Essential Idea:
Continued availability of carbon
in ecosystems depends on carbon cycling
Understandings:
- Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds
- In aquatic ecosystems carbon is present as dissolved carbon dioxide and hydrogen carbonate 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 oxidised 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 into either coal or into oil and gas that accumulates in porous rocks
- Carbon dioxide is produced by the combustion of biomass and fossilised organic matter
- Animals such as reef-building corals and mollusca have hard parts that are composed of calcium carbonate and can become fossilised in limestone
Applications:
- Estimation of carbon fluxes due to processes in the carbon cycle
- Analysis of data from air monitoring stations to explain annual fluctuations
Skills:
- Construct a diagram of the carbon cycle