Water Pollution: Sources, Effects, and Prevention Measures

1. Chapter 21 Water Pollution

2. Chapter Overview Questions • What pollutes water, where do these pollutants come from, and what effects do they have? • What are the major water pollution problems in streams and lakes? • What causes groundwater pollution, and how can it be prevented? • What are the major water pollution problems affecting oceans?

3. Chapter Overview Questions (cont’d) • How can we prevent and reduce surface water pollution? • How safe is drinking water, and how can it be made safer?

4. Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. • InfoTrac: Cleaning Up an Effluent Society. Business Week Online, March 22, 2006. • InfoTrac: Nuclear Reactors Found to Be Leaking Radioactive Water. Matthew L. Wald. The New York Times, March 17, 2006 pA21(L). • InfoTrac: Water and farms: towards sustainable use. Kevin Parris, Wilfrid Legg. OECD Observer, March 2006 i254 p14(3). • WHO: Arsenic in Drinking Water • National Ocean Service: Welcome to Nonpoint Source Pollution • EPA: Surface and Groundwater

5. Core Case Study: Using Nature to Purify Sewage • Ecological wastewater purification by a living machine. • Uses the sun and a series of tanks containing plants, snails, zooplankton, crayfish, and fish (that can be eaten or sold for bait). Figure 21-1

6. WATER POLLUTION: SOURCES, TYPES, AND EFFECTS • Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses. • Point source: specific location (drain pipes, ditches, sewer lines). • Nonpoint source: cannot be traced to a single site of discharge (atmospheric deposition, agricultural / industrial / residential runoff)

7. Fig. 20-2, p. 545

8. Fig. 20-3, p. 546

9. Table 21-2, p. 495

10. Table 20-1, p. 547

11. Major Water Pollutants and Their Effects • A fecal coliform bacteria test is used to indicate the likely presence of disease-causing bacteria in water. Figure 21-2

12. Fig. 20-A, p. 548

13. Major Water Pollutants and Their Effects • Water quality and dissolved oxygen (DO) content in parts per million (ppm) at 20°C. • Only a few fish species can survive in water less than 4ppm at 20°C. Figure 21-3

14. POLLUTION OF FRESHWATER STREAMS • Flowing streams can recover from a moderate level of degradable water pollutants if they are not overloaded and their flows are not reduced. • In a flowing stream, the breakdown of degradable wastes by bacteria depletes DO and creates and oxygen sag curve. • This reduces or eliminates populations of organisms with high oxygen requirements.

15. Normal clean water organisms (Trout, perch, bass, mayfly, stonefly) Trash fish (carp, gar, leeches) Fish absent, fungi, sludge worms, bacteria (anaerobic) Trash fish (carp, gar, leeches) Clean Normal clean water organisms (Trout, perch, bass, mayfly, stonefly) Types of organisms 8 ppm Dissolved oxygen (ppm) 8 ppm Clean Zone Biological oxygen demand Recovery Zone Septic Zone Decomposition Zone Clean Zone Fig. 21-4, p. 497

16. POLLUTION OF FRESHWATER STREAMS • Most developed countries have sharply reduced point-source pollution but toxic chemicals and pollution from nonpoint sources are still a problem. • Stream pollution from discharges of untreated sewage and industrial wastes is a major problem in developing countries.

17. Global Outlook: Stream Pollution in Developing Countries • Water in many of central China's rivers are greenish black from uncontrolled pollution by thousands of factories. Figure 21-5

18. p. 570

19. Fig. 20-7, p. 550

20. Case Study: India’s Ganges River: Religion, Poverty, and Health • Religious beliefs, cultural traditions, poverty, and a large population interact to cause severe pollution of the Ganges River in India. • Very little of the sewage is treated. • Hindu believe in cremating the dead to free the soul and throwing the ashes in the holy Ganges. • Some are too poor to afford the wood to fully cremate. • Decomposing bodies promote disease and depletes DO.

21. Case Study: India’s Ganges River: Religion, Poverty, and Health • Daily, more than 1 million Hindus in India bathe, drink from, or carry out religious ceremonies in the highly polluted Ganges River. Figure 21-6

22. POLLUTION OF FRESHWATER LAKES • Dilution of pollutants in lakes is less effective than in most streams because most lake water is not mixed well and has little flow. • Lakes and reservoirs are often stratified and undergo little mixing. • Low flow makes them susceptible to runoff. • Various human activities can overload lakes with plant nutrients, which decrease DO and kill some aquatic species.

23. Fig. 20-5, p. 546

24. Cultural Eutrophication • Eutrophication: the natural nutrient enrichment of a shallow lake, estuary or slow moving stream, mostly from runoff of plant nutrients from the surrounding land. • Cultural eutrophication: human activities accelerate the input of plant nutrients (mostly nitrate- and phosphate-containing effluents) to a lake. • 85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication.

