Chapter 3 Freshwater Resources

1. Chapter 3 Freshwater Resources Water to Drink Balancing Water Needs Freshwater Pollution Water as an Energy Resource

2. Section 1: Water to Drink • IDENTIFY SOURCE OF WATER . . . • Sources of Drinking Water • Surface in rivers, lakes, reservoirs • Aquifers • Drinking Water comes from Public or Private Water Supply • Communities provide public water – collect, treat & distribute water • Rural Areas/smaller communities – private wells supply water

3. Section 1: Water to Drink • TREAT WATER: Simple filter . . . to well . . . to public treatment plant • Drinking Water Qualities • Water Quality – measure of substances in water besides water Cloudiness, odor and color impact water quality • Iron – effects taste/color – harmless unless large amount. • Acidity – measure of how acidic or basic; pH of water

4. Section 1: Water to Drink • Pure water is neutral, pH 7 • Lower pH = more acidic • Higher pH = more basic  • Hardness – level of calcium and magnesium in water • comes from types of rocks • hard water = leaves deposits • soft water= fewer deposits, more suds

5. Section 1: Water to Drink • Disease-Causing Organisms • coliform count (measures the # if e.colibacteria) • High count=too much bacteria in the Water • Environmental Protection Agency • Responsible for protecting quality of water & natural resources in U.S. • Oversee concentration (amount of one substance in a certain volume of another substance) limits for certain chemical, minerals & bacteria in drinking water

6. Section 1: Water to Drink • Steps in a Drinking Water Treatment Plant • Filtration – process passing water through series of screens not larger than particles • Trash, leaves, branches & large objects removed • Coagulation – chemical alum added to create flocs (sticky globs) to form – other particles in water stick to flocs • Heavy clumps sink to bottom of settling basins • Water then filtered again

7. Section 1: Water to Drink • Second Filtration – water trickles down through sand or gravel, filtering out algae, bacteria & some chemicals. • Chlorinate – chlorine added to water to kill microorganisms; some other chemicals also added at this point • Aeration – forcing air through water to releases gases – reduces unpleasant odors or taste • Additional Treatment – sodium or lime sometimes added to soften water; some communities add fluoride • Water from an aquifer may require less treatment than from river/lake

8. Section 1: Water to Drink • Water Distribution • From treatment plant, goes to central pumping station • Water pumped into underground network steel/concrete pipes == called water mains • Water mains branch off into smaller pipes • Feed into smaller copper/plastic pipes into homes • Water pressure causes water to move through system of pipes • Pumping stations keep water pressure steady throughout system • Typical distribution system can push water up against the downward force of gravity about 5 or 6 stories • Rather than central pumping station, some communities store water in the air – water tower or tank

9. Section 1: Water to Drink • Treating Wastewater • Sewage = wastewater and different kinds of waste in it • Networks of pipes = sanitary sewers = carry sewage away from homes = separated from storm sewers ( which drain rainwater & runoff from sidewalks, lawns, parking lots) • Most towns, sanitary sewer systems last only 200 years • * Most communities treat wastewater, making safe for environment *

10. Section 1: Water to Drink • Wastewater Treatment • Primary Treatment – deposits of fine solids (sludge) settle out from wastewater • Sludge useful when treated = fertilizer • Secondary Treatment – wastewater filtered through bed of gravel covered with colonies of bacteria, breaking down wastes left in sewage

11. Section 1: Water to Drink • Additional Treatment – water may be pumped into pools where air and sunlight purify water naturally. • Water evaporates into air as pure water vapor • Chlorine may be added before releasing treated water • Once through effective treatment process,returns to lakes, rivers, oceans or ground = rejoins water cycle • Treated wastewater not clean enough for drinking = “gray water” • Water golf courses, parks, irrigation, cooling factories

12. Section 1: Water to Drink • Septic Systems • Not all people are connected to public sanitary sewer systems • Includes a septic tank = underground tank with bacteria for treating wastewater as it passes through • Sludge settling at bottom of tank must be cleaned regularly – remaining water filters out through holes • Leach field = area around septic tank where remaining wastes naturally break down

13. Section 2: Balancing Water Needs • Give an example of what it means to have a limited resource Water Supply and Demand • Colorado River • A water shortage occurs when there is too little water or too great a demand in an area—or both.

