Environment

4. a substance that pollutes
7. the process by which land changes into desert, for example because there has been too much farming activity on it or because a lot of trees have been cut down
8. (of food or flowers) in a natural condition rather than artificially preserved by a process such as freezing
9. a poisonous form of oxygen/air that is clean and pleasant to breathe, especially near the sea
10. a plant such as a grain, fruit, or vegetable grown in large amounts
14. in danger of being harmed, lost, unsuccessful, etc.
15. poisonous or not pure
17. the general weather conditions usually found in a particular place
18. the fact of soil, stone, etc. being gradually damaged and removed by the waves, rain, or wind
19. a large amount of water covering an area that is usually dry

1. a long period when there is little or no rain
2. a natural or chemical substance that is spread on the land or given to plants, to make plants grow well
3. the waste gas from an engine, especially a car's, or the pipe the gas flows through
5. able to decay naturally and in a way that is not harmful
6. a situation in which something no longer exists
7. the cutting down of trees in a large area, or the destruction of forests by people
11. harmful or strong-smelling gases or smoke
12. to rub or be rubbed away gradually
13. the act of sending out gas, heat, light, etc.
16. the relationships between the air, land, water, animals, plants, etc., usually of a particular area, or the scientific study of this