 How Have We Depleted Ozone in the Stratosphere and What Can We Do about It? A. A layer of ozone in the lower stratosphere keeps about 95% of the sun’s ultraviolet radiation from reaching the earth. There is now a seasonal ozone thinning. B. CFCs are persistent chemicals that destroy protective ozone in the stratosphere. There are many other ozone-depleting chemicals. C. One effect of ozone depletion is increased damage to biological entities, and impairment or destruction of phytoplankton. D. It is suggested that all ozone-depleting chemicals be discontinued. If this happened, it would take about 100 years for the ozone layer to recover. E. The Montreal Protocol and the Copenhagen Protocol are treaties directed at phasing out ozone-depleting chemicals. These are now signed by all of the world’s countries. Teaching Tips Large Lecture Classes: There are some basic misunderstandings about ozone depletion, ozone pollution, and climate change. These can be helpful to address directly through a series of questions such as “Does air pollution help the ozone layer?” or “Does the ozone hole cause climate change?”. The key concepts to highlight here are that tropospheric ozone is different from stratospheric ozone, and that the ozone “hole” is not the cause of climate change. Although ozone depletion can affect atmospheric circulation and energy exchange, these effects are small relative to the direct effects of greenhouse gases, and students should clearly understand this. To increase interest in the class, you could start the class with five minutes from the “Inconvenient Truth” or from the “Day After Tomorrow.” Although the “Day after Tomorrow” is highly fictionalized, there are interesting core ideas embedded in the film (e.g., thermohaline circulation) that are worth talking about. Smaller Lecture Classes: Watch the first half hour of the “Day After Tomorrow.” Have students interrupt the film when they see information that is factually correct and information that is inaccurate. Have a discussion about fact versus fiction in movies such as this. If you need more information about the movie and what is accurately portrayed, see http://www.realclimate.org. Key Terms Carbon capturing and storage (CCS) Term Paper Topics 1. Variables that affect global warming: greenhouse gases, the climate system, the biosphere, volcanic eruptions, oceans, air pollution influences. 2. Potential effects of global warming: global warming and our coastlines; global warming and the incidence of severe storms; deforestation and global warming; climate and biodiversity; rates of global climate change and adaptation; global warming and agriculture. 3. Ozone depletion: varying patterns of ozone depletion in the northern and southern hemispheres; health effects of increased ultraviolet radiation (skin cancer, cataracts); distinguishing tropospheric and stratospheric ozone; CFCs: uses and control of production. 4. Do humans have a commitment to future generations? If so, how should this commitment be addressed in national or international greenhouse gas legislation/accords? 5. How much are humans willing to spend for energy efficiency in the short term to receive long-term economic payoffs and help slow potential global warming? What is the government’s role in these decisions, if any? 6. Should humans act to prevent global warming or adapt to global warming as it happens? 7. How can developed countries prevent developing countries from making the same environmental mistakes they did during their own industrial transition? 8. How was the Antarctic ozone hole discovered? What does this tell us about science? 9. What are the pros and cons of fossil fuel emission reductions versus carbon sequestration? Should we favor one approach over the other? 10. What are the pros and cons of a carbon tax versus a carbon cap and trade system? Which system would be better for the U.S.? Activities and Projects 1. Invite an atmospheric scientist (preferably a climatologist) to address your class on the subject of regional and global climatic change and why it is so difficult to forecast climate several years or decades into the future. What progress has been made in the development and testing of very large computerized models of global climate? 2. Have local emergency officials explain to your class the precautions that have to be taken in adverse weather conditions. Have the officials discuss the difficulty in planning for extreme events in the future (e.g., 100-year floods). 3. Have experts in various fields present their views on the impact that global warming will have on their arenas: for example, how will it affect farming, forestry, coastal zone management, and town planning? 4. Use a flashlight against the front wall of the lecture room to illustrate the effect of the angle of incidence and the amount of intervening atmosphere on the amount of radiant energy striking the earth. The inverse square law could also be demonstrated. 5. Have an ecologist knowledgeable about microclimate give a presentation to the class. 6. Have students calculate their carbon footprints and compare the use of energy across the class. Have each student develop a list of three inexpensive ways they can reduce their carbon emissions. 7. Visit a car dealership that sells hybrid vehicles and have someone describe how the hybrid system works. 8. Have a solar panel installation company come in to talk about how PV electric works and how much it costs. Develop student awareness of temperature effects by working out some of the following: • Heating degree days or cooling degree days (variation of daily mean in your locale from 65 degrees F.) • Growing degree days for several crops (taking the base temperature for a given crop and comparing it to the daily mean in your locale) • Temperature and humidity index using the formula: • Weather stress index (mean apparent temperatures averaged over 40 years compared to mean apparent temperature for a particular day) 9. Try to obtain a computer model that projects global climate change. Have students explore the potential of the program and evaluate its assumptions and limitations. 10. As a class project, carefully prepare a questionnaire to investigate what people know about global warming (causes and potential effects), attitudes toward potential global warming, and actions (if any) they are willing to take to ameliorate rapid global climate change. Administer the questionnaire to a variety of citizens, deciding upon a sampling strategy in advance. Summarize your results in appropriate tables, graphs, charts, and written descriptions. What conclusions can be drawn from your results? Who might be interested in receiving a copy of your work? 11. Try to develop projections of what the world's climate and environment would be like if the temperature of the earth dropped 10 degrees or 5 degrees or was raised by equal amounts. 12. Catalog all the changes you think might happen with continued global warming. 13. Use a computer program to model global climate change and its consequences. What assumptions does the program make? What patterns emerge? Do some factors appear more significant than others? What implications do the research findings have for policy-making? Attitudes and Values 1. What is your responsibility for reducing greenhouse gas emissions? Do you have a different responsibility that someone from the developing world? Answer: Individuals in developed countries may bear greater responsibility for reducing greenhouse gas emissions due to historically higher emissions and greater access to resources for mitigation. In contrast, people in developing nations often have fewer resources and contribute less to global emissions, though they may still take local actions to mitigate climate change. Ethical responsibility suggests that developed nations support developing countries in adopting sustainable practices. 2. There is a basic disagreement between those who say we have an obligation to change our use of energy now because of the potential impacts from global warming and those who say technological advances in the future will reduce our impacts. Both sides can make the argument from an ethical perspective. What are those arguments? Answer: Proponents of immediate action argue ethically that current generations must prevent harm to future generations by reducing emissions now. Those favoring reliance on future technological advances argue that innovation will mitigate climate impacts more efficiently and that current drastic measures could hinder economic growth. Both perspectives highlight ethical considerations of intergenerational responsibility and the balance between environmental stewardship and economic development. 3. Do you feel that humans have a responsibility to ameliorate the causes of global climate change? If so, what steps are you willing to take to slow the rate of global climate change? Answer: Humans have a responsibility to address climate change to protect the planet for future generations. Personally, steps could include reducing personal energy consumption, supporting renewable energy, advocating for sustainable policies, and minimizing waste. These actions, collectively, can help slow the rate of climate change and mitigate its effects. 4. The Montreal Protocol is generally viewed as one of the most highly successful international agreements. What is unique about international environmental accords compared to national legislation and what ethical/moral obligation is required for the implementation of an international agreement? Answer: International environmental accords like the Montreal Protocol require cooperation and commitment from multiple countries, unlike national legislation, which is confined to a single country's jurisdiction. The ethical obligation lies in the shared responsibility to address global issues that transcend borders, requiring nations to act in the global interest rather than purely national interests. Effective implementation demands mutual trust and adherence to agreed-upon standards. 5. One of the emerging concerns about climate change is that developing countries lack the resources and infrastructure to adapt to changes in climate. How serious an ethical issue is this and what should be done about it? Answer: This is a significant ethical issue, as those least responsible for climate change are often the most vulnerable to its impacts. The international community has a moral duty to support developing countries through financial aid, technology transfer, and capacity-building efforts. Equitable solutions should prioritize helping these nations build resilience and adapt to changing conditions. News videos Carbon Offsets; Environmental Science in the Headlines, 2007; DVD; ISBN 0495385433 A Closer Look: Alaska Adventure; Environmental Science in the Headlines, 2007; DVD; ISBN 0495385433 Does Clean Coal Exist? The Brooks/Cole Environmental Science Video Library, 2009; DVD 0538733551 Environmental Victory: Green Decision; Environmental Science in the Headlines, 2007; DVD; ISBN 0495385433 Global Warning: Where Have The Wild Things Gone? Environmental Science in the Headlines, 2008; DVD; ISBN 0495561908 Kalahari Desert Could Double in Size; The Brooks/Cole Environmental Science Video Library, 2009; DVD 0538733551 International Report: Cooling the Plane; Environmental Science in the Headlines, 2007; DVD; ISBN 0495385433 International Report: Global Warming; Environmental Science in the Headlines, 2007; DVD; ISBN 0495385433 Ozone Layer: Road to Recovery; Environmental Science in the Headlines, 2007; DVD; ISBN 0495385433 New Ideas for Dealing with Climate Change; The Brooks/Cole Environmental Science Video Library, 2009; DVD 0538733551 Additional Video Resources An Inconvenient Truth (Documentary, 2006) A documentary on Al Gore's campaign to make the issue of global warming a recognized problem worldwide. http://www.climatecrisis.net/ The Day After Tomorrow (Movie, 2004) A climatologist tries to figure out a way to save the world from abrupt global warming. Fragile Planet: Assault on the Ozone Layer (Documentary series) Global connections in destruction of the ozone layer. Greenhouse Crisis—The American Response (Documentary, 2004) The Union of Concerned Scientists looks at the interactions of energy consumption, greenhouse effect, and global warming. The Habitable Planet: A Systems Approach to Environmental Science: Energy Challenges and Earth’s Changing Climate (Documentary series, 2007). The tenth and twelfth videos in this series explore the effects of air pollution and the challenges of global energy use. http://www.learner.org/resources/series209.html NOVA: What's Up with the Weather? Main website: http://www.pbs.org/wgbh/warming/ Teachers Guide: http://www.pbs.org/wgbh/nova/teachers/programs/27gw_warming.html Scientific American Frontiers – Hot Planet – Cold Comfort (Scientific American Frontiers, TV series, 2005) http://www.pbs.org/saf/1505/ Strange Days on Planet Earth (TV Series, National Geographic, 2008) http://www.pbs.org/strangedays/ Too Hot Not To Handle (Documentary, HBO, 2006) A look at global warming and what we can do about it. http://www.hbo.com/docs/programs/toohot/index.html Web Resources Intergovernmental Panel on Climate Change Has links to all IPCC