Environment

4. the process by which land changes into desert
6. a large amount of water covering an area that is usually dry
8. strong, unpleasant and dangerous gas or smoke
9. a layer of pil that is floating over a large area of the surface of the sea, usually because an accident has caused it to scape from a ship or container
10. the cutting down of trees in a large area, the destruction of forests by people

1. rain which contains large amount of harmful chemicals
2. the number and variety of plant and animal species that exist in a particular environmental area
3. items intended to be thrown away after use
5. a sudden violent movement of the Earth's surface, sometimes causing great damage
7. a long period when there is little or no rain