14. Section 2: Balancing Water Needs • Drought: a water shortage due to the lack of rainfall in an area. • Aquifer Overuse • Too much is pumped out faster than it can recharge naturally • What can happen: • Land can sink (ex. Mexico City) • What can be done? • Artificial recharge (pump water back in) • Wastewater • Industrial water

15. Section 2: Balancing Water Needs Conserving Water • At home: what can you do? • Agriculture: • Drip irrigation • Plant crops that require less water • Industry • Reduce amount of water use • Recycle water they do use (clean) • Reuse the water

16. Section 2: Balancing Water Needs Fresh Water for the Future • Desalination: boiling water to evaporate and leave salt behind, condense/collect for usable water. • Expensive • Requires a large amount of energy • Icebergs • Changes in local weather • Energy to get it there

17. Section 3: Freshwater Pollution What is Pollution? • Water pollution: any substance that has a negative effect on water or living things that depend n the water.

18. Section 3: Freshwater Pollution Point and Nonpoint Sources • The major sources of water pollution are human wastes, industrial wastes, agricultural chemicals and runoff from roads Prentice Hall Science Explorer Earth’s Water

19. Section 3: Freshwater Pollution • As you go up the chain the DDT concentration increases. Why? Prentice Hall Science Explorer Earth’s Water

20. Section 3: Freshwater Pollution • Point Source: a specific place that can be identified as a source of pollution. • ex. A gushing sewer pipe • Nonpoint Source: pollution that cannot be tied to one specific source. • Ex. Run off

21. Section 3: Freshwater Pollution Human Wastes • Dr. Snow’s discovery • Connection between Cholera and human waste • Traced the pollution back to a well that people were drinking from • In cities today—still have issues with runoff when there are large storms • In rural areas—septic systems can leak into nearby water sources.

22. Section 3: Freshwater Pollution • Industry • Type of pollutants • Chemicals • Left over wastes leak out of containers or are deposited on land or directly into the water • Smoke • Burning of coal, oil • Acid Rain: precipitation that are more acidic than normal • Containing sulfuric and nitric acids • Eats away at stone, kills wildife • Heated water (thermal pollution)—too hot for life

23. Section 3: Freshwater Pollution • Agricultural Chemicals • The rich supply of nutrients from fertilizers encourages the growth of plants and algae in and around nearby bodies of water. • Pesticides: chemicals that are used to kill organisms that damage crops • Runoff from Roads • Salt or oil Prentice Hall Science Explorer Earth’s Water

24. Section 3: Freshwater Pollution • Cleaning Up Polluted Water • Lakes, streams and wetlands naturally filter out pollutants and break down wastes. • Bacteria break down toxic chemicals into a more useable form • Water passing through sand, gravel and soil leaves pollutants behind as it flows through

25. Section 3: Freshwater Pollution • Preventing Pollution • Governments create laws to protect water against pollution • Industry and Agriculture are working on recycling to help conserve • Cleaning water before returning it to the water supply • Filtering solutions around farms to keep wastes out of water supply

26. Section 3: Freshwater Pollution • What can you do? • Dispose of toxic chemicals appropriately • Avoid over fertilizing gardens or yard • Educate others

27. Section 4: Water as an Energy Resource • Remember back to physics!!!!!!! • Kinetic Energy: moving particles • Potential Energy: stored energy • Hydroelectric Power: the kinetic energy of water moving through a dam or over a waterfall that is collected and converted to electrical energy.

28. Section 4: Water as an Energy Resource • The Impact of Dams • Pros • Clean, safe, efficient • Water is free and generally renewable • No air pollution • Help to supply water for irrigation

29. Section 4: Water as an Energy Resource • Cons • Building is expensive $$$$$$$ • Only certain locations are suitable • Flood land behind • Separate ecosystems • Changes the flow of the river and amount of water available downstream