reports. http://www.ipcc.ch/ U.S. Climate Change Science Plan Multi-agency planning. http://www.climatescience.gov/ United Kingdom Climate Impacts http://www.ukcip.org.uk/ Suggested Answers to End of Chapter Questions Review Questions 1. Review the Key Questions and Concepts for this chapter on p. 493. Describe how Greenland’s melting glaciers (Core Case Study) provide evidence that climate disruption is occurring as projected, according to most climate scientists. Answer: Satellite measurements and computer modeling confirm that the Greenland ice sheet has been losing mass at an accelerating rate since the 1990s. 2. Explain why weather and climate are not the same. Describe atmospheric warming and cooling over the past 900,000 years and during the last century. How do scientists get information about past temperatures and climates? What is the greenhouse effect and why is it so important to life on the earth? How have human activities affected atmospheric greenhouse gas levels during the last 275 years and especially in the last 30 years? List the major human activities that add CO2, CH4, and N2O to the atmosphere. Answer: • Weather refers to short-term changes in wind, temperature, precipitation, and barometric pressure in a given area, while climate refers to the average weather conditions in a given area over a long period of time. • Over the past 900,000 years, the atmosphere has experienced prolonged periods of global cooling and global warming. These alternating cycles of freezing and thawing are known as glacial and interglacial (between ice ages) periods. For roughly 10,000 years, we have had the good fortune to live in an interglacial period characterized by a fairly stable climate and a fairly steady average global surface temperature. • Past temperature changes are estimated by analysis of a number of types of evidence, including radioisotopes in rocks and fossils; tiny bubbles of ancient air found in ice cores from glaciers; tree rings; and temperature measurements taken regularly since 1861. • The greenhouse effect warms the earth’s lower atmosphere. About 1% of the earth’s lower atmosphere is composed of greenhouse gases. Heat radiated into the atmosphere by the earth causes molecules of these greenhouse gases to vibrate and release infrared radiation into the lower atmosphere. This warms the lower atmosphere and the earth’s surface. • Life on the earth and the world’s economies are totally dependent on the natural greenhouse effect. Without this natural greenhouse effect, the world would be too cold to support the forms of life we find here today. • Carbon dioxide levels rose from 280 ppm before the Industrial Revolution to 389 ppm in 2010. Seventy percent of methane emissions in the past 275 years are from human activities and nitrous oxide levels have risen by 20% in that time period. The greatest increase has occurred within the past 30 years. • Carbon dioxide is added to the atmosphere primarily from burning fossil fuels. Methane is added as a result of human activities such as raising cattle and sheep, extracting fossil fuels, creating landfills, and flooding land to create reservoirs. Nitrous oxide accumulation is largely the result of using nitrogen fertilizers. 3. After studying past climate change and the nature of the earth’s climate system for almost three decades, what two general conclusions did most of the world’s climate scientists agree on about atmospheric warming over the past 30 years? How did scientists arrive at these two general conclusions, and why was this such a rare event? How do scientists use models to make projections about future temperature changes? What do a number of climate models project about temperature changes during this century? How can positive feedback loops affect future temperature changes and thus global climate? Give two examples of such loops. Describe the role that climate scientist James Hansen has played in improving our understanding of climate and projected climate disruption. Describe the contribution of waste heat from energy conversion devices to projected climate disruption. Answer: • There is general agreement that the climate has warmed by 0.6 degrees C and that human activities played a major role and are likely to continue to impact the climate. • This large group of scientists reviewed thousands of peer-reviewed studies and climate models. Conclusions were drawn after nearly two decades of research and debate. This high level of general agreement among the world’s top scientific experts on the subject of climate change or on any scientific subject is extremely rare. • Mathematical models simulate interactions among the earth’s sunlight, clouds, landmasses, oceans, ocean currents, concentrations of greenhouse gases and pollutants, and positive and negative feedback loops. • Climate models project that it is very likely that the earth’s mean surface temperature will increase by 2–4.5 C (3.6–8.1 F) between 2005 and 2100, with about 3 C (5.4 F) being the most likely rise, unless the world halts deforestation and makes drastic cuts in greenhouse gas emissions from fossil fuel–burning power plants, factories, and cars. • Positive feedback loops could amplify the projected changes in the average temperature of the atmosphere shown. • The world’s oceans help to moderate the earth’s average surface temperature and thus its climate by removing about 25–30% of the CO2 pumped into the lower atmosphere by human activities. The solubility of CO2 in ocean water decreases with increasing temperature. Thus, as the oceans heat up, some of their dissolved CO2 could be released into the lower atmosphere. This could amplify global warming and speed up climate change through a positive feedback loop. • Higher levels of CO2 in the ocean have increased the acidity of the ocean surface by 30% since preindustrial times. Increasing acidity reduces the ability of the oceans to remove CO2 from the lower atmosphere and storing it in bottom sediments. It thus can accelerate global warming and climate change in another positive feedback loop. • James Hansen sounded the alarm about climate change and kicked off the public debate over what most climate scientists believe is our greatest environmental challenge. He also helped to promote the idea of creating the Intergovernmental Panel on Climate Change. • Waste heat is added directly to our already warming atmosphere, exacerbating the effects of greenhouse gas emissions. 4. Describe how each of the following might contribute to projected atmospheric warming and resulting global climate disruption: (a) CO2 emissions, (b) a hotter sun, (c) the oceans, (d) cloud cover and (e) air pollution. What are three effects of increasing atmospheric CO2 levels on the oceans? Answer: • Carbon dioxide emissions play an important role in determining the average temperature of the atmosphere. More carbon dioxide entails warming. • A hotter sun would warm that stratosphere before warming the lower atmosphere. • Oceans absorb carbon dioxide and heat from the lower atmosphere. • Warmer temperatures increase evaporation of surface water and create more clouds. Depending on their content and reflectivity, these additional clouds can cool or warm the atmosphere. An increase in thick and continuous light-colored clouds at low altitudes could decrease surface warming by reflecting more sunlight back into space. But an increase in thin and discontinuous cirrus clouds at high altitudes could increase the warming of the lower atmosphere by preventing more heat from escaping into space. • Aerosols (suspended microscopic droplets and solid particles) of various air pollutants can either warm or cool the air and hinder or enhance cloud formation depending on factors such as their size and reflectivity. • Increasing levels of atmospheric carbon dioxide is leading to oceans getting warmer. They are also getting more acidic, and phytoplankton is dying off. 5. Briefly describe how projected climate disruption is likely to affect: (a) drought, (b) ice cover, (c) permafrost, (d) sea levels, (e) extreme weather, (f) biodiversity, (g) crop yields, and (e) human health during this century. Pick three of these factors and describe how each can become part of a positive feedback loop leading to climate disruption. Answer: • The projected change in the earth’s climate due to global warming could cause increased drought and flooding, decreased polar ice cover, rising sea levels, melting permafrost, shifts in ocean currents, increased extreme weather, loss of biodiversity, and shifts in locations of agriculture and wildlife habitats, and increases in a variety of human health problems. • Melting permafrost can lead to the release of large amounts of methane, which can accelerate climate change. Droughts lead to a reduction in biomass, meaning that less carbon dioxide will be removed from the atmosphere. Diminished ice cover implies that less radiation will be reflected, and more absorbed. This will further enhance the effects of climate disruption. 6. List seven examples of climate tipping points we could be approaching. What are five factors that make it difficult to deal with the problem of projected climate disruption? Describe the interactions among science, politics and climate. Describe John Sterman’s bathtub analogy as it applies to CO2 emissions. What are three major prevention strategies and three major cleanup strategies for dealing with projected climate disruption? What is carbon capture and storage (CCS)? Describe three problems associated with capturing and storing carbon dioxide emissions. What are geoengineering schemes (give two examples) and what is the major problem with most of them? Answer: • The seven tipping points are: ○ Atmospheric carbon level of 450 ppm ○ Melting of all Arctic summer sea ice ○ Collapse and melting of the Greenland ice sheet ○ Severe ocean acidification, collapse of phytoplankton populations, and a sharp drop in the ability of the oceans to absorb CO2 ○ Massive release of methane from thawing Arctic permafrost ○ Collapse and melting of most of the western Antarctic ice sheet ○ Severe shrinkage or collapse of Amazon rainforest • The problem of climate change is difficult to tackle because: ○ The problem is global. Dealing with this threat will require unprecedented and prolonged international cooperation. ○ The effects will last a long time. ○ The problem is a long-term political issue. Voters and elected officials generally respond well to short-term problems but have difficulty acknowledging and coping with long-term threats. ○ The harmful and beneficial impacts of climate change are not spread evenly. There will be winners and losers in the event of moderate climate. ○ Many proposed actions that might reduce the threat of climate change are controversial because they would disrupt economies and lifestyles. • One reason for continued debate in the arena of climate change is that the issue has been politicized in an effort to cast doubt on that reliability of the science. As the debate continues, the climate continues to warm. • The atmosphere is like a bathtub that gets inputs of CO2, which eventually drain from the tub. Before the Industrial Revolution, the system was receiving CO2 inputs at about the same rate as it was draining them. With the explosive increase in human-generated CO2 emissions, the bathtub is filling much faster than it can drain. • Prevention strategies include cutting fossil fuel use, improving energy efficiency, and shifting to renewable energy resources. Cleanup strategies include removing carbon dioxide from emissions, planting trees, and sequestering carbon underground. • Carbon capture and storage (CCS) is the removal of some of the CO2 from smokestacks to pump it deep underground into abandoned coal beds and oil and gas fields, or to liquefy it and inject it into sediments under the sea floor. • CCS problems include: ○ Power plants using CCS are much more expensive to build and operate than conventional coal-burning plants and thus would sharply raise the price of electricity for consumers. ○ CCS is an unproven technology that would remove only part of the CO2 from smokestack emissions. No plants using CCS exist, and building and testing them could take 20–30 years and huge amounts of money with no guaranteed successes. ○ CCS requires large inputs of energy, which could increase CO2 emissions. ○ CCS promotes the continued use of coal, which should probably be phased out. Coal is by far the world’s dirtiest fuel to dig up and burn. ○ Providing huge government subsidies and tax breaks for developing and testing CCS technology would divert or reduce the huge subsidies and tax breaks needed for the rapid development of solar, wind, geothermal, and other forms of renewable energy. ○ With CCS no leaks are allowed. Any large-scale leaks due to earthquakes, other geological events, or wars, as well as any number of smaller continuous leaks from storage sites around the world, could dramatically increase global warming and the resulting climate change in a very short time. • Geoengineering is an attempt to manipulate certain natural conditions to help counter an enhanced greenhouse effect. Two examples are launching sulfates into the stratosphere and bringing nutrient rich water from the deep oceans to