1. MILLER/SPOOLMAN
LIVING IN THE ENVIRONMENT 17TH
Chapter 20
Water Pollution
2. Water Pollution Comes from Point and
Nonpoint Sources (1)
• Water pollution
• 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
3. Water Pollution Comes from Point and
Nonpoint Sources (2)
• Nonpoint sources
• Broad, diffuse areas
• Difficult to identify and control
• Expensive to clean up
• Examples
4. Water Pollution Comes from Point and
Nonpoint Sources (3)
• Leading causes of water pollution
1. Agriculture activities
• Sediment eroded from the lands
• Fertilizers and pesticides
• Bacteria from livestock and food processing wastes
2. Industrial facilities
3. Mining
5. Point Source of Polluted Water in Gargas,
France
Fig. 20-3, p. 530
9. 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
12. Streams Can Cleanse Themselves If We Do
Not Overload Them
• Dilution
• Biodegradation of wastes by bacteria takes time
• Oxygen sag curve-when there are a lot of bacteria
decomposing material
13. Dilution and Decay of Degradable, Oxygen-
Demanding Wastes in a Stream
Fig. 20-7, p. 534
14. 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
17. 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
19. Cultural Eutrophication Is Too Much
of a Good Thing (1)
• Eutrophication
• 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
20. Cultural Eutrophication Is Too Much
of a Good Thing (2)
• Cultural eutrophication
• 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
21. 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
23. 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
24. 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
25. 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?
27. 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
28. 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
30. 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
31. Pollution Prevention Is the Only Effective
Way to Protect Groundwater
• Prevent
contamination of
groundwater
• Cleanup: expensive
and time consuming
32. 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
34. 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
35. 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
36. 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
37. 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
38. 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
40. 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?
41. A Large Zone of Oxygen-Depleted Water in the
Gulf of Mexico Due to Algal Blooms
Fig. 20-B, p. 546
42. 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
43. 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
46. 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
47. 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
48. 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?
49. 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
50. 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
53. 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
54. 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
56. What Can You Do?
Reducing Water Pollution
Fig. 20-22, p. 554
Editor's Notes
Figure 20.3: This point-source water pollution flows uncontrolled into a stream near Gargas, France.
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?
Figure 20.5: The water in this lake is polluted with mining wastes.
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.
Table 20-1
Table 20-2
Figure 20.7: N atural 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?
Figure 20.8: N atural capital degradation. This highly polluted river in central China has been turned greenish-black by uncontrolled pollution from thousands of factories. In some parts of China, river water is too toxic to touch, much less drink. The cleanup and modernization of Chinese cities such as Beijing and Shanghai are forcing polluting refineries and factories to move to rural areas where two-thirds of China’s population resides. Liver and stomach cancers, linked in some cases to water pollution, are among the leading causes of death in the countryside. Farmers too poor to buy bottled water must often drink polluted well water.
Figure 20.9: Global outlook: This garbage truck is dumping trash into a river in Peru.
Figure 20.10: Water pollution has killed the fish in this lake.
Figure 20.11: Global outlook: Severe cultural eutrophication has covered this lake near the Chinese city of Haozhou with algae.
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.
Figure 20.13: N atural 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?
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.
Figure 20.16: N atural 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)?
Figure 20.B: N atural 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 2008. 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)
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?
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.
Figure 20.19: S olutions. Septic tank systems are often used for disposal of domestic sewage and wastewater in rural and suburban areas.
Figure 20.20: S olutions. 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?
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?
Figure 20.22: I ndividuals matter. You can help reduce water pollution. Questions: Which three of these actions do you think are the most important? Why?
