Chapter 9 Aquatic Resources, Uses, and Management

1. Chapter 9 Aquatic Resources, Uses, and Management

2. The Importance of Water • All living things need water • You are about 60% water by weight • What do we use water for?

3. Water on Earth • About 97% Earth’s water is salty • Fresh water is distributed unevenly • 2025: 1/3 human population will live in areas lacking fresh water • What can be done about this? • Water is continuously cycling through the environment

4. Ocean Atmosphere Land Ocean Hydrologic Cycle

5. Surface Water • Streams, rivers, lakes, ponds, reservoirs, wetlands • Runoff replenishes surface water • Watershed • Area of land drained by a single river • Drainage basin

6. Groundwater • Supply of fresh water found under Earth’s surface • Stored in underground aquifers • Discharged into rivers, springs, etc… • Usually considered nonrenewable Canada’s Watersheds

7. Properties of Water • Molecules of water • 2 Hydrogens, 1 Oxygen • H2O • Polar • One end slightly positive • One end slightly negative • Appears “bent”

8. Properties of Water • Hydrogen bonds • Result of water’s polarity • Basis for many of water’s properties • High heat capacity • Moderates climate • Universal solvent

9. Water Resource Problems • Too much water • Too little water • Poor-quality water

10. Flooding • River’s discharge can’t be contained • Floods more disastrous today: why? • What can be done?

11. Too Little Water • Arid & semiarid lands • Irrigation • Needed to produce food • Greatest use of water (71%)

12. Aquifer Depletion • Removing groundwater faster than it is replenished • Lowers water table • Land subsidence • Saltwater intrusion • Salt water seeps into fresh water • Coastal areas

13. Overdrawing Surface Waters • Damaging to ecosystems • Wetlands dry up • Estuaries become too salty • Why are we removing so much water? • Availability of surface waters may be a serious regional problem

14. The Fraser River • Profound changes in hydrology • Average resident in Kamloops consumes 800 liters of water/day • Impacts of climate change • Less snow • River peaking earlier • Water quantity reduced

15. Salinization • Salt accumulates in soil • Result of irrigation: why? • Can hurt productivity • May render soils unfit for production • How can problem be solved/helped?

16. Water Pollution • Physical or chemical change in water that adversely affects the health of humans or other organisms • Global problem • Eight different categories

17. Types of Water Pollution • Sediment pollution • Sewage and waste water • Fecal coliform and other disease-causing agents • Eutrophication • Organic compounds • Inorganic chemicals • Radioactive substances • Thermal pollution

18. Sediment Pollution • Water and wind cause erosion • Slit, clay and sand are transported into waterways • Changes physical features, water flow, and water depth • Alters concentrations of dissolved substances in water • Increases turbidity, less sunlight penetrates

19. Sediment Pollution

20. Sewage • Wastewater from drains & sewers • Wastes, soaps, detergents, etc… • May cause disease • Biochemical oxygen demand (BOD) • Oxygen needed for microorganisms to decompose waste • Lots of sewage = high BOD = less oxygen available

21. Eutrophication • Enrichment of a body of water • Eutrophic lake • Increase of nutrients • Cloudy water • Oligotrophic lake • Fewer nutrients • Clear water • Artificial eutrophication: causes?

22. Eutrophic & Oligotrophic Lakes

23. Experimental Lakes Eutrophication Experiment • Research conducted in northwest Ontario • Two basins separated by curtain • One side control, other side is exposed to nutrient loads • Natural lake experiment • Exposes the dynamics of eutrophication • Winter fish kill, why?

