1. Chapter 20: Our Impact on Land
Table of Contents
Chapter 20: Our Impact on Land
Section 20.2: Using Land

2. Using Land 2
Agriculture
About (1) 16 million km2 of Earth's total land surface is used as farmland.
Some farmers (2) use higher-yielding seeds and chemical fertilizers.
(3) Herbicides and pesticides also are used to reduce weeds, insects, and other pests that can damage crops.

3. Using Land 2
Agriculture
Whenever vegetation is removed from an area, such as a construction site or tilled farmland, (4) soil is exposed. Nothing prevents the soil from being carried away by running water and wind. .
In some places, it can take more than (5) 1,000 years for new topsoil to develop.

4. Using Land 2
Forest Resources
Most of this deforestation occurred in (6) tropical regions.

5. Using Land 2
Forest Resources
If many trees are cut down, (7) less water enters the atmosphere and the region receives less rainfall.

6. Using Land 2
Sanitary Landfills
(8) linings, reduce the chance that pollutants will leak into the surrounding soil and groundwater.

7. Using Land 2
Hazardous Waste
In the 1980s, many states passed environmental laws that prohibit industries from disposing of hazardous wastes in sanitary landfills. However, (9) most hazardous wastes in landfills comes from household use.

8. Household Hazardous Waste
Using Land 2
Household Hazardous Waste
You can help by disposing of hazardous , such as: (10) paint, medicine, cleaners, batteries, chemicals

9. Natural Preserves 2 (11) Protected lands are natural preserves.
Using Land 2
Natural Preserves
(11) Protected lands are natural preserves.

10. Conserving Resources 3
Reduce, Reuse, Recycle
Ways to conserve resources include (13) reducing the use of materials, and reusing and recycling materials.

11. Conserving Resources 3
Recycling Materials
(14) Paper, metal, plastic and cardboard can all be recycled.

12. Importance of Clean Water
Water Pollution 1
Importance of Clean Water

13. Water Pollution 1
Sediment
The largest source of water pollution in the Unites States is (16) sediment.

14. Water Pollution 1
Sediment
(17) Sediment makes water cloudy and blocks sunlight that underwater plants need to make food.
Sediment also covers the eggs of organisms that live in water, preventing organisms from receiving the oxygen they need to develop.

15. Water Pollution 1
Metals
Many metals such as (18) mercury, lead, nickel, and cadmium can be poisonous, even in small amounts.

16. Water Pollution 1
Oil and Gasoline
(19) Oil and gasoline run off roads and parking lots into streams and rivers when it rains.

17. Causes of Air Pollution2
Causes of Air Pollution
The (22) brown haze you sometimes see forms from the exhaust of these vehicles.
Air pollution also comes from (23) burning fuels in factories, generating electricity, and burning trash.

18. Causes of Air Pollution2
Causes of Air Pollution
Natural sources of pollution also include (24) particles and gases emitted into air from erupting volcanoes and fires.

19. Air Pollution 2
What is smog?

20. Air Pollution 2
Acid Rain
When (25) gases from coal-burning power plants and cars combine with moisture in the air, they from acids.
Acid rain can corrode structures, damage forests and harm organisms.

21. Air Pollution 2
Acid Rain

22. Air Pollution 2
CFCs
(26) Chlorofluorocarbons (CFCs) from air conditioners and refrigerators might be (27) destroying this ozone layer.
Each CFC molecule can destroy thousands of ozone molecules.

23. Air Pollution 2
Health Disorders
(28) breathing disorders, heart problems, allergies.
About 70,000 deaths each year in the United States are blamed on air pollution.

24. Air Pollution in the United States2
Air Pollution in the United States

25. What causes climatic change?
Climatic Changes 3
What causes climatic change?
Catastrophic events, including (31) meteorite collisions and large volcanic eruptions, can affect climate
Climate change can operate over (30) short periods of time or very long periods of time.

26. Atmospheric Solids and Liquids
Climatic Changes 3
Atmospheric Solids and Liquids
Solar output is the (32)amount of energy given off by the sun.
Some ways that particles enter the atmosphere naturally include (33) volcanic eruptions, soot from fires, and wind erosion of soil particles.
Humans add particles to the atmosphere through (34) automobile exhaust and smoke stack emissions.

27. Climatic Changes Today3
Climatic Changes Today

28. Climatic Changes Today3
Climatic Changes Today
Greenhouse gasses: (35)water vapor, carbon dioxide, methane

29. Climatic Changes Today3
Climatic Changes Today
(36) Without these greenhouse gases, life would not be possible on Earth. It would be too cold at night to live here.
The planet (37) Venus has a very large greenhouse effect due to the large amount of carbon dioxide in its air.

30. Climatic Changes 3
Global Warming
Researchers hypothesize that the increase in global temperatures may be related to the (38) increase in atmospheric carbon dioxide.

31. Climatic Changes 3
Global Warming
If Earth’s average temperature continues to rise, (39) many glaciers could melt.
Low-lying coastal areas could experience increased flooding.

32. Human Activities— Burning Fossil Fuels
Climatic Changes 3
Human Activities— Burning Fossil Fuels
(40) Burning fossil fuels and cutting down vegetation have increased the amount of carbon dioxide in the atmosphere.

33. Deforestation
(41) Trees are being cut for land development, mining, roads.
As trees grow they take in carbon dioxide from the atmosphere.
(42) When trees are cut down, the carbon dioxide they could have removed from the atmosphere remains in the atmosphere