Natural world

2. a substance that pollutes water, air, etc.
3. relating to chemistry
9. relating to trade, industry, and money
10. not using a lot of money, fuel
11. to increase, or move to cover a larger area or affect a larger number of people
12. a small river
14. a long, natural area of water that flows across the land and into a sea, lake, or another river
16. a stream of water that flows from a high place, often to a pool below
19. not wanted

1. a fuel such as coal or oil that is obtained from under the ground (2 words)
4. an artificial river built for boats to travel along or to take water where it is needed
5. containing poison
6. strong, unpleasant, and often dangerous gas or smoke
7. an artificial lake where water is stored before it goes to people's houses
8. a body of water usually smaller than a lake
13. a part of a river where the current is fast and the surface is usually broken by obstructions (usually used in plural but singular or plural in construction)
15. a strong wall built across a river to stop the water and make a lake
17. a rising and overflowing of a body of water especially onto normally dry land
18. a large area of water that has land all around it