Carbon Cycle
The carbon cycle is the circulation and
transformation of carbon back and forth between
living things and the environment.
What Is Carbon?
Importance of Carbon
 Building block of life
 Fixed amount
 CO2 is only of the atmosphere (0.04%)
 Energy balance of the planet
 Protective blanket
Organic Carbon
 Hydrocarbons: CH4
 Carbohydrate: CH2O
Inorganic carbon
 Carbon Dioxide: CO2
 Calcium Carbonate: CaCO3
Mandale Limestone Quarry
Carbon
Carbon exists in the nonliving environment as:
 Carbon dioxide (CO2)
 Carbonic acid ( HCO3-)
 Carbonate rocks (limestone and corals = CaCO3)
 Deposits of Fossil fuels
 Dead organic matter
Carbon reservoirs
•The atmosphere
•The biosphere
•The oceans
•The lithosphere
(carbon dioxide)
(include fresh water systems and non-living
organic material, such as soil carbon)
( including dissolved inorganic carbon and
living and non-living marine biota)
(sediments, Earth core including fossil fuels)
Carbon reservoirs
Carbon in Oceans
 Additional carbon is stored in the ocean.
 Many animals pull carbon from water to use in shells, etc.
 Animals die and carbon substances are deposited at the
bottom of the ocean.
 Oceans contain earth’s largest store of carbon.
Carbon Cycle
 The same carbon atoms are used repeatedly on earth. They
cycle between the earth and the atmosphere.
Plants Use Carbon Dioxide
 Plants pull carbon dioxide from the atmosphere and use it to
make food –— photosynthesis.
 The carbon becomes part of the plant (stored food).
Photosynthesis
 CO2 + H2O + sunlight  CH2O + O2
Carbon is taken from the atmosphere
in several ways
 Photosynthesis.
 The oceans when the seawater becomes cooler, more CO2
dissolve and become carbonic acid.
 In the upper ocean areas organisms convert reduced carbon to
tissues, or carbonates.
Animals Eat Plants
 When organisms eat plants, they take in the carbon and some
of it becomes part of their own bodies.
Plants and Animal Die
 When plants and animals die, most of their bodies are
decomposed and carbon atoms are returned to the
atmosphere.
 Some are not decomposed fully and end up in deposits
underground (oil, coal, etc.).
Carbon Slowly Returns to Atmosphere
 Carbon in rocks and underground deposits is released very
slowly into the atmosphere.
 This process takes many years.
Carbon is released into the
atmosphere in several ways
 Respiration by plants and animals.
 Decay of animal and plant matter.
 Combustion of organic material
 Production of cement.
 The ocean releases CO2 into the atmosphere.
 Volcanic eruptions and metamorphism
Respiration
 CH2O + O2  CO2 + H2O + energy
Combustion or Oxidization of
hydrocarbon
CH4 + 2 O2  CO2 + 2 H2O + energy
Carbon Cycle Diagram
Carbon in Atmosphere
Decomposers
break down dead
things, releasing
carbon to
atmosphere and
soil
Fossil fuels are
burned; carbon
is returned to
atmosphere
Carbon slowly
released from
these substances
returns to
atmosphere
Plants use
carbon to make
food
Plants and
animals die
Bodies not
decomposed —
after many
years, become
part of oil or coal
deposits
Animals eat
plants and
take in carbon
The Carbon Cycle
Human Impact
 Fossil fuels release carbon stores very slowly
 Burning anything releases more carbon into atmosphere —
especially fossil fuels
Fossil Fuels
 Petroleum
 Natural Gas
 Coal
Fossil Fuel
86% of global primary energy consumption is
fossil fuels.
Human Impacts on the Carbon Cycle
Burning fossil fuels have serious impact on
the carbon cycle.
Keeling Curve
Green House Effect-Global Warming
 Increased carbon dioxide in atmosphere increases global
warming
Result
What We Need to Do
 Burn less, especially fossil fuels
 Promote plant life, especially trees
 Fewer plants mean less CO2 removed from atmosphere
Safe/Green Energy alternatives
Thanks for your attention!