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Chapter 20 Water Pollution
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The Seattle, Washington Area, U.S.
Figure 20.1: The U.S. city of Seattle, Washington, was founded on the shore of Puget Sound and quickly expanded eastward toward Lake Washington. Fig. 20-1, p. 528
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Core Case Study: Lake Washington
Sewage dumped into Lake Washington 1955: Edmondson discovered cyanobacteria in the lake Role of phosphorus Public pressure led to cleanup of the lake Sewage treatment plant effluent to Puget Sound New pollution challenges
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Water Pollution Comes from Point and Nonpoint Sources (1)
Change in water quality that can harm organisms or make water unfit for human uses Contamination with chemicals Excessive heat Point sources Located at specific places Easy to identify, monitor, and regulate Examples
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Water Pollution Comes from Point and Nonpoint Sources (2)
Broad, diffuse areas Difficult to identify and control Expensive to clean up Examples
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Water Pollution Comes from Point and Nonpoint Sources (3)
Leading causes of water pollution Agriculture activities Sediment eroded from the lands Fertilizers and pesticides Bacteria from livestock and food processing wastes Industrial facilities Mining
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Nonpoint Sediment from Unprotected Farmland Flows into Streams
Figure 20.4: Nonpoint sediment pollution eroded from farmland flows into streams and sometimes changes their courses or dams them up. As measured by weight, it is the largest source of water pollution. Question: What do you think the owner of this farm could have done to prevent such sediment pollution? Fig. 20-4, p. 530
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Plastic Wastes in Mountain Lake
Figure 20.6: Plastics and other forms of waste pollute this mountain lake as well as many bodies of water around the world, and can release harmful chemicals into the water. Fig. 20-6, p. 531
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Major Water Pollutants Have Harmful Effects
Infectious disease organisms: contaminated drinking water The World Health Organization (WHO) 1.6 million people die every year, mostly under the age of 5
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Major Water Pollutants and Their Sources
Table 20-1 Table 20-1, p. 532
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Common Diseases Transmitted to Humans through Contaminated Drinking Water
Table 20-2 Table 20-2, p. 532
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Science Focus: Testing Water for Pollutants (1)
Variety of tests to determine water quality Coliform bacteria: Escherichia coli, significant levels Level of dissolved oxygen (DO) Chemical analysis
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Science Focus: Testing Water for Pollutants (2)
Indicator species Examples Bacteria and yeast glow in the presence of a particular toxic chemical Color and turbidity of the water
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Water Quality as Measured by Dissolved Oxygen Content in Parts per Million
Figure 20.A: Scientists measure dissolved oxygen (DO) content in parts per million (ppm) at 20°C (68°F) as an indicator of water quality. Only a few fish species can survive in water with less than 4 ppm of dissolved oxygen at this temperature. Some warm-water species have evolved ways to tolerate low DO levels better than most cold-water species can. Question: Would you expect the dissolved oxygen content of polluted water to increase or decrease if the water is heated? Explain. Fig. 20-A, p. 533
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Streams Can Cleanse Themselves If We Do Not Overload Them
Dilution Biodegradation of wastes by bacteria takes time Oxygen sag curve
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Dilution and Decay of Degradable, Oxygen-Demanding Wastes in a Stream
Figure 20.7: Natural capital. A stream can dilute and decay degradable, oxygen-demanding wastes, and it can also dilute heated water. This figure shows the oxygen sag curve (blue) and the curve of oxygen demand (red). Depending on flow rates and the amount of biodegradable pollutants, streams recover from oxygen-demanding wastes and from the injection of heated water if they are given enough time and are not overloaded (Concept 20-2a). See an animation based on this figure at CengageNOW™. Question: What would be the effect of putting another discharge pipe emitting biodegradable waste to the right of the one in this picture? Fig. 20-7, p. 534
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Stream Pollution in More Developed Countries
1970s: Water pollution control laws Successful water clean-up stories Ohio Cuyahoga River, U.S. Thames River, Great Britain Contamination of toxic inorganic and organic chemicals by industries and mines
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Global Outlook: Stream Pollution in Developing Countries
Half of the world’s 500 major rivers are polluted Untreated sewage Industrial waste India’s rivers China’s rivers
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Too Little Mixing and Low Water Flow Makes Lakes Vulnerable to Water Pollution
Less effective at diluting pollutants than streams Stratified layers Little vertical mixing Little of no water flow Can take up to 100 years to change the water in a lake Biological magnification of pollutants
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Cultural Eutrophication Is Too Much of a Good Thing (1)
Natural enrichment of a shallow lake, estuary, or slow-moving stream Caused by runoff into lake that contains nitrates and phosphates Oligotrophic lake Low nutrients, clear water
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Cultural Eutrophication Is Too Much of a Good Thing (2)
Nitrates and phosphates from human sources Farms, feedlots, streets, parking lots Fertilized lawns, mining sites, sewage plants During hot weather or droughts Algal blooms Increased bacteria More nutrients Anaerobic bacteria
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Cultural Eutrophication Is Too Much of a Good Thing (3)
Prevent or reduce cultural eutrophication Remove nitrates and phosphates Diversion of lake water Clean up lakes Remove excess weeds Use herbicides and algaecides; down-side? Pump in air
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Cultural Eutrophication of Chinese Lake
Figure 20.11: Global outlook: Severe cultural eutrophication has covered this lake near the Chinese city of Haozhou with algae. Fig , p. 537
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Revisiting Lake Washington and Puget Sound
Severe water pollution can be reversed Citizen action combined with scientific research Good solutions may not work forever Wastewater treatment plant effluents sent into Puget Sound Now what’s happening?
