LIVING IN THE ENVIRONMENT, 18e G. TYLER MILLER SCOTT E. SPOOLMAN. Water Pollution. Cengage Learning 2015

Transcription

1 LIVING IN THE ENVIRONMENT, 18e G. TYLER MILLER SCOTT E. SPOOLMAN 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 Missouri River Mississippi River Basin Ohio River Mississippi River Fig. 20-1a, p. 544

4 Mississippi River 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 Water pollution 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.) Nonpoint sources 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 Fig. 20-2, p. 545

10 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, 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 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 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 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

21 Cultural Eutrophication Is Too Much of a Good Thing (cont d.) 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; 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 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 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 Polluted air Coal strip mine runoff Pumping well Deicing road salt Waste lagoon Accidental spills Pesticides and fertilizers Landfill Gasoline station Water pumping well Buried gasoline and solvent tanks Cesspool, septic tank Sewer Groundwater flow Freshwater aquifer Hazardous waste injection well Leakage from faulty casing Discharge 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: NO 3 - and PO 4 3- 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. Closed beach 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. Oxygen-depleted zone Closed 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 toxic microscopic algae, poisoning fish and marine mammals. 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 China Russia Alaska United States Japan Hawaii 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 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 Separate sewage and storm water lines Require secondary treatment of coastal sewage Ban dumping of wastes and sewage by ships in coastal waters Strictly regulate coastal development, oil drilling, and oil shipping Cleanup Improve oil-spill cleanup capabilities Use nanoparticles on sewage and oil spills to dissolve the oil or sewage (still under development) 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) Gas Scum Wastewater Sludge Drain field (gravel or crushed stone) Septic tank Distribution box Vent pipe Perforated pipe Fig , p. 565

57 Primary Secondary Bar screen Grit chamber Settling tank Aeration tank Settling tank Chlorine disinfection tank Raw sewage from sewers Sludge Activated sludge To river, lake, or ocean (kills bacteria) Air pump Sludge digester Sludge drying bed Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland 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 Fig , p. 568

61 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