Across
- 3. Insoluble solid formed when soap is used in hard water
- 7. Solution that turns milky with carbon dioxide
- 9. Final stage of water treatment that kills bacteria
- 12. Long-term changes in weather patterns such as temperature and rainfall
- 15. Property of water that stops soap forming a lather
- 17. Increase in Earth’s average temperature due to greenhouse gases
- 18. Most abundant gas in air at 78 percent
- 19. Plant nutrients required in small amounts
- 21. Loss of colour in corals when they expel zooxanthellae
- 23. Plant nutrients required in large amounts
- 24. Harmful substance released into air or water
- 25. Gas manufactured by the Haber process
- 26. Natural effect that traps heat in the atmosphere
- 27. Protective layer in the stratosphere that absorbs ultraviolet light
Down
- 1. Substance added to drinking water to reduce tooth decay
- 2. Solid material that settles during sewage treatment
- 4. Nitrogen fertiliser containing forty-seven percent nitrogen
- 5. First stage of drinking-water treatment that clumps dirt
- 6. Process where iron combines with oxygen and water
- 8. Stage of water treatment that uses layers of sand and gravel
- 10. Lowering of ocean pH caused by dissolved carbon dioxide
- 11. Gas that re-ignites a glowing wooden splint
- 13. Process of turning air into a liquid by cooling and compressing
- 14. Name of the industrial process that produces ammonia
- 16. Liquid released from a sewage treatment plant
- 20. Type of factor that slows plant growth when in short supply
- 22. Fractional method used to separate liquefied air
- 25. Noble gas making up about one percent of air