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Carbon Cycle

Carbon Cycle. Carbon. Carbon exists in the nonliving environment as: Carbon dioxide (CO 2 ) Carbonic acid ( HCO 3 − ) Carbonate rocks (limestone and coral = CaCO 3 ) Deposits of Fossil fuels Dead organic matter. Organic Carbon. Hydrocarbons: CH 4 Carbohydrate: CH 2 O lipids

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Carbon Cycle

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  1. Carbon Cycle

  2. 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

  3. Organic Carbon • Hydrocarbons: CH4 • Carbohydrate: CH2O • lipids • Other molecules

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

  5. Carbon Fixation The conversion process of inorganic carbon (carbon dioxide) to organic compounds by living organisms.

  6. Autotrophs absorb CO2 from atmosphere • Convert to carbohydrates, lipids & other carbon compounds • Reduces CO2 in atmosphere • Average concentration is 0.039%

  7. ???? • Why is the concentration of CO2 lower above parts of the earth’s surface where photosynthesis rates are high? • Where are these locations?

  8. ????? • Discuss with a neighbor how removing the rain forests would affect global CO2 levels.

  9. 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.

  10. Autotrophs absorb CO2 from atmosphere • Autotrophs utilize CO2. • Creates concentration gradient between cells <->atmosphere • Diffuses high to low • Stomata in plants

  11. Photosynthesis • CO2 + H2O + sunlight  CH2O + O2

  12. CO2 in solutions • Dissolves in water forming carbonic acid • CO2 + H2O  carbonic acid  hydrogen + carbonate ions • pH reduced • Carbon  carbohydrates, other

  13. 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

  14. Respiration • CO2 – aerobic waste product • Non-photosynthetic root cells • Animal cells • Saprotrophs • Diffuses out of cells into atmosphere & water

  15. Respiration • CH2O + O2 CO2 + H2O + energy

  16. Methanogenesis • the formation of methane by microbes known as methanogens. • Organisms capable of producing methane have been identified only from the domain Archaea

  17. 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

  18. ?????? • As permafrost melts due to increasing global temperatures explain the impact on CO2 levels. • Be able to support your reasoning.

  19. Oxidation of methane • Methane released into atmosphere is oxidized and converted to carbon dioxide and water • 12 years

  20. 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

  21. Combustion or Oxidization of hydrocarbon CH4 + 2 O2 CO2 + 2 H2O + energy CH4 + O + OH˙  CO2 + H2O

  22. 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

  23. 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

  24. 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)

  25. Fossil Fuels • Petroleum • Natural Gas • Coal

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

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

  28. Carbon reservoirs • 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).

  29. Carbon reservoirs

  30. Carbon Cycle

  31. Draw Carbon Cycle combustion

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

  33. Keeling Curve

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