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)

• 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.

• 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.

• 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.