6.2 a+b pumps

• Ocean sequestration

  • carbon sequestration = atmospheric CO2 removed due to the movement of carbon into carbon stores
  • movement of carbon within ocean: vertically by carbon pumps and horizontally by thermohaline circulation
• carbonate pump

  • organisms die + dissolve before ocean floor - entering deep ocean currents
  • combined with atmospheric CO2 - bicarbonates turned to carbonates stored in ocean
  • carbon transferred into rocks such as limestone
  • process locks up carbon in long term store - does not allow easy return to ocean surface so prevents venting into atmosphere.
• thermohaline circulation

  • CO2 absorbed by ocean surface through diffusion
  • dissolved carbon taken from surface to intermediate/deep ocean through downwelling current
  • cold water absorbs more CO2 so more absorbed at poles
  • salinity also increases, making water denser so it sinks, taking carbon to deep ocean store
  • allows more diffusion at surface and regulates atmospheric carbon
  • upwelling of carbon to surface - upwelling current and surface winds can return carbon to atmosphere
• Phytoplankton

  • carbon sequestered in ocean by photosynthesis by phytoplankton which converts CO2 into organic matter
  • biological organisms die - sinks and converted to carbonate rocks
  • regulates composition of atmosphere by moving carbon from surface to deep ocean stores.