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Case Study: Pollution in the Great Lakes (1)
1960s: Many areas with cultural eutrophication 1972: Canada and the United States: Great Lakes pollution control program Decreased algal blooms Increased dissolved oxygen Increased fishing catches Swimming beaches reopened Better sewage treatment plants Fewer industrial wastes Bans on phosphate-containing household products
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Case Study: Pollution in the Great Lakes (2)
Problems still exist Raw sewage Nonpoint runoff of pesticides and fertilizers Biological pollution Atmospheric deposition of pesticides and Hg
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Case Study: Pollution in the Great Lakes (3)
2007 State of the Great Lakes report New pollutants found Wetland loss and degradation Declining of some native species Native carnivorous fish species declining What should be done?
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The Great Lakes of North America
Figure 20.12: The five Great Lakes of North America make up the world’s largest freshwater system. Dozens of major cities in the United States and Canada are located on their shores, and water pollution in the lakes is a growing problem. Fig , p. 538
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Ground Water Cannot Cleanse Itself Very Well (1)
Source of drinking water Common pollutants Fertilizers and pesticides Gasoline Organic solvents Pollutants dispersed in a widening plume
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Ground Water Cannot Cleanse Itself Very Well (2)
Slower chemical reactions in groundwater due to Slow flow: contaminants not diluted Less dissolved oxygen Fewer decomposing bacteria Low temperatures
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Principal Sources of Groundwater Contamination in the U.S.
Figure 20.13: Natural capital degradation. These are the principal sources of groundwater contamination in the United States (Concept 20-3a). Another source in coastal areas is saltwater intrusion from excessive groundwater withdrawal. (Figure is not drawn to scale.) Question: What are three sources shown in this picture that might be affecting groundwater in your area? Fig , p. 540
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Groundwater Pollution Is a Serious Hidden Threat in Some Areas
China: 90% of urban aquifers are contaminated or overexploited U.S.: FDA reports of toxins found in many aquifers Threats Gasoline, oil Nitrate ions Arsenic
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Pollution Prevention Is the Only Effective Way to Protect Groundwater
Prevent contamination of groundwater Cleanup: expensive and time consuming
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Groundwater Pollution
Solutions Groundwater Pollution Prevention Cleanup Find substitutes for toxic chemicals Pump to surface, clean, and return to aquifer (very expensive) Keep toxic chemicals out of the environment Install monitoring wells near landfills and underground tanks Inject microorganisms to clean up contamination (less expensive but still costly) Require leak detectors on underground tanks Ban hazardous waste disposal in landfills and injection wells Figure 20.14: There are ways to prevent and ways to clean up contamination of groundwater but prevention is the only effective approach (Concept 20-3B). Questions: Which two of these preventive solutions do you think are the most important? Why? Store harmful liquids in aboveground tanks with leak detection and collection systems Pump nanoparticles of inorganic compounds to remove pollutants (still being developed) Fig , p. 541
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There Are Many Ways to Purify Drinking Water
Reservoirs and purification plants Process sewer water to drinking water Expose clear plastic containers to sunlight (UV) The LifeStraw PUR: chlorine and iron sulfate powder
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The LifeStraw: Personal Water Purification Device
Figure 20.15: The LifeStraw™, designed by Torben Vestergaard Frandsen, is a personal water purification device that gives many poor people access to safe drinking water. Here, four young men in Uganda demonstrate its use. Question: Do you think the development of such devices should make prevention of water pollution less of a priority? Explain. Fig , p. 542
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Case Study: Protecting Watersheds Instead of Building Water Purification Plants
New York City water Reservoirs in the Catskill Mountains Paid towns, farmers, and others in the watershed to restore forests, wetlands, and streams Saved the cost of building a plant: $6 billion
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Using Laws to Protect Drinking Water Quality
1974: U.S. Safe Drinking Water Act Sets maximum contaminant levels for any pollutants that affect human health Health scientists: strengthen the law Water-polluting companies: weaken the law
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Case Study: Is Bottled Water the Answer?