24. Sources of Water Pollution • Natural sources • Human-generated • Point source: specific source • Nonpoint source • Polluted runoff • Enters over a large area

25. Nonpoint Source Pollution • Agriculture • 72% of water pollution • Fertilizers, pesticides, manure • Soil erosion • Urban runoff • Variety of contaminants

26. Upland and Riparian Buffer Zones • Buffer zones supply natural “filters” • Slow water runoff • Water pollutants inflitrate into the ground • Pollutants are taken up by plants or decomposed by soil • Controls erosion • Removes excess nutrients • Protects fish and spawning habitat

27. Groundwater Pollution • Even confined aquifers can become contaminated • Most North American groundwater is safe • Sources of pollution? • Cleanup is costly!

28. Global Water Issues • Problems becoming more serious • By 2030, UN warns almost ½ of the world’s population will have water scarcity issues • Many people lack safe drinking water and sewage systems • Mexico City facing serious shortages • Less water will be available in the future: why?

29. Sharing Water Resources • 1950s: Soviet Union diverts water for irrigation • Aral Sea shrinks • 1991: Soviet Union breaks up • 5 countries working to help Aral Sea

30. Water Management • Goal: sustainable supply of high quality water • How do we supply water? • Building dams • Diversion • Desalination • Conservation

31. Columbia River • Fourth largest in N. America • More than 100 dams • Water used for • Electrical generation • Irrigation • Industry & households

32. Columbia River Dams • Benefits • Generate electricity • Flood control • Provide water • Problem • Bad for salmon • What should be done?

33. Water Conservation: Agriculture • Canada and US are top two users of water worldwide • Canadians use close to 200 liters water/day • Three common rules: • Reduce • Retrofit • Repair • What is a water footprint?

34. Global Water Footprint

35. Water Conservation: Agriculture • Much lost to evaporation or seepage • Solution: microirrigation • Perforated pipes distribute water • Goes straight to plants • Reduces water use 40-60% • Problem?

36. Water Conservation: Industry • In US, five industries consume 90% industrial water • Strict pollution control laws have helped • Many industries capture, purify and reuse water • U. S. Steel recycles ~ 2/3 of its water

37. Water Conservation: Municipal • Use gray water • Education • Water-saving fixtures • Repair leaks • Other ideas?

38. Toilet to Tap • California effort to reduce surface water • Waste water is treated: • Microfiltration • Reverse osmosis • Ultraviolet light • Hydrogen peroxide disinfection • Converts sewage water into drinking water

39. Improving Water Quality • Contaminants are removed • Drinking water purification • Treat with chemical coagulant • Suspended particles settle out • Filter water through sand • Disinfect

40. Improving Water Quality • Municipal sewage treatment • Primary treatment: remove suspended & floating particles • Secondary treatment: decompose suspended organics • Tertiary treatment: dissolved substances • Sludge must be managed

41. Municipal Sewage Treatment

42. Municipal Sewage Treatment • Winnipeg, Manitoba • Separate sewers in newer suburbs • Sanitary sewage goes to sewage treatment plant while stormwater is collected in stormwater retention ponds • Benefits? Disadvantages?

43. Native Plant Solutions • Engineered wetlands • What are the benefits?

44. Municipal Sewage Treatment • Arcata, California • Constructed wetlands that aid in treatment • Marshes absorb contaminants • Provides wildlife habitat

45. Controlling Water Pollution • Constitution Act, 1867 • CCME develops guidelines • New guidelines for Canadian Drinking Water Quality • Canada Water Act, 1970 • The Fisheries Act, 1868 • DFO, aimed at protecting fish and fish habitat

46. Preventing Water Pollution At Home

47. The Global Ocean • Covers 3/4 of Earth’s surface • Four sections: what are they? • Vast wilderness • Essential to hydrologic cycle; why?

48. Patterns of Circulation • Mass movements of surface water • Currents: prevailing winds blowing over the ocean • Gyres: large, circular currents • Coriolis effect influences • Clockwise in N. Hemisphere • Counterclockwise in S. Hemisphere

49. Surface Ocean Currents

50. Ocean-Atmosphere Interaction • Strongly linked to each other • El Niño-Southern Oscillation (ENSO) • Affects climate • Warm water expansion • Lasts 1-2 years