1. Water Pollution Chapter 20

2. 20-1 What Are the Causes and Effects of Water Pollution?  Concept 20-1A Water pollution causes illness and death in humans and other species and disrupts ecosystems.  Concept 20-1B The chief sources of water pollution are agricultural activities, industrial facilities, and mining, but growth in population and resource use make it increasingly worse.

3.  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.  Water quality, or its chemical and physical makeup, depends upon its intended use. Drinking water needs to be as pure H 2 O and possible Water used for washing your car or watering your lawn can be of lower quality Water Pollution Comes from Point and Nonpoint Sources

4.  Point source: specific location or from a single point Drain pipes, ditches, sewer lines, spills Fairly easy to identify, monitor, and regulate  Nonpoint source: cannot be traced to a single site of discharge Atmospheric deposition, runoff from agricultural / industrial / residential lands Difficult to identify and control and expensive to clean up because of the many diffuse sources Water Pollution Comes from Point and Nonpoint Sources

5.  Major sources of water pollution are: 1)Agricultural activities are by far the leading cause of water pollution. Sediment eroded from agricultural lands, fertilizers, pesticides, bacteria from livestock, salts from irrigation 2)Industrial facilities release a variety of harmful organic and inorganic chemicals. 3)Surface mining disturbs the Earth’s surface causing runoff of sediments and toxic chemicals. Water Pollution Comes from Point and Nonpoint Sources

6. Major Water Pollutants and Their Sources

7.  There are a variety of tests to determine water quality: Temperature pH Dissolved Oxygen Total Dissolved Solids Flow Rate Phosphates Nitrates Chlorides Color and turbidity of the water Coliform bacteria: E. coli Biological Assessment Indicator species Science Focus: Testing Water for Pollutants

8. 20-2 What Are the Major Water Pollution Problems in Streams and Lakes?  Concept 20-2A While streams are extensively polluted worldwide by human activities, they can cleanse themselves of many pollutants if we do not overload them or reduce their flows.  Concept 20-2B Addition of excessive nutrients to lakes from human activities can disrupt lake ecosystems, and prevention of such pollution is more effective and less costly than cleaning it up.

9.  Flowing streams can recover from a moderate level of water pollution if they are not overloaded with pollutants and their flows are not reduced. In a flowing stream, the breakdown of degradable wastes by bacteria depletes dissolved oxygen and creates an oxygen sag curve. Biodegradation of wastes by bacteria takes time This reduces or eliminates populations of organisms that require high amounts of oxygen until the stream is cleansed of wastes. Streams Can Cleanse Themselves If We Do Not Overload Them

10. Dilution and Decay of Degradable, Oxygen-Demanding Wastes in a Stream  Similar oxygen sag curves can result from thermal pollution.

11.  Most developed countries have sharply reduced point-source pollution but water contamination is still a problem. Accidental or deliberate releases of toxic chemicals by industries, mines, malfunctioning sewage treatment plants Non-point runoff of pesticides and nutrients from cropland and livestock Stream Pollution in Developed Countries

12.  Stream pollution in most developing countries is a major problem. Untreated sewage, infectious agents, industrial wastes  Most countries cannot afford water treatment plants.  Many don’t have water quality laws or the laws are not enforced. Stream Pollution in Developing Countries  Problems are made worse by the fact that many people in developing countries drink, bath, and wash clothes in rivers.

13. Millions of Hindus in India bathe, drink from, or carry out religious ceremonies in the Ganges. Very little of the sewage is treated Animal carcasses are thrown into river Hindu beliefs lead to cremation of the dead and spreading the ashes in the Ganges. Some are too poor to afford to cremate Decomposing bodies promote disease and depletes DO Case Study: India’s Ganges River: Religion, Poverty, Population Growth, and Health  Religious beliefs, cultural traditions, poverty, and a large population interact to cause severe pollution of the Ganges River in India.

14.  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 layered by temperature and undergo little mixing Low flow makes them susceptible to runoff  Rivers can be flushed of pollutants in days, compared to the years it would take to be removed from a lake.  Various human activities can overload lakes with plant nutrients, which decrease DO and kill some aquatic species. Low Water Flow and Too Little Mixing Makes Lakes Vulnerable to Water Pollution

15.  Eutrophication: natural nutrient enrichment of a shallow lake, estuary or slow moving stream, mostly from the runoff of plant nutrients from the surrounding land. The opposite = Oligotrophic lake Low nutrients, clear water  Cultural eutrophication: when human activities accelerate the input of plant nutrients (mostly nitrates and phosphates) to a lake. 85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication. Cultural Eutrophication Is Too Much of a Good Thing

