Transcript Carbon Cycle

Carbon Cycle
Carbon
Carbon exists in the nonliving environment as:
•
•
•
•
•
Carbon dioxide (CO2)
Carbonic acid ( HCO3−)
Carbonate rocks (limestone and coral = CaCO3)
Deposits of Fossil fuels
Dead organic matter
Organic Carbon
• Hydrocarbons: CH4
• Carbohydrate: CH2O
• lipids
• Other molecules
Inorganic carbon
• Carbon Dioxide: CO2
• Calcium Carbonate: CaCO3
Mandale Limestone Quarry
Carbon Fixation
The conversion process of
inorganic carbon (carbon dioxide)
to organic compounds by
living organisms.
Autotrophs absorb CO2 from
atmosphere
• Convert to carbohydrates, lipids & other
carbon compounds
• Reduces CO2 in atmosphere
• Average concentration is 0.039%
????
• Why is the concentration of CO2 lower above
parts of the earth’s surface where
photosynthesis rates are high?
• Where are these locations?
?????
• Discuss with a neighbor how removing the rain
forests would affect global CO2 levels.
Carbon is removed from the
atmosphere in several ways
• Photosynthesis.
• The oceans when the seawater becomes
cooler, more CO2 dissolve and become
carbonic acid. (ocean pH reduced)
Consequences????
• In the upper ocean areas organisms convert
reduced carbon to carbohydrates & other
compounds.
Autotrophs absorb CO2 from
atmosphere
• Autotrophs utilize CO2.
• Creates concentration gradient between cells
<->atmosphere
• Diffuses high to low
• Stomata in plants
Photosynthesis
• CO2 + H2O + sunlight  CH2O + O2
CO2 in solutions
• Dissolves in water forming carbonic acid
• CO2 + H2O  carbonic acid  hydrogen +
carbonate ions
• pH reduced
• Carbon  carbohydrates, other
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
•
•
•
•
•
CO2 – aerobic waste product
Non-photosynthetic root cells
Animal cells
Saprotrophs
Diffuses out of cells into atmosphere & water
Respiration
• CH2O + O2  CO2 + H2O + energy
Methanogenesis
• the formation of methane by microbes known as
methanogens.
• Organisms capable of producing methane have been
identified only from the domain Archaea
Methanogensisis
• Bacteria organic matter organic acids, alcohols,
H2, CO2
• Bacteria  organic acids + alcohols  acetate, H2,
CO2
• Archaeans produce CH4 from acetate, H2, & CO2
• Mud & swampy areas
• Guts of cattle, sheep
• Buried organic material
??????
• As permafrost melts due to increasing global
temperatures explain the impact on CO2 levels.
• Be able to support your reasoning.
Oxidation of methane
• Methane released into atmosphere is oxidized and
converted to carbon dioxide and water
• 12 years
Combustion
• Organic matter that burns in the presence of oxygen
produces carbon dioxide and water
• Forest fires & other biomass
• Natural causes
• Burning of rain forests for farm land
• Burning of fossil fuels
Combustion or Oxidization of
hydrocarbon
CH4 + 2 O2  CO2 + 2 H2O + energy
CH4 + O + OH˙  CO2 + H2O
Limestone
• Animals containing calcium carbonate that become
fossilized form limestone
• Mollusc shells
• Hard corals
• Deposits form in sea beds
• 10% of sedimentary rock
• 12% of the mass of calcium carbonate is carbon
Peat formation
•
•
•
•
•
Incomplete decomposition
Anaerobic conditions
Water logged – saprotrophs cannot thrive
Acidic conditions
Peat: dark brown, acidic, incompletely decomposed
organic matter
• 3% of Earth’s surface – up to 10 meters, bogs
Fossilized organic matter
• Coal- peat buried under sediments, compressed, heated
• Pennsylvanian sub-period of Carboniferous
• Sea level rose & fell
• Oil & natural gas- sea & lake mud
• Anaerobic conditions, incomplete decomposition
• Organic material buried, forms mixtures of liquid carbon
compounds & gases (methane)
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.
Carbon reservoirs
•The atmosphere.
•The biosphere
•The oceans
•The lithosphere
(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 Cycle
Draw Carbon Cycle
combustion
CO2 Concentration
Pre-Industrial value: 280 ppm (600 billion tons)
Current value: 380 ppm (800 billion tons)
Critical value: 560 ppm (1200 billion tons)
Keeling Curve