U.S.: some of the cleanest drinking water Bottled water Some from tap water 40% bacterial contamination Fuel cost to manufacture the plastic bottles Recycling of the plastic 240-10,000x the cost of tap water Growing back-to-the-tap movement
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Ocean Pollution Is a Growing and Poorly Understood Problem (1)
2006: State of the Marine Environment 80% of marine pollution originates on land Sewage Coastal areas most affected Deeper ocean waters Dilution Dispersion Degradation
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Ocean Pollution Is a Growing and Poorly Understood Problem (2)
Cruise line pollution: what is being dumped? U.S. coastal waters Raw sewage Sewage and agricultural runoff: NO3- and PO43- Harmful algal blooms Oxygen-depleted zones Huge mass of plastic in North Pacific Ocean
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Residential Areas, Factories, and Farms Contribute to Pollution of Coastal Waters
Figure 20.16: Natural capital degradation. Residential areas, factories, and farms all contribute to the pollution of coastal waters. According to the UN Environment Programme, coastal water pollution costs the world more than $30,000 a minute, primarily for health problems and premature deaths. Questions: What do you think are the three worst pollution problems shown here? For each one, how does it affect two or more of the ecological and economic services listed in Figure 8-5 (p. 172)? Fig , p. 545
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Science Focus: Oxygen Depletion in the Northern Gulf Of Mexico
Severe cultural eutrophication Oxygen-depleted zone Overfertilized coastal area Preventive measures Will it reach a tipping point?
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A Large Zone of Oxygen-Depleted Water in the Gulf of Mexico Due to Algal Blooms
Figure 20.B: Natural capital degradation. A large zone of oxygen-depleted water (containing less than 2 ppm dissolved oxygen) forms each year in the Gulf of Mexico (lower right drawing) as a result of oxygen-depleting algal blooms caused primarily by high inputs of plant nutrients from the Mississippi River basin (top). The drawing (bottom left), based on a satellite image, shows how these inputs spread along the coast during the summer of In the image, reds and greens represent high concentrations of phytoplankton and river sediment. This problem is worsened by loss of wetlands, which would have filtered some of these plant nutrients. Question: Can you think of a product you used today that was directly connected to this sort of pollution? (Data from NASA) Fig. 20-B, p. 546
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Ocean Pollution from Oil (1)
Crude and refined petroleum Highly disruptive pollutants Largest source of ocean oil pollution Urban and industrial runoff from land 1989: Exxon Valdez, oil tanker 2010: BP explosion in the Gulf of Mexico
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Ocean Pollution from Oil (2)
Volatile organic hydrocarbons Kill many aquatic organisms Tar-like globs on the ocean’s surface Coat animals Heavy oil components sink Affect the bottom dwellers
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Ocean Pollution from Oil (3)
Faster recovery from crude oil than refined oil Cleanup procedures Methods of preventing oil spills
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Coastal Water Pollution
Solutions Coastal Water Pollution Prevention Cleanup Reduce input of toxic pollutants Improve oil-spill cleanup capabilities Separate sewage and storm water lines Use nanoparticles on sewage and oil spills to dissolve the oil or sewage (still under development) Ban dumping of wastes and sewage by ships in coastal waters Ban dumping of hazardous material Figure 20.17: There are a number of methods for preventing or cleaning up excessive pollution of coastal waters (Concept 20-4B). Questions: Which two of these solutions do you think are the most important? Why? Require secondary treatment of coastal sewage Strictly regulate coastal development, oil drilling, and oil shipping Use wetlands, solar-aquatic, or other methods to treat sewage Require double hulls for oil tankers Fig , p. 547
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Deepwater Horizon Blowout in the Gulf of Mexico, April 20, 2010
Figure 20.18: On April 20, 2010 oil and natural gas escaping from an oil-well borehole ignited and caused an explosion on the British Petroleum (BP) Deepwater Horizon drilling platform in the Gulf of Mexico. The accident sank the rig and killed 11 of its crewmembers. The ruptured wellhead released massive amounts of crude oil that contaminated ecologically vital coastal marshes (Figure 8-8, p. 174), mangroves (Figure 8-10, p. 175), sea-grass beds (Figure 8-9, p. 174) 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. This disaster was caused by a combination of equipment failure, human error, failure by BP to prepare for a major oil release, and inadequate government regulation of oil drilling in the Gulf of Mexico. Fig , p. 547
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Case Study: The Exxon Valdez Oil Spill
1989: Alaska’s Prince William Sound 41 million liters of crude oil 5200 km of coastline Killed 250,000 seabirds $15 billion in damages to economy Exxon paid $3.8 billion in damages and clean-up costs Led to improvements in oil tanker safety and clean-up strategies
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Reducing Surface Water Pollution from Nonpoint Sources
Agriculture Reduce erosion Reduce the amount of fertilizers Plant buffer zones of vegetation Use organic farming techniques Use pesticides prudently Control runoff Tougher pollution regulations for livestock operations Deal better with animal waste
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Laws Can Help Reduce Water Pollution from Point Sources
1972: Clean Water Act 1987: Water Quality Act EPA: experimenting with a discharge trading policy that uses market forces Cap and trade system Could this allow pollutants to build up?
