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4.3 Carbon cycling

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Description

Nature of science:
Making accurate, quantitative measurements—it is important to obtain reliable data on the concentration of carbon dioxide and methane in the atmosphere. (3.1)
Understandings:
  • Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds.
  • In aquatic ecosystems carbon is present as dissolved carbon dioxide and hydrogencarbonate ions.
  • Carbon dioxide diffuses from the atmosphere or water into autotrophs.
  • Carbon dioxide is produced by respiration and diffuses out of organisms into water or the atmosphere.
  • Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere or accumulates in the ground.
  • Methane is oxidized to carbon dioxide and water in the atmosphere.
  • Peat forms when organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils.
  • Partially decomposed organic matter from past geological eras was converted either into coal or into oil and gas that accumulate in porous rocks.
  • Carbon dioxide is produced by the combustion of biomass and fossilized organic matter.
  • Animals such as reef-building corals and mollusca have hard parts that are composed of calcium carbonate and can become fossilized in limestone.
Applications and skills:
  • Application: Estimation of carbon fluxes due to processes in the carbon cycle.
  • Application: Analysis of data from air monitoring stations to explain annual fluctuations.
  • Skill: Construct a diagram of the carbon cycle.
Guidance:
  • Carbon fluxes should be measured in gigatonnes.
 Utilization:
Syllabus and cross-curricular links:
Physics
Topic 8.1 Energy sources
Chemistry
Topic C.2 Fossil fuels
Topic C.5 Environmental impact—global warming

Aims:
  • Aim 8: The ethical implications of diverting crops such as maize from a food to a fuel crop could be considered.

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