1. THE CYCLING OF Carbon

2. Carbon sources Carbon exists in the non-living environment as:
Carbon dioxide (CO2)
Carbonic acid ( HCO3−)
Carbonate rocks (limestone and coral = CaCO3)
Deposits of Fossil fuels
Dead organic matter

3. Organic Carbon Hydrocarbons: CH4 Oil, coal, gas Carbohydrate: CH2O
Glucose, sucrose, starch, etc

4. Inorganic carbon Carbon Dioxide: CO2 Calcium Carbonate: CaCO3
Mandale Limestone Quarry

5. Carbon reservoirs (Sinks)
Parts of the Earth system where carbon is stored is called carbon reservoirs

6. Carbon reservoirs (Sinks)
The atmosphere.
The biosphere (include fresh water systems and non-living organic material, such as soil carbon).
The oceans ( including dissolved inorganic carbon and living and non-living marine biota).
The lithosphere (sediments, Earth core including fossil fuels).

7. Carbon Cycle
The movement of carbon, in its many forms, between the biosphere, atmosphere, oceans, and geosphere is described by the carbon cycle.

8. Carbon is released into the atmosphere in several ways (Release agents)
Respiration by plants and animals.
Decay of animal and plant matter.
Combustion of organic material
Production of cement.
The oceans release CO2 into the atmosphere.
Volcanic eruptions and metamorphism
Through the respiration performed by plants and animals.
Through the decay of animal and plant matter.
Through combustion of organic material which oxidizes the carbon it contains.
Production of cement.
At the surface of the oceans where the water becomes warmer, dissolved carbon dioxide is released back into the atmosphere.
Volcanic eruptions and metamorphism release gases into the atmosphere.

9. Carbon is taken from the atmosphere in several ways (Release agents)
Photosynthesis.
The oceans when the seawater becomes cooler, more CO2 dissolve and become carbonic acid.
In the upper ocean areas organisms convert carbon to tissues, or carbonates.

10. Photosynthesis
CO2 + H2O + sunlight  CH2O + O2

11. Respiration
CH2O + O2  CO2 + H2O + energy

12. Combustion or Oxidization of hydrocarbon
CH4 + 2 O2  CO H2O + energy

13. Human Impacts on the Carbon Cycle
Burning fossil fuels have serious impact on the carbon cycle.

14. Fossil Fuel
86% of global primary energy consumption is fossil fuels.

15. Fossil Fuels
Petroleum
Natural Gas
Coal

16. CO2 Concentration Pre-Industrial value: 280 ppm (600 billion tons)
Current value: 380 ppm (800 billion tons)
Critical value: 560 ppm (1200 billion tons)