Earth Day

6. The surroundings or conditions in which a person, animal, or plant lives or operates.
7. Convert (waste) into reusable material.
9. A mixture that consists largely of decayed organic matter and is used for fertilizing and conditioning land.
10. Reuse (discarded objects or material) in such a way as to create a product of higher quality or value than the original.
12. Able to be maintained at a certain rate or level.
14. The branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
16. An odorless, colorless gas made up of three oxygen molecules (O3) and is a natural part of the environment.
17. (of a species, family, or other group of animals or plants) having no living members; no longer in existence.
18. Things that have been thrown away and that are lying on the ground in a public place.
19. (of a natural resource or source of energy) not depleted when used.

1. Relating to or derived from living matter.
2. Maintain (something) in its original or existing state.
3. The envelope of gases surrounding the earth or another planet.
4. The disposal of waste material by burying it, especially as a method of filling in and reclaiming excavated pits.
5. Contaminate (water, the air, etc.) with harmful or poisonous substances.
6. The production and discharge of something, especially gas or radiation.
8. A biological community of interacting organisms and their physical environment.
11. Protect (something, especially something of environmental or cultural importance) from harm or destruction.
13. Relating to or determined by the sun.
15. The natural home or environment of an animal, plant, or other organism.