Chapter 10 Freshwater Resources and Water Pollution

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Chapter 10 Freshwater Resources and Water
Pollution
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The Importance of Water

• All living things need water
• You are about 70 water by weight
• What do we use water for?

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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

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Hydrologic Cycle

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Hydrologic Cycle

• Precipitation
• Evaporation

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Surface Water

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

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Groundwater

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

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Properties of Water

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

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Properties of Water

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

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Water Resource Problems

• Too much water
• Too little water
• Poor-quality water

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Flooding

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

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Too Little Water

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

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Aquifer Depletion

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

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Ogallala Aquifer

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

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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

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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

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Salinization

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

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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?

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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

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Sharing Water Resources

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

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Water Management

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

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Columbia River

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

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Columbia River Dams

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

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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?

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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

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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?

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Water Conservation Municipal
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Water Pollution

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

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Types of Water Pollution
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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

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Effect of Sewage on BOD
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Eutrophication

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

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Eutrophic Oligotrophic Lakes
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Sources of Water Pollution

• Natural sources
• Human-generated
• Point source specific source
• Nonpoint source
• Polluted runoff
• Enters over a
• large area

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Nonpoint Source Pollution

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

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Groundwater Pollution

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

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Groundwater Pollution Sources
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Improving Water Quality

• Contaminants are removed
• Drinking water purification
• Treat with chemical coagulant
• Suspended particles settle out
• Filter water through sand
• Disinfect

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Purifying Drinking Water
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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

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Municipal Sewage Treatment
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Municipal Sewage Treatment

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

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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

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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?

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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

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Preventing Water Pollution At Home
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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

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Case Study The Great Lakes

• Provide drinking water for 38 million people
• Were highly polluted
• Toxic chemicals
• Eutrophication
• Fish kills common

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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

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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
• bioacumulation