Carbon Cycle
Carbon
Carbon exists in the nonliving environment as:
• Carbonic acid ( HCO3−)
• Carbonate rocks (limestone and coral = CaCO3)
• Deposits of Fossil fuels
Organic Carbon
• Hydrocarbons: CH4
• Carbohydrate: CH2O
Inorganic carbon
• Carbon Dioxide: CO2
• Calcium Carbonate: CaCO3
Mandale Limestone Quarry
Carbon Reservoirs
Carbon reservoirs
•The atmosphere -as carbon dioxide
•The biosphere - as organic carbon
(include
fresh water systems and non-living organic material, such as soil carbon).
•The oceans - as dissolved carbon dioxide
and molecules like calcium carbonate (
including dissolved inorganic carbon and living and non-living marine biota).
•The lithosphere as sedimentary rock like
limestone and metamorphic rock like
marble (sediments, Earth core including fossil fuels).
Carbon Cycle
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 made from limestone
•The ocean releases CO2 by diffusion into the
atmosphere.
•Volcanic eruptions and metamorphism
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 organic
molecules, or carbonates.
Photosynthesis
sunlight
6CO2 + 12H2O + ---------->C6H12O6 + 6 O2
Chlorophyll
Respiration
C6H12O6 + 6O2 --> 6CO2 + 6H2O + usable
energy(ATP)
Combustion or Oxidization of
hydrocarbon
CH4 + 2 O2 --> CO2 + 2 H2O + energy
Human Impacts on the Carbon Cycle
The burning of fossil fuels has a serious
impact on the carbon cycle.
Fossil Fuel
86% of global primary energy
consumption is fossil fuels.
Fossil Fuels
• Petroleum
• Natural Gas
• Coal
CO2 Concentration
Pre-Industrial value: 280 ppm (600 billion tons)
Current value: 400 ppm (840 billion tons)
Critical value: 560 ppm (1200 billion tons)
Keeling Curve
Question: Why does line of the curve go up and
down by about 5 ppmv instead of in a straight
line?
What process is occurring at each
number?
Plant Respiration
Animal
Respiration
Photosynthesis
Decay of plant
litter
Decay of animal
wastes
Carbon Cycle Summary
C changed
from
C changed to
CO2
C6H12O6
All organisms
C6H12O6
CO2
Decay bacteria,
Fungi
Organic
Carbon
Organic
Carbon
Process
Organism
Photosynthesis
Green Plants,
Algae, some
bacteria
Respiration
Decomposition
Combustion
Dissolution
(Dissolved)
Lithification
Eruption
of volcanos
N/A
Burning
N/A
In water
N/A
Forming rocks
N/A
Gas from volcanos
CO2
CO2
CO2
Carbonic acid
Plant and animal
remains
Fossil fuels
CaCO3
Calcium carbonate
Limestone,
Marble
Limestone,
Marble
CO2
Part II: The Carbon Reservoirs
On a global scale , carbon moves between four major reservoirs (also
called carbon
Atmosphere
sinks). These reservoirs include ______________________,
Ocean
Biosphere
______________________,______________________, and
Lithosphere
__________________________.
Lithosphere
Which reservoir contains the most carbon? _______________.
Part III: The Biological (Biotic) Processes
1. Photosynthesis is a process that takes place in organisms containing pigments
capable of capturing the energy of light. The main photosynthetic pigment is the green
pigment called chlorophyll found in green plants, algae, and Cyanobacteria. Organisms
Carbon dioxide
with this pigment are able to remove ___________________________ from the
Water
atmosphere and combine it with ________________ in the presence of chlorophyll and
Glucose
sunlight making ____________________ (energy storage molecules) and releasing the
Oxygen
gas _________________ to the atmosphere.
Complete the generalized equation:
Sunlight
C6H12O6
6 O2
12
H
O
6
CO
2
2
________ + ________
--------------------> ________ + ________
Chlorophyll
2. Cellular respiration is a process that takes place in cells that releases the chemical
energy stored in larger molecules to be restored in small molecules that cells can use.
Glucose
The process takes the larger energy storage molecule called __________________
Oxygen
and combines it with __________________ from the atmosphere. This releases the
ATP
chemical energy that is captured by the small energy molecules called ____________
carbon dioxide
that can be used by cells. End products of cellular respiration are _______________
water
and _________________ which is released into the atmosphere.
Complete the generalized equation:
ATP
6 CO2
C6H12O6
6 H2O
6 O2
__________ + __________ --------------------> _________ + __________ + __________
Part IV: The Inorganic (abiotic) Processes
1.The burning of any organic matter form fossil fuels to forests rapidly releases the
Carbon dioxide
carbon stored in its molecules as the gas _______________________ to the
atmosphere.
Carbon dioxide
2. Carbon as the gas _____________________ readily dissolves into bodies of water
from ponds to oceans. This gas readily combines with water molecules to form an acid
Carbonic Acid
called _______________________
often lowering the pH of the water.
3. Aquatic organisms that protect themselves with shells combine the gas
Carbon dioxide
Calcium carbonate
_____________________ with the mineral calcium making _____________________,
the material that forms its shell. When these shelled organisms died, their shells rain
down to the bottom of the lake or ocean collecting in deep layers as sediment. Slowly,
the shells are compressed into sedimentary rock in a process called
Limestone
_________________________
4. Over geologic time, sedimentary and metamorphic rock containing carbon are
subducted, melted and rise toward the surface of the earth as magma and gases
Carbon dioxide
like _________________________ which are released into the atmosphere when
Erupt
volcanos ______________________.