1. Why and how is matter recycled in our ecosystem?
The Cycles of Matter
Why and how is matter recycled in our ecosystem?

2. Cycles of Matter
All things in nature are made of matter. Nature recycles matter because matter cannot be created or destroyed.
Matter can only be transformed from one form to another.
Matter remains in nature, cycling from one form to another.

3. The Carbon Cycle
Carbon is an essential component of all biomolecules, such as protein and fats.
Carbon is also found in carbon dioxide and fossil fuels.

4. The Carbon Cycle
Carbon dioxide (CO2) is released into the atmosphere through respiration, the burning of fossil fuels and deforestation.
Plants take in carbon dioxide to help make glucose in photosynthesis.
Oxygen is released as an end product.
Consumers eat other organisms to obtain carbon, as well as other nutrients.

5. The Carbon Cycle
As consumers break down food to obtain energy and nutrition, some of the carbon is released back into the atmosphere as carbon dioxide.
Carbon dioxide is an end product of cellular respiration.
Even plants perform cellular respiration, so plants do release some carbon dioxide back into the atmosphere.

6. The Carbon Cycle
Sometimes, carbon gets trapped in carbon sinks. These are large reservoirs of carbon.
Carbonates and limestone are good examples.

7. The Carbon Cycle
Also, dead organisms can be deposited underground, and the carbon in their bodies can form fossil fuels.
What are some examples?

8. The Carbon Cycle

9. Humans and the Carbon Cycle
Recall that the burning of fossil fuels releases carbon dioxide in the atmosphere.
Many modern technologies rely on these fuels for power.

10. Humans and the Carbon Cycle
While carbon dioxide remains a trace gas, the amount of CO2 has steadily increased in the past century.

11. Humans and the Carbon Cycle
Recall that CO2 is a greenhouse gas. While we need CO2 to keep Earth warm, too much CO2 in the atmosphere has the potential to raise temperatures too high.
The increase in absorbed solar energy can possibly cause shifts in global climate patterns – year-to-year weather and precipitation cycles – otherwise known as climate change.

12. Humans and the Carbon Cycle
Furthermore, the ocean itself serves as a carbon sink. This means that an increase in atmospheric CO2 will raise the level of CO2 in the ocean.
As the ocean’s CO2 levels rise, the pH of ocean water drops, which has the potential to destroy marine ecosystems.

13. The Nitrogen Cycle Nitrogen is a key component of our proteins.
Nitrogen makes up 78% of our atmosphere, but we can’t use gaseous nitrogen as a nutrient.

14. The Nitrogen Cycle
Instead, nitrogen gas (N2) has to be converted to ammonia first.
Special bacteria called nitrogen fixers perform this key role.

15. The Nitrogen Cycle
Once nitrogen gas has been fixed, the ammonia can be converted to nitrates and nitrites, which are absorbed by plants for nutrition.
Once again, consumers have to eat other organisms to obtain nitrogen.

16. The Nitrogen Cycle
Decomposers are vital to the health of ecosystems, because they break down dead organisms into organic matter.
Decomposers return nitrogen to the soil, where other plants can absorb it.
Finally, other bacteria can convert some of the soil nitrogen back into nitrogen gas.

17. The Nitrogen Cycle

18. The Phosphorus Cycle
Phosphorus is a key molecule in nucleic acids (DNA and RNA).
Phosphorus is readily found in rocks and earth.

19. The Phosphorus Cycle
Phosphate is released from rock due to weathering, the breakdown of rock. Erosion then transports phosphate into the soil or into water sources.
In either case, phosphate can be absorbed by plants and other producers. Once again, consumers have to eat other organisms for phosphate.

20. The Phosphorus Cycle
Sometimes phosphate can collect at the bottom of large bodies of water, and form new rock.
Finally, decomposition returns phosphate to the soil, as it does other nutrients.

21. The Phosphorus Cycle

22. Humans and the Nitrogen/Phosphorus Cycles
Human farming activities often use fertilizers to stimulate future plant growth. Fertilizers contain additional nitrogen and phosphorus.
However, excessive use of fertilizer can lead to undesired plant growth in other ecosystems via runoff.

23. Humans and the Nitrogen/Phosphorus Cycles
Algal blooms are rapid and massive growths of algae. Algal blooms are particularly dangerous to local ecosystems, since they can drain vital nutrients from the ecosystem.
Algal blooms often occur when excess nitrogen and phosphorus is dumped into water sources.

24. Humans and the Nitrogen/Phosphorus Cycles
Also, adding too much nitrogen and phosphorus can lead to oversaturation of the soil. This means that other nutrients are lost, which damages the long-term stability of that ecosystem.
Lastly, plants that adapted to low levels of nitrogen can be put at risk of extinction, as they are not adapted to survive in high-nitrogen ecosystems.