1. 20
Water Pollution

2. Case Study: The Gulf of Mexico’s Annual Dead Zone
Spring and summer – huge inputs of nutrients from the Mississippi River basin
Depletion of dissolved oxygen in the Gulf of Mexico’s bottom layer of water
Contains little marine life
Disrupts nitrogen cycle

3. Mississippi River Basin
Missouri River
Mississippi River Basin
Ohio River
Figure 20.1 Water containing sediments, dissolved nitrate fertilizers, and other pollutants drains from the Mississippi River basin (top) into the Mississippi River and from there into the northern Gulf of Mexico (bottom). The boxed area at the bottom of the map shows the dead zone with the red area having the lowest oxygen level.
Mississippi River
Fig. 20-1a, p. 544

4. Mississippi River GULF OF MEXICO
Figure 20.1 Water containing sediments, dissolved nitrate fertilizers, and other pollutants drains from the Mississippi River basin (top) into the Mississippi River and from there into the northern Gulf of Mexico (bottom). The boxed area at the bottom of the map shows the dead zone with the red area having the lowest oxygen level.
GULF OF MEXICO
Fig. 20-1b, p. 544

5. 20-1 What Are the Causes and Effects of Water Pollution?
Water pollution causes illness and death in humans and other species, and disrupts ecosystems
Sources:
Primarily agricultural activities, industrial facilities, and mining
Growth of both the human population and our rate of resource use makes it increasingly worse

6. Water Pollution Comes from Point and Nonpoint Sources
Change in water quality that can harm organisms or make water unfit for human uses
Point sources
Located at specific places
Easy to identify, monitor, and regulate

7. Water Pollution Comes from Point and Nonpoint Sources (cont’d.)
Broad, diffuse areas
Difficult to identify and control
Expensive to clean up

8. Water Pollution Comes from Point and Nonpoint Sources (cont’d.)
Leading causes of water pollution
Agriculture activities
Sediment eroded from the lands
Fertilizers and pesticides
Industrial facilities
Inorganic and organic chemicals
Mining
Erosion and toxic chemicals

9. Figure 20-2: This is a point source of water pollution in Gargas, France.
Fig. 20-2, p. 545

10. Figure 20-3: Nonpoint sediment from farmland runoff 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. 20-3, p. 546

11. Major Water Pollutants Have Harmful Effects
Infectious disease organisms
Contaminated drinking water
An estimated 1.6 million people die every year, mostly under the age of five

12. Table 20-1
Table 20-1, p. 547

13. 20-2 What Are the Major Water Pollution Problems in Streams and Lakes?
Streams and rivers around the world are extensively polluted
However, they can cleanse themselves of many pollutants if we do not overload them or reduce their flows
Adding excessive nutrients to lakes from human activities can disrupt their ecosystems, and prevention of such pollution is more effective and less costly than cleaning it up

14. Streams Can Cleanse Themselves, If We Do Not Overload Them
Dilution
Biodegradation of wastes by bacteria takes time
Oxygen sag curve
Breakdown of biodegradable wastes by bacteria depletes oxygen

15. Point source
Normal clean water organisms (Trout, perch, bass, mayfly, stonefly)
Pollution-tolerant fishes (carp, gar)
Fish absent, fungi, sludge worms,
bacteria (anaerobic)
Pollution-tolerant fishes (carp, gar)
Normal clean water organisms (Trout, perch, bass, mayfly, stonefly)
8 ppm
Types of organisms
8 ppm
Dissolved oxygen (ppm)
Animated Figure 20-6: 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). 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). Question: What would be the effect of putting another discharge pipe emitting biodegradable waste to the right of the one in this picture?
Biochemical oxygen demand
Clean Zone
Recovery Zone
Septic Zone
Decomposition Zone
Clean Zone
Fig. 20-6, p. 549

16. 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

17. Stream Pollution in Less-Developed Countries
Half of the world’s 500 major rivers are polluted
Untreated sewage
Industrial waste
Water often used for human activities

18. Figure 20-7: Natural capital degradation
Figure 20-7: Natural capital degradation. This portion of China’s Yangtze River near the Three Gorges dam is heavily polluted with chemicals, sediment, and trash.
Fig. 20-7, p. 550

19. 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

20. Cultural Eutrophication Is Too Much of a Good Thing
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

21. Cultural Eutrophication Is Too Much of a Good Thing (cont’d.)
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; anaerobic bacteria
More nutrients

22. Cultural Eutrophication Is Too Much of a Good Thing (cont’d.)
Prevent or reduce cultural eutrophication
Remove nitrates and phosphates
Diversion of lake water
Clean up lakes
Remove excess weeds
Use herbicides and algaecides
Pump in air

23. Figure 20-8: In 2010, severe cultural eutrophication affected Chaohu Lake near Hefei City in China’s Anhui Province.
Fig. 20-8, p. 551