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Case Study: The U.S. Experience with Reducing Point-Source Pollution (1)
Numerous improvements in water quality Some lakes and streams are not safe for swimming or fishing Treated wastewater still produces algal blooms High levels of Hg, pesticides, and other toxic materials in fish
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Case Study: The U.S. Experience with Reducing Point-Source Pollution (2)
Leakage of gasoline storage tanks into groundwater Many violations of federal laws and regulations Need to strengthen the Clean Water Act
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Sewage Treatment Reduces Water Pollution (1)
Septic tank system Wastewater or sewage treatment plants Primary sewage treatment Physical process Secondary sewage treatment Biological process with bacteria Tertiary or advance sewage treatment Special filtering processes Bleaching, chlorination
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Sewage Treatment Reduces Water Pollution (2)
Many cities violate federal standards for sewage treatment plants Should there be separate pipes for sewage and storm runoff? Health risks of swimming in water with blended sewage wastes
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Solutions: Septic Tank System
Figure 20.19: Solutions. Septic tank systems are often used for disposal of domestic sewage and wastewater in rural and suburban areas. Fig , p. 550
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Solutions: Primary and Secondary Sewage Treatment
Figure 20.20: Solutions. Primary and secondary sewage treatment systems help to reduce water pollution. Question: What do you think should be done with the sludge produced by sewage treatment plants? Fig , p. 551
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We Can Improve Conventional Sewage Treatment
Peter Montague: environmental scientist Remove toxic wastes before water goes to the municipal sewage treatment plants Reduce or eliminate use and waste of toxic chemicals Use composting toilet systems Wetland-based sewage treatment systems
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Science Focus: Treating Sewage by Working with Nature
John Todd: biologist Natural water purification system Sewer water flows into a passive greenhouse Solar energy and natural processes remove and recycle nutrients Diversity of organisms used
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Solutions: Ecological Wastewater Purification by a Living Machine, RI, U.S.
Figure 20.C: Solutions. This is an ecological wastewater purification system called a living machine. This Solar Sewage Treatment Plant is in the U.S. city of Providence, Rhode Island. Biologist John Todd is demonstrating this ecological process he invented for purifying wastewater by using the sun and a series of tanks containing living organisms. Todd and others are conducting research to perfect such solar–aquatic sewage treatment systems based on working with nature. Fig. 20-C, p. 553
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There Are Sustainable Ways to Reduce and Prevent Water Pollution
Developed countries Bottom-up political pressure to pass laws Developing countries Little has been done to reduce water pollution China : ambitious plan
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Solutions: Methods for Preventing and Reducing Water Pollution
Figure 20.21: There are a number of ways to prevent and reduce water pollution (Concept 20-5). Questions: Which two of these solutions do you think are the most important? Why? Fig , p. 553
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What Can You Do? Reducing Water Pollution
Figure 20.22: Individuals matter. You can help reduce water pollution. Questions: Which three of these actions do you think are the most important? Why? Fig , p. 554
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Three Big Ideas There are a number of ways to purify drinking water, but the most effective and cheapest strategy is pollution control. The key to protecting the oceans is to reduce the flow of pollution from land and air, and from streams emptying into ocean waters.
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Three Big Ideas Reducing water pollution requires that we prevent it, work with nature in treating sewage, cut resource use and waste, reduce poverty, and slow population growth.
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