the surface to stimulate algal growth. The major problems are that they require large investments of energy and materials and there is no guarantee they will work. 7. List six steps that governments could take to help slow projected climate disruption. What is a pollutant and why is CO2 being classified as a pollutant? What are the advantages and disadvantages of using taxes on carbon emissions or energy use to help reduce greenhouse gas emissions? What is cap-and-trade and what are the advantages and disadvantages of using it to help reduce greenhouse gas emissions? What are the pros and cons of developing an international treaty to help deal with the threat of projected climate disruption? What is the U. S. city of Portland, Oregon, doing to help reduce its greenhouse gas emissions? What is China doing to help reduce its contribution to the climate disruption? What is the United States doing to help reduce its contribution to this problem? Answer: • Governments can: ○ Strictly regulate carbon dioxide (CO2) and methane (CH4) as climate-changing pollutants. ○ Impose carbon taxes or fees ○ Place a cap on total emissions and institute cap-and-trade ○ Increase subsidies to energy efficient technologies ○ Fund the transfer of green technologies from more-developed to less-developed countries ○ Create programs to help curb population growth • A pollutant is a chemical or other agent such as noise or heat in the environment that proves harmful to the health, survival, or activities of humans or other organisms. Carbon dioxide is considered a pollutant when it is present in high concentrations. • The advantages of carbon taxes are that they are simple to administer, there is a clear price on carbon, the taxes would cover all emitters, and they would generate predictable revenues. The disadvantages are that tax laws can be complex, the taxes could be vulnerable to loopholes, they don’t guarantee lower emissions, and they are politically unpopular. • Cap-and-trade means that governments would place a cap on total human-generated CO2 and CH4 emissions in a country or region, issue permits to emit these pollutants, and then let polluters trade their permits in the marketplace. The advantages are that there would be a clear legal limit on emissions, they would reward cuts in emissions, there would be a Record of success, and the expense would be low for consumers. The disadvantages are that revenues would not be predictable, the system is vulnerable to cheating, rich polluters can keep polluting, and it puts a variable price on carbon. • International treaties represent an important step in attempting to slow projected climate change. However, they are often seen as weak, slow and ineffective responses to an urgent global problem. • The first major U. S. city to establish programs to reduce greenhouse gas emissions was Portland, Oregon. Between 1993 and 2005, the city cut its greenhouse gas emissions back to 1990 levels, while national levels rose by 16%. The city promotes energy-efficient buildings and the use of electricity from wind and solar sources. It has also built bicycle trails and has greatly expanded its mass transit system. Far from hurting Portland’s economy, these strategies have produced an economic boom and have saved the city $2 million a year on its energy bills. • China has the most intensive energy efficiency program in the world. Chinese automobile fuel-efficiency standards are higher than U.S. standards. China’s government is working with the country’s top 1,000 industries to implement tough energy efficiency goals. China is also rapidly becoming the world’s leader in developing and selling solar cells, solar water heaters, wind turbines, advanced batteries, and plug-in hybrid electric cars. China may become the world leader in developing and selling these low-carbon technologies. • In 2009, 30 U.S. states had set goals for reducing greenhouse gas emissions and more than 450 U.S. cities have established programs for doing so. 8. Give two examples of what some major corporations have done and two examples of what some schools have done to reduce their carbon footprints. List five ways in which you can reduce your carbon footprint. List five ways in which we can prepare for the possible long- term harmful effects of climate change. Describe the no-regrets strategy for dealing with the problems associated with energy waste and fossil fuel use, regardless of climate change. Answer: • A number of major global companies, including Alcoa, DuPont, IBM, Toyota, General Electric, and British Petroleum (BP), have set goals for seriously reducing their greenhouse gas emissions. In 2006, DuPont slashed its energy usage and cut its greenhouse gas emissions by 72% and saved $3 billion, while the company increased its business by almost a third. Some colleges and universities are also taking action. Students and faculty at Oberlin College in the U.S. state of Ohio have asked their board of trustees to reduce the college’s CO2 emissions to zero by 2020 by buying or producing renewable energy. In the U.S. state of Pennsylvania, 25 colleges have joined to purchase wind power and other forms of mostly carbon-free renewable energy. • You can reduce your annual emissions of CO2: ○ Drive a fuel-efficient car, walk, bike, carpool, and use mass transit. ○ Use energy-efficient windows. ○ Use energy-efficient appliances and lights. ○ Heavily insulate your house and seal all air leaks. ○ Reduce garbage by recycling and reusing more items. ○ Insulate your hot water heater. ○ Use compact fluorescent light bulbs. ○ Plant trees to shade your house during summer. ○ Set your water heater no higher than 49°C (120°F). ○ Wash laundry in warm or cold water. ○ Use a low-flow showerhead. ○ Buy products from, or invest in, companies that are trying to reduce their impact on climate. • Ways to prepare for the possible long-term harmful effects of climate change include: ○ Developing crops that need less water ○ Wasting less water ○ Moving people away from low-lying coastal areas ○ Stockpiling a one- to five-year supply of key foods ○ Moving hazardous material storage tanks away from coast • The no-regrets strategy is based on the idea that efforts to deal with climate disruption lead to other very important environmental, health, and economic benefits. 9. Describe how human activities have depleted ozone in the stratosphere, and list five harmful effects of such depletion. Describe how scientists Sherwood Roland and Mario Molina help to awaken the world to this threat. What has the world done to help reduce the threat from ozone depletion in the stratosphere? How are the problems of atmospheric warming and ozone depletion connected? Answer: • Widespread use of certain chemicals has reduced ozone levels in the stratosphere and allowed more harmful ultraviolet radiation to reach the earth’s surface. • Expected effects of decreased levels of ozone include: ○ Human health: • Worse sunburns • More eye cataracts • More skin cancers • Immune system suppression ○ Food and forests: • Reduced yields for some crops • Reduced seafood supplies from reduced phytoplankton • Decreased forest productivity for UV-sensitive tree species ○ Wildlife: • Increased eye cataracts in some species • Decreased populations of aquatic species sensitive to it ○ UV radiation: • Reduced populations of surface phytoplankton • Disrupted aquatic food webs from reduced phytoplankton ○ Air Pollution and Materials: • Increased acid deposition • Increased photochemical smog • Degradation of outdoor paints and plastics ○ Climate Change: • While in troposphere, CFCs act as greenhouse gases. • See Science Focus: Sherwood Rowland and Mario Molina—A Scientific Story of Courage, and Persistence. • To reverse ozone depletion, we need to stop producing ozone-depleting chemicals and adhere to the international treaties that ban such chemicals. In1987, representatives of 36 nations met in Montreal, Canada, and developed the Montreal Protocol. This treaty’s goal was to cut emissions of CFCs by about 35% between 1989 and 2000. Representatives of 93 countries met in London in 1990 and then in Copenhagen, Denmark, in 1992. They adopted the Copenhagen Protocol, an amendment that accelerated the phase-out of key ozone-depleting chemicals. • The most widely used substitutes for CFCs are hydrofluorocarbons (HFCs), which act as greenhouse gases. An HFC molecule can be up to 10,000 times more potent in warming the atmosphere than a molecule of CO2 is. 10. What are this chapter’s three big ideas? Describe how we can apply the three principles of sustainability to the problems of projected climate disruption (Core Case Study) and ozone depletion. Answer: • The three big ideas are ○ Considerable scientific evidence indicates that the earth’s atmosphere is warming, mostly because of human activities, and that this is likely to lead to significant climate disruption during this century that could have severe and long-lasting harmful consequences. ○ Reducing the projected harmful effects of rapid climate disruption during this century requires emergency action to increase energy efficiency, sharply reduce greenhouse gas emissions, rely more on renewable energy resources, and slow population growth. ○ We need to continue phasing out the use of chemicals that have reduced ozone levels in the stratosphere and allowed more harmful ultraviolet radiation to reach the earth’s surface. • The scientific principles of sustainability can be applied to help reduce the harmful effects of air pollution, projected climate change, and stratospheric ozone depletion. We can reduce inputs of air pollutants, greenhouse gases, and ozone-depleting chemicals into the atmosphere by relying more on direct and indirect forms of solar energy than on fossil fuels; reducing the waste of matter and energy resources and recycling and reusing matter resources; and mimicking biodiversity by using a variety of carbon-free renewable energy resources, especially those that are available regionally and locally. We can enhance these strategies by finding substitutes for ozone-depleting chemicals, emphasizing pollution prevention, and reducing human population growth. Critical Thinking The following are examples of the material that should be contained in possible student answers to the end of chapter Critical Thinking questions. They represent only a summary overview and serve to highlight the core concepts that are addressed in the text. It should be anticipated that the students will provide more in-depth and detailed responses to the questions depending on an individual instructor’s stated expectations. 1. If you had convincing evidence that at least half of Greenland’s glaciers (Core Case Study) were sure to melt during this century, would you argue for taking serious actions now to slow projected climate disruption? If so, summarize the arguments you would use. If not, explain why you would be opposed to such actions. Answer: Yes, I would argue for taking serious action. The melting of the glaciers would lead to substantial sea level rise. This has the capacity to displace very large numbers of people and destroy habitats. In addition, a feedback loop would be generated that would increase the effects of climate change. Without the reflective capacity of the ice, the landscape would absorb much more heat, further contributing to the problem. 2. A top U.S. presidential economic adviser to the president once gave a speech in Williamsburg, Virginia (USA), to representatives of governments from a number of countries. He told his audience not to worry about atmospheric warming because the average global temperature increases predicted by scientists were much less than the temperature increase he had experienced that day in traveling from Washington, D.C., to nearby Williamsburg. What was the flaw in his reasoning? Write an argument that you could use to counter his claim. Answer: The misguided and misinformed politician that made this ludicrous statement was referring to a change of temperature that normally occurs within a region. It could be rainy and overcast in Washington D.C. but sunny and warm in Williamsburg which is around 200 miles south. There could be a large temperature difference between the two locations, or in the case of the day in question it could have been a small temperature difference. Of course, most people would not be able to tell the difference between a one or two degree change in the temperature so the suggested global temperature change is being trivialized. The politician is also referring to changes in the weather, whereas global warming refers to a change in the Earth’s climate, which looks at long term effects. It is just another example of how politicians and the media provide inappropriate non-scientific statements regarding the greenhouse gas emissions that are causing climate change on a global scale. 3. How might the earth’s climate change if the land area of the planet were larger than the planet’s ocean area? Answer: The earth’s climate would be hotter and dryer. The Oceans help absorb heat and also CO2, which reduces the effect of global warming. As the ocean temperatures increase and become more acidic, they seem to be absorbing less CO2, which means their dampening effects will not continue indefinably. 