Earth Day!

3. relating to or determined by the sun.
5. a place to dispose of refuse and other waste material by burying it and covering it over with soil,
7. able to be maintained at a certain rate or level.
9. the envelope of gases surrounding the earth or another planet.
10. (of a species, family, or other group of animals or plants) having no living members; no longer in existence.
13. convert (waste) into reusable material.
16. the surroundings or conditions in which a person, animal, or plant lives or operates.
17. the branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
19. reuse (discarded objects or material) in such a way as to create a product of higher quality or value than the original.

1. the natural home or environment of an animal, plant, or other organism.
2. contaminate (water, air, or a place) with harmful or poisonous substances.
4. (of a natural resource or source of energy) not depleted when used.
6. protect (something, especially an environmentally or culturally important place or thing) from harm or destruction.
8. the production and discharge of something, especially gas or radiation.
11. a colorless unstable toxic gas with a pungent odor and powerful oxidizing properties, formed from oxygen by electrical discharges or ultraviolet light. It differs from normal oxygen (O2) in having three atoms in its molecule (O3).
12. a biological community of interacting organisms and their physical environment.
14. trash, such as paper, cans, and bottles, that is left lying in an open or public place.
15. decayed organic material used as a plant fertilizer.
18. relating to or derived from living matter.