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Chapter 10 Freshwater Resources and Water Pollution

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Title: Chapter 10 Freshwater Resources and Water Pollution


1
Chapter 10 Freshwater Resources and Water
Pollution
2
The Importance of Water
  • All living things need water
  • You are about 70 water by weight
  • What do we use water for?

3
Water on Earth
  • About 97 Earths 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
Hydrologic Cycle

5
Hydrologic Cycle
  • Precipitation
  • Evaporation

6
Surface Water
  • Streams, rivers, lakes, ponds, reservoirs,
    wetlands
  • Runoff replenishes surface water
  • Watershed
  • Area of land drained by a single river
  • Drainage basin

7
Groundwater
  • Supply of fresh water found under Earths surface
  • Stored in underground aquifers
  • Discharged into rivers, springs, etc
  • Usually considered nonrenewable

8
Properties of Water
  • Molecules of water
  • 2 Hydrogens, 1 Oxygen
  • H2O
  • Polar
  • One end slightly positive
  • One end slightly negative
  • Appears bent

9
Properties of Water
  • Hydrogen bonds
  • Result of waters polarity
  • Basis for many of waters properties
  • High heat capacity
  • Moderates climate
  • Universal solvent

10
Water Resource Problems
  • Too much water
  • Too little water
  • Poor-quality water

11
Flooding
  • Rivers discharge cant be contained
  • Floods more disastrous today why?
  • What can be done?

12
Too Little Water
  • Arid semiarid lands
  • Irrigation
  • Needed to produce food
  • Greatest use of water (71)

13
Aquifer Depletion
  • Removing groundwater faster than it is
    replenished
  • Lowers water table
  • Land subsidence
  • Saltwater intrusion
  • Salt water seeps into fresh water
  • Coastal areas

14
Ogallala Aquifer
  • Worlds largest groundwater deposit
  • Used for irrigation
  • Being depleted 40 times faster than replacement
  • Will become unusable why?

15
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

16
The Colorado River
  • Provides water to 25 million people
  • Used for irrigation
  • 49 dams
  • Mexico has rights as well
  • Lower Colorado
  • becoming salty
  • Some limits in
  • effect today

17
Salinization
  • Salt accumulates in soil
  • Result of irrigation why?
  • Can hurt productivity
  • May render soils unfit for production
  • How can problem be solved/helped?

18
Global Water Issues
  • Problems becoming more serious
  • Many people lack safe drinking water and sewage
    systems
  • Mexico City facing serious shortages
  • Less water will be available in the future why?

19
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

20
Sharing Water Resources
  • Rhine River basin
  • 5 different countries
  • Was being polluted
  • Collective efforts have improved the water

21
Water Management
  • Goal sustainable supply of high quality water
  • How do we supply water?
  • Building dams
  • Diversion
  • Desalination
  • Conservation

22
Columbia River
  • Fourth largest in N. America
  • More than 100 dams
  • Water used for
  • Electrical generation
  • Irrigation
  • Industry households

23
Columbia River Dams
  • Benefits
  • Generate electricity
  • Flood control
  • Provide water
  • Problem
  • Bad for salmon
  • What should be done?

24
Water Conservation Agriculture
  • Single largest user of water worldwide
  • Much lost to evaporation or seepage
  • Solution microirrigation
  • Perforated pipes distribute water
  • Goes straight to plants
  • Reduces water use
  • 40-60
  • Problem?

25
Water Conservation Industry
  • 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

26
Water Conservation Municipal
  • Avg. person in U.S. uses how much water per day?
  • Use gray water
  • Education
  • Water-saving fixtures
  • Repair leaks
  • Other ideas?

27
Water Conservation Municipal
28
Water Pollution
  • Physical or chemical change in water that
    adversely affects the health of humans or other
    organisms
  • Global problem
  • Eight different
  • categories

29
Types of Water Pollution
30
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

31
Effect of Sewage on BOD
32
Eutrophication
  • Enrichment of a body of water
  • Eutrophic lake
  • Increase of nutrients
  • Cloudy water
  • Oligotrophic lake
  • Fewer nutrients
  • Clear water
  • Artificial eutrophication
  • causes?

33
Eutrophic Oligotrophic Lakes
34
Sources of Water Pollution
  • Natural sources
  • Human-generated
  • Point source specific source
  • Nonpoint source
  • Polluted runoff
  • Enters over a
  • large area

35
Nonpoint Source Pollution
  • Agriculture
  • 72 of water pollution
  • Fertilizers, pesticides, manure
  • Soil erosion
  • Urban runoff
  • Variety of
  • contaminants

36
Groundwater Pollution
  • Groundwater provides 1/2 of U.S. drinking water
  • Most U.S. groundwater is safe
  • Sources of pollution?
  • Cleanup is costly!

37
Groundwater Pollution Sources
38
Improving Water Quality
  • Contaminants are removed
  • Drinking water purification
  • Treat with chemical coagulant
  • Suspended particles settle out
  • Filter water through sand
  • Disinfect

39
Purifying Drinking Water
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
  • Arcata, California
  • Constructed wetlands that aid
  • in treatment
  • Marshes absorb
  • contaminants
  • Provides wildlife
  • habitat

43
Controlling Water Pollution
  • Safe Drinking Water Act
  • Passed 1974
  • Uniform standards for drinking water
  • Maximum contaminant levels
  • Suppliers must tell consumers what is in their
    water

44
Controlling Water Pollution
  • Clean Water Act
  • Affects rivers, lakes, aquifers, estuaries, and
    costal waters
  • 1972 Water Pollution Control Act
  • 1977 amended and renamed
  • Two goals
  • Eliminate discharge of pollutants
  • Safe water for humans and wildlife
  • Has it been successful?

45
U.S. Water Quality Today
  • Clean Water Act has helped point source
    pollution
  • 2002 National Water Quality Inventory
  • Some pollution has increased
  • Many places too polluted for swimming, fishing or
    drinking

46
Preventing Water Pollution At Home
47
Water Pollution In Developing Countries
  • 1.4 billion people lack safe drinking water
  • 2.9 billion people lack adequate sanitation
  • Water for drinking
  • polluted by human
  • wastes, chemicals,
  • human remains

48
Case Study The Great Lakes
  • Provide drinking water for 38 million people
  • Were highly polluted
  • Toxic chemicals
  • Eutrophication
  • Fish kills common

49
Case Study The Great Lakes
  • Canada U.S. cooperate today
  • 20 billion spent on cleanup since 1972
  • Many improvements
  • DDT in breast milk declined
  • PCBs in trout declined
  • Some animal species rebounding

50
Case Study The Great Lakes
  • Todays problems
  • Many invasive species
  • Too much shoreline development
  • Some persistent toxins remain
  • Fish may contain high levels of toxins
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