4. List three ways in which you could apply Concept 19-3 to making your lifestyle more environmentally sustainable. Answer: Student’s answers will vary but may include: Drive less Purchase a cleaner running car that gets better gas mileage Use less power at home, school, and work Limit the number of children that they have to replacement levels Choose to buy power from a source that generates it through renewable resources. 1. Adopt green technologies early to reduce impact. 2. Share knowledge about sustainable practices. 3. Support innovative startups focused on sustainability. 5. Explain why you would support or oppose each of the strategies listed in Figure 19-16 for slowing projected climate disruption caused by atmospheric warming. Answer: 1. Carbon Taxes: • Support: Reduces emissions by increasing costs. • Oppose: Can disproportionately impact lower-income groups. 2. Renewable Energy Investment: • Support: Cuts reliance on fossil fuels. • Oppose: High initial costs and integration challenges. 3. Energy Efficiency: • Support: Lowers energy use and emissions. • Oppose: Requires upfront investment and awareness. 4. Reforestation: • Support: Absorbs CO2 and restores ecosystems. • Oppose: Can lead to land use conflicts. 5. Carbon Capture and Storage (CCS): • Support: Reduces industrial CO2 emissions. • Oppose: High costs and uncertain long-term safety. 6. What changes might occur in (a) the global hydrologic cycle (see Figure 3-16, p. 67) and (b) the global carbon cycle (Figure 3-19, p. 70) if the atmosphere experiences significant warming? Explain. Answer: (a) Hydrologic Cycle: A change in global precipitation patterns could affect the severity and frequency of droughts, floods, and storms, Increased evaporation due to a higher temperature will give rise to greater levels of water vapor in the atmosphere, which itself is a greenhouse gas. This will result in an increase in global warming due to a positive feedback mechanism. (b) Carbon Cycle: Changes in global food production and wildlife habitats could occur. The natural range of vegetation and trees could shift. An increase in forest fires due to the warming temperatures would release more carbon dioxide into the atmosphere causing a greater greenhouse effect, again through a positive feedback mechanism. Increased carbon dioxide in seawater could affect the calcium metabolism in shellfish and the bone formation of other marine creatures. 7. One way to slow the rate of CO2 emissions is to reduce the clearing of forests—especially in less-developed tropical countries where intense deforestation is taking place. Should the United States and other more-developed countries pay poorer countries to stop cutting their forests? Explain. Answer: Yes, developed countries should forgive debts of the developing nations by introducing such strategies as “debt for nature” swaps. The developing countries debt is written off or forgiven in return for a termination of deforestation and initiating programs for conservation and habitat restoration. 8. What are three consumption patterns or other aspects of your lifestyle that directly add greenhouse gases to the atmosphere? Which, if any, of these habits would you be willing to give up in order to help slow projected climate disruption? Answer: Three things that I and most of my peers do is drive, use electricity, and heat and cool our living spaces. All of these cause the emission of greenhouse gases and other pollutants. These lifestyle patterns go against the principles of sustainability such as reliance on solar energy, biodiversity, nutrient recycling, and population. We are using too much fossil fuel rather than renewable energy. The production of these fossil fuels can harm biodiversity through surface mining and oil drilling both on and off shore. Many of the things that we buy that use electricity or fossil fuel are manufactured in ways that do not encourage material recycling. Because we are using more and more of these energy sources as our population increases we are also going against any population control strategies that are present in the natural ecosystems of the Earth. I do not think it would be easy to give up driving, using electricity, or heating or cooling our homes. However I could look at these lifestyle consumption patterns and address them in such a way as to reduce my ecological footprint. I do car pool, ride a bike, walk, and use public transportation whenever possible. I also drive a hybrid car already. I can turn off electrical appliances when they are not being used to reduce the amount of ghost current that is being used. I can only buy energy star (energy efficient) electrical items. I can alter the thermostat to become more energy efficient, open windows rather than using the air conditioner, and put on a warm sweater rather than turn up the heat. 9. Congratulations! You are in charge of the world. List your three most important strategies for dealing with the problems of (a) climate disruption due to atmospheric warming caused mostly by human activities, and (b) depletion of ozone in the stratosphere. Answer: (a) Global Warming: (i) Move from a carbon-based fuel system to one which uses more renewable energy sources. (ii) Increase energy efficiency in all aspects of our lifestyles. (iii) Invest more money in research and development of new renewable technologies such as wind and hydrogen fuel systems. (b) Ozone Depletion: (i) Continue the ban on CFCs and clamp down on the black market distribution of such chemicals. (ii) Phase out the use of HCFC and HFC chemicals by developing more ozone- friendly alternatives. (iii) Educate the public about the dangers of spending too much time out in the sun between 10 am and 2 pm without protecting themselves with sunscreen, sunglasses, hats, shirts, etc. 10. List two questions that you would like to have answered as a result of reading this chapter Answer: 1. What are the most effective strategies for balancing economic growth with climate action? 2. How can emerging technologies be scaled up to significantly reduce greenhouse gas emissions? Ecological Footprint Analysis Largely because of the intense use of fossil fuels, per capita CO2 emissions for the United States are more than four times the world average. According to a recent report from the International Energy Agency, the average American is responsible for adding 19.6 metric tons (21.6 tons) of CO2 per year to the atmosphere, compared with a world average of 4.23 metric tons (4.65 tons). The table below is designed to help you understand the sources of your personal inputs of CO2 into the atmosphere and how you can reduce them. You will be making calculations to fill in the blanks in this table. Some typical numbers are provided in the “Typical Quantity per Year” column of the table. However, your calculations will be more accurate if, in place of those typical values, you can substitute information based on your own personal lifestyle, which you can enter in the blank “Personal Quantity” column. For example, you could add up your monthly utility bills for a year and divide the total by the number of persons in your household to determine your own utility use, and you could analyze your driving habits to determine how much fuel you use in your vehicle if you own one. When you are finished with this exercise, you can check your results against those you would get by using the greenhouse gas emissions calculator provided on the Web by the EPA at www.epa.gov/climatechange/emissions/ind_calculator.html. Also, compare your results with those of your classmates. Questions: 1. Calculate your carbon footprint. To calculate your emissions, first complete the blank “Personal Quantity” column as described above. If your information is not available, use the data listed in the “Typical Quantity per Year” column. Then, for each activity, calculate your annual consumption (using the units specified in the “Units per Year” column), and multiply your annual consumption by the associated number in the “Multiplier” column to obtain an estimate of the pounds of CO2 resulting from that activity, which you will enter in the “Emissions per Year” column. Finally, add the numbers in that column to find your carbon footprint, and express the final CO2 result in both pounds and tons (1 ton = 2,000 lbs) and in kilograms and metric tons (1 kilogram = 2.2 pounds; 1 metric ton = 1.1 tons). 2. Compare your emissions with those of your classmates and with the per capita U.S. average of 19.6 metric tons (21.6 tons) of CO2 per person per year. (Actually, your answer should be considerably less—roughly about half the per capita value—because this computation only accounts for direct emissions. For instance, CO2 resulting from driving a car is included, but the CO2 emitted in manufacturing or disposing of the car is not.) 3. Consider and list actions you could take to reduce your carbon footprint by 20%. 1. Answer: 2. Answer: This is higher than U.S. average of 19.6 metric tons (21.6 tons) of CO2 per person per year. Roughly the personal emissions value calculated using this calculator model should be about half of the U.S. per capita average because the calculations in this table only included estimated of your direct inputs of CO2. For example, your estimate of direct inputs of CO2 from driving a car did not include additional indirect inputs of CO2 as a result of manufacturing and disposing of the car. 3. Answer: Student’s answers will vary. They may focus on more efficient means of transportation, less travel, or more recycling. 1. Reduce car travel by using public transport or carpooling. 2. Switch to energy-efficient appliances and lighting. 3. Adopt a plant-based diet or reduce meat consumption. 4. Conserve energy by improving home insulation and reducing heating/cooling use. 5. Minimize waste through recycling and reducing single-use plastics. Chapter 20 Water Pollution Summary 1. Water pollutants include infectious agents from human or animal wastes; oxygen-demanding wastes from sewage, paper mills, and food processing; inorganic chemicals from surface runoff, industrial effluents, and household cleaners; organic chemicals from oil, plastics, pesticides, and detergents; sediment from erosion; and thermal pollution from power plant cooling. 2. Water pollution problems in streams and lakes relate to chemical and biological pollutants, with the greater problems being cultural eutrophication. 3. Groundwater pollution is caused by leaks from waste ponds and underground storage tanks, chemical dumping or spilling, surface runoff, and fertilizers. It can be prevented by finding substitutes for toxic chemicals, installing monitoring wells near landfills and underground tanks, requiring leak detectors on underground tanks, banning hazardous waste disposal in landfills and injection wells, and storing harmful liquids in aboveground tanks. 4. Water pollution of oceans relates to nitrogen oxide from industry and cars, heavy metals from effluents, toxic sediment, sewage, runoff of pesticides, manure, fertilizers, and red tides from excess nitrogen. 5. Reduction or prevention of water pollution can be achieved through reduction of use of toxic pollutants, banning of ocean dumping of sludge, protection of sensitive areas from oil drilling and oil transport, regulation of coastal development, and regulation of sewage treatment. 6. The U.S. Safe Drinking Water Act of 1974 requires that drinking water contain less than the maximum contaminant levels for any pollutants that may have adverse effects on human health. Restructuring of water treatment systems, enforcing current regulations, banning the use of lead in new structures, and chemical tests and biological indicators can be used to make drinking water safer. Key Questions and Concepts 20-1 What Are the Causes and Effects of Water Pollution? CORE CASE STUDY: Seattle’s suburbs surround lake Washington, and in the 1950’s treated waste water from 10 municipalities was being dumped into the body of water. This led to the spread of blue-green algae, and the subsequent decline of fish species. Public education efforts and citizen pressure led to the diversion of effluents to Puget Sound and recovery of the lake’s ecosystem. A. Water is polluted is any physical change in water quality that has a harmful effect on living organisms or makes the water unfit for human uses. B. Water pollution can come from a single source or from a variety of dispersed sources. Point sources discharge pollutants at specific locations through drain pipes, ditches, or sewer lines into bodies of surface water. Non-point sources are scattered and diffuse and can’t be traced to any single site of discharge. C. The leading sources of water pollution are agriculture, industries, and mining. D. Common diseases are transmitted to humans through contaminated drinking water (Table 20-2). The World Health Organization (WHO) estimates that 1.6 million people, most of whom are children, die prematurely every year from infections diseases spread by contaminated water or lack of water for adequate hygiene. SCIENCE FOCUS: Scientists monitor water quality by using bacterial counts, chemical analysis, and indicator organisms. 