25. Fig. 20-8, p. 551

26. Utah Lake

27. https://www.washingtonpost.com/video/national/timelapse-shows-toxic-algae-spread-through-utah-lake/2016/07/25/71f1a058-5237-11e6-b652-315ae5d4d4dd_video.htmlhttps://www.washingtonpost.com/video/national/timelapse-shows-toxic-algae-spread-through-utah-lake/2016/07/25/71f1a058-5237-11e6-b652-315ae5d4d4dd_video.html

28. 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

29. 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

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

31. Fig. 20-11, p. 553

32. POLLUTION OF GROUNDWATER • Groundwater can become contaminated with a variety of chemicals because it cannot effectively cleanse itself and dilute and disperse pollutants. • The drinking water for about half of the U.S. population and 95% of those in rural areas comes from groundwater.

33. Polluted air Pesticides and fertilizers Hazardous waste injection well Deicing road salt Coal strip mine runoff Buried gasoline and solvent tanks Gasoline station Pumping well Cesspool, septic tank Water pumping well Waste lagoon Sewer Leakage from faulty casing Landfill Accidental spills Discharge Unconfined freshwater aquifer Confined aquifer Confined freshwater aquifer Groundwater flow Fig. 21-7, p. 501

34. POLLUTION OF GROUNDWATER • It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of degradable wastes. • Nondegradable wastes (toxic lead, arsenic, flouride) are there permanently. • Slowly degradable wastes (such as DDT) are there for decades.

35. Leaking tank Aquifer Bedrock Water table Groundwater flow Free gasoline dissolves in groundwater (dissolved phase) Gasoline leakage plume (liquid phase) Migrating vapor phase Water well Contaminant plume moves with the groundwater Fig. 21-8, p. 502

36. POLLUTION OF GROUNDWATER • Leaks from a number of sources have contaminated groundwater in parts of the world. • According the the EPA, one or more organic chemicals contaminate about 45% of municipal groundwater supplies. • By 2003, the EPA had completed the cleanup of 297,000 of 436,000 underground tanks leaking gasoline, diesel fuel, home heating oil, or toxic solvents.

37. Fig. 20-4, p. 546

38. Case Study: Arsenic in Groundwater - a Natural Threat • Toxic Arsenic (As) can naturally occur at high levels in soil and rocks. • Drilling into aquifers can release As into drinking water supplies. • According to WHO, more than 112 million people are drinking water with As levels 5-100 times the 10 ppb standard. • Mostly in Bangladesh, China, and West Bengal, India.

39. Solutions Groundwater Pollution Prevention Cleanup Pump to surface, clean, and return to aquifer (very expensive) Find substitutes for toxic chemicals Keep toxic chemicals out of the environment Inject microorganisms to clean up contamination (less expensive but still costly) Install monitoring wells near landfills and underground tanks Require leak detectors on underground tanks Pump nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed) Ban hazardous waste disposal in landfills and injection wells Store harmful liquids in aboveground tanks with leak detection and collection systems Fig. 21-9, p. 504

40. OCEAN POLLUTION • Oceans, if they are not overloaded, can disperse and break down large quantities of degradable pollutants. • Pollution of coastal waters near heavily populated areas is a serious problem. • About 40% of the world’s population lives near on or near the coast. • The EPA has classified 4 of 5 estuaries as threatened or impaired.

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; Urban sprawl Bacteria and viruses from sewers and septic tanks contaminate shellfish beds 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. Red tides Excess nitrogen causes explosive growth of toxicmicroscopic algae, poisoning fish and marine mammals. Closed shellfish beds Closed beach Oxygen-depleted zone 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. 21-10, p. 505

42. OCEAN POLLUTION • Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from sewage and agricultural runoff. Figure 21-11

43. Fig. 20-16, p. 559

44. 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

45. Mississippi River GULF OF MEXICO Fig. 20-1b, p. 544

46. Missouri River Mississippi River Basin Ohio River Mississippi River MS LA LOUISIANA Mississippi River TX Depletedoxygen Gulf of Mexico Gulf of Mexico Fig. 21-A, p. 507

47. Fig. 20-10, p. 552

48. Case Study: The Chesapeake Bay – An Estuary in Trouble • Pollutants from six states contaminate the shallow estuary, but cooperative efforts have reduced some of the pollution inputs. Figure 21-12

49. OCEAN OIL POLLUTION • Most ocean oil pollution comes from human activities on land. • Studies have shown it takes about 3 years for many forms of marine life to recover from large amounts of crude oil(oil directly from ground). • Recovery from exposure to refined oil (fuel oil, gasoline, etc…) can take 10-20 years for marine life to recover.

50. Fig. 20-19, p. 561