Across
- 5. an ecosystem that includes marshes, swamps, and bogs
- 7. an educated guess
- 8. pollution that washes into rivers from roads, farms, and houses
- 9. the low area next to a river which is often flooded
- 10. the variable that the scientist changes in an experiment
- 12. small streams or rivers that flow into a major river or body of water
- 13. the type of pollution that cannot be traced to a single source
Down
- 1. an area where freshwater and saltwater meet
- 2. the group that does not receive treatment in an experiment
- 3. the outcome of an experiment
- 4. the variable that is being measured in an experiment
- 5. an area of land that drains into a body of water
- 6. the nonliving factors in an ecosystem
- 7. the source of a river
- 11. the cloudiness or clarity of water