1. The Carbon Cycle & The Nitrogen Cycle
Nutrient Cycles
The Carbon Cycle
&
The Nitrogen Cycle

2. Carbon Cycle: What is it?
It is the matter cycle in which carbon atoms move from inorganic form to organic form, and back again.
Inorganic form- carbon found in the air, the water or soil.
Organic form- carbon found in living things.
This is done through photosynthesis, digestion, respiration, decomposition, and combustion.

3. Organic carbon is held in reservoirs (living things) through the breathing in of carbon. Carbon is returned to the cycle through decomposition, or through respiration. This carbon that is released is taken in through the plants again.
This Carbon is unavailable to the cycle until it is released through the burning of fossil fuels (combustion) as well as weathering.
Plants create glucose through photosynthesis and the carbon in the food is made into carbon dioxide through cellular respiration
The Carbon dioxide that is released goes into the atmosphere, the water and the soil.
Carbon is also released into the soil through decaying animals. This carbon is compressed to make fossil fuels.

4. In a little more detail…
Each year about billion tonnes of carbon from inorganic carbon dioxide are recycled through photosynthesis.
6CO2 + 6H2O + light C6H O2
Glucose is further broken up into carbon dioxide and released back into the atmosphere.
We breathe in 0.03% of carbon.

5. The Human Impact
Humans have affected the carbon cycle by releasing carbon from organic reservoirs quicker than they would naturally be released, through mining, burning fossil fuels, and deforestation.

6. Deforestation

7. Mining
Burning
Fossil Fuels

8. Deforestation:
By clearing away forests and vegetation, the amount of photosynthesis in the cycle is reduced and the levels of carbon dioxide increase.
Burning Fossil Fuels:
Through the burning of fossil fuels, organic reservoirs of carbon are released before the time that they would have naturally been reintroduced to the cycle. This creates too much carbon dioxide in the atmosphere.

9. Nitrogen Cycle: What is it?
It is the movement of nitrogen atoms from inorganic form to organic form and back again.
This happens through nitrogen fixation, synthesis, decomposition, and denitrification.

10. Nitrogen Fixation: the process that converts atmospheric nitrogen into nitrates which is done by lightning or bacteria.
Lightning- the energy from lightning causes nitrogen gas to react with oxygen in the air to produce nitrates (NO3). This nitrate dissolves in rain or surface water which then enters the soil where it can enter the roots of plants.
Bacteria- some bacteria can turn N2 into ammonia or into nitrates. When the bacteria decompose, they release the nitrogen into the soil.
Plants use the nitrate to make DNA, and convert nitrates into amino acids for protein.

11. Decomposers
All organisms produce waste or die, and when they do, a series of decomposers break down the nitrogen chemicals into simpler chemicals (ammonia).
Plants thrive based on the nitrogen that is entered into the cycle. Farmers and gardeners use manures and soils that have an excess of nitrogen so the plants will grow bigger and stronger.

12. Denitrification
The process in which nitrates are converted to nitrites, and then to nitrogen gas. This is the last stage in the nitrogen cycle and ensures the balance among, soil nitrates, nitrites, and atmospheric nitrogen.
This is carried out by bacteria that do not require oxygen.
The process of denitrification speeds up when the soil has an excess of acid or when the oxygen content is very low.

13. N2 composes 79% of the earth’s atmosphere.
N2 is turned into nitrates through nitrogen fixation (lightning/bacteria).
Denitrification occurs, releasing N2 back into the atmosphere.
The nitrates enter the soil, and are absorbed by the plants, or compressed into fossil fuels.
The nitrates are turned into proteins in plants and are then eaten by animals. They go back into the soil through decomposition.

14. N2 is turned into nitrates through nitrogen fixation (lightning/bacteria).
N2 composes 79% of the earth’s atmosphere.
Denitrification occurs, releasing N2 back into the atmosphere.
The nitrates are turned into proteins in plants and are then eaten by animals. They go back into the soil through decomposition.
The nitrates enter the soil, and are absorbed by the plants, or compressed into fossil fuels.

16. Human Impact
Humans have increased the amount of nitrogen circling between the soil, water, and air.
They do this by producing and using fertilizers with nitrogen, and by burning fossil fuels that are composed of nitrogen.

17. What does this do?
When soil has more nitrogen, it loses calcium and potassium.
Through the burning of fossil fuels, large amount of nitrous oxide (N2O) enter the atmosphere. Nitrous oxide is a dangerous greenhouse gas and encourages the creation of smog.
Too much nitrogen has caused changes in the plant and animal life.

18. Nutrient Cycle Quiz
1. What is an example of an organic form in the carbon cycle?
2. How are fossil fuels created in the carbon cycle?
Animals decay leaving carbon in the soil which is compressed into fossil fuels.
3. Name one of the processes that are part of the carbon cycle.
4. What is one example of how humans affect the carbon cycle?
Bonus:
How much carbon do we breathe in through our air?
0.03% carbon

19. Continued… 1. What are the two ways in which nitrogen fixation occurs?
Through lightning and through bacteria.
2. What is the last stage of the nitrogen cycle?
Denitrification
3. How are humans exposed to the nitrogen in the cycle?
By breathing in nitrogen and eating plants with proteins.
4. What is the greenhouse gas created by nitrogen?
Nitrous oxide
Bonus:
How much of our atmosphere is made up of nitrogen?
79%