Across
- 6. contaminate (water, air, or a place) with harmful or poisonous substances
- 7. no longer in existence
- 8. convert (waste) into reusable material
- 12. relating to or derived from living matter
- 13. the production and discharge of something, especially gas or radiation
- 14. something related to the sun
- 15. protect something from harm or danger
- 17. able to be maintained at a certain rate or level
- 19. 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
- 20. able to be renewed
Down
- 1. the branch of biology that deals with the relations of organisms to one another and to their physical surroundings
- 2. maintain something in its original or existing state
- 3. reuse
- 4. trash thrown into a public or open space
- 5. the natural home or environment of an animal, plant, or other organism
- 9. decayed organic material used as plant fertilizer
- 10. a biological community of interacting organisms
- 11. the conditions in which a human, plant, or animal lives/operates
- 16. envelope of gases that surrounds the earth
- 18. a place to dispose of refuse and other waste material by burying it and covering it over with soil, especially as a method of filling in or extending usable land