Carbon Cycle - Biological Carbon Cycle

An Overview:
  • Living organisms use Co2 for shells, woods, bones etc in the seas, the shells enter the deep ocean. Stores a lot of carbon in the deep ocean.
  • Plants photosynthesise and ‘sequester’ carbon. Sequestration is taking up or storing carbon. Plants use carbon dioxide for structures like wood. Forests are the main store.
  • Sediments in the ocean and soils on land also store carbon from decaying and decomposing.
Types Of Pumps:
  • Phytoplankton are tiny organisms that use sunlight for energy
  1. Biological Pumps: CO2 sequestered from the atmosphere into small green plants.
    1. Half the world’s biomass. 0.1% of carbon reaches deep oceans. It has a fast flux rate.
  2. Carbonate Pump: Movement of carbon through ocean waters in small marine organisms that have shells.
    1. Carries carbon deep into the ocean as organisms sink when they die. They flow into the ocean due to the density of the water.
  3. Physical Pump: Less than 10% of the ocean’s carbon dioxide in dissolved form.
    1. Moves from the ocean into the atmosphere.
      1. Cold water absorbs CO2 much better, tropical warm water has less CO2. Global warming will raise sea temperature and more carbon dioxide will flux from the ocean water to the atmosphere.
Carbon Exchanges:
  • Living organisms like plants and phytoplankton sequesters carbon through photosynthesis
    • Releases a lot of carbon through respiration
  • The exchanges also balance i.e the flux rate is very similar
  • Occur on shorter timescales to some other fluxes e.g years for trees, days for phytoplankton.
Dead Organic Matter:
  • Decomposed organic matter such as leaves, woods in soils are decomposed by decomposers such as warms which releases CO2 back into the atmosphere
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