Across
- 1. a scale used to specify the acidity or basicity of an aqueous solution
- 3. pollution pollution that comes from many places,
- 6. the amount of cloudiness in the water.
- 7. compounds that involve nitrogen and oxygen molecules
- 9. the amount of oxygen that is present in water.
Down
- 1. safe drinking water
- 2. an organism whose status in an ecosystem is analyzed as an indication of the ecosystem's heath
- 4. that improves the quality of water
- 5. richness of nutrients in a lake or other body of water
- 8. aking care of something