1. Water, Air, and Land Resources 4.3

2. Point Source Pollution Water pollution that comes from a known and specific location.

3. Nonpoint Source Pollution Water pollution that does not have a specific point of origin.

4. Runoff Water that flows over the land surface rather than seeping into the ground.

5. Global Warming The increase in average temperature of Earth and the atmosphere due in part to increased carbon dioxide levels.

6. Key Concept Why is fresh water a vital resource? People use fresh water for drinking, cooking, bathing, and growing food.

7. Key Concept Why is the chemical composition of the atmosphere important? The chemical composition of the atmosphere helps maintain life on Earth.

8. Key Concept What are Earth’s important land resources? Earth’s land provides soil and forests, as well as mineral and energy resources.