Earth Day Project

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