20-2 What Are the Major Water Pollution Problems in Streams and Lakes? A. Streams can recover from moderate levels of degradable water pollutants if the flows are not reduced. A combination of dilution and biodegradation can allow recovery of stream pollution if they are not overloaded, or have reduced flow due to damming, agricultural diversion, or drought. B. Most developed countries have reduced point source pollution, but toxic chemicals and pollution from non-point sources are still problems. C. Stream pollution in most developing countries is a serious and growing problem. Half of the world’s 500 major rivers are heavily polluted and most of them run through developing countries where waste treatment is minimal or nonexistent. 1. More than half of China’s population lives without sewage treatment. D. Lakes have stratified layers and little flow and so are less effective at diluting pollutants that enter them. E. Human activities can overload lakes with plant nutrients that reduce dissolved oxygen and kill some aquatic species. Nutrient enrichment of lakes from runoff is called eutrophication. CASE STUDY: The Great lakes constitute 95% of North America’s fresh surface water. Less than 1% of the water entering the lakes flows out, so pollutants can take as long as 100 years to flush. In the 1960’s the lakes suffered from cultural eutrophication. In 1972 Canada and the US signed the Great Lakes Water Quality Agreement, and the situation has improved. However, the lakes still suffer from ongoing pollution problems, and lack of funding for cleanup. 20-3 What Are the Major Pollution Problems Affecting Groundwater and Other Drinking Water Sources? A. Groundwater is vulnerable to contamination because it can’t effectively cleanse itself and dilute or disperse pollutants. Contaminated water in the aquifer will slowly flow along and create a plume of contaminated water. It can take hundreds of years to cleanse degradable wastes; nondegradable wastes are there permanently. B. The extent of groundwater contamination is generally unknown since there has been little tracking and testing done on aquifers. C. Prevention is the most effective and affordable way to protect groundwater from pollutants. D. Groundwater pollution can include human pollutants and natural pollutants such as Arsenic. E. The technology exists to purify wastewater to be used as drinking water, but it is expensive and faces public opposition. CASE STUDY: Some major cities have avoided the cost of building water treatment facilities by protecting watersheds. New York City is an example. F. Fifty-four countries have standards for safe drinking water. The U.S. Safe Drinking Water Act of 1974 requires the EPA to establish minimum contaminant levels for pollutants that may adversely affect human health. CASE STUDY: The United States has the world’s cleanest drinking water, yet its people consume the most bottled water of any nation. Use of bottled water is energy intensive and creates a lot of waste. Currently, there is a growing back-to-the-tap movement. 20-4 What Are the Major Water Pollution Problems Affecting Oceans? A. Oceans can disperse and break down large quantities of degradable pollutants if they are not overloaded. B. Pollution of coastal water near heavily populated areas is a serious problem. About 40% of the world’s population lives on or within 62 miles of the coast, and this puts a tremendous burden on the wetlands, estuaries, coral reefs and mangrove swamps found along the coast. C. Runoff of sewage and agricultural waste increases nitrate and phosphate levels and can lead to algal blooms. These then cause oxygen-depleted zones. SCIENCE FOCUS: The world’s third largest oxygen depleted zone is at the mouth of the Mississippi River. This watershed contains almost 2/3 of the United States’ land area. The oxygen depleted zone forms because of algal blooms associated with the influx of nitrate from agriculture upstream. The solutions involve more sustainable farming methods and improved flood control. D. Most ocean pollution comes from human activities on land such as changing and dumping motor oil. E. Oil pollution can have a number of harmful ecological and economic effects, but most disappear within 3 to 20 years. CASE STUDY: The 1989 Exxon Valdez oil spill was the worst in U.S history and caused widespread ecological damage. Congress has since passed the Oil Pollution Act, banning single hull tankers in U.S. waters by 2010, but the oil industry has successfully delayed it until 2015. 30-5 How Can We Best Deal with Water Pollution? A. Reduce non-point pollution by preventing it from reaching bodies of surface water. Reduce soil erosion and the amount of fertilizer that runs off. B. The Federal Water Pollution Control Act of 1972, the Clean Water Act of 1977 and the 1987 Water Quality Act are the basis of pollution control of surface waters in the U.S. CASE STUDY: The Clean Water Act led to improvements that include more community water systems meeting federal health standards, more streams being fishable and swimmable, a greater portion of the populations served by sewage treatment plants, and reduced wetland losses. There is still need for improvement and some scientists call for strengthening the Clean Water Act. C. Septic tanks and various levels of sewage treatment can reduce point-source water pollution. D. In urban areas, sewage and runoff flow to wastewater treatment plants, where waters undergo primary (a physical process) and secondary (a biological process) treatment. E. Preventing toxic chemicals from reaching sewage treatment plants would eliminate these from sludge and water that is discharged. F. Natural and artificial wetlands and other ecological systems can be used to treat sewage. SCIENCE FOCUS: Some communities and individuals are experimenting with using various organisms to purify water in holding tanks. Others use natural or artificially-created wetlands to this end. Teaching Tips: Large Lecture Courses: Start the class with five bottles of water from around the world. Have a handful of students taste the bottles and pick their favorite. One bottle should be filled with tap water. When the students have voted on a favorite, show the prices of the water on a per liter basis compared to other products such as gasoline. Use the comparison to start students thinking about the irony of assuming drinking imported water is very safe water versus what is available from a tap, and as a counterpoint mention statistics on worldwide access to safe drinking water. Smaller Lecture Classes: Borrow or buy several camping water filters from the college outdoor center or a local store. Go through how the filters work and what types of chemicals and size of filtration units are used in each filter. Have students choose different filters for different places on the planet. For example, have students pick a filter that would be best for drinking water out of an irrigation ditch in Iowa. This particular filter should handle dissolved ions like nitrate as well as organic compounds such as pesticides and herbicides. Other examples would be for use while camping in the Congo (water borne viruses) or near an organic farm (bacterial contamination more likely with organic fertilizers). Key Terms cultural eutrophication eutrophication nonpoint sources point sources primary sewage treatment secondary sewage treatment septic tank water pollution Term Paper Research Topics 1. Water pollution: animal feedlot wastes; electric power plants and thermal pollution; pesticides; deep-well disposal and groundwater contamination; sanitary landfills and groundwater contamination; hazardous storage and disposal problems; leaking underground gasoline tanks; salinity problems in irrigated areas. 2. Water pollution and human health: waterborne disease-causing agents and their control; waterborne disease problems in developing countries. 3. Case studies in water pollution: the fight to save Lake Erie; Lake Baikal; James River kepone spill; Chesapeake Bay; ocean dumping in the New York Bight; Exxon Valdez oil spill. 4. How responsible are upstream communities for ensuring that high-quality water is delivered to downstream communities? 5. Is the public ready for water recycling? What are some examples of this approach in use in the U.S.? 6. Would privatization of water resources lead to improved water quality? Why or why not? 7. National policy: the Safe Drinking Water Act of 1974; protection of groundwater; the Clean Water Act; problems in enforcing water quality standards; the role of the Environmental Protection Agency in water quality management; the Toxic Substances Control Act; the National Eutrophication Survey; the Coastal Barrier Resources Act; water-rights battles in the West. 8. International policy: UN Conference on the Law of the Sea. 9. Chesapeake Bay: What is the problem, what are the causes, and what work is underway to fix these problems? 10. Non-point source pollution and the Gulf of Mexico dead zone. What are the problems and causes, and why is this so difficult to address? Activities and Projects 1. Invite a local, state, or federal water pollution control official to discuss water pollution control methods, progress, and problems with your class. Answer: Invite a water pollution control official to speak with your class about the methods used to control water pollution, the progress made in reducing pollution, and the challenges faced in maintaining water quality. This discussion can provide insights into regulatory frameworks, innovative technologies, and the role of public and private sectors in ensuring clean water. 2. Visit a sewage treatment plant with your class. Find out what level of sewage treatment is used in your community. What is the volume of effluent discharged? If effluent is discharged into a river or stream, is the water subsequently used for drinking water supply? Are there bodies of water in your locale unfit for fishing or swimming because of inadequately treated sewage effluent? If so, is anything being done to correct the problem? Answer: During a visit to a sewage treatment plant, investigate the level of sewage treatment employed, the volume of effluent discharged, and whether this water is reused as a drinking water supply. Determine if there are any water bodies unsuitable for recreation due to poorly treated effluent and whether corrective measures are being implemented to address these issues. 3. Investigate if anyone in your community is looking at alternative sewage treatment solutions. Is anyone researching more natural systems of waste treatment than sewage treatment plants? Is anyone developing strategies for recycling of "gray" water? Answer: Research whether local initiatives or organizations are exploring alternative sewage treatment methods, such as natural systems like constructed wetlands, or developing strategies for recycling "gray" water. This exploration can uncover innovative approaches aimed at reducing environmental impact and enhancing sustainability. 4. Have your class identify the present or potential sources of contaminants in your community's drinking water supply. If surface water from a river or lake is used, how and to what degree is it being polluted before it is withdrawn for your use? If groundwater is used, is the aquifer subject to contamination by leaking sanitary landfills, improperly functioning septic tanks, unconfined hazardous wastes, or other sources of pollution? (Ask a public health and/or environmental official to discuss these problems with your class.) Answer: Identify potential contaminants in your community's drinking water supply, including surface water pollution from rivers or lakes and groundwater contamination risks from sources like leaking landfills and septic systems. Invite a public health or environmental official to discuss these issues and the measures taken to protect water quality. 5. Ask your students to explore the principal sources of industrial water pollution in your community. What specific types of chemicals are removed in the treatment of these industrial wastes? How is this accomplished? Answer: Students should investigate the main sources of industrial water pollution in the community, identifying specific chemicals removed during treatment and the processes used for their removal. This exploration can include discussions on filtration, chemical neutralization, and other treatment technologies employed to ensure safe discharge. 6. Take a class field trip to the nearest lake, river, or stream, preferably with a biologist. Note its smell, appearance, taste (if safe), flow, and ecological characteristics. How have these changed over the past 20 years? What plants and animals do you find living in or near the water? What are their functions? If possible, measure oxygen content, temperature, and pH. Use the library to determine what types of fish and other plant and aquatic life might exist under these conditions. What shifts would happen if acidity and/or dissolved oxygen and/or temperature were increased? Decreased? What might happen if acidity decreased and temperature increased? Try to visit other sites upstream and downstream from your town to compare water quality. Which sites did you prefer? Why? Answer: On a field trip to a local water body, observe and document its physical and ecological characteristics, noting any changes over the past 20 years. Investigate the presence and roles of local flora and fauna, and measure parameters like oxygen content, temperature, and pH. Consider potential ecological shifts with changes in these parameters and compare water quality at different sites to identify preferred locations and reasons for the preference. 