Unit 8 Crossword

2. any other type of land use or land cover, commonly referred to as "the country".
4. concentrations of toxic substances that can be greatly magnified.
6. chemicals that cause cancer.
9. human activities that occur on land and are directly related to the land.
11. minimizes erosion on steep hillsides.
12. the matter or energy that is released into the environment, causing negative effects.
19. chemicals that affect the nervous system.
21. the deterioration of the soil characteristics needed for plant growth or other ecosystem services.
22. the shift of population from the countryside to urban areas.
24. a disease that has appeared in the human population for the first time, or that has existed for a while but is increasing rapidly or spreading around the world.
25. the vegetation and manufactured structures that cover land.

1. diseases caused by a pathogen, such as a virus or bacterium.
3. made up of the facilities, services, and installations needed for the functioning of a community.
5. help prevent erosion and often limit nitrogen loss, because they are often nitrogen-fixing crops.
7. the planting of different crops in mixed arrangements.
8. a mineral that forms long, thin microscopic fibers.
10. a widespread technique for reducing wind erosion.
13. farmers alternate crops grown in field.
14. build up large concentrations of toxic substances in their bodies.
15. the turning-over of soil before planting.
16. an area in which the temperature is several degrees higher than that of surrounding area.
17. a colorless, odorless, highly toxic radioactive gas.
18. the spread of low-density urban or suburban development outward from an urban center.
20. mostly developed land covered mainly with buildings and roads that has a human population of 2500 or more,
23. chemicals that harm embryos and fetuses.