16.  Eutrophication can lead to a large fish kill events. Excessive nutrients cause out of control algae growth Algae use up all the nutrients, die, and decompose The decomposition process results in low oxygen levels and an oxygen sag is created 1000’s or 10,000’s of fish can be killed at a time In Iowa, fish kills are caused by large amounts of manure being spilled into rivers, streams, lakes Cultural Eutrophication Is Too Much of a Good Thing

17. 20-3 Pollution Problems Affecting Groundwater, Other Water Sources  Concept 20-3A Chemicals used in agriculture, industry, transportation, and homes can spill and leak into groundwater and make it undrinkable.  Concept 20-3B There are simple ways and complex ways to purify drinking water, but protecting it through pollution prevention is the least expensive and most effective strategy.

18.  The drinking water for about half of the U.S. population and 95% of those in rural areas comes from groundwater.  Common groundwater pollutants are gasoline, fertilizers, pesticides, and organic solvents  Sources: spills, leaking underground pipes and tanks, seepage down from the surface  Once a pollutant contaminates groundwater, it fills the pores between the sediment particles like a sponge This makes removal and cleanup very difficult and costly Ground Water Cannot Cleanse Itself Very Well

19. Principal Sources of Groundwater Contamination in the U.S.

20.  When groundwater pollutants reach an aquifer, they spread out and form a specific shape called a plume. Direction of water flow Ground Water Cannot Cleanse Itself Very Well

21.  Groundwater can become contaminated with a variety of chemicals because it cannot effectively cleanse itself or dilute and disperse pollutants. Slow flow: contaminants not diluted Less dissolved oxygen – less decomposition Fewer decomposing bacteria Colder temperatures slow down chemical reactions  As a result, it can take 100’s to 1000’s of years for contaminated groundwater to cleanse itself of degradable wastes. Non-degradable wastes (toxic lead, arsenic, flouride) are there permanently. Ground Water Cannot Cleanse Itself Very Well

22. Solutions: Groundwater Pollution, Prevention and Cleanup  Groundwater contamination is the most clear situation where prevention is the only true solution.  All cleanup methods are expensive and time consuming

23.  Centralized water treatment plants and watershed protection can provide safe drinking water for cities in developed countries.  Simpler and cheaper ways can be used to purify drinking water for developing countries. Boiling water or exposure to the sun’s UV rays for 3 hours can kill infectious microbes.  While most developed countries have drinking water quality standards and laws, most developing countries do not. There Are Many Ways to Purify Drinking Water

24.  The U.S. Safe Drinking Water Act requires the EPA to establish national drinking water standards (maximum contaminant levels) for any pollutant that may have adverse effects on human health. Originally, it only focused on standards for water treatment Now, it includes protections for drinking water sources as well rivers, lakes, springs, groundwater Using Laws to Protect Drinking Water Quality

25.  The U.N. estimates that 5.6 million Americans drink water that does not meet EPA standards.  1 in 5 Americans drinks water from a treatment plant that violated one or more safety standard.  Industry pressures to weaken the Safe Drinking Act: Eliminate national tests and public notification of violations Allow rights to pollute if provider cannot afford to comply Reduce EPA’s budget which limits its ability to monitor and enforce water quality standards Using Laws to Protect Drinking Water Quality

26. NO!! Is Bottled Water the Answer?  ¼ of bottled water is just tap water  40% of bottled water is lower quality than tap water and costs much more.  Fossil fuels are used to make plastic bottles. The oil used to produce plastic bottles in the U.S. each year would fuel 100,000 cars. 1.4 million metric tons of plastic bottles are thrown away.

27. 20-4 What Are the Major Water Pollution Problems Affecting Oceans?  Concept 20-4A The great majority of ocean pollution originates on land and includes oil and other toxic chemicals and solid wastes, which threaten aquatic species and other wildlife and disrupt marine ecosystems.  Concept 20-4B The key to protecting the oceans is to reduce the flow of pollutants from land and air and from streams emptying into these waters.

28.  Oceans, if they are not overloaded, can handle large quantities of degradable pollutants. There is a lot of water to dilute, disperse, and degrade pollutants  However, 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 An estimated 80% of all marine pollution originates on land Ocean Pollution Is a Growing and Poorly Understood Problem

29.  Harmful algal blooms (HABs) are caused by explosive growth of harmful algae from sewage and agricultural runoff.  They create oxygen-depleted zones that suffer from hypoxia (very low oxygen levels) Sometimes incorrectly called “dead zones” Not absent of life – decomposers thrive Ocean Pollution Is a Growing and Poorly Understood Problem