7. With your class, visit the nearest reservoir, pond, or lake and try to find evidence of natural eutrophication and human-induced eutrophication. How deep is the body of water? How do depth and water quality vary throughout the year? How old is the body of water? What factors appear to limit growth of organisms in the body of water? What might the normal life span of the body of water be? Its actual life span? If possible, get a chemist or biologist to help you gather physical data (pH, salinity, turbidity, algae counts, species diversity, depth of bottom sediments) to establish the stage of succession. Try to find people who have lived near the body of water for a number of years and ask them to describe changes they have observed. Answer: Visit a nearby water body to identify signs of natural and human-induced eutrophication. Assess depth, seasonal variations in water quality, and the factors limiting organism growth. Determine the water body's age and projected life span, gathering physical data with a chemist or biologist's help. Interview long-time residents for observations on changes over time to understand the water body's ecological succession stage. Attitudes and Values 1. Is clean drinking water a basic human right? Why or why not? Answer: Yes, clean drinking water is a basic human right because it is essential for survival, health, and human dignity. Access to safe water is a fundamental need that underpins other rights, including the right to health, food, and an adequate standard of living. Denying access to clean water can lead to severe health issues and undermine overall well-being. 2. Compare and contrast access to clean water in the developed and developing world. How do the problems in the developing world rank against other important environmental issues? Answer: Access to clean water is generally more consistent and reliable in developed countries due to better infrastructure and regulation, while many developing nations face significant challenges, including scarcity, contamination, and inadequate infrastructure. These water issues are critical in the developing world, often ranking alongside other pressing environmental concerns like deforestation and pollution, as they directly impact health and economic development. 3. How aggressively should water quality be protected? What is the balance between individual rights and societal benefits? Answer: Water quality should be protected aggressively to safeguard public health and the environment. The balance between individual rights and societal benefits lies in ensuring that regulations and protections do not unduly infringe on personal freedoms while prioritizing the collective good. Policies should aim to provide safe water for all, preventing pollution and ensuring sustainable use of resources. 4. Is there an ecological obligation to protect water quality? How do natural and biological systems compare against human needs for water? Answer: There is an ecological obligation to protect water quality, as healthy aquatic ecosystems are vital for biodiversity, natural processes, and overall planetary health. Natural and biological systems depend on clean water for survival, just as humans do. While human needs often take precedence, it is essential to recognize and protect the intrinsic value of ecosystems to maintain the balance necessary for long-term sustainability. 5. Who should pay for non-point source pollution? Is it a federal, local, state, or individual issue? From an ethical standpoint, where does the responsibility for management lie? Answer: The cost of addressing non-point source pollution should be shared among federal, state, and local governments, with contributions from individuals and businesses as appropriate. Ethically, the responsibility lies with all parties contributing to the problem and benefiting from the solution. Effective management requires coordinated efforts to allocate resources and enforce regulations to mitigate pollution. News videos Bottle Backlash; Environmental Science in the Headlines, 2007; DVD; ISBN 0495385433 Additional Video Resources Crapshoot: The Gamble with Our Wastes (Documentary, 2004) How waste can pollute our water sources. The Habitable Planet: A Systems Approach to Environmental Science: Risk, Exposure, and Health and Water Resources (Documentary series, 2007). The sixth and eighth videos in this series explore water resources, and water cleanup efforts. . http://www.learner.org/resources/series209.html High Schooler's Water Cleaner Fights Pollution from Teflon Plant (Popular Mechanics) High Schooler devises a plan to clean up her local water way. http://www.popularmechanics.com/technology/industry/4224766.html Pointless Pollution: America's Water Crisis (Documentary) Non-point source pollution. Swim for the River (Documentary, 2006) The story of the Hudson, and the battle to save it, are told as Chris Swain swims the entire length of the river. http://www.swimfortheriver.com/ We all Live Downstream (Documentary, 1991) A look at pollution in the Mississippi River and the effects on human health. http://www.videoproject.com/wea-281-v.html Web Resources United Nations Water program Links to statistics and programs around the world. http://www.unwater.org/flashindex.html U.S. Environmental Protection Agency Report to congress on water quality including links to state-level data. http://www.epa.gov/305b/ Environment Canada Report on threats to drinking water sources in Canada. http://www.nwri.ca/threats/intro-e.html. U.S. Geological Survey Water Quality Information Links to data, techniques, and reports. http://water.usgs.gov/owq/ Suggested Answers to End of Chapter Questions Review Questions 1. Review the Key Questions and Concepts for this chapter on p. 529. Describe the cleanup of Lake Washington near Seattle (Core Case Study) and list the three lessons learned from this process. Answer: • The U. S. city of Seattle was founded near Lake Washington. By the mid- 1950s, sewage treatment plants were dumping huge amounts of treated wastewater into the lake. The high level of nutrients caused a bloom of cyanobacteria which caused the water to become cloudy and populations of desirable fish declined. Researchers hypothesized that the cause of the bloom was phosphorus coming from the sewage treatment plants. They wrote letters and articles to educate the general public about the nature of Lake Washington’s pollution. Within 3 years, citizen pressure on elected officials led to the development of a scheme to divert nutrient-rich effluents from Seattle’s sewage treatment plants into the nearby Puget Sound, where tides would mix and dilute them with ocean water. By 1976, the blue- green algae were virtually gone. The clarity of the lake water improved dramatically, fish populations in the lake recovered, and recreationists returned to Lake Washington. Three lessons learned were: adding nutrients can disturb the balance of an ecosystem and cause harmful effects; that technical solutions can be found for environmental problems and that citizens matter - public pressure on officials can lead to actions to solve environmental problems. 2. What is water pollution? Distinguish between point sources and nonpoint sources of water pollution, and give an example of each. List nine major types of water pollutants and give an example of each. List three diseases transmitted to humans by polluted water. Describe chemical and biological methods that scientists use to measure water quality. Answer: • Water pollution is any change in water quality that harms humans or other living organisms or makes water unsuitable for desired uses. It can come from single (point) sources or from larger and dispersed (nonpoint) sources. • Point sources discharge pollutants at specific locations through drain pipes, ditches, or sewer lines into bodies of surface water. Examples include factories, sewage treatment plants (which remove some, but not all, pollutants), underground mines, and oil tankers. • Nonpoint sources are broad, diffuse areas, rather than points, from which pollutants enter bodies of surface water or air. Examples include runoff of chemicals and sediments from cropland, livestock feedlots, logged forests, urban streets, parking lots, lawns, and golf courses. • See Table 20- 1 Major Water Pollutants and Their Sources for the major types of water pollutants and examples of each. • See Table 20- 2 Common Diseases Transmitted to Humans through Contaminated Drinking Water • See SCIENCE FOCUS Testing Water for Pollutants for chemical and biological methods used to measure water quality. 3. Describe how streams can cleanse themselves and how these cleansing processes can be overwhelmed. Describe the state of stream pollution in more-developed and less-developed countries. Answer: • Flowing rivers and streams can recover rapidly from moderate levels of degradable, oxygen-demanding wastes through a combination of dilution and biodegradation of such wastes by bacteria. But this natural recovery process does not work when streams become overloaded with such pollutants or when drought, damming, or water diversion reduces their flows. Depending on flow rates and the amount of biodegradable pollutants, streams recover from injection of oxygen-demanding wastes or heated water if they are given enough time and are not overloaded. • Water pollution control laws enacted in the 1970s have resulted in a great increase in the number and quality of wastewater treatment plants in the United States and most other developed countries. In addition, such laws require industries to reduce or eliminate their point source discharges of harmful chemicals into surface waters. This has enabled the United States to hold the line against increased pollution by disease-causing agents and oxygen-demanding wastes in most of its streams. This is an impressive accomplishment given the country’s increased economic activity, resource consumption, and population growth since passage of these laws. In most developing countries, stream pollution from discharges of untreated sewage and industrial wastes is a serious and growing problem. According to the World Commission on Water in the 21st Century, half of the world’s 500 rivers are heavily polluted, and most of these polluted rivers run through developing countries. Most of these countries cannot afford to build waste treatment plants and do not have, or do not enforce, laws for controlling water pollution. 4. Give two reasons why lakes cannot cleanse themselves as readily as streams can. Distinguish between eutrophication and cultural eutrophication. List ways to prevent or reduce cultural eutrophication. Describe the pollution of the Great Lakes and the progress made in reducing it. Answer: • Lakes and reservoirs are generally less effective at diluting pollutants than streams for two reasons. First, deep lakes and reservoirs often contain stratified layers that undergo little vertical mixing. Second, they have little or no flow. The flushing and changing of water in lakes and large artificial reservoirs can take from 1 to 100 years, compared with several days to several weeks for streams. • Eutrophication is the name given to the natural nutrient enrichment of a shallow lake, estuary, or slow-moving stream. It is caused mostly by runoff of plant nutrients, such as nitrates and phosphates, from surrounding land. An oligotrophic lake is low in nutrients and its water is clear. Over time some lakes become more eutrophic as nutrients are added from natural and human sources in the surrounding watersheds. Near urban or agricultural areas, human activities can greatly accelerate the input of plant nutrients to a lake—a process called cultural eutrophication. Mostly nitrate- and phosphate-containing effluents in runoff from various sources cause this change. These sources include farmland, animal feedlots, urban areas, chemically fertilized suburban yards, mining sites, and treated and untreated municipal sewage outlets. Some nitrogen also reaches lakes by deposition from the atmosphere. • Cultural eutrophication can be prevented or reduced by (1) using advanced waste treatment to remove nitrates and phosphates before wastewater enters lakes, banning or limiting the use of phosphates in household detergents and other cleaning agents and (3) by employing soil conservation and land-use control to reduce nutrient runoff. • The Great Lakes of North America are vulnerable to pollution from point and nonpoint sources. By the 1960s, many areas of the Great Lakes were suffering from severe cultural eutrophication, huge fish kills, and contamination from bacteria and a variety of toxic industrial wastes. Since 1972, Canada and the United States have joined forces and spent more than $ 20 billion on a Great Lakes pollution control program. This program has decreased algal blooms, increased dissolved oxygen levels and sport and commercial fishing catches in Lake Erie, and allowed most swimming beaches to reopen. Despite this important progress, many problems remain. Dozens of municipal sewage systems combine storm water with wastewater and allow emergency overflows into the lakes. Sediments in 26 toxic hotspots remain heavily polluted. And biological pollution in the form of invasions by zebra mussels and more than 180 other alien species threaten some native species and cause billions of dollars in damages. 