Nutrient Cycles

3. This step in the water cycle is when water gets into the atmosphere.
4. When you burn this it releases CO2 into the atmosphere.
8. This is the main regulator of CO2 in the atmosphere.
10. This is a natural source for CO2.
11. Higher organisms use nitrogen to make this.
14. This is a problem in the water cycle when chemicals get into the rain.
16. These nitrogen rich products are created by animal waste decaying by the action of bacteria.
18. When this is in the soil it can break down the ammonia into the gaseous form of nitrogen.

1. This is the process when plants use CO2 to make sugar.
2. In nature phosphorous is not found in a free state but is contained mostly in these.
5. Some of the phosphorous in soils can be washed into this.
6. If too much CO2 gets into the atmosphere it is responsible for this effect.
7. This is a man-made source of phosphorous in the water.
9. When there is too much phosphorous in the water it leads to this problem in plants.
12. This is when water falls to the ground during the water cycle.
13. Phosphorous makes up this essential chemical for life.
15. Animals use oxygen in this process to make more CO2.
17. This product helps return sulphur from animals for the next generation of phosphorous.
19. This is when phosphorous-rich fertilizers get into the water.
20. This is made up of 78% nitrogen gas.