24. Revisiting The Gulf of Mexico: An Extreme Case of Cultural Eutrophication
Nitrates discharged from the Mississippi have nearly tripled since 1950
Nitrogen cycle disrupted
Blue-green algae blooms
Flood-control along the Mississippi
Flow faster; increase sediment pollution
Fish kills

25. Case Study: Pollution in the Great Lakes
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
Better sewage treatment plants

26. Case Study: Pollution in the Great Lakes (cont’d.)
Pollution control program (cont’d.)
Fewer industrial wastes
Bans on phosphate-containing household products
Problems still exist
Raw sewage and biological pollution
Nonpoint runoff of pesticides and fertilizers
Atmospheric deposition of pesticides and Hg

27. Case Study: Pollution in the Great Lakes (cont’d.)
Continuing problems
Urban sprawl and runoff
Biological pollution
Zebra mussels
Atmospheric deposition of pollutants

28. Figure 20-11: 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. 553

29. 20-3 What Are the Major Pollution Problems Affecting Groundwater?
Chemicals used in agriculture, industry, transportation, and homes can spill and leak into groundwater and make it undrinkable
There are both simple ways and complex ways to purify groundwater used as a source of drinking water, but protecting it through pollution prevention is the least expensive and most effective strategy

30. Ground Water Cannot Cleanse Itself Very Well
Source of drinking water for about half of the U.S. population
Common pollutants
Fertilizers and pesticides
Gasoline
Organic solvents
Fracking
Pollutants dispersed in a widening plume

31. Ground Water Cannot Cleanse Itself Very Well (cont’d.)
Slower chemical reactions in groundwater due to:
Slow flow – contaminants not diluted
Less dissolved oxygen
Fewer decomposing bacteria
Low temperatures

32. Leakage from faulty casing
Polluted air
Hazardous waste
injection well
Pesticides
and fertilizers
Coal strip mine runoff
Deicing road salt
Buried gasoline and solvent tanks
Pumping well
Gasoline station
Cesspool, septic
tank
Water pumping well
Waste lagoon
Sewer
Landfill
Leakage from faulty casing
Accidental spills
Figure 20-12: Natural capital degradation. 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 figure that might be affecting groundwater in your area?
Discharge
Freshwater aquifer
Freshwater aquifer
Freshwater aquifer
Groundwater flow
Fig , p. 554

33. 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
Nitrate ions
Can turn into cancer causing chemicals
Slowly degrading wastes
Non-degradable wastes

34. Case Study: Arsenic in Drinking Water
Rocks rich in arsenic can contaminate wells
Long-term exposure can lead to:
Skin, lung, bladder cancer
Treatment
Nanoparticles of rust

35. 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

36. Case Study: Is Bottled Water a Good Option?
Bottled water can be useful but expensive
The U.S. has some of the world’s cleanest drinking water
Bottled water less regulated than tap water
Use of bottled water can create environmental problems

37. 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

38. 20-4 What Are the Major Water Pollution Problems Affecting Oceans?
Most ocean pollution originates on land and includes:
Oil and other toxic chemicals
Solid waste, which threaten fish and wildlife and disrupt marine ecosystems
Key to protecting the oceans
Reduce the flow of pollution from land and air and from streams emptying into ocean waters

39. Ocean Pollution Is a Growing and Poorly Understood Problem
Municipal sewage from less-developed countries are often dumped into oceans without treatment
Deeper ocean waters
Dilution
Dispersion
Degradation

40. Ocean Pollution Is a Growing and Poorly Understood Problem (cont’d.)
U.S. coastal waters
Raw sewage – viruses
Sewage and agricultural runoff: NO3- and PO43-
Harmful algal blooms
Oxygen-depleted zones

41. Industry
Nitrogen oxides
from autos and smokestacks, toxic chemicals, and heavy metals in effluents flow into bays and estuaries.
Cities
Toxic metals and oil from streets and parking lots pollute waters; sewage adds nitrogen and phosphorus.
Urban sprawl
Bacteria and viruses from sewers and septic tanks contaminate shellfish beds and close beaches; runoff of fertilizer from lawns adds nitrogen and phosphorus.
Construction sites
Sediments are washed into waterways, choking fish and plants, clouding waters, and blocking sunlight.
Farms
Runoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.
Closed
shellfish beds
Red tides
Excess nitrogen causes explosive growth of toxic microscopic
algae, poisoning fish
and marine mammals.
Closed beach
Oxygen-depleted zone
Figure 20-15: Natural capital degradation. Residential areas, factories, and farms all contribute to the pollution of coastal waters. Question: What do you think are the three worst pollution problems shown here? For each one, how does it affect two or more of the ecosystem and economic services listed in Figure 8-5?
Toxic sediments
Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and accumulate in the tissues of bottom feeders.
Oxygen-depleted zone
Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat.
Healthy zone
Clear, oxygen-rich waters promote growth of plankton and sea grasses, and support fish.
Fig , p. 559

