environmental systems A

4. a stubstance used for destroying insects or other organisms
7. physical substance in general, as distinct from mind and spirit
11. an area or ridge of land that separates waters flowing to different rivers, basins, or seas
12. the process of eroding or being eroded by wind, water, or other natural agents
15. mutual dependence between things.
17. the ability to be maintained at a certain rate or level
19. physical rather than biological; not derived from living organisms
21. a rule or directive made and maintained by an authority
22. rainfall made sufficiently acidic by atmospheric pollution that it causes environmental harm, typically to forests and lakes
23. waste water and excrement conveyed in sewers
24. a large naturally occurring community of flora and fauna occupying a major habita

1. is the physical material at the surface of the earth.
2. wear away or change the appearance or texture of (something) by long exposure to the air.
3. relating to or resulting from living things,
4. the action of preserving something.
5. involves the management and modification of natural environment
6. all the waters on the earth's surface, such as lakes and seas, and sometimes including water over the earth's surface, such as clouds.
8. the draining away of water
9. a rule or directive made and maintained by an authority.
10. the presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects
13. prevention of wasteful use of a resource
14. the weather conditions prevailing in an area in general or over a long period.
16. a biological community of interacting organisms and their physical environment
18. physical rather than biological; not derived from living organisms
20. a system of interlocking and interdependent food chains.