Across
- 2. water under ground
- 4. environmental protection agency
- 5. things draining into water, polluting it
- 7. smoke and fog
- 9. number of billions of people in the world
- 10. a greenhouse gas that is recognisable by smell
- 11. compound of oxygen with another element
- 13. able to be maintained at a certain level
- 15. the number of people plants or animals that can be sustained
- 18. man made substance that causes some plants to spot
- 19. natural fuel such as coal
Down
- 1. the total mass of organisms in a given area or volume
- 2. gas that contributes radiation
- 3. limit of population growth due to resources
- 6. farming ground must be this
- 8. percent of pollution caused by transportation
- 12. pollutant in the air that joins with smog and reduces visibility
- 14. farming
- 16. the state of being able to see or be seen
- 17. volatile organic compounds