42. Case Study: Ocean Garbage Patches: There Is No Away
North Pacific Garbage Patch
Two rotating gyres
On or just beneath the water surface
Tiny plastic pieces harmful to wildlife
No practical way to clean up

43. Canada Russia Alaska United States China Japan Hawaii PACIFIC OCEAN
Figure 20-17: The North Pacific Garbage Patch is actually two vast, slowly swirling masses of small plastic particles floating just under the water. Four other huge garbage patches have been discovered in the world’s other major oceans.
PACIFIC OCEAN
Fig , p. 560

44. Ocean Pollution from Oil
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 Deepwater Horizon in the Gulf of Mexico

45. Ocean Pollution from Oil (cont’d.)
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. Ocean Pollution from Oil (cont’d.)
Faster recovery in warm water with rapid currents
In cold, calm waters recovery can take decades
Methods of preventing oil spills
Double hulls

47. Figure 20-19: The Deepwater Horizon drilling platform burned and sank in the Gulf of Mexico after exploding on April 20, 2010.
Fig , p. 561

48. Case Study: The BP Deepwater Horizon Oil-Rig Spill
Spill from deep-sea oil drilling – 1 mile deep
Released 4.9 million barrels of crude oil
Contaminated vast areas of coastline
Caused by equipment failure and poor decisions
Government developed new standards for offshore drilling procedures

49. 20-5 How Can We Deal with Water Pollution?
Reducing water pollution requires that we:
Prevent it
Work with nature to treat sewage
Use natural resources far more efficiently

50. Reducing Ocean Water Pollution
Reduce flow of pollution from land
Land-use
Air pollution
Linked to energy and climate policy

51. Solutions Coastal Water Pollution Prevention Cleanup
Separate sewage and storm water lines
Ban dumping of wastes and sewage by ships
in coastal waters
Improve oil-spill cleanup capabilities
Use nanoparticles on sewage and oil spills to dissolve the oil or sewage (still under development)
Require secondary treatment of coastal sewage
Strictly regulate coastal development, oil drilling, and oil shipping
Figure 20-21: Methods for preventing excessive pollution of coastal waters and methods for cleaning it up (Concept 20-4B). Question: Which two of these solutions do you think are the best ones? Why?
Use wetlands and other natural methods to treat sewage
Require double hulls for oil tankers
Fig , p. 563

52. 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
Institute tougher pollution regulations for livestock operations

53. Case Study: The U.S. Experience with Reducing Point-Source Pollution
1972 – Clean Water Act
1987 – Water Quality Act
Experimenting with a discharge trading policy that uses market forces
What are some achievements of the Clean Water Act?

54. Sewage Treatment Reduces Water Pollution
How do septic tank systems work?
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

55. Sewage Treatment Reduces Water Pollution (cont’d.)
Many cities violate federal standards for sewage treatment plants
Federal law requires primary and secondary treatment
Exemptions from secondary treatment
There are health risks of swimming in water with blended sewage wastes

56. Manhole cover (for cleanout) Septic tank Gas Distribution box Scum
Wastewater
Sludge
Drain field (gravel or crushed stone)
Figure 20-23: Solutions. Septic tank systems are often used for disposal of domestic sewage and wastewater in rural and suburban areas.
Vent pipe
Perforated pipe
Fig , p. 565

57. Chlorine disinfection tank Bar screen Grit chamber Settling tank
Primary
Secondary
Chlorine disinfection tank
Bar screen
Grit chamber
Settling tank
Aeration tank
Settling tank
To river, lake, or ocean
Sludge
Raw sewage from sewers
Activated sludge
(kills bacteria)
Air pump
Figure 20-24: 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?
Sludge digester
Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland
Sludge drying bed
Fig , p. 566

58. We Can Improve Conventional Sewage Treatment
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
Work with nature

59. 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
Small sewage treatment plants
How can we avoid producing water pollutants in the first place?

60. Figure 20-26: Ways to prevent or reduce water pollution (Concept 20-5)
Figure 20-26: Ways to prevent or reduce water pollution (Concept 20-5). Question: Which two of these solutions do you think are the best ones? Why?
Fig , p. 568

61. Figure 20-27: Individuals matter. You can help reduce water pollution
Figure 20-27: Individuals matter. You can help reduce water pollution. Question: Which three of these steps do you think are the most important ones to take? Why?
Fig , p. 570

62. Three Big Ideas
There are a number of ways to purify drinking water, but the most effective and least costly strategy is pollution prevention
The key to protecting the oceans is to reduce the flow of pollution from:
Land and air
Streams emptying into ocean waters

63. Three Big Ideas Reducing water pollution requires that we: Prevent it
Work with nature in treating sewage
Use natural resources far more efficiently

64. Tying It All Together: Dead Zones and Sustainability
Dead zones disrupt ecological interactions between species in river and coastal systems
We can use solar energy to purify water and reduce waste
We can use natural nutrient cycles to purify water