5. Explain why groundwater cannot cleanse itself very well. What are the major sources of groundwater contamination in the United States? Describe the threat from arsenic in groundwater. List ways to prevent or clean up ground-water contamination. Describe three ways to provide safe drinking water in poor countries. Answer: • When groundwater becomes contaminated, it cannot cleanse itself of degradable wastes as quickly as flowing surface water does. Groundwater flows so slowly that contaminants are not diluted and dispersed effectively. • The United States had leaking gasoline, diesel fuel, home heating oil, or toxic solvents into groundwater. During this century, scientists expect many of the millions of such tanks, which have been installed around the world, to become corroded and leaky, possibly contaminating groundwater and becoming a major global health problem. • Another problem is toxic arsenic, which contaminates drinking water when a well is drilled into aquifers where soils and rock are naturally rich in arsenic or when human activities such as mining and ore processing release arsenic into drinking water supplies. • Methods for preventing contamination of groundwater includes: find substitutes for toxic chemicals, keep toxic chemicals out of the environment, install monitoring wells near landfills and underground tanks, require leak detectors on underground tanks, ban hazardous waste disposal in landfills and injection wells, and store harmful liquids in aboveground tanks with leak detection and collection systems. • Methods for clean-up of groundwater includes: pump to surface, clean, and return to aquifer (very expensive), inject microorganisms to clean up contamination (less expensive but still costly), and pump nanoparticles of inorganic compounds to remove pollutants (still being developed). • Three ways to provide safe drinking water are exposing water to UV rays from the sun, using inexpensive portable water filters, or treating the water with chlorine and iron sulfate. 6. Describe U. S. laws for protecting drinking water quality. Describe the environmental problems caused by the wide-spread use of bottled water. Answer: • The U. S. Safe Drinking Water Act of 1974 requires the EPA to establish national drinking water standards, called maximum contaminant levels, for any pollutants that may have adverse effects on human health • Use of bottled water causes environmental problems. Each year, the number of plastic water bottles thrown away, if lined up end- to- end, could circle the earth’s equator eight times. Toxic gases and liquids are released during the manufacture of plastic water bottles, and greenhouse gases and other air pollutants are emitted by the fossil fuels burned to make them and to deliver bottled water to suppliers. Withdrawing water for bottling is helping to deplete some underground aquifers. 7. How are coastal waters and deeper ocean waters polluted? What causes harmful algal blooms and what are their negative effects? Describe oxygen depletion in the northern Gulf of Mexico. How serious is oil pollution of the oceans, what are its effects, and what can be done to reduce such pollution? Describe the 2010 oil well blowout in the U.S Gulf Coast. Describe the effects of the 1989 Exxon Valdez oil spill in Alaskan waters. Answer: • Residential areas, factories, and farms all contribute to the pollution of coastal waters and bays. According to a 2006 study by the U. N. Environment Programme, an estimated 80% of marine pollution originates on land, and that 80– 90% of the municipal sewage from most coastal developing countries and from some coastal developed countries is dumped into oceans untreated. This dumping often overwhelms the ability of some coastal waters to biodegrade such wastes. Cruise ships also cause pollution. A cruise liner can generate as much waste as a small city produces. Much of this waste, including perchloroethylene from dry-cleaning and benzene from paint and solvents, is highly toxic. Cruise ships also generate huge amounts of plastic gar-age and waste oil. For decades, cruise ships and other ocean vessels, have been dumping their wastes at sea. • Runoff of sewage and agricultural wastes into coastal waters introduces large quantities of nitrate (NO3 –) and phosphate (PO4 3–) plant nutrients, which can cause explosive growths of harmful algae. These harmful algal blooms are called red, brown, or green toxic tides. They can release waterborne and airborne toxins that damage fisheries, kill some fish-eating birds, reduce tourism, and poison seafood. Harmful algal blooms lead to the poisoning of about 60,000 Americans a year who eat shellfish contaminated by the algae. • See Science Focus: Oxygen Depletion in the Northern Gulf of Mexico. • Tanker accidents and blowouts at offshore drilling rigs get considerable publicity, but studies show that the largest source of ocean oil pollution is urban and industrial runoff from land. Volatile organic hydrocarbons in oil immediately kill many aquatic organisms. Other chemicals in oil form tar-like globs that float on the surface and coat the feathers of birds and the fur of marine mammals, causing many of them to drown or die of exposure from loss of body heat. Heavy oil components that sink to the ocean floor or wash into estuaries can smother bottom- dwelling organisms such as crabs, oysters, mussels, and clams, making them unfit for human consumption. Some oil spills have killed coral reefs. • See Figure 20-17 Methods for preventing and cleaning up excessive pollution of coastal waters. • The 2010 accident involved a ruptured wellhead that released massive amounts of crude oil that contaminating ecologically vital coastal marshes, mangroves, sea-grass beds and deep ocean aquatic life. It also disrupted the livelihoods of people depending on the gulf’s coastal fisheries and caused large economic losses for the gulf’s tourism business. • The Exxon oil spill was the largest in U.S. history. The oil from this spill killed about 250,000 seabirds and large numbers of fish, fish eggs, shellfish, sea otters, killer whales, and harbor seals. The accident also disrupted the culture and livelihoods of 32,000 coastal residents of Alaska and caused an estimated $15 billion in damages. 8. List ways to reduce water pollution from (a) non-point sources and (b) point sources. Describe the U. S. experience with reducing point-source water pollution. What is a septic tank and how does it work? Describe how primary sewage treatment and secondary sewage treatment are used to help purify water. What are the options for dealing with sewage sludge? Answer: • Nonpoint-source water pollution may be reduced by farmers keeping cropland covered with vegetation, decreasing the amount of fertilizer that runs off into surface waters and leaches into aquifers by using slow-release fertilizer, using no fertilizer on steeply sloped land, and planting buffer zones of vegetation between cultivated fields and nearby surface waters. Laws and regulations have been effective in reducing point source pollution. • See CASE STUDY: U.S. Experience with Reducing Point-Source Water Pollution. • Septic tanks are used in rural and suburban areas with suitable soils. Household sewage and wastewater is pumped into a settling tank, where grease and oil rise to the top and solids fall to the bottom and are decomposed by bacteria. The resulting partially treated wastewater is discharged into a large drainage field. As these wastes drain from the pipes and percolate downward, the soil filters out some potential pollutants and soil bacteria decompose biodegradable materials. • Raw sewage reaching a treatment plant typically undergoes one or two levels of wastewater treatment. The first is primary sewage treatment: a physical process that uses screens and a grit tank to remove large floating objects and to allow solids such as sand and rock to settle out. Then the waste stream flows into a primary settling tank where suspended solids settle out as sludge. A second level is secondary sewage treatment: a biological process in which aerobic bacteria remove as much as 90% of dissolved and biodegradable, oxygen-demanding organic wastes. • Sludge can be disposed of in a landfill, in the ocean or applied to cropland, pasture, or rangelands as fertilizer. 9. How would Peter Montague improve conventional sewage treatment? What is a composting toilet system? Describe how we can use wetlands to treat sewage. Describe John Todd’s use of living machines to treat sewage. List six ways to prevent or reduce water pollution. List five things you can do to reduce water pollution. Answer: • Environmental scientist Peter Montague calls for redesigning the conventional sewage treatment system. The idea is to prevent toxic and hazardous chemicals from reaching sewage treatment plants and thus from getting into sludge and water discharged from such plants. Montague suggests two major ways to do this. One is to require industries and businesses to remove toxic and hazardous wastes from water sent to municipal sewage treatment plants. Another is to encourage industries to reduce or eliminate use and waste of toxic chemicals. Another suggestion is to require or encourage more households, apartment buildings, and offices to eliminate sewage outputs and reduce water usage by switching to waterless, odorless composting toilet systems to be installed, maintained, and managed by professionals. • More than 800 cities and towns around the world and 150 in the United States (including West Palm Beach, Florida, and Phoenix, Arizona) use natural or artificially created wetlands to treat sewage as a lower cost alternative to expensive waste treatment plants. For example, Arcata, California—a coastal town of 17,000 people—created some 65 hectares (160 acres) of wetlands between the town and the adjacent Humboldt Bay. The marshes and ponds, developed on land that was once a dump, act as a natural waste treatment plant. • See SCIENCE FOCUS Treating Sewage by Working with Nature for a description of the use of living machines to treat sewage. • Methods for preventing and reducing water pollution include: ○ Prevent groundwater contamination. ○ Reduce nonpoint runoff. ○ Reuse treated wastewater for irrigation. ○ Find substitutes for toxic pollutants. ○ Work with nature to treat sewage. ○ Practice the three Rs of resource use (reduce, reuse, recycle). ○ Reduce air pollution. ○ Reduce poverty. ○ Slow population growth. • Ways that individuals can help prevent and reduce water pollution include: ○ Fertilize garden and yard plants with manure or compost instead of commercial inorganic fertilizer. ○ Minimize your use of pesticides, especially near bodies of water. ○ Prevent yard wastes from entering storm drains. ○ Do not use water fresheners in toilets. ○ Do not flush unwanted medicines down the toilet. ○ Do not pour pesticides, paints, solvents, oil, antifreeze, or other products containing harmful chemicals down the drain or onto the ground. 10. Describe connections between the cleanup of Lake Washington (Core Case Study) and the three principles of sustainability. Answer: • The story of Lake Washington is an example of people loving a natural resource and abusing it at the same time. Seattle residents learned that the numbers of people using the lake could overwhelm this natural system. A technical solution was found for dealing with sewage treatment effluent, but now continually increasing pressures due to a growing population, are again overwhelming the natural systems of Lake Washington and Puget Sound. Using the four principles of sustainability can us shift our emphasis from cleaning up water pollution to reducing and preventing it. We can use solar energy to purify the water we use. Recycling more water will help us to reduce water waste, and natural nutrient cycles can be used to treat our waste in wetland- based sewage treatment systems. Preserving biodiversity by avoiding disruption of aquatic systems and their bordering terrestrial systems, which in turn help to reduce pollution, is a key factor in maintaining water supplies and water quality. And controlling human population growth and levels of resource use and waste is fundamental to maintaining water quality. Critical Thinking The following are examples of the material that should be contained in possible student answers to the end of chapter Critical Thinking questions. They represent only a summary overview and serve to highlight the core concepts that are addressed in the text. It should be anticipated that the students will provide more in-depth and detailed responses to the questions depending on an individual instructor’s stated expectations. 