Across
- 1. protect (something, especially an environmentally or culturally important place or thing) from harm or destruction.
- 4. able to be maintained at a certain rate or level.
- 5. contaminate (water, air, or a place) with harmful or poisonous substances.
- 7. a biological community of interacting organisms and their physical environment.
- 9. trash, such as paper, cans, and bottles, that is left lying in an open or public place
- 10. the branch of biology that deals with the relations of organisms to one another and to their physical surroundings.
- 11. 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.
- 12. decayed organic material used as a plant fertilizer
- 16. the natural world, as a whole or in a particular geographical area, especially as affected by human activity.
- 17. maintain (something) in its original or existing state.
- 18. reuse (discarded objects or material) in such a way as to create a product of higher quality or value than the original.
- 19. the envelope of gases surrounding the earth or another planet.
Down
- 2. relating to or derived from living matter.
- 3. the natural home or environment of an animal, plant, or other organism.
- 6. (of a species, family, or other group of animals or plants) having no living members; no longer in existence.
- 7. the production and discharge of something, especially gas or radiation.
- 8. relating to or determined by the sun.
- 13. 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).
- 14. (of a natural resource or source of energy) not depleted when used.
- 15. convert (waste) into reusable material.