Transcript Unit 4 Lesson 1 and 2 teacher notesx

Unit 4
Lesson 1: Human Impact on Water
Lesson 2: Human Impact on Land
1
Water, Water Everywhere….
Why is water important?
• Water shapes Earth’s surface and
affects Earth’s weather and climates.
• Water needed for life.
• Living things are made up of water
• Water is a natural resource
2
Water, Water Everywhere….
There is lots of water, so what’s the problem?
• 97% of water on Earth is salty.
• 3% is freshwater.
• 2/3 of that freshwater is frozen as ice and snow.
• Humans need fresh, clean water to survive.
• Freshwater is becoming a natural resource that cannot be
replaced at the same rate at which it is used.
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Where do we get water?
• Fall as precipitation or may melt from ice and snow.
• Freshwater is found as either surface water or ground
water.
• Surface water – fresh and salt water above the ground.
• Ground water – found under the earth’s surface.
• Aquifer – a body of rock underground that can store a lot
of water and allows water to flow through it easily.
• Permafrost – a frozen layer of soil.
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Under Threat….
• Water pollution – when waste or other material is added
to water so that it is harmful to organisms that use it or live
in it.
• 2 Types
– 1. Point-source pollution – waste from one specific site.
• A major chemical spill or oil spill. A manufacturing plant.
• Can be controlled once the source is found.
– 2. Nonpoint-source pollution – comes from many small sources
and is more difficult to control.
• Sources include runoff from city streets, roads and drains, farms and mines.
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Under Threat….
• Thermal Pollution – any heating of natural water that
results from human activity.
– Water that is used for cooling power plants gets warmed up.
– Warm water has less oxygen available for organisms that live in
the water.
• Chemical pollution – occurs when harmful chemicals are
added to water supplies.
– Chemicals used in agriculture; such as pesticides, herbicides and
fertilizers (dissolved nutrients).
– Industry such as factories produce toxic wastes.
– Acid rain – forms when gases formed by burning fossil fuels mix
with water in the air.
• Makes both water and soil more acidic
• Can harm both plants and animals
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Under Threat….
• Biological Pollution – microbes (small organisms) in the
water that can cause diseases such as dysentery
(diarrhea), typhoid fever (bacteria in food) and cholera
(intestinal disease).
• Eutrophication – An increase in the amount of nutrients in
water from decomposing organisms.
– Occurs naturally in water.
– Human activity increases nutrients
in the water from fertilizer runoff.
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How is water quality measured?
• Measurements of water quality include testing the levels
of:
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–
–
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–
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dissolved oxygen (oxygen gas in water)
pH (how acidic or basic)
temperature (how hot or cold)
dissolved solids (harmful chemicals or calcium build-up)
the number and type of microbes (small organisms) in the water.
turbidity (cloudiness or clarity of water)
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How is water treated for human use?
• Water enters sewage systems where pipes carry it to
wastewater treatment plants.
• Screens are used to remove large debris.
• Chemicals are added to remove harmful bacteria and
other microbes.
– Chlorine kills bacteria
– Fluoride is added to help prevent tooth decay.
• Air is bubbled through the water to increase oxygen and
cleanliness.
• Potable – water that is suitable to drink.
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Water Treatment Plants
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How does water get to the faucet?
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Lesson 2: Human Impact on Land
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Land of Plenty
Why is land important?
• Land supplies a solid surface for buildings and roads.
• The soil provides nutrients for plants and hiding places for
animals.
• Minerals below the surface can be used for construction
materials.
• Fossil fuels found underground; burned for energy.
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Different Types of Land Use
1. Recreational – we use natural areas/wild places
- Include forests, grasslands, and dessert areas.
- Used for hiking, bird-watching, biking, hunting, other fun
activities.
2. Transportation – consists of roads and train tracks.
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Roads in the U.S. highway system cover 4 million miles of land.
Trucks transport goods.
Smaller vehicles carry passengers.
Railroads carry freight and passengers.
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Different Types of Land Use
3. Agricultural – used to grow crops and raise livestock.
4. Residential – where we live.
- Urban = cities and towns
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Have large numbers of people and small areas of open land.
- Rural = open land
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Have low numbers of people and large areas of open land.
- Urbanization – the growth of urban areas caused by people
moving into cities.
5. Commercial and Industrial – small and large businesses
take over by replacing rural areas.
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Why is Soil so Important?
• Soil is a mixture of minerals, organic material, water and
air.
• Soil forms when rocks break down and dead organisms
decay.
1. It provides a habitat for organisms to live like insects and
worms.
- Decomposers (fungi and bacteria) break down dead organisms
releasing nutrients back into the soil
2. It stores water and nutrients for Plants.
- Plants are the base of a food chain which is important for the chain
to continue.
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How can human activities affect land
and soil?
• Human activities can have negative effects on land and soil.
• Land degradation – the process by which human activity
and natural processes damage land to the point that it can
longer support the local ecosystem.
1. Urban Sprawl – urbanization; cities
taking over rural areas.
2. Erosion – the process by which wind,
water, or gravity transports soil and
sediment from one place to another.
- clearing land for farming.
- deforestation
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How can human activities affect land
and soil?
3. Nutrient Depletion and Land Pollution –
Plants need the right balance of
nutrients to grow.
4. Desertification – the process in which land
becomes more desert like and unable
to support life.
- overgrazing from animals.
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How can human activities affect land
and soil?
5. Deforestation – the removal of trees and other
vegetation from an area.
- Logging for wood
- Removing vegetation
- Urbanization
- Can lead to increased soil erosion
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