1. What were two important roles played by the scientists who studied Lake Washington as discussed in the Core Case Study that opens this chapter? Explain how the story might have been different if the scientists had not fulfilled each role? Answer: Scientists were the first to identify the presence of cyanobacteria in the lake and then to link the growth of the cyanobacteria to sewage treatment plants. The scientists also made the public aware of changes in the lake. Without this observation of cause and effect and efforts to educate the public, the lake would have continued to decline. 2. Lake Washington and Puget Sound now face new problems similar to those of the past, as suggested in the Core Case Study. Describe the nature of those problems and suggest possible solutions. Answer: Both Lake Washington and Puget Sound now face problems of cultural eutrophication. These problems, like the earlier ones, are caused by excess loading of nitrogen and phosphorus into the lakes. Now the loading is from a variety of sources including agricultural settings, air pollution, and local fertilizer use so any solutions will require approaches that include all of these potential causes as well as new scientific studies to identify the most important problems. 3. A large number of dead fish are found floating in a lake. How would you determine whether they died from cultural eutrophication or from exposure to toxic chemicals? Answer: Test the water for the presence of dissolved organic matter that may be impacting the BOD of the lake. Test the dissolved oxygen concentrations in the lake at different locations and at different depths. Perform a full toxicological analysis of the lake water to determine if any chemical pollutants are present in the lake. Only then can any determination be made as to the cause of the fish kill. 4. If you were a regulator charged with drawing up plans for controlling water pollution, briefly describe one idea for controlling water pollution from each of the following sources: (a) an pipe from a factory discharging effluent into a stream, (b) a parking lot at a shopping mall bordered by a stream, and (c) a farmer’s field on a slope next to a stream. Answer: (a) I would identify, monitor, and regulate organic and inorganic contaminants in the effluent stream coming out of the pipe from the factory. Laws would be introduced and enforced to control harmful discharges from such point sources from industry to prevent it entering and damaging ecosystems. (b) It is difficult to regulate nonpoint sources of pollution from areas such as parking lots from shopping malls. However, measures could be taken to help with this problem. Petroleum, oil, rubber particles from tires, and litter may all be contaminants in the parking lot runoff. The construction of an onsite water treatment facility that collects and treats all of the runoff before it is discharged into the stream could be a solution. The cost of the facility would be shared between the mall owners and the companies that occupy the space in the mall. The surface of the parking lots could be assessed to make sure that it channels the water to a drainage system that delivers the water to the treatment facility. Rather than infiltrate into the groundwater through cracks in the surface, the parking lot would need to be checked periodically. (c) Runoff from farms and agricultural activities is a leading cause of water pollution. Regulations that could be introduced that would limit the amount of fertilizers and pesticides that are used; not allow cattle to graze on the slope close to the stream; mandate the practice of contour farming, strip cropping, and no-till agriculture on the slope, and plant a vegetative buffer zone along the bottom of the sloping field near the stream bank. 5. What role does population growth play in the problems of (a) groundwater pollution problems and (b) coastal water pollution problems? Answer: (a) Groundwater pollution is caused by a variety of different activities, but one of the most important causes is fertilizer leaching from agricultural field. The use of fertilizers in agriculture is one of the consequences of increased demand for food to feed a growing population so increased pollution can, in this sense, be linked back to population issues. (b) Coastal water pollution is caused also by fertilizer use, so for the same reasons as described above, population growth can lead to problem with agricultural fertilizer runoff. In addition, growth of populations in coastal areas, and particularly the development of areas such as mangroves and wetlands, reduces the ability of these systems to filter out contaminants before they reach the open water. 6. When you flush your toilet, where does the wastewater go? Trace the actual flow of this water in your community from your toilet through sewers to a wastewater treatment plant and from there to the environment. Try to visit a local sewage treatment plant to see what it does with your wastewater. Compare the processes it uses with those shown in Figure 20-20. What happens to the sludge produced by this plant? What improvements, if any, would you suggest for this plant? Answer: In my rural community everyone has a septic tank system, which is used for the disposal of domestic sewage and household wastewater. The septic tank is pumped out every few years and the sludge is taken to a sewage treatment plant for disposal. The septic tank drains into a leach field, which lies underneath the vegetable garden. We have our own well so the groundwater that is used by our household goes through the leach field and then percolates back into the ground to recharge the aquifer. The nearest local sewage treatment facility disposes of the sludge produced by sending it to a landfill. This is because of the contaminants in the sludge that arise from the toxic materials from the local businesses and industries that have discharges entering the wastewater stream. I would separate the discharges from the factories and have that water treated in another facility. This would allow the sludge produced by the “household” sewage to possibly be used as a soil additive on local farms. It does not make sense that the sewage that is pumped from septic systems from houses in our area gets mixed in with the contaminated sewage at this facility. We are not using the sustainable principle of nutrient recycling. 7. In your community, a. What are the principal nonpoint sources of contamination of surface water and groundwater? b. What is the source of drinking water? c. How is drinking water treated? d. How many times during each of the past 5 years have levels of tested contaminants violated federal standards? Were violations reported to the public? e. What problems related to drinking water, if any, have arisen in your community? What actions, if any, has your local government taken to solve such them? f. Is groundwater contamination a problem? If so, where, and what has been done about the problem? g. Is there a vulnerable aquifer or critical recharge zone that needs protection to ensure the quality of groundwater? Is your local government aware of this? What action (if any) has it taken? Answer: (a) Farmlands and local strip malls along the roads. (b) Most people have their own wells. (c) Some houses have water softening systems in the basement. (d) A few years ago, the water in the nearest town center was found to be contaminated with a microorganism and the water had to be boiled before use. Some local restaurants had to close for several days until the problem was dealt with. The public was kept aware of the problem and the situation at all times. (e) Yes, the public is strongly urged not to eat fish that is caught in local rivers and lakes due to potentially high levels of toxic materials such as mercury. Those people who choose to eat fish, such as local trout, have been told that they should not eat more than one fish per month. It has been broadly communicated that children, the elderly, and pregnant women should never eat any fish from these local rivers and lakes. (f) The only groundwater problem that I have heard of in my area was from a leaking underground gas tank at a local service station. The tank had to be dug up and replaced and the contaminated soil was taken away and incinerated. (g) There are signs along the roadside in my area that let people know they are entering a protected watershed area that is used for supplying drinking water. I have not specifically heard of any problem with the aquifer recharge area, although whenever any new construction takes place I imagine it is affecting the amount of water that infiltrates the ground. The signs by the road do make people aware of the importance of the watershed and how we depend on it for our drinking water. Being educated about the aquifer will hopefully help protect it. 8. List three ways in which you could apply Concept 20-5 to make your lifestyle more environmentally sustainable. Answer: 1. I can use organic rather than industrial fertilizers in my yard. 2. I can support the protection of wetlands as a natural mechanism for sewage treatment. 3. I can work with and/or support organizations committed to reducing poverty and slowing population growth. 9. Congratulations! You are in charge of the world. What are three actions you would take to (a) sharply reduce point-source water pollution in more-developed countries, (b) sharply reduce nonpoint-source water pollution throughout the world, (c) sharply reduce groundwater pollution throughout the world, and (d) provide safe drinking water for the poor and for other people in less-developed countries? Answer: (a) Point-source/developing countries: 1. Build sewage and water treatment plants. 2. Introduce laws to control water pollution from businesses and industry. 3. Regulate industrial waste discharges. (b) Nonpoint/worldwide: 1. Restore degraded wetlands. 2. Mandate and support best management practices for all agricultural operations. 3. Regulate household fertilizer and pesticide use on lawns and gardens. (c) Groundwater/worldwide: 1. Ban all hazardous waste disposal in landfills. 2. Keep toxic chemicals out of the environment and use/search for non-toxic alternatives. 3. Use above-ground tanks for storage of hazardous chemicals and gasoline/oil, which have leak detector and spill collection systems. (d) Safe drinking water/poor/developing countries: 1. Implement the WHO suggestions for tropical countries-put water in plastic containers (provided free) and expose them to the sun to kill bacteria. 2. Provide filtering systems to remove bacteria from drinking water (using the latest micropore and nanotechnology filters). 3. Supply purifying chemical sachets free of charge as part of an international aid program while water treatment facilities are being constructed. 10. List two questions that you would like to have answered as a result of reading this chapter. Answer: 1. How can brands adapt to different markets while keeping a consistent global identity? 2. What are the main challenges in managing brand image across segments? Data Analysis In 2006, scientists assessed the overall condition of the estuaries on the western coasts of the U.S. states of Oregon and Washington. To do so, they took measurements of various characteristics of the water, including dissolved oxygen (DO), in selected locations within the estuaries. The concentration of DO for each site was measured in terms of milligrams (mg) of oxygen per liter (L) of water sampled. The scientists used the following DO concentration ranges and quality categories to rate their water samples: water with greater than 5 mg/L of DO was considered good for supporting aquatic life; water with 2 to 5 mg/L of DO was rated as fair; and water with less than 2mg/L of DO was rated as poor. The following graph shows measurements taken in bottom water at 242 locations. Each triangle mark represents one or more measurements. The x-axis on this graph represents DO concentrations in mg/L. The y-axis represents percentages of the total area of estuaries studied (estuarine area). LEARNING ONLINE To read this graph, pick one of the triangles and observe the values on the x- and y-axes. For example, note that the circled triangle lines up approximately with the 5-mg/L mark on the x-axis and with a value of about 34% on the y-axis. This means that waters at this particular measurement station (or stations), along with about 34% of the total area being studied, are estimated to have a 5% or lower DO concentration. Use this information, along with the graph to answer the following questions: 1. Half of the estuarine area has waters falling below a certain DO concentration level, and the other half has waters above that level. What is that level, in mg/L? 2. Give your estimate of the highest DO concentration measured and your estimate of the lowest concentration. 3. Approximately what percentage of the estuarine area studied is considered to have poor DO levels? About what percentage has fair DO levels, and about what percentage has good DO levels? 1. Answer: Approximately 6 mg/L 2. Answer: • Highest DO concentration: Approximately 14 mg/L. • Lowest DO concentration: Approximately 1 mg/L. 3. Answer: Approximately 3% has poor DO levels, 31% has fair levels, and 66% has good levels. Solution Manual for Living in the Environment: Principles, Connections, and Solutions G. Tyler Miller, Scott Spoolman 9780538735346