30. Residential Areas, Factories, and Farms Contribute to Pollution of Coastal Waters

31.  Severe hypoxia occurs every spring and summer in the Gulf of Mexico as a result of HABs.  The low oxygen levels suffocate fish, crabs, and shrimp that cannot move to less polluted areas.  Why? Science Focus: Oxygen Depletion in the Northern Gulf Of Mexico

32.  37-50% of ocean oil pollution comes from human activities on land. Runoff from land where oil was spilled, dumped, or leaked  However, oil spills and tanker accidents get all the news headlines. Exxon Valdez Crashed into rocks in 1989 in Prince William Sound Spilled over 11,000,000 gallons of crude oil Ocean Oil Pollution Is a Serious Problem

33.  The spill posed threats to the delicate food chain that supports Prince William Sound's commercial fishing industry.  Also in danger were ten million migratory shore birds and waterfowl, hundreds of sea otters, dozens of other species, such as harbor porpoises and sea lions, and several varieties of whales. Ocean Oil Pollution Is a Serious Problem

34.  Tanker accidents and blowouts at offshore drilling rigs can be extremely devastating to marine life especially diving birds and animals with fur. Ocean Oil Pollution Is a Serious Problem

35. Solutions: Coastal Water Pollution, Prevention and Cleanup

36. 20-5 How Can We Best Deal with Water Pollution?  Concept 20-5 Reducing water pollution requires preventing it, working with nature to treat sewage, cutting resource use and waste, reducing poverty, and slowing population growth.

37.  The key to reducing nonpoint pollution – most of it from agriculture – is to prevent it from reaching bodies of water. Farmers can reduce runoff by planting buffers and locating feedlots away from steeply sloped land, and flood zones. Buffers help to prevent soil erosion and filter pollutants. We Need to Reduce Surface Water Pollution from Nonpoint Sources

38.  The U.S. Clean Water Act sets standards for allowed levels of key water pollutants and requires polluters to get permits limiting how much they can discharge into aquatic systems. EPA is experimenting with a discharge trading policy similar to that for air pollution control. Early focus of the CWA was on point sources, but with the 1987 amendment, efforts to control nonpoint sources have increased. The act does not deal directly with groundwater. But remember, the U.S. Safe Drinking Water Act does… Laws Can Help Reduce Water Pollution from Point Sources

39.  Important CWA vocabulary: Water quality standards (WQS) are risk-based requirements which set site-specific allowable pollutant levels for individual water bodies, such as rivers, lakes, streams and wetlands. States set WQS by designating uses for the water body (e.g., recreation, water supply, aquatic life, agriculture) Total Maximum Daily Load (TMDL), is a calculation of the maximum amount of a pollutant that a water body can receive and still meet WQS. Laws Can Help Reduce Water Pollution from Point Sources

40.  A septic tank is a small scale sewage treatment system used by a single home or building. The term septic comes from the anaerobic bacteria that break down the organic waste. Sewage Treatment Reduces Water Pollution

41.  Septic tanks and various levels of sewage treatment can reduce point-source waste or nutrient pollution. Solutions: Septic Tank System  About 25% of homes in the U.S. are served by septic systems.

42. Sewage Treatment Reduces Water Pollution  Raw sewage reaching a municipal wastewater or sewage treatment plant typically undergoes: Primary sewage treatment Secondary sewage treatment Tertiary or advance sewage treatment

43. Primary sewage treatment Physical process Screens and a grit tank are used to remove large objects As water sits in settling tanks, smaller suspended solids fall out of the water Sludge is the solid material removed during this process Solutions: Primary and Secondary Sewage Treatment

44. Secondary sewage treatment Biological process Aerobic bacteria removes as much as 90% of the organic wastes Oxygen is added to help with the bacterial decomposition Solutions: Primary and Secondary Sewage Treatment

46.  Advanced or tertiary sewage treatment Uses series of chemical and physical processes to remove specific pollutants that still remain. Nitrates or phosphates  Before discharge, water is bleached to remove coloration and chlorinated (disinfected) to and to kill disease-carrying bacteria and some viruses  The final effluent can be discharged into a stream, river, bay, lagoon or wetland, or it can be used for the irrigation of a golf course, or park. Sewage Treatment Reduces Water Pollution

47.  Lagoons or wetlands are used to allow for natural filtration and purification processes. Sewage Treatment Reduces Water Pollution

48.  Wetland-based sewage treatment systems Natural and artificial wetlands and other ecological systems can be used to treat sewage. California created a 65 hectare wetland near Humboldt Bay that acts as a natural wastewater treatment plant for the town of 16,000 people. The project cost less than half of the estimated price of a conventional treatment plant. We Can Improve Conventional Sewage Treatment

49. Solutions: Water Pollution, Methods for Preventing and Reducing Water Pollution